Abstract:
A quick, economical and environmentally friendly, “green”, process for the continuous purification of biodiesel (fatty acid alkyl esters (FAAE)) is described using a powdered, granulated or extruded adsorbent. The adsorbent is contained in a column system and is regenerated for reuse multiple times. The process employs an adsorbent such as, but not limited to, carbon, silica, clay, zeolite or a metal silicate contained in a column to remove the impurities from fatty acid alkyl esters (FAAE) or crude biodiesel in a continuous process. The process utilizes the adsorbent column system for the purification of biodiesel, rather than water or filtration, to remove soaps and other impurities entrained in a crude biodiesel. The crude biodiesel is contacted with an adsorbent packed into a column, or multiple columns in series, for a sufficient amount of time to remove impurities such as, but not limited to, soaps, metals, free glycerin, sterol glucosides and many of the other impurities that reduce the stability of biodiesel. The resulting finished biodiesel exiting the column(s) is ready for the methanol recovery process. Once the adsorbent no longer removes the desired amount of impurities, it is regenerated for reuse. The solvent used for the regeneration process is reclaimed and reused by recycling it back to the transesterification reaction.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/063,982, filed Feb. 7, 2008, the entirety of which is hereby incorporated by reference into this application. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to purification of fatty acid alkyl esters (FAAE), in particular, biodiesel, and more particularly, to a process for quick, continuous purification of crude biodiesel by treating crude biodiesel with an adsorbent material contained in one or more columns and regenerating the adsorbent material for re-use. 
         [0004]    2. Description of Related Art 
         [0005]    Economically viable renewable energy has been a policy goal of governments around the world. One source of renewable fuel that has been promoted and developed is biodiesel. The attraction of biodiesel is the similar properties it possesses in relation to petroleum-based diesel fuel. Biodiesel is a desirable energy alternative to wind, solar, and ethanol derived energy in that the energy content to capital requirement is close to a break-even point, depending, of course, upon the price of petroleum derived energy. 
         [0006]    Biodiesel is the purified alkyl esters of fatty acids generally referred to as fatty acid alkyl esters (FAAE). Production of these fatty acid alkyl esters (FAAE) is achieved by the transesterification of animal or vegetable fats or oils or the esterification of fatty acids, including free fatty acids (FFA) found in degraded fat or oil. The process involves the reaction of triacylglycerol with an alcohol, typically methanol, in the presence of a catalyst, typically sodium or potassium hydroxide or methoxide, a reaction referred to as transesterification. Alternately, fatty acids, including those found in degraded fat or oil containing high levels of free fatty acids (FFA), typically referred to as yellow grease, brown grease, or trap grease, are reacted with an alcohol, typically methanol, in the presence of an acid, a reaction referred to as esterification. When using degraded fat or oil as a raw material, esterification is performed prior to transesterification in order to provide for a complete conversion of fatty acids into FAAE. Unreacted methanol from both processes is typically removed by flash evaporation so that it can be reused for the esterification and/or transesterification reaction(s). 
         [0007]    However, simply performing the esterification and/or transesterification of fatty acids is not enough to produce a usable biodiesel fuel. Fatty acid alkyl esters (FAAE) contain impurities that can crystallize, foul engines, and cause numerous problems for the user. As a result, regulations have been developed to address the needs of the consumer with respect to quality. Strict standards for commercial biodiesel have been developed by most countries, including the U.S. Government in the specifications set forth in ASTM International&#39;s ASTM D6751 and the European Union in the specifications set forth by the European Committee for Standardization in EN 14214. 
         [0008]    The specifications for ASTM D6751-07a are as follows: 
         [0000]    Biodiesel is defined as the mono alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, for use in compression-ignition (diesel) engines. This specification is for pure (100%) biodiesel prior to use or blending with diesel fuel. 
         [0000]                                                                                                                                                                                      Property   ASTM Method   Limits   Units                                Calcium &amp; Magnesium, combined   EN 14538   5   max   ppm (ug/g)       Flash Point (closed cup) D 93       93   min.   Degrees C.       Alcohol Control (One of the       following must be met)       1. Methanol Content   EN14110   0.2   Max   % volume       2. Flash Point   D93   130   Min   Degrees C.       Water &amp; Sediment   D 2709   0.05   max.   % vol.            Kinematic Viscosity, 40 C.   D 445   1.9-6.0   mm2/sec.            Sulfated Ash   D 874   0.02   max.   % mass       Sulfur            S 15 Grade S 500 Grade   D 5453 D 5453   0.0015 max. (15) 0.05 max.   % mass (ppm) % mass               (500)   (ppm)            Copper Strip Corrosion   D 130   No. 3   max.           Cetane   D 613   47   min.            Cloud Point   D 2500   Report   Degrees C.            Carbon Residue 100% sample   D 4530*   0.05   max.   % mass       Acid Number   D 664   0.50   max.   mg KOH/g       Free Glycerin   D 6584   0.020   max.   % mass       Total Glycerin   D 6584   0.240   max.   % mass       Phosphorus Content   D 4951   0.001   max.   % mass       Distillation, T90 AET   D 1160   360   max.   Degrees C.       Sodium/Potassium. combined   EN 14538   5   max   ppm       Oxidation Stability   EN 14112   3   min   hours               Workmanship = Free of undissolved water, sediment, &amp; suspended matter BOLD = BQ-9000 Critical Specification Testing Once Production Process Under Control       *The carbon residue shall be run on the 100% sample.       # A considerable amount of experience exists in the US with a 20% blend of biodiesel with 80% diesel fuel (B20). Although biodiesel (B100) can be used, blends of over 20% biodiesel with diesel fuel should be evaluated on a case-by-case basis until further experience is available.       Source: SPECIFICATION FOR BIODIESEL (B100) - ASTM D6751-07a (March 2007).            
The specifications for EN 14214 are as follows:
 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Limits 
                   
               
             
          
           
               
                 Property 
                 Unit 
                 Minimum 
                 Maximum 
                 Test method 
               
               
                   
               
             
          
           
               
                 Ester content 
                 % (m/m) 
                 96.5 
                   
                 EN 14103 
               
               
                 Density at 15° C. 
                 kg/m 3   
                 860 
                 900 
                 EN ISO 3675 
               
               
                   
                   
                   
                   
                 EN ISO 12185 
               
               
                 Viscosity at 40° C. 
                 mm 2 /s 
                 3.50 
                 5.00 
                 EN ISO 3104 
               
               
                 Flash Point 
                 ° C. 
                 120 
                 — 
                 prEN ISO 3679 
               
               
                 Sulfur content 
                 mg/kg 
                 — 
                 10.0 
                 prEN ISO 20846 
               
               
                   
                   
                   
                   
                 prEN ISO 20884 
               
               
                 Carbon residue 
                 % (m/m) 
                 — 
                 0.30 
                 EN ISO 10370 
               
               
                 (on 10% distillation residue) 
               
               
                 Cetane number 
                   
                 51.0 
                   
                 EN ISO 5165 
               
               
                 Sulfated ash content 
                 % (m/m) 
                 — 
                 0.02 
                 ISO 3987 
               
               
                 Water content 
                 mg/kg 
                 — 
                 500 
                 EN ISO 12937 
               
               
                 Total contamination 
                 mg/kg 
                 — 
                 24 
                 EN 12662 
               
             
          
           
               
                 Copper strip corrosion 
                 rating 
                 class 1 
                 EN ISO 2160 
               
               
                 (3 h at 50° C.) 
               
             
          
           
               
                 Oxidation stability 110° C. 
                 hours 
                 6.0 
                 — 
                 EN 14112 
               
               
                 Acid value 
                 mg KOH/g 
                   
                 0.50 
                 EN 14104 
               
               
                 Iodine value 
                 gr iodine/100 gr 
                   
                 120 
                 EN 14111 
               
               
                 Linolenic acid methyl ester 
                 % (m/m) 
                   
                 12.0 
                 EN 14103 
               
               
                 Polyunsaturated (&gt;=4 double bonds) 
                 % (m/m) 
                   
                 1 
               
               
                 methyl esters 
               
               
                 Methanol content 
                 % (m/m) 
                   
                 0.20 
                 EN 14110 
               
               
                 Monoglyceride content 
                 % (m/m) 
                   
                 0.80 
                 EN 14105 
               
               
                 Diglyceride content 
                 % (m/m) 
                   
                 0.20 
                 EN 14105 
               
               
                 Triglyceride content 
                 % (m/m) 
                   
                 0.20 
                 EN 14105 
               
               
                 Free glycerol 
                 % (m/m) 
                   
                 0.02 
                 EN 14105 
               
               
                   
                   
                   
                   
                 EN 14106 
               
               
                 Total glycerol 
                 % (m/m) 
                   
                 0.25 
                 EN 14105 
               
               
                 Group I metals (Na + K) 
                 mg/kg 
                   
                 5.0 
                 EN 14108 
               
               
                   
                   
                   
                   
                 EN 14109 
               
               
                 Group II metals (Ca + Mg) 
                 mg/kg 
                   
                 5.0 
                 PrEN 14538 
               
               
                 Phosphorus content 
                 mg/kg 
                   
                 10.0 
                 EN 14107 
               
               
                   
               
               
                 Source: European Standard EN 14214: Automotive fuels-Fatty acid methyl esters (FAME) for diesel engines-Requirements and test methods (approved on 14 Feb. 2003) 
               
             
          
         
       
     
         [0009]    Because they are usually the most economical raw material, fats and oils are commonly used as a feedstock for the esterification and/or transesterification reaction(s) to produce biodiesel. Fats and oils commonly undergo purification to remove contaminants prior to being used as the feedstock for biodiesel and other applications. The following patents relate to the purification of fats and oils. 
         [0010]    U.S. Pat. No. 1,745,952 discloses a method to decolorize fats and oils. U.S. Pat. No. 2,401,339 discloses a method of removing impurities from fats, oils and waxes through the use of solid adsorbents and distillation. U.S. Pat. No. 3,862,054 discloses a method of removing phosphorus compounds and free fatty acids from vegetable oils. U.S. Pat. No. 5,252,762 discloses a method to remove contaminants (free fatty acids, soaps, phosphorus, metal ions and color bodies) from glyceride oils with a base treated adsorbent. All of the above described patents are directed to the purification of the fats and oils themselves, and not biodiesel or any other fatty acid alkyl esters. While fats and oils can be used as a feedstock for the production of biodiesel, the fats and oils do not constitute biodiesel. 
         [0011]    As a result of the above-described transesterification reaction, two products are produced: fatty acid alkyl esters (FAAE) (typically Fatty Acid Methyl Esters) and glycerin. The glycerin portion is separated from the fatty acid alkyl esters (FAAE) portion, either by centrifugation or gravity settling, and the resulting fatty acid alkyl esters (FAAE) is referred to as crude biodiesel. The crude biodiesel portion consists of fatty acid alkyl esters (FAAE) containing impurities that must be removed before it can be commercially marketed as biodiesel. These impurities include, but are not limited to, alcohol, glycerin, soaps, residual catalyst, metals, free fatty acids, sterol glycosides as well as other impurities that reduce the stability of biodiesel. Therefore, at this point in the process, the fatty acid alkyl esters (FAAE) is not considered to be biodiesel and cannot be commercially marketed as biodiesel until the proper specifications (e.g. ASTM D6751, EN 14214, and the like) are achieved. 
         [0012]    Conventional solutions to remove impurities from a crude biodiesel and produce a product that meets relevant specifications, include water wash, ion-exchange resin, and filtration using an adsorbent powder. Some conventional methods have combined the techniques to help achieve regulatory specifications. The unreacted methanol is removed from the crude biodiesel portion either prior to the purification process or after the purification process depending on which purification techniques) are used. 
         [0013]    U.S. Patent Application Publication No. 2005/0018143 describes a process to produce a fatty acid alkyl ester for diesel fuel using water washing to remove the impurities. After the water washing process is completed, the fatty acid alkyl ester is treated with a high-water-absorptive resin to remove the water from the fatty acid alkyl ester. 
         [0014]    U.S. Pat. No. 4,371,470 describes a method for producing a high quality fatty acid ester by esterification process, water washing to remove impurities and using an adsorbent to remove color from the fatty acid ester. The adsorbent is described as either activated clay or a mixture of activated clay and activated carbon. 
         [0015]    The drawbacks of water wash are the large volume of fresh water needed to treat the biodiesel, the long amount of time required to treat the biodiesel, the potential for emulsion formation and resulting waste, and the large volume of wastewater either to be disposed of or treated. 
         [0016]    Various patents describe purification of biodiesel, esters and related chemicals using adsorbents such as clay, carbon, silicon based adsorbents, such as magnesium silicate and zeolites. 
         [0017]    U.S. Pat. No. 6,982,340 describes a process for purifying an ester with adsorption-treating with clay/activated carbon and a hydrogenating decomposition-type adsorbent using a carrier. The adsorbents in this process are used for the removal of sulfur compounds from an ester, not biodiesel. Even though biodiesel is a type of ester, there are numerous ester compounds not associated with biodiesel. 
         [0018]    U.S. Patent Application Publication No. 2005/0081436 describes a method by which biodiesel is purified using an adsorptive filtration process using synthetic magnesium silicate. 
         [0019]    U.S. Patent Application Publication No. 2005/0188607 describes a system for the removal of methanol from crude biodiesel using adsorptive filtration with a silicon based adsorbent (e.g. magnesium silicate). The removal of glycerin, and sodium or potassium hydroxide is also included. 
         [0020]    U.S. Patent Application Publication No. 2006/0260184 describes an apparatus and process to refine biodiesel fuel through the use of an adsorbent material (e.g. magnesium silicate). This process also uses filtration. 
         [0021]    U.S. Pat. No. 5,401,862 describes a process for the decolorization of fatty acid esters particularly the fatty acid esters suitable for use in foods and cosmetics. A solution of fatty acid ester dissolved in a polar solvent is passed through a column containing an adsorbent (mixture of montmorillonite clay and group consisting of silica gel and activated carbon). The solvent is then eliminated from the ester. The only contaminant claimed to be removed from this process is color. 
         [0022]    U.S. Pat. No. 4,049,688 describes a method by which saturated esters of fatty acids can be separated from unsaturated esters through use of selective adsorption using an X or Y Zeolite. 
         [0023]    The major drawback of adsorbent treatment of biodiesel is the disposal of the spent adsorbent filter cake. 
         [0024]    None of these patents describe a continuous process using column purification or adsorbent regeneration. It is desirable to provide a continuous process for the purification of biodiesel. It is further desirable to provide a process that once charged with adsorbent comprises a closed system requiring no fresh water or new adsorbent for operation and generating no waste water or solid waste that needs to be treated or disposed of. Such a system is both economical and environmentally friendly. 
         [0025]    A regenerable column adsorption system has been described. U.S. Pat. No. 6,635,595 describes a process for simultaneous alkyl esterification of edible oil and regeneration of spent oil purification medium. The process includes the simultaneous regeneration of spent clay and in situ recovery of oil from spent clay and conversion of the same to alkyl esters by treating the spent clay with alcohols. The process treats a mixture of spent clay (which contains residual oil from the edible oil refining processes) and vegetable oil such that the clay can be regenerated at the same time the oil is converted into alkyl esters. After this process, the regenerated spent bleaching earth is further activated at 120-500° C. for 2-6 hours so that it can be reused for the bleaching of vegetable oils (in refining process). The regeneration of the clay adsorbent material is described in this patent such that it could be reused in the vegetable oil refining process, but not in biodiesel purification. 
       SUMMARY OF THE INVENTION 
       [0026]    A quick, economical and environmentally friendly, “green”, process for the continuous purification of biodiesel (fatty acid alkyl esters (FAAE)) is described using a powdered, granulated or extruded adsorbent. The adsorbent is contained in a column system and is regenerated for reuse multiple times. The process employs an adsorbent such as, but not limited to, carbon, silica, clay, zeolite, or a metal silicate contained in one or more columns to remove the impurities from fatty acid alkyl esters (FAAE) or crude biodiesel in a continuous process. The process utilizes the adsorbent column system for the purification of biodiesel, rather than water or filtration, to remove soaps and other impurities entrained in crude biodiesel. The crude biodiesel is contacted with an adsorbent packed into a column, or multiple columns in series, for a sufficient amount of time to remove impurities such as, but not limited to, soaps, metals, free glycerin, sterol glycosides and many of the other impurities that reduce the stability of biodiesel. The resulting finished biodiesel exiting the column(s) is ready for the methanol recovery process. The life cycle of the adsorbent in the column(s) depends on the level of impurities in the incoming crude biodiesel, the quantity and adsorptive capacity of the adsorbent in the column(s), and the flow rate of the crude biodiesel through the column system. When the biodiesel exiting the column system no longer meets required specifications, the adsorbent is regenerated for reuse. 
         [0027]    Regeneration of the adsorbent column is accomplished with a polar solvent such as methanol typically used in the transesterification process. The use of the same polar solvent for the regeneration step as the transesterification step provides for simplicity, economy, and cost containment through purchasing economies. The polar solvent is infused with a small quantity of acid, such as sulfuric acid, and passed through the adsorbent in the column to remove the adsorbed impurities contained in and on the adsorbent. The alcohol/acid is passed through the column and recycled back to the transesterification reaction until such time as little or no impurities are in the alcohol/acid filtrate. The adsorbent is then ready for reuse. 
         [0028]    This regeneration process makes this system both economical and environmentally friendly. Regeneration and reuse of the adsorbent eliminates the large amounts of fresh water, resulting effluent, and/or solid filter cake waste produced during water or adsorbent filtration biodiesel purification processes. Biodiesel so treated results in a product acceptable to proceed to the methanol recovery step without the need for water washing or adsorptive treatment with filtration. The reclamation of the solvent used for regeneration further enhances the economics of the process and its environmental benefits. 
         [0029]    Ion exchange resin, while very expensive, has been shown to effectively adsorb glycerin and remove some metals by ion exchange of metal for hydrogen, thereby converting metal soaps to free fatty acids. Because free fatty acids are released into the crude biodiesel filtrate after ion exchange treatment, careful monitoring of the treated crude biodiesel is required to insure that the acid value specification is met in the finished biodiesel if only ion exchange purification is used. It has further been shown that ion exchange resin may be regenerated for reuse for removal of glycerin from crude biodiesel but it cannot be regenerated for reuse for the removal of metals from crude biodiesel (see Table 2). When used alone in a biodiesel process, the ion exchange resin must be disposed of when the resin becomes saturated with metals. For this reason, ion exchange resin is not economically suitable by itself for the purification of crude biodiesel. However, it may be used as a pretreatment to remove glycerin from crude biodiesel prior to further processing by passing through the adsorbent column for removal of soaps, metals, and other impurities. 
         [0030]    Ion-exchange resin may be packed into one or more columns and can be used first in series for treatment of the biodiesel before the biodiesel is contacted with the adsorbent column(s). Alcohol can also be used for the regeneration of the ion-exchange resin. The alcohol/impurities mixture from the ion-exchange resin column containing alcohol, glycerin and residual fatty acid alkyl esters (FAAE) can be directed to a settling tank to separate the glycerin from the alcohol and residual FAAE. The alcohol/acid/impurities mixture from the adsorbent column containing alkyl soaps, metals, glycerin and residual fatty acid alkyl esters (FAAE) can be directed to a reaction vessel and reacted with an acid, such as sulfuric acid, in the previously described esterification reaction prior to being directed to the settling tank to separate the glycerin and other impurities from the alcohol and residual FAAE. The acid selected for the esterification reaction may be the same as selected for the regeneration process in order to provide for simplicity, economy, and cost containment through purchasing economies of scale. 
         [0031]    The invention will be more fully described by reference to the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a schematic diagram of a system for biodiesel purification using an adsorbent column purification method in accordance with the teachings of the present invention. 
           [0033]      FIG. 2  is a schematic diagram of the system for biodiesel purification during regeneration of the adsorbent. 
           [0034]      FIG. 3  is a schematic diagram of an alternative embodiment of a system for biodiesel purification using multiple adsorbent columns in accordance with the teachings of the present invention. 
           [0035]      FIG. 4  is a schematic diagram of the system shown in  FIG. 3  in which the lead column of  FIG. 3  is being regenerated. 
           [0036]      FIG. 5  is a schematic diagram of an alternative embodiment of a system for biodiesel purification using an ion-exchange and adsorption column purification method in accordance with the teachings of the present invention. 
           [0037]      FIG. 6  is a schematic diagram of the system shown in  FIG. 5  during regeneration of the ion-exchange and/or adsorbent columns. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
         [0039]      FIG. 1  is a schematic diagram of continuous biodiesel purification by adsorbent system  10  in accordance with the teachings of the present invention. In a first embodiment, a single adsorbent column  12  packed with adsorbent material  14  is used to purify crude biodiesel  16 . Crude biodiesel  16  comprises a crude feed of fatty acid alkyl esters (FAAE). Crude biodiesel  16  is contacted with a sufficient amount of adsorbent material  14  for a sufficient amount of time to remove impurities, such as, but not limited to soaps, catalyst, metals, free glycerin, sterol glycosides and other impurities that reduce the stability of biodiesel. Suitable adsorbent materials  14  include carbon, silica, metal silicate, zeolite, bleaching clay and activated bleaching clay. In a preferred embodiment, the adsorbent material is synthetic magnesium silicate. 
         [0040]    Purified biodiesel  17  exiting adsorbent column  12  is a purified biodiesel suitable to proceed to methanol recovery without the need for water washing or adsorptive treatment with filtration. Purified biodiesel  17  exiting adsorbent column  12  is fed to flash evaporator  18 . Flash evaporator  18  recovers alcohol, for example, methanol, from purified biodiesel  17  to produce finished biodiesel product  19 . 
         [0041]    During the column adsorption purification step, crude biodiesel  16  flows through column  12  until such time as adsorbent material  14  no longer removes sufficient impurities from crude biodiesel  16 . This is determined by comparing the level of impurities in crude biodiesel  16  entering adsorbent column  12  to those in purified biodiesel  17  exiting adsorbent column  12 . At such time as purified biodiesel  17  exiting adsorbent column  12  no longer meets the required specification or desired parameters, a regeneration of adsorbent material  14  is performed. 
         [0042]    During regeneration, crude biodiesel  16  feed is stopped from adsorption column  12  and adsorbent material  14  within adsorbent column  12  is regenerated, as shown in  FIG. 2 . Solvent feed  20  is passed through adsorbent column  12  until such time that mixture  21  exiting adsorbent column  12  contains an acceptable impurity level, such as an impurity level having a value of zero, indicating that most if not all impurities have been stripped for the impurity saturated adsorbent. A suitable solvent feed  20  is a solution of a solvent containing an acid. In one embodiment, the solvent is alcohol. For example, the solvent can be methanol. In one embodiment, the acid is sulfuric acid, citric acid, or malic acid. The amount of acid added to the alcohol is about 0.005% to about 3.00% by weight. 
         [0043]    After regeneration, mixture  21  exiting adsorbent column  12  is directed to acid esterification vessel  22  and is reacted with acid  23 . Acid  23  selected for the esterification reaction in esterification vessel  22  can be the same or different than the acid described above used in regeneration of the adsorbent. For example, a suitable acid  23  is sulfuric acid. Acid  23  is used as a catalyst to directly esterify the corresponding alkyl soaps into crude fatty acid alkyl esters (FAAE). Mixture  24  exiting esterification vessel  22  comprises alcohol, fatty acid alkyl esters (FAAE), glycerin, excess acid, and water. Mixture  24  is sent to settling tank  26  to separate glycerin and other impurities from alcohol/fatty acid alkyl esters (FAAE). Mixture  24  is separated into glycerin/impurities phase  27  and alcohol/FAAE phase  28 . Glycerin/impurities phase  27  is combined with the glycerin phase from the transesterification reaction. Alcohol/FAAE phase  28  can be sent directly to the transesterification reaction for further processing. 
         [0044]    After the regeneration of adsorbent material  14 , adsorbent column  12  is restarted by passing crude biodiesel  16  through adsorbent column  12  as shown in  FIG. 1 . While regeneration is performed on a first adsorbent column  12 , the use of a second adsorbent column can be employed for the purification process while the first column is being regenerated providing for a continuous process. 
         [0045]    In a second embodiment, a plurality of adsorbent columns  12   a - 12   b  packed with adsorbent material  14  are used in series to purify crude biodiesel  16  in system  100 , as shown in  FIG. 3 . The use of multiple adsorbent columns allows for a continuous process. After crude biodiesel  16  is separated from glycerin, it is contacted with adsorbent material  14  in lead adsorbent column  12   a . Purified biodiesel  17   a  exiting adsorbent column  12   a  is contacted with adsorbent material  14  in lag adsorbent column  12   b  containing adsorbent material  14  to intercept impurities remaining in the crude biodiesel. Purified biodiesel  17   b  exiting adsorbent column  12   b  is subjected to flash evaporation to remove residual alcohol. 
         [0046]    During the column adsorption purification step, crude biodiesel  16  flows through adsorbent column  12   a  until such time as adsorbent material  14  no longer removes sufficient impurities from crude biodiesel  16 . This is determined by comparing the level of impurities in the crude biodiesel entering adsorbent column  12   a  to those in purified biodiesel  17   a  exiting adsorbent column  12   a . At such time as purified biodiesel  17   a  exiting adsorbent column  12   a  no longer meets the required specification or desired parameters, regeneration of adsorbent material  14  is performed in lead adsorbent column  12   a , as shown in  FIG. 4 . During regeneration, first lag column  12   b  in the series becomes the new lead column and any subsequent lag column(s) are moved up in the order of contact. Adsorbent material  14  in the original lead adsorbent column  12   a  is regenerated for reuse and becomes the last column in system  100 . 
         [0047]    In a third embodiment, one or more adsorbent column(s)  12  containing adsorbent material  14  and one or more ion-exchange column(s)  32  containing an ion-exchange resin  34  are used in series to purify crude biodiesel  16  in system  200 , as shown in  FIG. 5 . The ion-exchange resin can be cationic. One or more ion-exchange resin column(s)  32  are used first in the series to intercept any free glycerin and some of the metals from the alkyl soaps remaining in crude biodiesel  16 . The resulting biodiesel  33  is then passed through one or more adsorbent column(s)  12  packed with adsorbent material  14  to remove the remaining impurities resulting in purified biodiesel  17  suitable to proceed to methanol recovery without the need for water washing or adsorptive treatment with filtration. 
         [0048]    The crude biodiesel is contacted in one or more ion-exchange column(s)  32  and adsorbent column(s)  12  and until such time as the ion-exchange resin and/or adsorbent material  14  no longer remove sufficient impurities from crude biodiesel  16 . This is determined by comparing the level of impurities in crude biodiesel  16  entering ion-exchange column(s)  32  and/or adsorbent column(s)  12  to those in biodiesel  33  and purified biodiesel  17  exiting the respective columns. At such time as biodiesel  33  and purified biodiesel  17  exiting ion-exchange column(s)  32  and/or adsorbent column(s)  12  no longer meets the desired specifications or parameters, a second identical set of ion-exchange column(s)  32  and/or adsorbent exchange column(s)  12  is employed. While employing the second set of columns, the ion-exchange resin and/or adsorbent in the first set of columns are regenerated for re-use, as shown in  FIG. 6 . After the regeneration process, ion-exchange column(s)  32  and adsorbent column(s)  12  are ready for reuse and can be brought back on stream as a second set of columns, as desired. 
         [0049]    Regeneration of ion-exchange resin column  32  is accomplished with a polar solvent such as alcohol, typically methanol, used in the transesterification process and is passed through ion-exchange column(s)  32  to remove primarily glycerin, contained in and on ion-exchange resin  33 . The solvent is passed through ion-exchange column(s)  32  until such time as little or no glycerin is in the solvent filtrate  41 . 
         [0050]    The invention can be further illustrated by the following examples thereof, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated. All percentages, ratios, and parts herein, in the Specification, Examples, and Claims, are by weight and are approximations unless otherwise stated. 
       Example 1 
     Single Column Purification Using Adsorbent Materials 
       [0051]    Crude biodiesel was passed through a single column containing 2 g adsorbent material. The two adsorbents used in the example were: synthetic magnesium silicate (MAGNESOL® D-SOL D60 from The Dallas Group of America, Whitehouse, N.J.) and an acid activated clay (REFOIL RO-365 from Refoil Earth Pvt. Ltd., Vadodara, India). A summary of the results obtained from these two products is shown in Table 1. The crude biodiesel was passed through the column until such time that the soap content of the biodiesel exiting the column was greater than 50 ppm. The value of 50 ppm soap was chosen as the cutoff point as it corresponds to the 5 ppm specification of metals (sodium+potassium). 
         [0052]    At such time that the biodiesel exiting the column contained more than 50 ppm soap, the column treatment was stopped and either the synthetic magnesium or the acid activated clay in the column was regenerated. A solution containing 0.10% sulfuric acid (93%) in methanol was passed through the column until such time that the methanol/sulfuric acid mixture exiting the column contained a soap value of zero. 
         [0053]    After the regeneration of the product, the column was restarted by passing the crude biodiesel through the column. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Results for Single Column Purification Using Adsorbent Materials 
               
             
          
           
               
                   
                 REFOIL RO-365 
                 MAGNESOL D-SOL D60 
               
             
          
           
               
                   
                 Column Throughput 
                   
                 Column Throughput 
                   
               
               
                 SINGLE COLUMN 
                 (mL) 
                   
                 (mL) 
               
             
          
           
               
                 Column Loading 
                 per 
                   
                 % Treatment 
                 per 
                   
                 % Treatment 
               
               
                 2 g 
                 Cycle 
                 Cumulative 
                 Cumulative 
                 Cycle 
                 Cumulative 
                 Cumulative 
               
               
                   
               
             
          
           
               
                 Initial Cycle 
                 203 
                 203 
                 1.095% 
                 569 
                 569 
                 0.391% 
               
               
                 After 1st Regeneration 
                 617 
                 820 
                 0.271% 
                 510 
                 1079 
                 0.206% 
               
               
                 After 2 nd  Regeneration 
                 303 
                 1123 
                 0.198% 
                 487 
                 1566 
                 0.142% 
               
               
                 After 3 rd  Regeneration 
                 739 
                 1862 
                 0.119% 
                 833 
                 2399 
                 0.093% 
               
               
                 After 4th Regeneration 
                 542 
                 2404 
                 0.092% 
                 773 
                 3172 
                 0.070% 
               
               
                 After 5th Regeneration 
                 77 
                 2481 
                 0.090% 
                 799 
                 3971 
                 0.056% 
               
               
                 After 6th Regeneration 
                 395 
                 2876 
                 0.077% 
                 1215 
                 5186 
                 0.043% 
               
               
                 After 7th Regeneration 
                 346 
                 3222 
                 0.069% 
                 661 
                 5847 
                 0.038% 
               
               
                 After 8th Regeneration 
                 415 
                 3637 
                 0.061% 
                 1005 
                 6852 
                 0.032% 
               
               
                 After 9th Regeneration 
                 401 
                 4038 
                 0.055% 
                 950 
                 7802 
                 0.028% 
               
               
                 After 10th Regeneration 
                 0 
                 4038 
                 0.055% 
                 971 
                 8773 
                 0.025% 
               
               
                 After 11th Regeneration 
                 95 
                 4133 
                 0.054% 
                 1171 
                 9944 
                 0.022% 
               
               
                 After 12th Regeneration 
                 115 
                 4248 
                 0.052% 
                 794 
                 10738 
                 0.021% 
               
               
                 After 13th Regeneration 
                 182 
                 4430 
                 0.050% 
                 1185 
                 11923 
                 0.019% 
               
               
                 After 14th Regeneration 
                 418 
                 4848 
                 0.046% 
                 1175 
                 13098 
                 0.017% 
               
               
                 AVERAGE mL 
                 404 
                   
                   
                 873 
               
               
                 TOTAL mL 
                 4038 
                   
                   
                 13098 
               
               
                 TOTAL g 
                 3634 
                   
                   
                 11788 
               
               
                 % Treatment 
                 0.055% 
                   
                   
                 0.017% 
               
               
                   
               
             
          
         
       
     
       Example 2 
     Comparative Examples of Ion-Exchange Resin for Regeneration 
       [0054]    Crude biodiesel was passed through a single column containing 2 g ion-exchange resin (AMBERLITE BD10DRY from Rohm and Haas, West Philadelphia, Pa.). The crude biodiesel was passed through the column until such time that the soap content of the biodiesel exiting the column was greater than 50 ppm. The value of 50 ppm soap was chosen as the cutoff point as it corresponds to the 5 ppm specification of metals (sodium+potassium). The results from the use of AMBERLITE BD10DRY are shown in Table 2. 
         [0055]    At such time that the biodiesel exiting the column contained more than 50 ppm soap, the column treatment was stopped and an attempt to regenerate the ion-exchange resin in the column was made. A solution containing 0.10% sulfuric acid (93%) in methanol was passed through the column and the resulting soap content of the methanol exiting the column was periodically checked. There was no measurable soap content in the methanol/sulfuric acid exiting the column. 
         [0056]    After passing 200 mL of the methanol/sulfuric acid through the column containing the ion-exchange resin, flow of crude biodiesel through the column was restarted by passing the crude biodiesel through the column. The resulting biodiesel exiting the column was again monitored for soap content, but was never below 50 ppm. These results show that the ion-exchange resin cannot be regenerated for soap removal from the crude biodiesel. However, the ion-exchange resins did remove free glycerin from the crude biodiesel after regeneration. Therefore, the regeneration of ion exchange resin applies only to free glycerin and not soaps or metals. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Results for Column Treatment of Crude Biodiesel 
               
               
                 Using AMBERLITE BD10DRY (ion-exchange resin) 
               
             
          
           
               
                 Amount through 
                 Time 
                 Flow Rate 
                 Soap 
                 % Free 
                 Water 
               
               
                 column (ml) 
                 (min) 
                 (ml/min) 
                 (ppm) 
                 Glycerin 
                 (ppm) 
               
               
                   
               
             
          
           
               
                 Initial Startup 
                   
               
             
          
           
               
                 100 
                 646 
                 0.15 
                 45 
                 0.002 
                 225 
               
               
                 198 
                 1428 
                 0.14 
                 68 
               
               
                 273 
                 2193 
                 0.12 
                 64 
               
               
                 333 
                 2577 
                 0.13 
                 199 
                 0.009 
                 435 
               
             
          
           
               
                 After 1st Regeneration 
                   
               
             
          
           
               
                 100 
                 751 
                 0.13 
                 117 
                   
                   
               
               
                 187 
                 1262 
                 0.15 
                 233 
                 0.012 
                 304 
               
               
                   
               
             
          
         
       
     
       Example 3 
     Dual Column Purification Using Synthetic Magnesium Silicate 
       [0057]    Crude biodiesel was passed through a two column system in series containing 2 g adsorbent material in each column. The two adsorbents used in the example were: synthetic magnesium silicate (MAGNESOL D-SOL D60 from The Dallas Group of America, Whitehouse, N.J.) and an acid activated clay (REFOIL RO-365 from Refoil Earth Pvt. Ltd., Vadodara, India). A summary of the results obtained from these two products is shown in Table 3. The crude biodiesel was passed through the column until such time that the soap content of the biodiesel exiting the column was greater than 50 ppm. The value of 50 ppm soap was chosen as the cutoff point as it corresponds to the 5 ppm specification of metals (sodium+potassium). 
         [0058]    At such time that the biodiesel exiting the column contained more than 50 ppm soap, the column treatment was stopped and either the synthetic magnesium silicate or acid activated clay in the lead column was regenerated. A solution containing 0.10% sulfuric acid (93%) in methanol was passed through the column until such time that the methanol/sulfuric acid mixture exiting the column contained a soap value of zero. 
         [0059]    After the regeneration of the product, the lag column became the new lead column and the regenerated lead column was placed back in series as the new lag column. Thereafter, crude biodiesel was passed through the column system. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Results for Dual Column Purification Using Synthetic Magnesium Silicate 
               
             
          
           
               
                   
                 REFOIL RO-365 
                 MAGNESOL D-SOL D60 
               
             
          
           
               
                 TWO COLUMNS 
                 Column Throughput 
                   
                 Column Throughput 
                   
               
               
                 Column Loading 
                 (mL) 
                 % Treatment 
                 (mL) 
                 % Treatment 
               
             
          
           
               
                 4 g 
                 per Cycle 
                 Cumulative 
                 Cumulative 
                 per Cycle 
                 Cumulative 
                 Cumulative 
               
               
                   
               
             
          
           
               
                 Initial Cycle 
                 1297 
                 1297 
                 0.343% 
                 1826 
                 1826 
                 0.243% 
               
               
                 After 1st Regen. 
                 1432 
                 2729 
                 0.163% 
                 1744 
                 3570 
                 0.124% 
               
               
                 After 2nd Regen. 
                 1209 
                 3938 
                 0.113% 
                 1257 
                 4827 
                 0.092% 
               
               
                 After 3rd Regen. 
                 1631 
                 5569 
                 0.080% 
                 2486 
                 7313 
                 0.061% 
               
               
                 After 4th Regen. 
                 1031 
                 6600 
                 0.067% 
                 1743 
                 9056 
                 0.049% 
               
               
                 After 5th Regen. 
                 1288 
                 7888 
                 0.056% 
                 2944 
                 12000 
                 0.037% 
               
               
                 After 6th Regen. 
                 655 
                 8543 
                 0.052% 
                 1797 
                 13797 
                 0.032% 
               
               
                 After 7th Regen. 
                 1203 
                 9746 
                 0.046% 
                 3053 
                 16850 
                 0.026% 
               
               
                 AVERAGE mL 
                 1218 
                   
                   
                 2106 
               
               
                 TOTAL mL 
                 9746 
                   
                   
                 16850 
               
               
                 TOTAL g 
                 8771 
                   
                   
                 15165 
               
               
                 % Treatment 
                 0.046% 
                   
                   
                 0.026% 
               
               
                   
               
             
          
         
       
     
       Example 4 
     Dual Column Purification Using Ion-Exchange Resin—Synthetic Magnesium Silicate 
       [0060]    Crude biodiesel was passed through a two column system in series containing 2 g of a commercially available ion-exchange resin (AMBERLITE BD10Dry from Rohm and Haas, West Philadelphia, Pa.) and 2 g synthetic magnesium silicate (MAGNESOL DSOL D60 from The Dallas Group of America, Whitehouse, N.J.) in each column. The ion-exchange resin was set as the lead column and the magnesium silicate was placed in the system as the lag column. The crude biodiesel was passed through the column until such time that the soap content of the biodiesel exiting the column was greater than 50 ppm. The value of 50 ppm soap was chosen as the cutoff point as it corresponds to the 5 ppm specification of metals (sodium+potassium). The results from this series of tests are shown in Table 4 below. 
         [0061]    At such time that the biodiesel exiting the column contained more than 50 ppm soap, the column treatment was stopped and both the ion-exchange resin in the lead column and the synthetic magnesium silicate in the lag column were regenerated. The ion-exchange resin was regenerated according to the procedure described in embodiment 3 using pure methanol and the magnesium silicate was regenerated according to the procedure under the section “Regeneration of Adsorbent”. A solution containing 0.10% sulfuric acid (93%) in methanol was passed through the column containing the synthetic magnesium silicate until such time that the methanol/sulfuric acid mixture exiting the column contained a soap value of zero. 
         [0062]    After the regeneration of the product, both columns were placed back into series in the same order, with the ion-exchange resin as the lead column and the magnesium silicate as the lag column. Once again, crude biodiesel was passed through the column system. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Results for Dual Column Purification Using AMBERLITE BD10Dry 
               
               
                 (ion-exchange resin) - MAGNESOL D-SOL D60 (synthetic 
               
               
                 magnesium silicate) 
               
             
          
           
               
                   
                   
                 AMBERLITE-MAGNESOL 
               
               
                   
                 TWO 
                 D-SOL D60 
               
             
          
           
               
                   
                 COLUMNS 
                 Column Throughput 
                   
               
               
                   
                 Column Loading 
                 (mL) 
                 % Treatment 
               
             
          
           
               
                   
                 4 g 
                 per Cycle 
                 Cumulative 
                 Cumulative 
               
               
                   
                   
               
             
          
           
               
                   
                 Initial 
                 4173 
                 4173 
                 0.107% 
               
               
                   
                 After 1st Regen. 
                 2642 
                 6815 
                 0.065% 
               
               
                   
                 After 2nd Regen. 
                 2088 
                 8903 
                 0.050% 
               
               
                   
                 After 3rd Regen. 
                 735 
                 9638 
                 0.046% 
               
               
                   
                 After 4th Regen. 
                 1003 
                 10641 
                 0.042% 
               
               
                   
                 After 5th Regen. 
                 780 
                 11421 
                 0.039% 
               
               
                   
                 After 6th Regen. 
                 600 
                 12021 
                 0.037% 
               
               
                   
                 After 7th Regen. 
                 670 
                 12691 
                 0.035% 
               
               
                   
                 AVERAGE mL 
                 1586 
               
               
                   
                 TOTAL mL 
                 12691 
               
               
                   
                 TOTAL g 
                 11422 
               
               
                   
                 % Treatment 
                 0.035% 
               
               
                   
                   
               
             
          
         
       
     
       Example 5 
     Regeneration of Adsorbent Using Methanol/Acid 
       [0063]    Crude biodiesel was passed through a column containing 40 g synthetic magnesium silicate (MAGENSOL D-SOL D60 from The Dallas Group of America, Inc., Whitehouse, N.J.) at a rate of 20 mL/minute until the synthetic magnesium silicate powder contained 0.45 g soap per gram of adsorbent. The soap content of the crude biodiesel was 2094 ppm. Samples were taken of the biodiesel exiting the column throughout the test and analyzed for soap content, as shown in Table 5. Once the synthetic magnesium silicate reached the 0.45 g soap per gram of adsorbent, the column was stopped and the adsorbent saturated with soap was taken out of the column. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
             
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Loading of Soap onto MAGNESOL D-SOL D60 
               
               
                 (synthetic magnesium silicate) 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Soap 
               
               
                   
                 Soap 
                 mL 
                 g 
                 g 
                 Adsorbed 
               
               
                 Sample 
                 (ppm) 
                 Biodiesel 
                 Biodiesel 
                 Soap 
                 (ppm) 
               
               
                   
               
             
          
           
               
                 Initial 
                 2094 
                   
               
             
          
           
               
                 100 
                 ml 
                 34 
                 100 
                 90 
                 0.1854 
                 2060 
               
               
                 200 
                 ml 
                 0 
                 100 
                 90 
                 0.18846 
                 2094 
               
               
                 300 
                 ml 
                 22 
                 100 
                 90 
                 0.18648 
                 2072 
               
               
                 400 
                 ml 
                 51 
                 100 
                 90 
                 0.18387 
                 2043 
               
               
                 900 
                 ml 
                 173 
                 500 
                 450 
                 0.86445 
                 1921 
               
               
                 1400 
                 ml 
                 218 
                 500 
                 450 
                 0.8442 
                 1876 
               
               
                 1900 
                 ml 
                 246 
                 500 
                 450 
                 0.8316 
                 1848 
               
               
                 2400 
                 ml 
                 227 
                 500 
                 450 
                 0.84015 
                 1867 
               
               
                 2900 
                 ml 
                 245 
                 500 
                 450 
                 0.83205 
                 1849 
               
               
                 3400 
                 ml 
                 312 
                 500 
                 450 
                 0.8019 
                 1782 
               
               
                 3900 
                 ml 
                 409 
                 500 
                 450 
                 0.75825 
                 1685 
               
               
                 4400 
                 ml 
                 492 
                 500 
                 450 
                 0.7209 
                 1602 
               
               
                 4900 
                 ml 
                 581 
                 500 
                 450 
                 0.68085 
                 1513 
               
               
                 5400 
                 ml 
                 693 
                 500 
                 450 
                 0.63045 
                 1401 
               
               
                 5900 
                 ml 
                 740 
                 500 
                 450 
                 0.6093 
                 1354 
               
               
                 6400 
                 ml 
                 792 
                 500 
                 450 
                 0.5859 
                 1302 
               
               
                 6900 
                 ml 
                 803 
                 500 
                 450 
                 0.58095 
                 1291 
               
               
                 7400 
                 ml 
                 703 
                 500 
                 450 
                 0.62595 
                 1391 
               
               
                 7900 
                 ml 
                 702 
                 500 
                 450 
                 0.6264 
                 1392 
               
               
                 8400 
                 ml 
                 635 
                 500 
                 450 
                 0.65655 
                 1459 
               
               
                 8900 
                 ml 
                 729 
                 500 
                 450 
                 0.61425 
                 1365 
               
               
                 9400 
                 ml 
                 615 
                 500 
                 450 
                 0.66555 
                 1479 
               
               
                 9900 
                 ml 
                 618 
                 500 
                 450 
                 0.6642 
                 1476 
               
               
                 10400 
                 ml 
                 624 
                 500 
                 450 
                 0.6615 
                 1470 
               
               
                 10900 
                 ml 
                 651 
                 500 
                 450 
                 0.64935 
                 1443 
               
               
                 11400 
                 ml 
                 681 
                 500 
                 450 
                 0.63585 
                 1413 
               
               
                 11900 
                 ml 
                 695 
                 500 
                 450 
                 0.62955 
                 1399 
               
               
                 12400 
                 ml 
                 700 
                 500 
                 450 
                 0.6273 
                 1394 
               
               
                 12900 
                 ml 
                 713 
                 500 
                 450 
                 0.62145 
                 1381 
               
               
                   
                   
                 TOTALS 
                 12900 
                 9810 
                 18.00306 
               
             
          
           
               
                   
                 Amount of Soap adsorbed (g) per gram of adsorbent 
                 0.4500765 
               
               
                   
                   
               
             
          
         
       
     
         [0064]    The synthetic magnesium silicate loaded with soap was split into 5 gram portions, each placed into smaller columns to be regenerated. The regeneration of the adsorbent was carried out using different concentrations of 93% sulfuric acid, citric acid and malic acid powder in methanol. The solutions of acid/methanol were passed through the adsorbent in the column until such time that the soap content of the solution exiting the column was approximately zero. 
         [0065]    Table 6 summarizes the conditions and results of the regenerations using 93% sulfuric acid with methanol. Table 7 shows results for regenerations using citric acid with methanol. Table 8 shows results for regenerations using citric acid with methanol. It is clear from these results that the adsorbent is effectively stripped of the impurities adsorbed from crude biodiesel and, is therefore suitable for reuse in the purification of crude biodiesel. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Summary of Conditions and Results Of Regeneration of MAGNESOL D- 
               
               
                 SOL D60 (synthetic magnesium silicate) Using Methanol/Sulfuric Acid 
               
             
          
           
               
                 Volume (ml) 
                 Hr. 
                 Min 
                 Flow Rate (mL/min.) 
                 Soap (ppm) 
               
               
                   
               
             
          
           
               
                 0.10% w/w Sulfuric Acid in Methanol 
               
             
          
           
               
                 52 
                 2 
                 32 
                 0.34 
                 7926 
               
               
                 104 
                 5 
                 3 
                 0.34 
                 1547 
               
               
                 154 
                 7 
                 35 
                 0.34 
                 781 
               
               
                 200 
                 9 
                 43 
                 0.34 
                 193 
               
               
                 230 
                 11 
                 13 
                 0.34 
                 83 
               
               
                 260 
                 12 
                 47 
                 0.34 
                 0 
               
             
          
           
               
                 0.20% w/w Sulfuric Acid in Methanol 
               
             
          
           
               
                 27 
                 1 
                 27 
                 0.31 
                 13309 
               
               
                 75 
                 4 
                 1 
                 0.31 
                 1889 
               
               
                 100 
                 5 
                 5 
                 0.33 
                 957 
               
               
                 131 
                 6 
                 36 
                 0.33 
                 167 
               
               
                 163 
                 8 
                 11 
                 0.33 
                 0 
               
             
          
           
               
                 0.39% w/w Sulfuric Acid in Methanol 
               
             
          
           
               
                 26 
                 1 
                 16 
                 0.34 
                 13060 
               
               
                 55 
                 2 
                 40 
                 0.34 
                 1605 
               
               
                 88 
                 4 
                 16 
                 0.34 
                 0 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Summary of Conditions and Results of Regeneration of MAGNESOL D- 
               
               
                 SOL D60 (synthetic magnesium silicate) Using Methanol/Citric Acid 
               
             
          
           
               
                 Volume (ml) 
                 Hr. 
                 Min 
                 Flow Rate (mL/min.) 
                 Soap (ppm) 
               
               
                   
               
             
          
           
               
                 0.11% w/w Citric Acid in Methanol 
               
             
          
           
               
                 52 
                 2 
                 29 
                 0.35 
                 8134 
               
               
                 104 
                 4 
                 57 
                 0.35 
                 3980 
               
               
                 154 
                 7 
                 24 
                 0.35 
                 3991 
               
               
                 200 
                 9 
                 11 
                 0.36 
                 720 
               
               
                 258 
                 12 
                 2 
                 0.36 
                 184 
               
               
                 312 
                 14 
                 42 
                 0.35 
                 0 
               
             
          
           
               
                 0.23% w/w Citric Acid in Methanol 
               
             
          
           
               
                 56 
                 2 
                 46 
                 0.34 
                 8173 
               
               
                 116 
                 5 
                 26 
                 0.36 
                 3519 
               
               
                 169 
                 8 
                 13 
                 0.34 
                 1892 
               
               
                 195 
                 9 
                 23 
                 0.35 
                 0 
               
             
          
           
               
                 0.45% w/w Citric Acid in Methanol 
               
             
          
           
               
                 50 
                 2 
                 27 
                 0.34 
                 9061 
               
               
                 100 
                 4 
                 55 
                 0.34 
                 5211 
               
               
                 140 
                 6 
                 55 
                 0.34 
                 2526 
               
               
                 195 
                 9 
                 36 
                 0.34 
                 0 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 Summary of Conditions and Results of Regeneration of MAGNESOL D- 
               
               
                 SOL D60 (synthetic magnesium silicate) Using Methanol/Malic Acid 
               
             
          
           
               
                 Volume (ml) 
                 Hr. 
                 Min 
                 Flow Rate (mL/min.) 
                 Soap (ppm) 
               
               
                   
               
             
          
           
               
                 0.11% w/w Malic Acid with Methanol 
               
             
          
           
               
                 49 
                 2 
                 29 
                 0.33 
                 8322 
               
               
                 100 
                 5 
                 6 
                 0.33 
                 4691 
               
               
                 125 
                 6 
                 18 
                 0.33 
                 4867 
               
               
                 171 
                 9 
                 21 
                 0.30 
                 2544 
               
               
                 200 
                 10 
                 18 
                 0.32 
                 2003 
               
               
                 253 
                 13 
                 6 
                 0.32 
                 88 
               
               
                 280 
                 14 
                 32 
                 0.32 
                 0 
               
             
          
           
               
                 0.23% Malic Acid with Methanol 
               
             
          
           
               
                 29 
                 1 
                 23 
                 0.35 
                 12120 
               
               
                 74 
                 3 
                 40 
                 0.34 
                 8409 
               
               
                 119 
                 5 
                 56 
                 0.33 
                 3750 
               
               
                 161 
                 8 
                 1 
                 0.33 
                 406 
               
               
                 191 
                 9 
                 32 
                 0.33 
                 0 
               
             
          
           
               
                 0.40% Malic Acid with Methanol 
               
             
          
           
               
                 27 
                 1 
                 23 
                 0.33 
                 16614 
               
               
                 72 
                 3 
                 40 
                 0.33 
                 7269 
               
               
                 116 
                 5 
                 56 
                 0.33 
                 30 
               
               
                 157 
                 8 
                 1 
                 0.33 
                 0 
               
               
                   
               
             
          
         
       
     
         [0066]    It is to be understood that the above-described embodiments are illustrative of only a few of the many possible specific embodiments, which can represent applications of the principles of the invention Numerous and varied other arrangements can be readily devised in accordance with these principles by those skilled in the art without departing from the spirit and scope of the invention.