Glycerol purification

There are basically two options in the purification, that is, the water washing process and adsorbent treatment process (water-free process). In the water washing process the main drawbacks are the amount of wastewater produced and the energy costs to evaporate and recover water for re-use. In the adsorbent treatment process the problems are the high cost of adsorbent (e.g., Mg-silicate) and the disposal of the spent adsorbents. A potential cleaner process should thus eliminate the catalyst cleanup step and simplify biodiesel and glycerol purification. The options are (i) the use of heterogeneous solid catalysts, (ii) the use of an enzymatic transesterification processes and (iii) a catalyst-free process, using, for example, supercritical methanol. 

MetaUic ions are precipitated as their hydroxides from aqueous caustic solutions. The reactions of importance in chlor—alkali operations are removal of magnesium as Mg(OH)2 during primary purification and of other impurities for pollution control. Organic acids react with NaOH to form soluble salts. Saponification of esters to form the organic acid salt and an alcohol and internal coupling reactions involve NaOH, as exemplified by reaction with triglycerides to form soap and glycerol,... 

The sweet water from continuous and batch autoclave processes for splitting fats contains tittle or no mineral acids and salts and requires very tittle in the way of purification, as compared to spent lye from kettle soapmaking (9). The sweet water should be processed promptly after splitting to avoid degradation and loss of glycerol by fermentation. Any fatty acids that rise to the top of the sweet water are skimmed. A small amount of alkali is added to precipitate the dissolved fatty acids and neutralize the liquor. The alkaline liquor is then filtered and evaporated to an 88% cmde glycerol. Sweet water from modem noncatalytic, continuous hydrolysis may be evaporated to ca 88% without chemical treatment. 

Dilute glycerol Hquors, after purification, are concentrated to cmde glycerol by evaporation. This process is carried out in conventional evaporation (qv) under vacuum heated by low pressure steam. In the case of soap—lye glycerol, means are suppHed for recovery of the salt that forms as the spent lye is concentrated. Multiple effort evaporators are typically used to conserve energy while concentrating to a glycerol content of 85—90%. 

The methods of analysis of the American Oil Chemists Society (AOCS) are the principal procedures followed in the United States and Canada and are official in commercial transactions. When the material is for human consumption or dmg use, it must meet the specifications of the USP (12). Commercial distilled grades of glycerol do not requite purification before analysis by the usual methods. The deterrnination of glycerol content by the periodate method (13), which replaced the acetin and dichromate methods previously used, is more accurate and more specific as well as simpler and more rapid. 

The following are some of the typical industrial applications for liquid-phase carbon adsorption. Generally liquid-phase carbon adsorbents are used to decolorize or purify liquids, solutions, and liquefiable materials such as waxes. Specific industrial applications include the decolorization of sugar syrups the removal of sulfurous, phenolic, and hydrocarbon contaminants from wastewater the purification of various aqueous solutions of acids, alkalies, amines, glycols, salts, gelatin, vinegar, fruit juices, pectin, glycerol, and alcoholic spirits dechlorination the removal of... 

Snape JR, NA Walkley, AP Morby, S Nicklin, GF White (1997) Purification, properties, and sequence of glycerol trinitrate reductase from Agrobacterium radiobacter. J Bacterial 179 7796-7802. 

Interestingly, the Fischer indole synthesis does not easily proceed from acetaldehyde to afford indole. Usually, indole-2-carboxylic acid is prepared from phenylhydrazine with a pyruvate ester followed by hydrolysis. Traditional methods for decarboxylation of indole-2-carboxylic acid to form indole are not environmentally benign. They include pyrolysis or heating with copper-bronze powder, copper(I) chloride, copper chromite, copper acetate or copper(II) oxide, in for example, heat-transfer oils, glycerol, quinoline or 2-benzylpyridine. Decomposition of the product during lengthy thermolysis or purification affects the yields. 

The alcoholysis of the cyclic phosphate of catechol by alditols can lead, after acid hydrolysis of intermediate, cyclic phosphates, to the selective formation of phosphoric esters of the primary hydroxyl groups in the alditols. Thus, erythritol and D-mannitol afford, after chromatographic purification of the reaction products, their 1-phosphates in yields of 31 and 38%, respectively.217 The method was used to convert riboflavine into riboflavine 5 -phosphate.218 1-Deoxy-1-fluoro-L-glycerol has been converted into the 3-(dibenzyl phosphate) in 54% yield by selective reaction with dibenzyl phosphorochloridate. 219... 

Dilute the 100,0OOg supernatant with Tris-HCl, 20 mM pH 7.5, 10% glycerol, 3 mMsodium azide, 10 mMmercaptoethanol to achieve partial purification of the enzymes. 

The resulting product (II) is subsequently coupled to bovine-serum-albumin in a glycerol-w ater mixture in the presence of dicyclohexylcarbodiimide. The mixture is incubated overnight at 4°C, and the protein-hapten complex is dialysed against distilled water thereby causing its purification. Conjugation of the respective barbiturate to the protein carrier, comparison of the barbiturate BGG-conjugate to control BGG-solution and preparation of 14C-pentobarbital sodium are carried out respectively. 

R. Verger, Purification and Characterization of a Porcine Liver Microsomal Triacyl-glycerol Hydrolase , Biochemistry 1997, 36, 1861-1868. 

Fractionation by Stepwise Elution. Information obtained from the analytical separation was applied for a preparative purification. Lignin peroxidase concentrate was bound to a Q-Sepharose colunm (0= 5 cm, V = 1000 ml) after ultrafiltration and eluted stepwise with 0.08 M, 0.18 M and 0.28 M sodium acetate, pH 6.0. The fraction which was eluted with 0.28 M buffer (V= 3.91, 4400 U/1) was purified further. It was bound to Q-Sepharose and eluted with 0.18 M and 0.3 M sodium acetate. En rnie in the latter fraction was precipitated and dissolved in glycerol as previously described. The volume was 15 ml. 

---