GB733376A - Purification of sugar solutions - Google Patents

Abstract

Metal cations are partially removed from technical sugar solutions, e.g. cane and beet raw juices, carbonation juices, thick juices, syrups, liquors and molasses, by passing the solutions through a filter bed consisting of a weakly acidic cation exchanger which strongly adsorbs organic non-sugars, e.g. colloids and colouring matter, the cation exchanger being produced by oxidizing carbonaceous and carbonizable materials either directly or indirectly. The cation exchanger may be prepared by oxidizing coal, anthracite or semi-coke in oxygen or an oxygen-containing current of gas at increased temperature, then hydrolysing the product with a solution of an alkali, e.g. caustic soda or caustic potash, and finally treating the hydrolysed product with a dilute acid, e.g. hydrochloric acid. Coal may be sulphonated with strong sulphuric acid, oleum or chlorosulphuric acid and subjected to pyrolysis to remove strongly acid groups. The cation exchanger may be obtained by pyrolysis of acid sludge, i.e. the residue from sulphuric acid refining of petroleum and like products. The filter bed may be treated with ammonia so that a mixed bed of H-ion exchanging and NH4-ion exchanging materials, e.g. in the ratio 1 : 1, becomes available for treating the sugar solutions. The cation exchanger may be regenerated with dilute sulphuric, hydrochloric or sulphurous acid.