EPA/600/R-09/037 | April 2009 | www.epa.gov/athens 

Composition and Behavior of 

Fuel Ethanol 

Ecosystems Research Division, Athens, GA 30605 

National Exposure Research Laboratory 

Office of Research and Development 
EPA/600/R-09/037 

April 2009 

Composition and Behavior of Fuel Ethanol 

by 

James W. Weaver(a)

Sheldon A. Skaggs(b)

David L. Spidle(a)

Guthrie C. Stone(c)

(a) Ecosystems Research Division, National Exposure Research Laboratory, Office of Research and 

Development, United States Environmental Protection Agency, Athens, Georgia 

(b) Sheldon Skaggs, Inc, Athens, Georgia 

(c) The University of Georgia, Athens Georgia 

Ecosystems Research Division 

National Exposure Research Laboratory 

Office of Research and Development 

United States Environmental Protection Agency 

Athens, Georgia 30605 

U.S. Environmental Protection Agency 

Office of Research and Development 

Washington, DC 20460
Notice 

The U.S. Environmental Protection Agency through its Office of Research and 

Development funded and managed the research described here. It has been subjected to 

the Agency=s peer and administrative review and has been approved for publication as an 

EPA document. Mention of trade names or commercial products does not constitute 

endorsement or recommendation for use. 

The information provided in this paper is not intended for determining compliance with 

state or federal regulations for air quality, gasoline composition or other similar purposes. 

For these purposes, information should be obtained from the appropriate local, state and 

federal regulatory agencies, the Clean Air Act, the United States Code, the Code of 

Federal Regulations, the Federal Register and other sources. 

2
Abstract 

Ethanol usage in the United States has increased due in part to the elimination of 

methyl tert-butyl ether from the fuel supply and to the mandates of Congress. Two 

samples, one each from a wet mill and a dry mill ethanol plant, were obtained before 

denaturing. Each of these samples contained mostly ethanol, but also low concentrations 

of water, methanol, and higher molecular weight alcohols (up to five carbons). The wet 

mill sample also contained ethyl acetate and an ether, 1,1-diethoxyethane. The allowable 

denaturants for fuel ethanol are similar to gasoline. Since the denaturants are immiscible 

with water, the ability of the denatured fuel ethanol to absorb water is limited. 

Experiments with E95 and E85 showed that these both began to phase separate when 

about 15% water was added to the E95 or E85. The gasoline was released gradually as 

water was added to the fuel. For E95, there is a smaller amount of gasoline in the fuel 

(2% to 5%) so less gasoline can be released. The changes in volume when water and 

ethanol or water and E85 are mixed displayed a deficit of 3% at maximum. The 

byproducts of fuel ethanol production are less soluble, sorb more, diffuse less readily, 

and are less volatile than ethanol. It’s likely, however, that the increased ethanol 

concentration in water will increase the solubility of the byproducts, as it does the 

petroleum hydrocarbons The production byproducts compose less than 1% of the mass of 

the fuel. Releases of fuel ethanol will be dominated by the ethanol. 

 

3
Foreword 

The National Exposure Research Laboratory=s Ecosystems Research Division (ERD) in 

Athens, Georgia, conducts research on organic and inorganic chemicals, greenhouse gas 

biogeochemical cycles, and land use perturbations that create direct and indirect, 

chemical and non-chemical stresses, exposures, and potential risks to humans and 

ecosystems. ERD develops, tests, applies and provides technical support for exposure 

and ecosystem response models used for assessing and managing risks to humans and 

ecosystems, within a watershed / regional context. 

The Regulatory Support Branch (RSB) conducts problem-driven and applied research, 

develops technology tools, and provides technical support to customer Program and 

Regional Offices, States, Municipalities, and Tribes. Models are distributed and 

supported via the EPA Center for Exposure Assessment Modeling (CEAM) and through 

access to Internet tools (www.epa.gov/athens/onsite). 

Fuel composition provides the starting point for evaluation of releases to the 

environment. For ethanol gasolines, the composition of the fuel differs from typical 

gasoline by the addition of large amounts of ethanol and the presence of fermentation 

byproducts. Physically, the fuel can be subject to phase separation upon contact with 

water. This report provides basic information on usage of ethanol in U.S. gasoline, fuel 

ethanol production methods, analytical methods for fuel and water samples, fuel ethanol 

composition and properties, and phase behavior. This information forms the starting 

point for evaluation of potential environmental impacts and ecosystem and human 

exposures. 

Eric J. Weber, Ph.D. 

Acting Director 

Ecosystems Research Division 

Athens, Georgia 

4
Oil Spill Report Series 

 

 

A series of research reports is planned to present data and models for oil spill planning 

and response. To date, these include: 

 

1. Oil Composition 

James W. Weaver, Sheldon A. Skaggs, David C. Spidle, Guthrie Stone, 2009, 

 Composition of Fuel Ethanol, United States Environmental Protection 

 Agency, Washington, D.C., EPA/600/R-09/037. 

 

Zhendi Wang, B.P. Hollebone, M. Fingas, B. Fieldhouse, L. Sigouin, M. Landriault, P. 

 Smith, J. Noonan, and G. Thouin, 2003, Characteristics of Spilled Oils, Fuels, and 

 Petroleum Products: 1. Composition and Properties of Selected Oils, United 

 States Environmental Protection Agency, National Exposure Research 

 Laboratory, EPA/600/R-03/072. 

2. Dispersants 

George Sorial, Subhashini Chandrasekar, James W. Weaver, 2004, Characteristics of 

 Spilled Oils, Fuels, and Petroleum Products: 2a. Dispersant Effectiveness Data 

 for a Suite of Environmental Conditions – The Effects of Temperature, 

 Volatilization, and Energy, United States Environmental Protection Agency, 

 National Exposure Research Laboratory, EPA/600/R-04/119. 

 

3. Simulation Models 

James W. Weaver, 2004, Characteristics of Spilled Oils, Fuels, and Petroleum Products: 

 3a. Simulation of Oil Spills and Dispersants Under Conditions of Uncertainty, 

 United States Environmental Protection Agency, National Exposure Research 

 Laboratory, EPA/600/R-04/120. 

As more reports are added to the series, they may be found on EPA’s web site at: 

http://www.epa.gov/athens/publications. 

5
Leaking Underground Storage Tank Assessment Report 

Series 

A series of research reports is planned to present data and models for leaking 

underground storage tank risk assessments. To date these include: 

1. Gasoline Composition

James W. Weaver, Sheldon A. Skaggs, David C. Spidle, Guthrie Stone, 2009, 

 Composition of Fuel Ethanol, United States Environmental Protection 

 Agency, Washington, D.C., EPA/600/R-09/037. 

James W. Weaver, Linda R. Exum, Lourdes M. Prieto, 2008, Gasoline Composition 

 Regulations Affecting LUST Sites, United States Environmental Protection 

 Agency, Washington, D.C., EPA/600/R-08/xxx. 

Weaver, James W., Lewis Jordan and Daniel B. Hall, 2005, Predicted Ground Water, Soil 

 and Soil Gas Impacts from US Gasolines, 2004: First Analysis of the Autumnal 

 Data, United States Environmental Protection Agency, Washington, D.C., 

 EPA/600/R-05/032. 

2. Simulation Models

Gorokhovski, Vikenti M. and James W. Weaver, 2007, A Catalog of Ground Water Flow 

 Solutions for Plume Diving Calculations, United States Environmental Protection 

 Agency, Washington, D.C. 

Weaver, James W., 2004, On-line Tools for Assessing Petroleum Releases, United States 

Environmental Protection Agency, Washington, D.C., EPA 600/R-04/101. 

3. Model Background and Evaluation 

Weaver, James W. and C. S. Sosik, 2007, Assessment of Modeling Reports for Petroleum 

Release and Brownfields Sites, United States Environmental Protection Agency, 

Washington, D.C., EPA 600/R-07/101. 

As more reports are added to the series, they may be found on EPA=s web site at: 

http://www.epa.gov/athens/publications. 

6
Contents 

Notice.................................................................................................................................. 2 

Abstract............................................................................................................................... 3 

Foreword............................................................................................................................. 4 

Oil Spill Report Series........................................................................................................ 5 

Leaking Underground Storage Tank Assessment Report Series........................................ 6 

Contents.............................................................................................................................. 7 

Figures................................................................................................................................. 8 

Tables................................................................................................................................ 10 

Terminology...................................................................................................................... 11 

Introduction....................................................................................................................... 12 

Background and Literature Review .................................................................................. 14 

Regulatory History of Gasoline .................................................................................... 14 

Ethanol Use in Gasoline................................................................................................ 14 

Gasoline Production in the United States..................................................................... 16 

Fuel Ethanol.................................................................................................................. 21 

Byproducts in Fuel Ethanol .......................................................................................... 22 

Analytical Methods....................................................................................................... 24 

Phase Separation and Co-solvency ............................................................................... 24 

Fuel Ethanol Analyses...................................................................................................... 29 

Phase Separation ............................................................................................................... 35 

Fuel Ethanol Component Properties................................................................................. 39 

Solubility....................................................................................................................... 39 

Octanol-Water Partition Coefficient............................................................................. 41 

Water and Air Phase Diffusion Coefficients ................................................................ 41 

Vapor Pressure.............................................................................................................. 41 

Henry’s Constant .......................................................................................................... 42 

Property Variation with Temperature ........................................................................... 42 

Discussion and Conclusions ............................................................................................. 46 

References......................................................................................................................... 48 

Appendix A Analytical Methods..................................................................................... 52 

Fuel Ethanol Analysis................................................................................................... 52 

Phase Separation ........................................................................................................... 53 

Appendix B Detected and tentatively identified chemicals from an ethanol plant in 

Minnesota [10].................................................................................................................. 55 

Appendix C Ethanol and Water Mixtures........................................................................ 57 

Appendix D Comparison of results from the EPI SuiteTM calculator and SPARC for Kow 

for 5 oC and 25 oC. ............................................................................................................ 59 

Appendix E SPARC Property Results for 5 o

C to 45 oC ................................................. 61 

7
Figures 

Figure 1 Renewable and biofuel mandates from the Energy Policy Act (EPAct) of 2005 

and the Energy Independence and Security Act (EISA) of 2007. .................................... 15 

Figure 2 DOE gasoline production and importation data. Prior to the Clean Air Act 

Amendments, there was no distinction between conventional and reformulated gasoline. 

The proportion of conventional gasoline (2/3) has remained roughly constant over the 

period 1995 to 2007. ......................................................................................................... 17 

Figure 3 Production of reformulated gasoline with ether and alcohol, conventional 

gasoline with alcohol and total gasoline production on a weekly basis. .......................... 18 

Figure 4 Benzene and ethanol content in conventional gasoline collected by Northop 

Grumman in 2007. ............................................................................................................ 20 

Figure 5 Benzene and ethanol content in reformulated gasoline collected by Northop 

Grumman in 2007. ............................................................................................................ 20 

Figure 6 Methanol-Water-Hydrocarbon phase diagram.................................................. 25 

Figure 7 Estimated benzene solubility using the co-solvency relationship developed by 

Heerman and Powers [19]. The hypothetical mixtures consisted of blendstock containing 

1 vol % benzene mixed with ethanol containing 2% of a denaturant that itself contained 

1% benzene. Curves are plotted for the average parameters from Heerman and Powers 

[19] and their extreme parameter sets giving the lowest and highest peak benzene 

concentrations. .................................................................................................................. 28 

Figure 8 Wet mill sample chromatogram. Retention times are shown in Error! Reference 

source not found................................................................................................................ 30 

Figure 9 Dry mill sample chromatogram. Retention times are shown in Table 1.......... 31 

Figure 10 QA blank -- showing internal standard (1, 3-Dibromo-2-propanol with 

retention time of 17.089 minutes) and alcohol matrix (retention time of 2.192 and 2.326 

minutes)............................................................................................................................. 31 

Figure 11 Unbranched alcohols: Methanol CH4O (top) and Ethanol C2H6O (center) and 

1-Propanol C3H8O (bottom) molecules. ........................................................................... 32 

Figure 12 Branched chain alcohols: Isobutyl alcohol C4H10O (top), 2-methyl 1-butanol 

C5H12O (center) and 3-methyl 1-butanol C5H12O (bottom) molecules. .......................... 33 

Figure 13 Ethyl acetate C4H8O2 molecule........................................................................ 34 

Figure 14 Ethers: The di-ether 1,1-diethoxyethane C6H14O2 (top) and MTBE C6H12O 

(bottom) molecules. .......................................................................................................... 34 

Figure 15 Release of gasoline from E95 (top) and E85 (bottom) at varying amounts of 

water added. The gasoline is normalized to the nominal amount of gasoline in the E95 

(5% of 7 ml) or E85 (15% of 20 ml). The water is normalized to the volume of E95 (7 

ml) or E85 (20 mL)........................................................................................................... 37 

8
Figure 16 Volume changes as water is added to a sample of E85. All the volumes are 

normalized to the volume of E85 (20 ml)......................................................................... 38 

Figure 17 Total volume reduction during addition of water to ethanol.......................... 38 

Figure 18 Benzene C6H6 molecule.................................................................................. 40 

Figure 19 Estimates from the EPA EPI Suite calculator, SPARC at 5 o

C and 25 oC 

plotted against experimental results reported with EPI Suite results................................ 59 

Figure 20 Example of variation in SPARC results given an assumed variability (error) of 

one-half log unit. The left hand graph shows results on a log-log scale. The right hand 

graph shows the same variation on a linear scale. ............................................................ 60 

Figure 21 Solubility of the alcohols found in the wet and dry mill samples. Ethanol and 

methanol do not appear because their solubility is infinite............................................... 61 

Figure 22 Solubility of ethyl acetate and 1,1-diethoxy ethane, compounds found in the 

wet mill sample. Solubilities of bezene and MTBE are plotted for comparison. ............ 61 

Figure 23 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion 

coefficient, octanol/water partition coefficient) for methanol and ethanol estimated by the 

SPARC calculator. ............................................................................................................ 62 

Figure 24 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion 

coefficient, octanol/water partition coefficient) for 1-propanol and isobutyl alcohol 

estimated by the SPARC calculator.................................................................................. 63 

Figure 25 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion 

coefficient, octanol/water partition coefficient) for 2-methyl 1-butane and 3-methyl 1-

butane estimated by the SPARC calculator. ..................................................................... 64 

Figure 26 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion 

coefficient, octanol/water partition coefficient) for ethyl acetate estimated by the SPARC 

calculator........................................................................................................................... 65 

Figure 27 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion 

coefficient, octanol/water partition coefficient) for 1,1-diethoxyethane estimated by the 

SPARC calculator. ............................................................................................................ 66 

Figure 28 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion 

coefficient, octanol/water partition coefficient) for benzene and methyl tert-butyl ether 

(MTBE) estimated by the SPARC calculator. .................................................................. 67 

9
Tables 

Table 1 Compounds identified by GC-MS in two samples of fuel ethanol. 

Concentrations were determined by retention time analysis using GC-FID. ................... 30 

Table 2 Solubility, Henry's Constant, Vapor Pressure, Air Phase Diffusion Coefficient 

and Octanol-Water Partition Coefficient estimated by the SPARC calculator for fuel 

ethanol components, benzene and MTBE at 15 C............................................................ 43 

Table 3 SPARC estimated properties at 15 oC ranked from lowest to highest............... 44 

10
Terminology 

Following ASTM D 4806 – 08a Standard Specification for Denatured Feul Ethanol for 

Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel. 

 

Denaturant -- a material added to fuel ethanol to make it unsuitable for beverage 

use, but not for unsuitable for automotive use. 

Fuel Ethanol -- ethanol with impurities common to its production including 

water but not denaturants. 

Denatured Fuel Ethanol – fuel ethanol made unfit for beverage use by the 

addition of denaturants. 

Higher Molecular Weight Alcohols – aliphatic alcohols of general formula 

CnH2n+1OH with n from 3 to 8. 

Following the Code of Federal Regulations (40 CFR) Part 80 – Regulation of Fuels and 

Fuel Additives: 

Reformulated Gasoline (RFG) is any gasoline whose formulation has been 

certifited under 40 CFR § 80.40 and which meets each of the standards and 

requirements prescribed under 40 CFR § 80.41. 

From 1995 until 2006, RFG was required to contain 2 % by weight oxygencontaining compounds (“oxygenates”) 

Conventional Gasoline (CG) is any gasoline which has not been certified under 

40 CFR § 80.40. 

Oxygenated Gasoline (OG) is any gasoline which contains a measurable amount 

of oxygenate. 

11
Introduction

 Gasoline composition has changed because of engine requirements, clean-air and 

energy-policy legislation, and EPA rule-making. Although ethanol has been in use in 

motor gasolines for many years, its usage began to increase after 2000 due to concerns 

over methyl tert-butyl ether (MTBE) pollution of ground waters and the resulting state 

bans of MTBE. Later Congress passed legislation that both removed the oxygenate 

requirement for reformulated gasoline and required increased use of renewable fuels. 

Thus since 2006 there has been a large increase in the use of ethanol in the U.S. 

 The object of this report is the composition and behavior of fuel ethanol, 

denatured fuel ethanol, and consumer blends (particularly the 15% gasoline-containing 

E85). Because of Bureau of Alcohol and Tobacco regulations, producers of fuel ethanol 

generally do not distribute their product in a non-denatured form. Further, analysis of 

denatured fuel ethanol is complicated by the addition of the numerous constituents of the 

typical denaturant, namely gasoline. An objective of this research was to obtain samples 

of non-denatured fuel ethanol. One sample each of the two main production methods – 

wet milling and dry milling -- was obtained for analysis. The quantity of these samples 

was limited so analyses were performed on slightly less limited quantities of denatured 

fuel ethanol (E95) and the easily obtained consumer product E85. 

 These samples were used to investigate composition of fuel ethanol. Literature 

on alcohol production for fuel and beverages was used as a guide for the possible 

constituents of these products. Gas chromatography (GC) coupled with mass 

spectroscopy (MS) was used for unambiguous identification of the constituents. 

Subsequent analyses using GC with a flame ionization detector (FID) and Karl Fischer 

12
titration was used to quantify the concentrations of the constituents. Properties of the 

identified components of fuel ethanol were then estimated using the SPARC chemical 

property estimator. SPARC was used so that temperature dependence of properties could 

be explored. 

 Phase separation of E95 and E85 was studied because when spilled or released to 

the environment, in most cases these fuels will encounter either surface water in the form 

of flowing streams, creeks, or rivers; ponds, lakes or estuaries; or soil moisture and 

ground water. Response to incidents may vary if the fuel forms a separate phase or mixes 

with water. Since the fuels have a certain water tolerance, phase separation may depend 

on the composition of the fuel and the nature of the release to water. Ethanol and water 

are known not to mix in direct proportion to their volumes. This effect might change the 

behavior of the fuel/water system during releases. Simple experiments were devised to 

determine the volume changes in various ethanol/gasoline blends. 

The report is intended to provide a brief overview of the composition and 

properties of ethanol fuels and contains the following sections describing four topics: 

composition, chemical properties, phase separation and volume changes. 

13
Background and Literature Review 

The background and literature review is divided into seven sections, each of which 

bears on the objectives of the report. The topics are 

• Regulatory History of Gasoline, 

• Ethanol Use in Gasoline, 

• Gasoline Production in the United States, 

• Fuel Ethanol, 

• Byproducts in Fuel Ethanol, 

• Analytical Methods, and 

• Phase Separation and Co-solvency. 

Regulatory History of Gasoline 

The Clean Air Act Amendments of 1990 introduced a number of different 

requirements that had a major impact on gasoline composition throughout the entire 

United States from their implementation in 1992 and 1995 until the present. See Weaver 

et al. [1] for more detail. The most important factors for understanding the current usage 

of ethanol were the total ban on lead in gasoline, requirements for conventional gasoline 

(CG), reformulated gasoline (RFG), and oxygenated gasoline (OG). Both RFG and OG 

programs required usage of oxygenated gasoline additives, and for the first years of the 

programs, the most commonly used oxygenate was MTBE. 

Ethanol Use in Gasoline 

Because of subsurface water quality concerns from releases of fuels containing 

MTBE, states began in 2000 to ban MTBE and, in some cases, other ethers and alcohols 

14
as fuel additives. Since they were actions taken by state legislatures, they did not affect 

federal requirements for oxygenate usage. The bans had the effect of causing ethanol 

usage as a fuel oxygenate to increase in the U.S. The oxygen mandate for reformulated 

gasoline was removed by the Energy Policy Act of 2005. The act also required usage of 

renewable fuels, causing another increase in ethanol usage. The Energy Independence 

and Security Act (EISA) of 2007 increased the mandated amounts of biofuels for 2008 

through 2012 and extended the period of required use of biofuels to 2022. The EISA also 

required targeted amounts of advanced and cellulosic biofuels for the periods 2009 to 

2022 and 2010 to 2022, respectively (Figure 1). 

2006 2008 2010 2012 2014 2016 2018 2020 2022

Year

0

10

20

30

40

Billion Gallons

Renewable Fuel Mandates

EISA 2007 Renewable Fuel

EISA 2007 Conventional Biofuel

EISA 2007 Conventional and Cellulosic Biofuel

EPAct 2005 Renewable Fuel

Cellulosic

Conventional (starch based)

Other

Advanced

Figure 1 Renewable and biofuel mandates from the Energy Policy Act (EPAct) of 2005 and the 

Energy Independence and Security Act (EISA) of 2007. 

15
Gasoline Production in the United States 

Gasoline production data compiled by the Department of Energy’s Energy 

Information Agency (EIA) documents the production and importation of conventional 

and reformulated gasoline [2]. These data show that production of RFG began in 

September 1994 shortly before the implementation of the RFG program (Figure 2). RFG 

replaced part of the total production of gasoline in the U.S. The remainder became 

conventional gasoline simply by definition (see 40 CFR §80.2). Production of both types 

of gasoline tended to increase, although RFG production increased faster than 

conventional gasoline production. Even so, conventional gasoline accounts for roughly 

two thirds of U.S. gasoline, a proportion that has been consistent since the beginning of 

the RFG/CG designation. EIA began differentiating RFG containing ether, alcohol or no 

oxygenate in 2004 (Figure 3). By this time most of the MTBE bans were in place so 

alcohol use in RFG was highest. The use of MTBE was slowly declining until the 

oxygenate mandate was removed by the Energy Policy Act of 2005 (EPAct 2005). In 

mid 2006 MTBE was abruptly removed from the fuel supply (Figure 3) and the amount 

of RFG made with ether decreased to a negligible amount, while the amount of RFG 

made with alcohol abruptly increased. The EPAct 2005 legislation also required 

increased use of biofuels. Conventional gasoline showed increasing amounts of alcohol, 

especially after mid 2007. In 2007 the Energy Independence and Security Act mandated 

increased levels of biofuel usage through 2022. As of March, 2009, EIA data show that 

75% of the total gasoline produced in the U.S. contained alcohol.1

 

1

 For the week ending March 6, 2009, there were 8539 thousand barrels produced per day of finished 

motor gasoline. Of this there were 2896 thousand barrels produced per day of reformulated gasoline 

16
 

198219841986198819901992199419961998200020022004200620082010

Date

0

2000

4000

6000

8000

10000

Thousand Barrels Per Day

Total Production

Conventional

Reformulated

Figure 2 DOE gasoline production and importation data. Prior to the Clean Air Act Amendments, 

there was no distinction between conventional and reformulated gasoline. The proportion of 

conventional gasoline (2/3) has remained roughly constant over the period 1995 to 2007. 

 containing alcohol and 3549 thousand barrels produced per day of conventional gasoline containing 

alcohol. 

17
2004

200520062007200820092010

Date

0

2000

4000

6000

8000

10000

Thousand Barrels per Day

Total Production

Conventional and Reformulated

with Alcohol

Reformulated with Alcohol

Reformulated with ether

Figure 3 Production of reformulated gasoline with ether and alcohol, conventional gasoline with 

alcohol and total gasoline production on a weekly basis. 

Petroleum product surveys are conducted annually by Northrop Grumman [3]. 

Samples are collected from service stations and analyzed for selected compositional and 

physical properties. The benzene and ethanol data presented below were determined by 

ASTM methods [3]. These data show the variability of ethanol content within the 

conventional and reformulated classes from cities representing the continental United 

States. The benzene data were included because it is an important gasoline component 

and is subject to specific regulation by the Clean Air Act. 

18
 For the summer sampling of 2007, conventional gasoline (Figure 4) contained 

varying amounts of ethanol with two dominant levels: about 10% and, with fewer 

samples, none. The samples with about 10% ethanol represent E10 and illustrate the 

observed variability for summer 2007. Outliers contained as much as 14.4% ethanol. 

Both premium (defined here as octane numbers (ON) greater than 90) and regular had 

ethanol contents throughout the range from 0 to 11%. Benzene levels ranged to 3.6% 

which is due to the benzene levels in conventional gasoline being set from 1990 

producer/importer baselines [1] The summer 2007 reformulated gasoline (Figure 5) 

showed also showed two dominant ethanol levels: around 10% and just under 6%.. 

Regular and premium gasoline showed no discernable patterns, but were represented 

throughout the data range. Compared to conventional gasoline, benzene levels were 

lower in reformulated gasoline due to clean air act requirements. Most samples showed 

benzene levels below 1% by volume. 

19
Conventional Gasoline

0

0.5

1

1.5

2

2.5

3

3.5

4

0 2 4 6 810 12 14 16

Ethanol (vol %)

Benzene (vol %)

CG < 90 ON

CG > 90 ON

Figure 4 Benzene and ethanol content in conventional gasoline collected by Northop Grumman in 

2007. 

Reformulated Gasoline

0

0.5

1

1.5

2

2.5

3

3.5

4

0 2 4 6 8 10 12 14 16

Ethanol (vol %)

Benzene (vol %)

RFG < 90 ON

RFG > 90 ON

Figure 5 Benzene and ethanol content in reformulated gasoline collected by Northop Grumman in 

2007. 

20
Fuel Ethanol 

Fuel ethanol is produced by several methods. The most common is the dry mill 

process that accounts for 75% of current production. Dry mill plants typically produce 

ethanol as the primary product with animal feed (called Dried Distiller’s Grains with 

Solubles, DDGS) and carbon dioxide as co-products. In dry milling the entire corn 

kernel is ground and used as the feed stock for ethanol production [4, 5]. In wet milling, 

the corn is first separated into its components: starch, fiber, gluten and germ [4]. These 

plants produce ethanol as one of several food industry products including corn oil, corn 

syrup, and corn sugar. After fermentation the alcohol is distilled to 190 proof to reduce 

the water content. Afterward, molecular sieve technology is used to remove the 

remaining water. 

For use as a fuel, ethanol is made unfit for drinking by addition of a denaturant. 

ASTM [6] gives requirements for fuel ethanol and acceptable denaturants for use in 

automobile engines. Fuel ethanol is permitted by ASTM to contain 1.76% to 5.0% 

denaturant. Beginning on January 1, 2009, the 2008 Food, Conservation, and Energy 

Act allows a full ethanol production credit only so long as the denaturant content is no 

more than 2% [7]. Because of measurement difficulties, the Internal Revenue Service is 

temporarily allowing credits as long as the denaturant(s) do not exceed 2.5% of the 

volume of the fuel ethanol [8]. The allowable denaturants are: 

• natural gasoline, 

• gasoline components, or 

• unleaded gasoline. 

. 

21
The ethanol content, after denaturing, is to be a minimum of 92.1% at the time of 

blending with gasoline and the water content of the fuel ethanol is to be less than 1%. 

ASTM also specifies prohibited denaturants: 

• hydrocarbons with an end boiling point above 225 oC, 

• methanol not meeting ASTM D1152, 

• pyrroles, 

• turpentine, 

• ketones, and 

• tars. 

These substances are said to have potentially extreme adverse effects on fuel stability, 

automotive engines, and fuel systems. Since the typical boiling range of gasoline is 90 

o

C to 200 oC [9], the first prohibited denaturant listed above indicates that denaturants for 

fuel ethanol are intended to be very much like gasoline. 

Byproducts in Fuel Ethanol 

Fermentation of corn starch produces ethanol and other compounds. Although 

ethanol is the dominant alcohol produced, a variety of others have been documented 

[10]. Air emissions from a beer brewer/dry-mill ethanol plant were monitored and a 

number of hydrocarbons were identified. Classes of compounds included tearing agents 

(lacrimators), respiratory irritants and odorants. Specific examples included 

formaldehyde, acetaldehyde, furfural, 2-Furancarboxaldeyde, acrolein, benzene, 

methanol, ethanol, glycerol, styrene, lactic acid and acetic acid [11]. The complete list 

of compounds is given in Appendix B, although most of these have not been reported as 

constituents of fuel ethanol itself. The main byproducts of ethanol production are 

isopropyl and isobutyl alcohols, but also include methyl, amyl, iso-amyl, n-propyl, 

22
glycerol (1,2,3-propanetriol), higher alcohols, ethers, acetic aldehyde and acids. The 

presence of pentoses leads to production of furfural (furan-2-carbaldehyde), which 

degrades rubber or elastomeric seals2. Production of the byproducts can reduce ethanol 

production by 10%. Because of competition among microorganisms, the longer that 

fermentation continues, the more equilibrium shifts toward the higher alcohols, 

aldehydes, acids or methane [11]. 

For comparison purposes, the following literature on beverage alcohol production 

was reviewed as a related production activity might show insight into issues of fuel 

ethanol. In production of beverages [13] found acetals (i.e., 1-1 diethoxyethane) 

occurring in small quantities. The occurrence of acetals began to be significant after 4 

hours of fermentation and is related to higher acidity related to infections of acid-forming 

bacteria. Esters are formed from organic acids and predominantly ethanol. In the first 

hours of fermentation ethyl and methyl esters of acetic acid were produced. In later 

stages of fermentation esters of higher alcohols appeared (isoamyl acetate, isobytyl 

acetate, and ethyl hexanate). Other compounds produced include 2-propanol, acroleine 

(in the form of acroleine diethylacetal), acetic aldehyde [13] .

Production of fermentation byproducts is important to beverage producers or 

consumers because volatile esters impart flavors [13, 14], contaminants can be present in 

illegally produced alcohol [15], and reduction in some byproducts is needed for foodgrade alcohol [16]. Fan and Qian found a large number of flavor imparting compounds 

in increased concentration in five-year old Chinese Liquor which was aged in a clay 

vessel [14]. In a study of contaminants of illegally-produced drinking alcohol, analysis 

 

2

 Corrosion of steel is attributed to the formation of ethanol/water molecular structures as well as the 

amount of water itself [12]. 

23
was performed for the ethanol, isopropanol, acetone, methanol, ethylene glycol and lead 

contents [15]. A later summary of studies indicated analysis for ethanol, methanol, 1-

propanol, iso-butanol and isoamyl alcohol were commonly analyzed in evaluation of 

these liquors [17]. 

Analytical Methods 

There are common aspects of analytical methods for alcohol analyses. ASTM 

specifies a long nonspecific narrow-bore capillary column and direct injection to a gas 

chromatograph (GC) with a flame ionization detector (FID) [18]. Others have used 

direct injection to a CG-FID [19] using a wax column [13] or non-polar fused silica 

column [20]. Trace level analyses of ethanol, MTBE and other alcohols and ethers have 

been conducted with solid phase micro extraction (SPME) using a DVB/Carbozen/PDMS 

fiber, a GC equipped with a fused silica column and mass selective detector [14, 21]. 

Solid phase extraction was used to concentrate impurities in Brazilian ethanol prior to 

GC-MS identification [22]. 

Phase Separation and Co-solvency 

Although water and gasoline are mutually immiscible, a small amount of each is 

soluble in the other. Typical water contents of non-ethanol gasolines are on the order of 

0.01%. As the ethanol content increases, the amount of water that can be accommodated 

in the fuel increases. There is a limit, however, to this tolerance beyond which the fuel 

separates into a predominantly water phase and a predominantly gasoline phase. Phase 

24
partitioning data that represent this phenomena are commonly represented on tri-linear 

phase diagrams, where a boundary separates the single- from the two-phase regions. An 

example phase diagram is shown in Figure 6. The solid curve on the diagram represents 

the boundary between a one-phase region and a two-phase region. At any point on the 

diagram, the amount of water, ethanol and hydrocarbon can be read from the three axes. 

If a mixture contained 85% ethanol, 15% hydrocarbon and no water, its location on the 

diagram is the beginning point of the dashed arrow. The mixture would exist as a single 

phase. By increasing the water content, the mixture moves in the direction of the arrow. 

Once the phase boundary is reached, then the mixture breaks into two phases: a 

predominantly aqueous/alcohol phase and an predominantly oil phase. Note, however, 

each of the three components is present to some degree in the two phases. 

0 0.2 0.4 0.6 0.8 1

% Hydrocarbon

1

0.8

0.6

0.4

0.2

0

% Ethanol

1

0.8

0.6

0.4

0.2

0

% Water

Two Phase

One

Phase

Figure 6 Methanol-Water-Hydrocarbon phase diagram. 

For gasoline fuels, the tri-linear diagram has some conceptual utility, but there are 

many more than three species present. Regardless, the approach allows for a visual 

25
representation of the various combinations of water, ethanol, and “gasoline” that co-exist 

in solution in either a single or dual phase. Letcher et al. [23] measured phase separation 

in gasoline-water-alcohol systems and found somewhat suppressed phase separation at 

higher temperatures. Phase separation was also suppressed in the order: methanol, 1-

butanol, ethanol and 1-propanol. K. Y. Lee [24] compared published phase equilibrium 

data against predicted phase boundaries in three phase water/solvent and BTEX systems 

and also in systems with a mixed solvent. These showed reasonable agreement for 

ethanol and methanol as solvents. Nakayama [25] described phase separation in 

methanol-gasolines as potentially including three layers: water, emulsified watergasoline and gasoline. Higher molecular weight alcohols were shown by H. K. Lee and 

coworkers [26] to have suppressed phase separation at low temperatures in methanolsurrogate gasoline blends. French and Malone [27] presented an extensive review of the 

effects of ethanol on gasoline, including increased vapor pressure at certain ethanol 

concentrations, materials compatibility and the influence of temperature on phase 

separation. More detail on potential impacts from subsurface releases from ethanol fuels 

can be found in Rixey and co-workers [28]. 

In multicomponent systems, ethanol has the ability to increase the apparent 

solubility of a partly miscible compound. For the case of the ethanol gasoline, there 

might be sufficient ethanol present to increase the concentration of gasoline components 

in water. Heermann and Powers [19] determined the equilibrium phase concentrations of 

benzene, toluene, ethylbenzene and xylenes (BTEX) for various amounts of ethanol in 

solution. Their purpose was to determine the degree of co-solvency caused by the 

alcohol and to identify modeling approaches for predicting equilibrium concentrations. 

26
They concluded that the best fit consisted of a piecewise model that had a linear 

relationship for low ethanol contents (approximately 25% or less) and a log-linear 

relationship for higher ethanol contents. Data were fit to a surrogate gasoline consisting 

of eight compounds and then used to predict BTEX concentrations for commercial 

gasolines. 

Estimated aqueous concentrations of benzene calculated from the method 

developed by Heerman and Powers are shown in Figure 7. The aqueous concentration of 

benzene from a gasoline mixture depends on the amount of benzene present in the fuel 

and the co-solvency due to the presence of ethanol in water3

. As the amount of ethanol 

increases, so does the co-solvency, but this effect is balanced by the decline in benzenecontaining blendstock used in formulating higher ethanol content fuels. A hypothetical 

mixture of blendstock containing 1% benzene and denatured fuel ethanol is plotted in 

Figure 7. The fuel ethanol was assumed to be denatured with 2% gasoline which itself 

contained 1% benzene. At ethanol contents below about 25 volume %, there is no 

increase in benzene solubility for this mixture. The aqueous benzene concentration peaks 

at about 85% ethanol. Higher ethanol content causes a decline in the benzene 

concentration due to the reduction in benzene content of the fuel. The plot shows the 

estimated concentration for the average parameter set and the extreme values of the fitted 

parameters that give the lowest and highest peak concentration. The latter are included 

because Heerman and Powers gave 95% confidence limits on their fitted parameters. The 

estimate of benzene concentration from these considerations is 645 +/- 85 mg/L at a 

 

3

 When phase separation of an ethanol blend gasoline occurs the bulk of the ethanol partitions to the water 

phase [23]. thus, assuming that most of the alcohol initially present in the gasoline phase moves to the 

water phase is reasonable. This behavior differs from mixtures where 1-propanol or 1-butanol serve as the 

alcohol phase. For these the bulk of the alcohol stays with the gasoline phase. 

27
volume fraction of 87.5% denatured alcohol. This value is about 20 times the aqueous 

phase concentration of benzene when no ethanol is present (i.e., 33.7 mg/L). 

Estimated Benzene Concentration

0

100

200

300

400

500

600

700

800

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Ethanol Volume Fraction

Estimated Benzene Concentration 

(mg/L)

Average

Case 3

Case 6

Figure 7 Estimated benzene solubility using the co-solvency relationship developed by Heerman and 

Powers [19]. The hypothetical mixtures consisted of blendstock containing 1 vol % benzene mixed 

with ethanol containing 2% of a denaturant that itself contained 1% benzene. Curves are plotted for 

the average parameters from Heerman and Powers [19] and their extreme parameter sets giving the 

lowest and highest peak benzene concentrations. 

28
Fuel Ethanol Analyses 

Two samples of corn-based, fuel ethanol (non-denatured) were obtained from 

their manufacturers and analyzed according to the following procedure. There was one 

sample each from a wet mill and dry mill process. First, gas chromatography/mass 

spectroscopy (GC/MS) was used to identify the unknown constituents of the samples, 

followed by quantitation of the concentration using GC/FID, and Karl Fischer titration of 

the samples for their water content. The details of the analytical methods used in this 

study are presented in Appendix A. 

Analysis of the wet and dry mill samples showed that the fuel ethanol samples 

included one-, two- and three-carbon unbranched alcohols: methanol, ethanol and 

propanol (Table 1 and Figure 11); four- and five-carbon branched alcohols: isobutyl 

alcohol and the two isomers of pentanol (also known as amyl alcohol, see Figure 12): 2-

methyl 1-butanol (active amyl alcohol) and 3-methyl, 1-butanol (isoamyl alcohol). The 

wet mill sample contained two additional compounds both known byproducts of 

fermentation: ethyl acetate (Figure 13) and, the di-ether, 1,1-diethoxyethane (Figure 14). 

Although higher molecular weight alcohols were found in each sample, the bulk 

of the samples, 97.30% of the wet mill and 96.60% of the dry mill sample were 

composed of ethanol. The three to five carbon alcohols composed 0.26% and 0.19% of 

the samples, respectively. Subtracting the total weight percents of the quantitated 

compounds and water from 1.00, gives the amount of unidentified material as 1.28% and 

3.00% respectively. 

29
Table 1 Compounds identified by GC-MS in two samples of fuel ethanol. Concentrations were 

determined by retention time analysis using GC-FID. 

 

Name Formula CAS. Number Retention Concentration (wt. %) 

Time 

(min) 

Wet Mill 

Sample 

Dry Mill 

Sample 

Water(1) H2O 7732-18-15 n.a. 0.65 0.08 

Methanol CH4O 67-55-1 2.191 0.07 0.06 

Ethanol(2) C2H6O 64-17-5 2.324 97.3 96.60 

1-Propanol C3H8O 71-23-8 2.673 0.03 0.08 

Isobutyl Alcohol C4H10O 78-83-1 3.186 0.10 0.08 

2-Methyl 1-

Butanol 

C5H12O 137-32-6 5.147 0.06 0.01 

3-Methyl 1-

Butanol 

C5H12O 123-51-3 5.033 0.21 0.02 

Ethyl Acetate C4H8O2 141-78-6 3.077 0.02 -- 

1,1-

Diethoxyethane 

C6H14O2 105-57-7 4.958 0.28 -- 

(1) Determined by Karl Fischer titration 

(2)Determined by remainder of other compounds 

Figure 8 Wet mill sample chromatogram. Retention times are shown in Error! Reference source not 

found.. 

30
Figure 9 Dry mill sample chromatogram. Retention times are shown in Table 1. 

Figure 10 QA blank -- showing internal standard (1, 3-Dibromo-2-propanol with retention time of 

17.089 minutes) and alcohol matrix (retention time of 2.192 and 2.326 minutes). 

31
Figure 11 Unbranched alcohols: Methanol CH4O (top) and Ethanol C2H6O (center) and 1-Propanol 

C3H8O (bottom) molecules. 

32
Figure 12 Branched chain alcohols: Isobutyl alcohol C4H10O (top), 2-methyl 1-butanol C5H12O 

(center) and 3-methyl 1-butanol C5H12O (bottom) molecules. 

33
Figure 13 Ethyl acetate C4H8O2 molecule. 

Figure 14 Ethers: The di-ether 1,1-diethoxyethane C6H14O2 (top) and MTBE C6H12O (bottom) 

molecules. 

34
Phase Separation 

 Phase separation results for an E95 and an E85 sample are shown in Figure 15. A 

limited amount of E95 was available for testing so a simplified procedure was used (See 

Appendix A). The results show that phase separation occurs with addition of water to 

each of these fuels. Each fuel accommodated a certain amount of water. In both cases 

this was approximately 15% to 20% of the fuel volume. When the water added to the 

fuel increased beyond this level, gasoline was released from the fuel. The release of 

gasoline, however, occurred over an interval of water additions that continued until 

approximately 45% of the E95 volume and 50% of the E85 volume. At higher amounts 

of water added, the maximum amount of gasoline was released. Since the amount of 

gasoline in the E95 and E85 was unknown the released volumes might not have reached 

the presumed total (i.e, the normalized gasoline levels are below 1.0). Particularly for the 

E95, the volume of gasoline was very small (0.21 mL or less), so that the measurement 

accuracy is fairly low. 

For higher levels of water added to E85, the gasoline volume was reduced from 

its maximum. This might have occurred because of the small volumes of gasoline 

released, the presence of an emulsified layer, and volume changes when E85 and water 

are combined. When ethanol is added to gasoline, the volume of the mixture is slightly 

greater than the sum of the volumes. When water is added to ethanol the volume of the 

mixture is less than the sum of the volumes. This phenomena occurs because some of the 

polar ethanol molecules are accommodated within the structure that forms from the polar 

water molecules [29]. The volume reduction for alcohol-water mixtures is on the order 

35
of 5%. (See Appendix C for a discussion of the physical chemistry of these ethanolwater volume effects.) 

Figure 16 shows the volume changes observed when water was added to E85. 

Here the average values from the four experiments plotted in Figure 15 were used to 

determine the average volume of the aqueous phase (solid line), the average volume of 

the gasoline phase and the total volume (dot-dash line). These are compared against the 

total volume added during the experiments (upper dashed line). The figure shows that 

the total volume resulting from the addition of water to E85 is less than the sum of the 

water and E85 combined (upper dashed line). The deficit of volume was about 3% for 

these experiments. Figure 17 shows experimental and theoretical results for the volume 

of mixtures of water and ethanol. The theoretical calculation was made from the theory 

presented in Appendix C and the data published by Pečar and Doleček [30]. The 

maximum reduction found in both the experiment and theoretical calculation of about 

3.5% roughly corresponds to the reduction in volume observed for mixtures of E85 and 

water (Figure 16). 

36
0 0.4 0.8 1.2 1.6 2

Normalized Water Addition

0

0.2

0.4

0.6

0.8

1

Normalized Gasoline Released

E85 and E95

E85 - 1

E85 - 2

E85 - 3

E85 - 4

0 0.4 0.8 1.2 1.6 2

Normalized Water Addition

0

0.2

0.4

0.6

0.8

1

Normalized Gasoline Released

E85 and E95

E95

Figure 15 Release of gasoline from E95 (top) and E85 (bottom) at varying amounts of water added. 

The gasoline is normalized to the nominal amount of gasoline in the E95 (5% of 7 ml) or E85 (15% of 

20 ml). The water is normalized to the volume of E95 (7 ml) or E85 (20 mL). 

37
0 0.4 0.8 1.2 1.6

No

2

rmalized Water Added

0.8

1.2

1.6

2

2.4

2.8

3.2

Normalized Volume

Volume Effects

Cumulative Volume Added

Average Aqueous and Fuel Phases

Average Aqueous Phase 

Figure 16 Volume changes as water is added to a sample of E85. All the volumes are normalized to 

the volume of E85 (20 ml). 

0 0.4 0.8 1.2 1.6 2

Fraction of Water Volume Added

to Ethanol Volume

0

1

2

3

4

Percent Volume Reduction

Ethanol-Water Volume Mixtures

Theory 25 C at 0.1 MPa

Experiment 1

Experiment 2

Figure 17 Total volume reduction during addition of water to ethanol. 

38
Fuel Ethanol Component Properties 

 The properties of the chemicals found in the fuel ethanol samples were estimated 

using the SPARC calculator [31] that is available for use via the Internet.4 These 

estimates were used, because all parameters were not found in the literature for all 

chemicals and, more importantly, measured values are not available for all temperatures 

of interest (5 oC to 45 oC). For comparison purposes, properties of benzene and methyl 

tert-butyl ether (MTBE) were also estimated from SPARC. Appendix D contains a 

comparison of SPARC-generated and EPI SuiteTM-generated properties, along with an 

estimate of error in SPARC properties. 

Table 2 shows the results for 15 oC from SPARC for solubility, Henry’s constant, 

vapor pressure, the air phase diffusion coefficient, the water phase diffusion coefficient, 

and the octanol-water partition coefficient. The compounds are ordered first by number 

of oxygen atoms (one or two) and then by number of carbon atoms. Table 3 shows the 

same 15 o

C results ordered by parameter value. 

Solubility 

Solubility can be viewed as a direct measurement of hydrophobicity or the 

tendency of water to exclude a substance from solution. The solubility is the maximum 

concentration which an aqueous solution will tolerate before the onset of phase separation 

[32]. Ethanol and methanol are infinitely soluble in water. Any amount of ethanol or 

methanol can be dissolved in water without forming a separate phase. All of the other 

 

4

 http://ibmlc2.chem.uga.edu/sparc/ 

39
compounds found in the samples have finite solubility. Alcohols, though, have a greater 

affinity for water than either benzene, MTBE or the 1,1-diethoxyethane. Benzene is nonpolar (observe the symmetric structure with no oxygen in Figure 18) so it’s solubility is 

the lowest of this group. Figure 21 and Figure 22 show the variation in solubility from 5 

o

C to 45 oC. 

The actual water phase concentrations resulting from partitioning of these 

compounds or other constituents of gasoline are significantly lower than these 

solubilities. In effect the concentration obtained from a mixture depends on the solubility 

of a component and the amount present in the mixture [33]. Consequently the solubilities 

presented in Table 2, Table 3, Figure 21 and Figure 22 are much greater than the 

concentrations that would be observed in water contacted with gasoline. 

Figure 18 Benzene C6H6 molecule. 

40
Octanol-Water Partition Coefficient 

The octanol-water partition coefficient, Kow, is a measure of the tendency for a 

chemical to preferentially partition from water to organic matter [34]. This coefficient is 

generally inversely related to solubility and provides information similar to the 

compound’s solubility—albeit in an inverse sense. The most soluble compounds have 

the least degree of partitioning to octanol. The SPARC results show almost a direct 

reversal from solubility. In the environment the octanol-water partition coefficient 

corresponds to the tendency to partition to soil organic matter or animal tissues. 

Water and Air Phase Diffusion Coefficients 

The diffusion coefficients for water and air are measures of the ability of the 

molecule to diffuse through intermolecular collisions [34]. Generally, the air phase 

diffusion coefficients are roughly four orders of magnitude higher than the water phase 

diffusion coefficients. Obviously, diffusion through air occurs much more readily that 

diffusion in water (similarly diffusion coefficients in solids are again much lower than 

those for water). Generally smaller molecules diffuse more readily than larger molecules 

and this trend is evident in the SPARC results for both water and air. 

Vapor Pressure 

Vapor pressure is a measure of the maximum possible concentration of a 

compound in the gas phase at a given temperature. This quantity represents equilibrium 

partitioning of an organic chemical between the gaseous phase and compound itself 

41
42

(liquid or solid). It provides information on the attractive forces among the compound’s 

molecules in the condensed phase [35]. Table 3 shows that at 15 oC the vapor pressures 

of the alcohols were inversely related to their molecular weight. Therefore methanol had 

the highest vapor pressure and 3-methyl 1-butanol the lowest. 

Henry’s Constant 

The Henry’s Constant measures equilibrium partitioning between air and water. 

Table 3 shows that for the alcohols the Henry’s Constants increase with increasing 

molecular weight. The ordering is generally inverse to that for the solubility, as the 

higher the water solubility the less tendency to partition to the air. 

Property Variation with Temperature 

 The SPARC calculator provides prediction of temperature-dependence of all its 

estimated property values. The variation over the range of 5 oC to 45 oC of the properties 

discussed here are presented in Appendix E. 
Table 2 Solubility, Henry's Constant, Vapor Pressure, Air Phase Diffusion Coefficient and Octanol-Water Partition Coefficien

SPARC calculator for fuel ethanol components, benzene and MTBE at 15 C. 

 SPARC(1) estimated properties at 15 C 

Solubility Henry’s 

Constant 

Vapor 

Pressure 

Air Diffusion 

Coefficient 

Water 

Diffusion 

Coefficient 

Name Formula 

(mg/L) (atm 

m3/mol) 

(torr) (cm2/s) (cm2/s) 

Methanol CH4O Infinite 3.4 x 10-6 77 0.150 1.3 x 10-5 

Ethanol C2H6O Infinite 5.4 x 10-6 46 0.110 1.0 x 10-5 

1-Propanol C3H8O 2.2 x 105 7.3 x 10-6 15 0.094 8.7 x 10-6 

Isobutyl Alcohol C4H10O 9.3 x 104 9.0 x 10-6 7 0.081 7.7 x 10-6 

2-Methyl 1-Butanol C5H12O 2.8 x 104 1.1 x 10-5 3 0.072 7.0 x 10-6 3-Methyl 1-Butanol C5H12O 1.9 x 104 1.2 x 10-5 2 0.071 6.9 x 10-6 

Benzene C6H6 1.0 x 103 7.0 x 10-3 69 0.085 8.7 x 10-6 

MTBE C6H12O 1.8 x 104 1.2 x 10-3 190 0.074 6.5 x 10-6 

Ethyl Acetate C4H8O2 4.3 x 104 1.5 x 10-4 54 0.080 7.4 x 10-6 

1,1-Diethoxyethane C6H14O2 2.1 x 104 1.8 x 10-4 24 0.062 5.8 x 10-6 

(1) SPARC estimates were generated from May 2008 release w4.2.1405-s4.2.1408, http://ibmlc2.chem.uga.edu/sparc/ on 8/3
Table 3 SPARC estimated properties at 15 o

C ranked from lowest to highest. 

Solubility Octanol-Water Partition 

Coefficient 

Water Diffusion Coefficient 

g/L (dimensionless) cm2

/s 

name value name value name value 

Benzene 1.0x 103 Methanol 0.24 1,1-Diethoxyethane 5.8 x 10-6

MTBE 1.8 x 103 Ethanol 0.74 MTBE 6.5 x 10-6

3-methyl 1-butanol 1.9 x 104 1-Propanol 3.31 3-methyl 1-butanol 6.9 x 10-6

1,1-Diethoxyethane 2.1 x 104 Ethyl Acetate 7.08 2-methyl 1-butanol 7.0 x 10-6

2-methyl 1-butanol 2.8 x 104 Isobutyl Alcohol 8.51 Ethyl acetate 7.4 x 10-6

Ethyl acetate 4.3 x 104 2-Methyl 1-Butanol 23.40 Isobutyl alcohol 7.7 x 10-6

Isobutyl alcohol 9.3 x 104 3-Methyl 1-Butanol 33.11 Benzene 8.7 x 10-6

1-Propanol 2.2 x 105 1,1-Diethoxyethane 34.67 1-Propanol 8.7 x 10-6

Ethanol Infinite MTBE 34.67 Ethanol 1.0 x 10-5

Methanol infinite Benzene 147.91 Methanol 1.3 x 10-5

44
45

Table 3 (continued) SPARC estimated properties at 15 oC ranked from lowest to highest. 

Henry’s Constant Vapor Pressure Air Diffusion Coefficient 

atm m3

/mol torr cm2/s 

name value Name value Name value 

Methanol 3.4 x 10-6 3-Methyl 1-Butanol 2 1,1-Diethoxyethane 0.062 

Ethanol 5.4 x 10-6 2-Methyl 1-Butanol 3 3-Methyl 1-Butanol 0.071 

1-Propanol 7.3 x 10-6 Isobutyl Alcohol 7 2-Methyl 1-Butanol 0.072 

Isobutyl Alcohol 9.0 x 10-6 1-Propanol 15 MTBE 0.074 

2-methyl 1-Butanol 1.1 x 10-5 1,1-Diethoxyethane 24 Ethyl Acetate 0.080 

3-methyl 1-Butanol 1.2 x 10-5 Ethanol 46 Isobutyl Alcohol 0.081 

Ethyl Acetate 1.5 x 10-4 Ethyl Acetate 54 Benzene 0.085 

1,1-Diethoxyethane 1.8 x 10-4 Benzene 69 1-Propanol 0.094 

MTBE 1.2 x 10-3 Methanol 77 Ethanol 0.110 

Benzene 7.0 x 10-3 MTBE 190 Methanol 0.150 
Discussion and Conclusions 

 Ethanol usage in the United States has increased due in part to the elimination of 

methyl tert-butyl ether from the fuel supply and to the mandates of Congress. Required 

amounts of ethanol in fuel with increase the total through the year 2022. Current data 

show that 75% of U.S. produced gasoline contains ethanol. For the year 2007, the 

amounts in conventional gasoline ranged from none to 10.5%, with outliers at higher 

concentration. Premium gasoline showed two maximums one near 6% and the other at 

about 10%. Two samples of non-denatured fuel grade ethanol, one each from a wet mill 

and a dry mill ethanol plant, were obtained before denaturing. Each of these samples 

contained mostly ethanol, but also low concentrations of water, methanol, and higher 

molecular weight alcohols (up to five carbons). The wet mill sample also contained ethyl 

acetate and an ether, 1,1-diethoxyethane. These two compounds might have been 

present due to the difference in production method, as wet milling is intended to produce 

a wide range of products from the components of corn. 

 The allowable denaturants for fuel ethanol are similar to gasoline. Unleaded 

gasoline, gasoline range hydrocarbons, natural gasoline or condensate can be used for this 

purpose. Since pure ethanol, the primary constituent of fuel ethanol is miscible in water, 

a large amount of water can be accommodated in fuel ethanol. Since the denaturants are 

immiscible with water, the ability of the denatured fuel ethanol to absorb water is limited. 

Experiments with E95 and E85 showed that these both began to phase separate when 

about 15% water was added to the E95 or E85. The gasoline was released gradually as 

water was added to the fuel. Because about 50% water was needed for complete phase 

46
separation of the E95 and E85, phase separation effects in flowing water can be 

estimated: If the flow in the receiving water body is 50% or greater than the release rate 

of the E95 or E85 phase separation is a likelihood. In these cases an “oil” slick composed 

of gasoline should be expected. For E95, there is a smaller amount of gasoline in the fuel 

(2% to 5%) and the slick would be less massive than for the same spill of E85. The 

changes in volume when water and ethanol or water and E85 are mixed displayed a 

deficit of 3% at maximum. For example, a fuel spill that caused a release to a creek 

would increase the flow volume by its volume less 3%. This phenomena for is unlikely 

to be environmentally significant. 

 The byproducts of fuel ethanol production are less soluble, sorb more, diffuse 

less readily, and are less volatile than ethanol. It’s likely, however, that the increased 

ethanol concentration in water will increase the solubility of the byproducts, as it does the 

petroleum hydrocarbons. The byproducts compose less than 1% of the mass of the fuel 

so releases of fuel ethanol will be dominated by the ethanol. Increased solubility of 

petroleum hydrocarbons is possible when the ethanol fraction is greater than about 20%. 

The solubility of benzene could increase by a factor of 20 due to the presence of the 

ethanol. 

47
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ethanol, MTBE, and related oxygenate compounds in water using solid-phase 

microextraction and gas chromatograhpy/mass spectrometry. Analytical 

Chemistry, 2000. 72: p. 4654 - 4658. 

22. Vilar, R., R. da Silva, P. Schossler, R. Veses, C. Piatnicki, D. Samios, and E. 

Caramao, Preliminary characterization of anhydrous ethanol used in Brazil as 

automotive fuel. Journal of Chromatography A, 2003. 985: p. 367-373. 

23. Letcher, T.M., S.W. Heyward, and B. Shuttleworth, Ternary phase diagrams for 

gasoline-water-alcohol mixtures. Fuel, 1986. 65: p. 891 - 894. 

24. Lee, K.Y., Phase partitioning modeling of ethanol, isopropanol, and methanol 

with BTEX compounds in water. Environmental Pollution, 2008. 154: p. 320 - 

329. 

25. Nakayama, M., Water tolerability of methanol-gasoline blends (phase separation 

and SI engine performances). SAE Technical Paper Series. 852200: p. 185 - 191. 

26. Lee, H.K., D.O. Shah, and N.D. Brinkman, Enhancing low-temperature phase 

stability of a 50/50 methanol/hydrocarbon blend. SAE Technical Paper Series, 

1988. 881680: p. 1 -8. 

27. French, R. and P. Malone, Phase equilibria of ethanol fuel blends. Fluid Phase 

Equilibria, 2005. 228-229: p. 27 - 40. 

28. Rixey, W.G., X.H. He, and B.P. Stafford, The Impact of Gasohol and Fuel-Grade 

Ethanol on BTX and Other Hydrocarbons in Ground Water: Effect on 

Concentrations Near a Source, API Soil and Groundwater Technical Task Force 

No. 23. 2005, American Petroleum Institute: Washington, DC. 

29. Pinho, S.P. and E.A. Macedo, Experimental measurement and of modeling KBr 

solubility in water, methanol, ethanol, and its binary mixed solvents at different 

temperatures. Journal of Chemcial Thermodymanics, 2002. 34: p. 337 - 360. 

30. Pecar, D. and V. Dolecek, Volumetric properties of ethanol-water mixtures under 

high temperature and pressures. Fluid Phase Equilibria, 2005. 230: p. 36 - 44. 

31. Karickhoff, S.W., V.K. McDaniel, C. Melton, A.N. Vellino, D.E. Nute, and L.A. 

Carriera, Predicting chemical reactivity by computer. Environmental Toxicology 

and Chemistry, 1991. 10: p. 1405-1416. 

49
32. Mackay, D., Solubility in Water, in Handbook of Property Estimation Methods for 

Chemicals, Environmental and Health Sciences, R.S. Boethling and D. Mackay, 

Editors. 2000, Lewis Pulishers: Boca Raton. p. 125-139. 

33. Cline, P.V., J.J. Delfino, and P.S.C. Rao, Partitioning of aromatic constituents 

into water from gasoline and other complex solvent mixtures. Environmental 

Science and Technology, 1991. 25: p. 914-920. 

34. Gustafson, J.B., J.G. Tell, and D. Orem, Selection of Representative TPH 

Fractions Base on Fate and Transport Considerations. Total Petroleum 

Hydrocarbon Criteria Working Group Series. Vol. 3. 1997, Amherst, 

Massachusetts: Amherst Scientific Publishers. 102. 

35. Schwarzenbach, R.P., P.M. Gschwend, and D.M. Imboden, Environmental 

Organic Chemistry. Second ed. 2003, Hoboken, New Jersey: Wiley-Interscience. 

36. Harris, D.C., Quantitative Chemical Analysis. 5th ed. 1999, New York: W. H. 

Freeman and Company. 

37. Silbey, R.J. and R.A. Alberty, Physical Chemistry. 2000, New York, New York: 

John Wiley & Sons. 959. 

50
Acknowledgments

The authors appreciate the assistance of Mark Toso, Andrew Sedeky, and Tom Higgins 

of the Minnesota Pollution Control Agency; Ileana Rhodes of Shell Global Solutions; 

Stephen Duirk, Said Hilal and Susan Richardson of the U.S. EPA, Office of Research and 

Development in Athens, Georgia. The authors also appreciate the comments from 

reviewers representing academia, industry and government. 

51
Appendix A Analytical Methods 

Fuel Ethanol Analysis 

The undenatured fuel ethanol samples were directly injected into an Agilent 6890 

GC with a 5973 MSD. The 2.0 μL injected sample was split in the injector at a 200:1 

ratio with the injector temperature at 250 ̊C. Separation of the compounds was achieved 

with a 30m Restek Rtx-200 MS column with an ID of 250 μm, film thickness of 0.5 μm, 

and a flow rate of 0.7 mL / minute. Initial oven temperature was 40 ̊C for 4 minutes, 

followed by a 1 ̊C / minute temperature ramp to 50 ̊C. A final temperature ramp of 30 ̊C 

/ minute to 250 ̊C was used to elute late boilers and clean the column. Once reaching 

250 ̊C, there was a final hold time of 5.33 minutes. Total run time was 26 minutes. The 

transfer line to the MSD was kept at 280 ̊C, the MS source at 230 ̊C, and the MS 

quadrupole at 150 ̊C for the entire analysis. The sample was ionized as it entered the 

MSD by electron impact. The MSD was turned on after a 1 minute solvent delay, and 

scanned from 15 to 550 M/Z. 

Subsequently, chemical standards were obtained and three calibration curves were 

developed for an Agilent 6890 gas chromatograph with a flame ionization detector (GCFID). For all the compounds except ethanol 1.0 μL was injected and the split ratio and 

temperature programs were the same. Ethanol analysis was achieved by first diluting the 

sample in acetone to 0.5% of the starting concentration and only splitting the sample 

50:1. Compound separation was achieved with a 30m J&W HP-5 column with an ID of 

320 μm, film thickness of 0.25 μm, and flow of 0.5 mL per minute. Calibration curve 

points were 2.0%, 1.0%, 0.5%, 0.2%, 0.1%, and 0.05% by volume of each suspected 

52
compound. Linear correlation lines were compared to area counts from the fuel samples 

to determine the percentages of compounds in the samples. Because of overlapping 

retention times, 3-Methyl 1-Butanol and ethanol were calibrated separately from the rest 

of the compounds. An internal standard of 0.1% by volume of 1, 3-Dibromo-2-propanol 

was spiked into every sample. 

The Karl Fischer (KF) coulometric method was used to determine the water 

content in the ethanol samples [36]. Samples were analyzed using a Brinkman Metrohm 

Titrino 831 KF Coulometer with Coulomat AG reagent. This system detects trace 

amounts of water by titrating the sample to a bipotentiometric end point and is selective 

to water. One to three milliliters of sample was weighed to the nearest 0.0001 g. The 

sample was then injected into the titration vessel, and the sample weight was entered into 

the titrator software. The sample was automatically titrated by the instrument and the 

water content calculated by the software which was displayed to the nearest 0.01%. 

Water content values were manually recorded into a laboratory notebook. 

Phase Separation 

Separation experiments were conducted by adding various amounts of deionized 

water to a fixed amount of E-85 fuel at ambient temperature. E-85: water ratios included 

5:0.5, 5: 0.625, 5:0.75, 5:0.875, 5:1, 5:1.5, 5:2, 5:2.5, 5:3, 5:3.5, 5:4, 5:4.5, 1:1, 1:1.25, 

1:1.5, 1:1.75, and 1:2. First, 20 ml of E-85 was transferred by class “A” volumetric 

pipette into a separatory funnel that was appropriately sized for the total volume 

expected. Amounts of deionized water were then added to the E-85 to the desired ratio 

by class “A” volumetric pipette. The separatory flask was then gently shaken and vented 

53
three times before allowing the mixture to remain undisturbed for five minutes in order to 

allow separation to occur. After five minutes the aqueous (bottom) phase was slowly and 

carefully drained into an appropriately sized graduated cylinder. The remaining oil (top) 

phase was then slowly and carefully drained into an appropriately sized graduated 

cylinder. The volume of the liquid in each cylinder was then recorded for each phase. 

A screening method was developed for rapid assessment of phase separation 

potential, that was particularly useful since the available volume of sample was limited. 

Measured portions of three commercial ethanol/gasoline mixed samples (E10, E85, and 

E95) were placed in a 10 ml graduated cylinder. A burette was used to deliver 0.1 ml of 

deionized water at set increments. Sample mixing was obtained by a continual stirring of 

a magnetic stir bar at the base of the graduated cylinder. Emulsions were allowed to stir 

for five minutes before any readings were taken. The affects of the addition of the water 

(emulsion and/or the presence of two phase behavior) was noted after each addition. The 

volume of the bottom phase (assumed to be ethanol/water) was read from the markings 

on the graduated cylinder. Shrinkage of the total volume was also noted by reading the 

total volume of the solution in the graduated cylinder compared to the initial 

ethanol/gasoline volume plus the added water volume. Synthetic samples of 

approximately E25 and E35 were created by adding 1 ml and 2 ml of 100% Ethanol to 5 

ml of E10. These were tested in the same manner as the E10. 

54
Appendix B Detected and tentatively identified 

chemicals from an ethanol plant in Minnesota [10]. 

Chemical 

Detected 

Chemical Tentatively 

Identified 

Chemical Tentatively 

Identified 

Plant Location: DDGS Dryer Stack 

Methanol 1,3-butadiene 2-methyl-butanal 

Ethanol 1,3-butadiene, 2-methyl- 2-methyl-furan 

Toluene 1,3-pentadiene 2-methypropenal 

Ethylbenzene 1-2-propadiene 2-pentyl-furan 

Acetone 1-4-pentadiene 2-propen-1-ol 

Formaldehyde 1-decene 2-propenal 

Acetaldehyde 1-dodecene 3-methyl-butanal 

Acrolein 1-heptene 6-heptenoic acid 

Benzene 1-hexene acetaldehyde 

Styrene 1-methy-2-cyclopropene benzaldehyde 

Lactic Acid 1-nonene ethanol 

Acetic Acid 1-octene furan 

Furfuraldehyde 1-undecene hexanal 

2-butanone Nitro-methane 

2-butenal nonanal 

2-furancarboxaldehyde propene 

2-heptenal 

2-methyl-1-pentene 

2-methyl-2-propenal 

55
Chemical Detected Chemical Tentatively Identified 

Plant Location: Distillation Dryer Stack 

Methanol 1 butanol 3-methyl 

Ethanol 1 butanol 3-methyl, aceta 

Carbonyl Sulfide 1-butanol, 3methyl- (S) 

Formaldehyde 1-butanol, 3methyl- aceta 

Acetaldehyde butane 

MEK/Butyraldehydes butane, 2, 2-dimethyl 

m,p-Tolualdehyde butane, 2, 3-dimethyl 

butane, 2-methyl 

cyclopentane, methylethanol 

ethyl acetate 

heptane 

hexane 

hexane 2-methyl 

hexane, 3-methyl 

pentane 

pentane, 2 methyl 

2-methyl-1-pentene 

2-methyl-2-propenal 

Chemical Detected Chemical Tentatively Identified 

Plant Location: Fermetation Scrubber 

 

Methanol 1 butanol 3-methyl 

Ethanol 1 butanol 2-methyl 

Carbonyl Sulfide 1 butanol 2-methyl (s) 

Formaldehyde 1-butanol, 3methyl- aceta 

Acetaldehyde 1,3-pentadiene 

Hydrogen Sulfide 1-propanol 

Dimethyl Sulfide 1-propanol, 2-methyl 

acetaldehyde 

dimethyl sulfide 

ethanol 

ethyl acetate 

formic acid 

pentane 

propanoic acid 

56
Appendix C Ethanol and Water Mixtures 

When water and ethanol form a mixture, a unique volumetric effect occurs: the 

resulting volume is less than the sum of the individual water and ethanol volumes. This 

phenomenon of contracting volume is a result of interstitial packing and molecular 

interaction (hydrogen bonding) between water and ethanol molecules in solution. 

Because the volume of the solution depends on its composition, it is convenient to 

discuss volumetric effects of ethanol-water mixtures in terms of partial molar volume. 

 The partial molar volume, Vi, is defined as follows: 

Vi = (∂V/∂ni)T,p,nj. 

The equation above can be stated by saying that Vi is the change in total volume per mole 

of “i” added, when some amount of “i” is added to the mixture at constant temperature, 

pressure and amount of other substances [37]. Using partial molar volumes, the total 

volume of a solution can be given by the following equation: 

VT = V1n1 + V2n2 +...+ VNnN 

VT = (∂V/∂n1)T,p,nj * n1 + (∂V/∂n2)T,p,nj * n2 +...+ (∂V/∂nN)T,p,nj * nN 

 The total volume of the solution can be discovered by determining the partial 

molar volumes of ethanol and water, as well as the mass fractions of the mixture. Partial 

molar volumes of water and ethanol can be found using the equation below [30]. 

Ve = (υ + ωw(∂V/∂ωe)T,p,nj.) Me & Vw = (υ + ωe(∂V/∂ωw)T,p,nj.) Mw, 

In this equation, υ refers to the specific volume of the solution, ω represents the mass 

fraction, M is indicative of molecular weight, and the subscripts “e” and “w” refer to 

57
water and ethanol, respectively. The densities of 54 different water-ethanol mixtures are 

given by Pecar and Dolecek along with their respective mole fractions of ethanol. The 

mass fraction of ethanol and its corresponding specific volume are calculated using the 

data provided for these different mixtures. Specific volumes are plotted against the mass 

fraction of ethanol and the best fit curve is applied to the data-plot by the third degree 

polynomial. Then, the derivative of this polynomial is deduced, and the partial molar 

volume can be determined. The total volume of solution can then be predicted using the 

following equation: 

VT = (∂V/∂ne)T,p,nj * ne + (∂V/∂nw)T,p,nj * n2 

By assuming that 1 mole of solution is present, ne & nw can be set equal to the mole 

fractions of ethanol and water, respectively. 

 Using the equations above and data provided by Pecar & Dolecek it can be shown 

that approximately one mole of ethanol and a relatively small amount of water has a total 

volume nearly equal to the molar volume of ethanol. However, when significant amounts 

of both water and ethanol are present in a mixture, the total volume is less than the 

individual volumes of ethanol and water standing alone. A table illustrating these 

volumetric effects is provided with a maximum contraction of -3.4% occurring at an 

ethanol mole fraction of 0.2745. 

58
Appendix D Comparison of results from the EPI SuiteTM 

calculator and SPARC for Kow for 5 oC and 25 oC. 

Figure 19 shows a comparison of log Kow results from SPARC at 5 oC and 15 oC, 

EPI-SuiteTM, and experimental data reported by EPI-SuiteTM. Generally good agreement 

was seen among these sources. The SPARC results show more variation with temperature 

at higher Kows than for the low values. Figure 20 shows assumed variability of one-half 

log unit in SPARC Kow results on both log-log and linear scales. Note that as the value of 

Kow increases so does the variability on the linear scale. 

-10 1 2

EPI Suite Reported Experimental Log Kow

3

-1

0

1

2

3

Estimated Log Kow

Comparison

EPI Suite

SPARC 5 C

SPARC 25 C

Figure 19 Estimates from the EPA EPI Suite calculator, SPARC at 5 o

C and 25 oC plotted against 

experimental results reported with EPI Suite results. 

59
-2 0 2 4

Log Median Value

-2

0

2

4

Log Median Value +/- 1/4 log unit

Vairation

Median

Median - 1/4 log unit

Median + 1/4 log unit

0 200 400 600 800 1000

Median Value

0

400

800

1200

1600

2000

Figure 20 Example of variation in SPARC results given an assumed variability (error) of one-half 

log unit. The left hand graph shows results on a log-log scale. The right hand graph shows the same 

variation on a linear scale. 

60
Appendix E SPARC Property Results for 5 o

C to 45 oC 

10 20 30 40

Temperature (C)

0

50000

100000

150000

200000

250000

Solubility (mg/L)

1-Propanol

Isobutyl Alcohol

2-Methyl 1-Butanol

3-Methyl 1-Butanol

Figure 21 Solubility of the alcohols found in the wet and dry mill samples. Ethanol and methanol do 

not appear because their solubility is infinite. 

10 20 30 40

Temperature (C)

0

10000

20000

30000

40000

50000

Solubility (mg/L)

Ethyl Acetate

1,1-diethoxy ethane

MTBE

Benzene

Figure 22 Solubility of ethyl acetate and 1,1-diethoxy ethane, compounds found in the wet mill 

sample. Solubilities of bezene and MTBE are plotted for comparison. 

61
0 10 20 30 40 50

0

1E-005

2E-005

3E-005

4E-005

5E-005

Henry's Law Coefficient 

(atm m

3/mol)

0 10 20 30 40 50

0.1

1

10

100

1000

Vapor Pressure 

(Torr)

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

Air Phase

Diffusion Coefficient

(cm2/s)

0 10 20 30 40 50

Temperature (C)

0

0.2

0.4

0.6

0.8

1

Octanol Water

Partition Coefficient

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

4E-005

5E-005

0 10 20 30 40 50

0.1

1

10

100

1000

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

0 10 20 30 40 50

Temperature (C)

0

0.2

0.4

0.6

0.8

1

Methanol Ethanol

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Water Phase 

Diffusion Coefficient 

(cm2/s)

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Figure 23 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion coefficient, 

octanol/water partition coefficient) for methanol and ethanol estimated by the SPARC calculator. 

62
0 10 20 30 40 50

0

1E-005

2E-005

3E-005

4E-005

5E-005

Henry's Law Coefficient 

(atm m

3/mol)

0 10 20 30 40 50

0.1

1

10

100

1000

Vapor Pressure 

(Torr)

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

Air Phase

Diffusion Coefficient

(cm2/s)

0 10 20 30 40 50

Temperature (C)

0

5

10

15

Octanol Water

Partition Coefficient

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

4E-005

5E-005

0 10 20 30 40 50

0.1

1

10

100

1000

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

0 10 20 30 40 50

Temperature (C)

0

5

10

15

1-Propanol Isobutyl Alcohol

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Water Phase 

Diffusion Coefficient 

(cm2/s)

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Figure 24 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion coefficient, 

octanol/water partition coefficient) for 1-propanol and isobutyl alcohol estimated by the SPARC 

calculator. 

63
0 10 20 30 40 50

0

1E-005

2E-005

3E-005

4E-005

5E-005

Henry's Law Coefficient 

(atm m

3/mol)

0 10 20 30 40 50

0.1

1

10

100

1000

Vapor Pressure 

(Torr)

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

Air Phase

Diffusion Coefficient

(cm2/s)

0 10 20 30 40 50

Temperature (C)

0

10

20

30

40

50

Octanol Water

Partition Coefficient

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

4E-005

5E-005

0 10 20 30 40 50

0.1

1

10

100

1000

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

0 10 20 30 40 50

Temperature (C)

0

10

20

30

40

50

2-Methanol 1-Butanol 3-Methyl 1-Butanol

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Water Phase 

Diffusion Coefficient 

(cm2/s)

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Figure 25 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion coefficient, 

octanol/water partition coefficient) for 2-methyl 1-butane and 3-methyl 1-butane estimated by the 

SPARC calculator. 

64
0 10 20 30 40 50

0

0.0002

0.0004

0.0006

0.0008

0.001

Henry's Law Coefficient 

(atm m

3/mol)

0 10 20 30 40 50

0.1

1

10

100

1000

Vapor Pressure 

(Torr)

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

Air Phase

Diffusion Coefficient

(cm2/s)

0 10 20 30 40 50

Temperature (C)

0

2

4

6

8

10

Octanol Water

Partition Coefficient

Ethyl Acetate

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Water Phase 

Diffusion Coefficient 

(cm2/s)

Figure 26 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion coefficient, 

octanol/water partition coefficient) for ethyl acetate estimated by the SPARC calculator. 

65
0 10 20 30 40 50

0

0.0004

0.0008

0.0012

0.0016

0.002

Henry's Law Coefficient 

(atm m

3/mol)

0 10 20 30 40 50

0.1

1

10

100

1000

Vapor Pressure 

(Torr)

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

Air Phase

Diffusion Coefficient

(cm2/s)

0 10 20 30 40 50

Temperature (C)

0

2

4

6

8

10

Octanol Water

Partition Coefficient

1,1-Diethoxyethane

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Water Phase 

Diffusion Coefficient 

(cm2/s)

Figure 27 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion coefficient, 

octanol/water partition coefficient) for 1,1-diethoxyethane estimated by the SPARC calculator. 

66
0 10 20 30 40 50

0

0.002

0.004

0.006

0.008

0.01

Henry's Law Coefficient 

(atm m

3/mol)

0 10 20 30 40 50

0.1

1

10

100

1000

Vapor Pressure 

(Torr)

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

Air Phase

Diffusion Coefficient

(cm2/s)

0 10 20 30 40 50

Temperature (C)

0

50

100

150

200

Octanol Water

Partition Coefficient

0 10 20 30 40 50

0

0.002

0.004

0.006

0.008

0.01

0 10 20 30 40 50

0.1

1

10

100

1000

0 10 20 30 40 50

0

0.04

0.08

0.12

0.16

0.2

0 10 20 30 40 50

Temperature (C)

0

50

100

150

200

Benzene MTBE

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Water Phase 

Diffusion Coefficient 

(cm2/s)

0 10 20 30 40 50

0

1E-005

2E-005

3E-005

Figure 28 Properties (Henry's Law coefficient, vapor pressure, air phase diffusion coefficient, 

octanol/water partition coefficient) for benzene and methyl tert-butyl ether (MTBE) estimated by the 

SPARC calculator. 

67
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