D ate : August 1 5 , 2012

S ubject : Comparison of Studies on Non

- PFOS Fume Suppressant Performance Emission Standards Technical Support a nd Post Promulgation Activities
Contract No. EP

- D

- 11

- 084; EPA Work Assignment No. 0

- 07 RTI Project No. 0213199.000.007

From : Richard Marinshaw

To : Phil Mulrine , EPA/OAQPS/SPPD/MMG

This memorandum summarizes and compares the results of two recent studies that investigated the performance of wetting agent fume suppressants (WAFS) that do not contain perfluorooctyl sulfonic acid (PFOS) in controlling emissions from chromium electroplating. Section I provide s a description of the two studies; Section II compares the methods and results
of the st udies; and references are provided in Section III.

I. Overview of Studies

Two studies were conducted recently that evaluated the performance of non

- PFOS WAFS in controlling emissions from chromium electroplating: a study conducted by the
Institute für Galvano

- und Oberflächentechnik Solingen GmbH & Co , hereafter referred to as the German Study; and a study conducted by Danish Ministry of the Environment, hereafter referred to as the Danish Study. Details on each of the studies are provided below.

Ger man Study (IGOSG, 2012)

The purpose of this study was to investigate the performance of a non

- PFOS product, which had not yet been commercialized, compared to a PFOS

- based WAFS and to a non

- PFOS

based WA F S product that is currently available in the marke t. Three phases of testing were performed. The first phase evaluated emissions from hard chromium electroplating for baseline conditions (no WAFS used), and each of the three WAFS products. In the second phase,
emissions from decorative chromium electro plating were sampled for the baseline, commercial

non

- PFOS product

, and the experimental product. The third phase of testing evaluated the de

frothing effects of the experimental product on the commercialized non

- PFOS product. Since this last phase had n o bearing on the performance of PFOS or non

- PFOS WAFS, it is not
discussed further in this memorandum.

Bench

- scale tests were performed using a 5

- liter (L) glass beaker as the electroplating “tank” for each of the products tested. The volume of the electroplating solution was 4.5 L. Emissions were captured using a fabricated perforated piping system that surrounded each test vessel. Sampling was performed using DIN EN 13284, Stationary source emissions

- Determination of low rang e mass concentration of dust , and the samples were analyzed using2

DIN EN 15205

- Determination of hexavalent chromium in corrosion protection layers

- Qualitative analysis. For most of the testing, three test runs were performed, and the t est run s varied from 33 to 50 minutes in duration. Regarding the surface tension of the plating solution, the report states that a tensiometer was used to develop a calibration curve that relates WAFS concentration to “bubble lifetime” and surface tension. However, it i s unclear if surface tensions were measured during the testing

. A separate document prepared by EMD presents the results of the study and indicates that surface tensions were about 30 dynes per centimeter (dynes/cm) during the testing (EMD, 2012) , but the actual study report does not present surface tension data.
B ased on the technical data sheet (Atotech, 2010) for the non

- PFOS product used ( Fumetrol 21 )
and the reported concentration during test (2.0 to 2.5 m illiliter per liter [m l/L ] ), the surface
tension should have been about 3 5 to 4 7 dynes/cm for the non

- PFOS fume suppressant test

.

Table 1 summarizes the test results in units of milligrams per dry standard cubic meter (mg/dscm), as presented in the report . The conclusions of the study generall y relate to the performance of the experimental product. However, the study also concludes that the PFOS and

non

- PFOS products both reduced emissions by more than 95 percent.

Table 1. Summary of Results for German Study as Reported
Test condition WAFS P roduct No. of

test runs Chromium e missions, mg/dscm
Minimum Maximum Average

Hard Cr electroplating None (baseline) 9 0.280 0.529 0.378 Experimental non

- PFOS 3 0.515 0.936 0.681
PFOS 2 0.006 0.007 0.006
Non

- PFOS 3 0.017 0.043 0.027
Decorative Cr electroplating Experimental non

- PFOS 9 0.537 1.077 0.837
Non

- PFOS 3 0.004 0.021 0.012

The data indicate that the experimental non

- PFOS product actually increased emissions
of chromium. However, as this product is still under development and not commercially
available , the results are not relevant to the performance of WAFS for controlling chromium electroplating emissions in the U.S. and are not discussed further in this memorandum.

As reported, the results for the commercially available non

- PFOS product appear to indicate that emissions would not meet the current emissions limits specified in the Chromium Electroplating NESHAP for large or new small hard chromium electroplating (0.015 mg/dscm)

,
or for decorative chromium electro plating (0.01 mg/dscm). However, on closer examination, the
data show that the ventilation rate for the test vessel was much lower than is recommended for a chromium electroplating tank in the U.S. Based on the reported flow rate (3 L/min) and the test

v essel surface area (0.008 square meters), the ventilation rate wa s 1.2 cubic feet per minute per square foot of surface area (CFM/ft 2 ) . The minimum recommended ventilation rate in the U.S. is
250 CFM/ft 2 (ACGIH, 1986) , or approximately 200 times the venti lation used rate during the test. If the flow rate were normalized using the recommended ventilation rate, hard chromium electroplating emissions for the both the PFOS product (0.000033 mg/dscm) and the non

- PFOS product (0.000137 mg/dscm) would be well be low the NESHAP emission limits. For decorative chromium electroplating, emissions for the non

- PFOS product (0.000063 mg/dscm) also would
be well below the NESHAP limit. Although scaling flow rates and adjusting emissions3

concentrations by that large of a factor is questionable, the magnitude of the adjusted emissions concentrations also raises the question of whether the exhaust system was capturing all of the
emissions. It should also be noted that the uncontrolled results, 0.0019 mg/dscm when scaled for ventilation rate, are more than three orders of magnitude lower than typical uncontrolled emissions in the U.S., which are 3.1 mg/dscm based on AP

- 42 data (EPA, 1996).

In summary, t he test conditions and results also call into question the representativ e ness of this study for full scale chromium electroplating operations and the appropriateness of the test results for comparing the performance of PFOS and non

- PFOS WAFS

. Specifically:

• The purpose of the study, and thus the study design, was to examine the performance of an experimental product tha t is not commercially available;

• The t est vessel, which had a volume of 4.5 L wa s at least two orders of magnitude smaller than the tanks commonly used in the electroplating industry ;

• The exhaust system design, fabricated from piping placed around the outside of the vessel, does not resemble tank hoods and ductwork used in the industry;

• The ventilation rate was more than 200 times lower than what is recommended in the U.S.; and

• The analytical test method used was not developed for analyzing emission samples and, based on the method title, is a qualitative, rather than a quantitative method.

Danish Study (DME, 2011)

The purpose of this study was to compare the performance of PFOS

- based WAFS to non

PFOS

- based WAFS. Commercially available products were tested in a small hard chromium electroplating tank. The tests consisted of five test runs, each of which was 24 hours in duration. In addition, one uncontrolled 12

- hour run was conducted to establish the b aseline (i.e., without WAFS). The entire tank was fitted with a hood to capture all emissions from the process. Emissions were sampled and analyzed using BS EN 14385:2004, Stationary source emissions. Determination of the total emission of As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sb, TI and V

.

It does not appear that surface tensions were measured during the testing. However, the study reports that WAFS were dosed at approximately 50 percent more than manufacturer’s specification

. B ased on the technical data sheet (Atotech, 2010) for the non

- PFOS product used ( Fumetrol 21 ) and the reported concentration during test (3.6+ ml/L), the surface tension should
have been about 2 8 to 35 dynes/cm for the non

- PFOS fume suppressant test.

Table 2 summarizes the emission test results in mg/dscm, as presented in the report.

Table 2 . Summary of Results for Danish Study as Reported
Test condition WAFS Product No. of

test runs Chromium e missions, mg/dscm
Minimum Maximum Average

Hard Cr electroplating None (baseline) 1 12.0
PFOS 5 0.011 0.30 0.12
Non

- PFOS 5 0.013 0.089 0.0364

The results indicated that the non

- PFOS product performed better than the PFOS product in reducing chromium emissions. However, the results

, as reported

, indicate that for neither test
did emissions meet the NESHAP limit of 0.015 for large hard chromium electroplating tanks. As was the case for the German Study, it appears that the ventilation rates were lower than would be the design practice in the U.S. Based on the reported flow rat e (180 cubic meters per hour) and the test tank surface area (0.22 square meters), the ventilation rate was 45 CFM/ft 2 . The minimum recommended ventilation rate in the U.S. (250 CFM/ft 2 ) is approximately 5.6 times the
ventilation rate used during the test. If the flow rate were normalized using the recommended
minimum ventilation rate, emissions for the PFOS product are 0.022 mg/dscm, and, for the non

PFOS product are 0.0067 mg/dscm. However, it should noted that t he recommended ventilatio n rate of 250 CFM/ft2 in the U.S. is what is required “to maintain minimum control velocities”
across the tank surface area. Thus, tanks are typically designed for higher ventilation rates, thereby decreasing emissions concentration. Therefore, the calcu lated value of 0.0067 mg/dscm is considered a maximum value and actual tanks would have greater flow rate and lower
emissions concentrations. Nevertheless, t his result for the non

- PFOS product is generally
consistent with data on emissions from tanks cont rolled with PFOS

- based WAFS in the U.S. The result for uncontrolled emissions (12 mg/dscm) also is consistent for uncontrolled hard
chromium emissions in the U.S.

In summary, although the test tank was smaller than most electroplating tanks, the test
de sign and conditions appear to be representative of hard chromium electroplating in the U.S. The exhaust system (completely hooded tank) and test method used indicate that the emissions concentrations were appropriately quantified. T he ventilation rate wa s lower than would be required in the U.S., but not to the extent that would compromise the adjusted concentrations.

II. Comparison of Studies

Table 3 provides a side

- by

- side comparison of the two studies and the results for hard chromium electroplating emissions

. In summary, the Danish Study appears to be much more representative of chromium electroplating operations and used a more appropriate test design and test methods, than the German Study.

III

. R eferences

1

. Institute für Galvano

- und Oberflächentechnik Solingen GmbH & Co . KG. Report on Findings, 20110508, English Edition, Solingen, Germany, July 14, 2012 (IGOSG, 2012).

2

. EMD. Effect of Cr(VI) Emissions and Surface Tension of Non

- PFOS Mist Suppressa nts in Hard and Decorative Chrome Plating. Merck KGaA, Darmstadt, Germany, 2012 (EMD, 2012 )

.

3

. Atotech. D ata S heet , Fumetrol® 21 LF, Chromium Mist Suppressant, Version: 02 . June 29, 2010 (Atotech, 2010).

4

. American Conference of Governmental Industrial Hygien ists. Industrial Ventilation

– A Manual of Recommended Practice, 19 th Edition. Lansing, Michigan, 1986 (ACGIH, 1986)

.5

5

. U.S. Environmental Protection Agency, Emission Factor Documentation for AP

- 42 Section 12.20 Electroplating. July 1996 (EPA, 1996).

6

. Danish Ministry of the Environment, Environmental Protection Agency. Substitution of
PFOS for Use in non

- Decorative Hard Chrome Plating. Denmark, 2011 (DME, 2011)

.6

Table 3. Comparison of German and Danish Studies

Item German Study Danish Study Remarks Process type Hard Cr Hard Cr For both studies, current density was 50 A/dm 2 Plating Tank Volume, gallons 1.2 29 German Study was lab

- scale; Danish Study was full scale Exhaust capture system Perforated pip e Full hooding German Study used a fabricated capture system consisting of perforated pipe surrounding the test vessel; Danish Study used fully hooded tank , thereby ensuring 100% capture PFOS product HSO FL Fumetrol 140 PFOS product for German Study not typicall y used in U.S. Non PFOS product Fumetrol 21 Fumetrol 21 Both studies used non

- PFOS that is widely used in U.S.
Surface tension Not specified (a) Not specified (b) No surface tension measurements reported. See Notes (a) and (b) below for estimated surface tensions
Test Method EN 15205 (c) EN 14385 (d) Method used for German study was not meant for quantifying emissions and is a “qualitative” method; m ethod used for Danish Study was developed for quantifying stack emissions
No. of test runs PFOS: 2
Non

- PFOS: 3 PFOS: 5
Non

- PFOS: 5 Danish Study included more test runs

Test run duration, hours 33 to 50 1,440 T est run durations for the German Study are less than what is commonly used in the U.S

. and may not be adequate to properly quantify results ; for the Danish Study, test runs were
24 hours each , which should be more than adequate Detection limit, ug/m3 Not specified 0.9 German Study did not specify detection limit Average Cr concentration, adjusted for ventilation rate, mg/dscm
PFOS 0.000033 0.022 See Section I for discussion of representativeness of results for
the two studies Non

- PFOS 0.00014 0.0067 (a) Study included calibration curves that relate fume suppressant concentration and bubble lifetime to surface tension, but it unclear how the calibration curves were used; report states that PFOS and non

- PFOS chemical concentrations were in accordance to manufacturer’s specifications; based on Fumetrol 21 data sheet and reported concentration during test (2.0 to 2.5 ml/L), the su rface tension should have been about 35 to 47 dynes/cm for the non

- PFOS fume suppressant test.

(b) Report states that both PFOS and non

- PFOS chemical concentrations were 50% more than manufacturer’s specification; based on Fumetrol 21 data sheet and

repor ted concentration during test (3.6+ ml/L), the surface tension should have been about 2 8 to 35 dynes/cm for the non

- PFOS fume suppressant test.

(c) DIN EN 15205, Determination of hexavalent chromium in corrosion protection layers

- Qualitative analysis

.

( d) BS EN 14385:2004, Stationary source emissions. Determination of the total emission of As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sb, TI and V

.