GB633343A - Improvements in or relating to process of purifying glycerine containing ionizable impurities - Google Patents

Abstract

Crude glycerine solutions containing at least 1000 parts per million of ionisable impurities are purified by passing them through a number of pairs of ion exchangers, the first member of each pair being a cation-active or hydrogen zeolite exchanger and the second an anion exchanger. The process is continued while the influent to the final anion exchanger contains less than about 600 parts per million of anions and 50 parts per million of cations, or while the pH of the influent to the final anion exchanger is at least 3 and/or that of the effluent from such exchanger is at least 4. It is stated that the use of more than four pairs of ion exchangers is not economical. The purified glycerine may be finally distilled in a relatively simple still and a product of high quality obtained. The process is preferably employed with relatively dilute solutions such as 5 to 20 per cent glycerine, but may also be used with glycerine containing only 1 or 2 per cent of water. In such cases the final distillation step may be eliminated. The anion and cation active materials are regenerated after use in the conventional manner by treatment with dilute solutions of alkali or acid solutions respectively and subsequent washing with water. As cation-active materials may be used a resinous material prepared by reacting furfurylacetone sulphonate with furfural (see U.S.A. Specification 2,372,233), aldehyde condensation products of a -furyl substituted organic sulphonates (see U.S.A. Specification 2,373,152), polyhydric phenolaldehyde condensation products such as catechol-tannin-formaldehyde, aromatic sulphonic acid-formaldehyde condensation products (see U.S.A. Specification 2,204,539), or the carbonaceous zeolites, i.e. sulphated or sulphonated carbonaceous materials such as coal, peat, or lignite. As anion-active materials may be used resins prepared from guanidine, guanyl urea, and biguanide as prepared according to Specification 561,896, [Group IV], or the aldehyde condensation products of m-phenylene diamine, biguanide, guanyl urea, substituted guanidines such as methyl guanidine, substituted biguanidines such as phenyl biguanide, polyethylene polyamines, &c.