GB745393A - Process for the manufacture of cation exchange resins - Google Patents

Abstract

Cation-exchange resins capable of removing from sugar solutions calcium ions from slightly dissociated organic calcium salts are prepared by condensing an aldehyde, e.g. formaldehyde, with a monohydric phenol, which may be partly sulphonated, and with a sulphonic acid of a mono-, di- or tri-methyl benzene. Preferably, 0.084 to 2.1 mol. of the methyl benzene sulphonic acid is used per mol. of phenol. With less than 1.35 mol. of the methyl benzene sulphuric acid, the phenol should be partly sulphonated to ensure sufficient exchange capacity. In examples: 200 c.c. of toluene are sulphonated at 100-105 DEG C. for 3 hours with concentrated sulphuric acid. After cooling, 100 c.c. phenol and 200 c.c. 40 per cent formalin are added slowly while cooling and stirring. The resin which forms is broken up, ground and dried. (2) Similar to (1) but using 1.3.5-trimethylbenzene. (3) Similar to (1) using meta-xylene. (4) 200 c.c. of phenol are sulphurated for 2 hours at 160 DEG C. after cooling, 100 c.c. of the toluene sulphuric acid-sulphuric acid mixture of example (1) are added, then 50 c.c. water and 190 c.c. of 40 per cent formaldehyde with cooling and stirring. The resin formed is broken up, ground and dried. In a table the performance of the resins of examples (3) and (4) are compared with the performance of a phenolsulphonic-acid cation exchanger in the removal of calcium ions from a calcium citrate solution and in the softening of a clarified sugar juice.ALSO:Calcium ions are removed from calcium citrate solutions by passing the solution through a bed of an ion-exchange resin made by condensing an aldehyde, a monohydric phenol and a sulphonic acid of a mono-, di-, or tri-methyl benzene (see Group IV (a)). In an example 800 cc. of a calcium citrate solution having a hardness of 5.8 German degrees was passed through two different resins according to the invention, and for comparison through a phenol sulphonic acid ion-exchange resin, all three resins having been regenerated with common salt. Figures are given for the hardness of the effluents, which for the resins of the invention did not exceed 0.2 degrees, while for the third resin varied from 0.2 degrees for the first 100 cc. of effluent to 0.8 degrees for the last 100 cc.ALSO:Sugar solutions are softened by passing them through a cation exchange resin made by condensing an aldehyde, a monohydric phenol and a mono-, di-, or tri-methyl benzene sulphonic acid; (see Group IV(a)). In an example, a clarified sugar juice having a hardness of 5,4 German degrees was passed through two beds of resins according to the invention and for comparison through a bed of a phenol-sulphonic acid cation exchange resin. In the first two cases the hardness of the effluent was 0,0 degrees and in the third case 0,45 degrees.