| 摘要 |
A mixed bed of cation-exchange material having strongly acidic ion-exchange group and anion-exchange material having strongly basic ion-exchange groups, used for removing electrolytes passed therethrough, is periodically regenerated by treating one part of the bed with strong alkali and the other part with strong acid without separating the anion-exchange and cation-exchange constituents and then thoroughly mixing the two parts. The cation- and anion-exchange groups are sufficiently strongly acidic and basic respectively to prevent appreciable hydrolysis of the compounds formed on regeneration. Suitable groups are sulphonic acid groups and quarternary ammonium groups respectively. Suitable regenerants are 5% solutions of HCl and NaOH. Amphoteric ion-exchange material may also be used. The regeneration may be effected by passing the different regenerants through different parts of the bed or by passing one regenerant through the whole bed and then passing the other through only part of the bed. In an example a mixed bed of a cation-exchange resin made by sulphonating polystyrene cross-linked with divinyl benzene and an anion-exchange resin obtained from the same polymer by chlormethylation and treatment with trimethylamine is regenerated by treating the whole bed with 5% NaOH and then the bottom half with 5% HCl. |
