| 摘要 |
Strong acids of MW less than 200 and ionization constant greater than 1.0 x 10-3 are separated from acidic polymers of MW at least 1000 by dialysis through an anion-exchange membrane. Preferred anion-exchangers are those with quaternary ammonium groups, particularly those with an anion-exchange capacity of at least 1.0 meq./g. of dry membrane. Particularly mixtures separated are those resulting from the sulphonation of vinyl aromatic polymers, e.g. polyvinyl toluene or styrene/ divinyl benzene resin, and containing sulphuric acid together with the sulphonated polymer. The membrane may be a polyethylene-styrene graft polymer with quaternary ammonium groups.ALSO:Strong acids of MW less than 200 and ionization constant greater than 1.0 x 10-3 are separated from acidic polymers of MW at least 1000 by dialysis through an anion-exchange membrane. Preferred anion-exchanges are those with quaternary ammonium groups particularly those with an anion-exchange capacity of at least 1.0 meq./g. of dry membrane. Styrene grafted onto polyethylene film and substituted in the aromatic nucleus with anion exchange groups is also specified. The membrane may be in the form of flat sheets but tubes and hollow fibres are also referred to. Particularly mixtures separated are those resulting from the sulphonation of vinyl aromatic polymers and containing sulphuric acid together with the suphonated polymer. Other acids removable by the process of the invention include mono-, di-, and tri-chloracetic acids, oxalic, maleic, o-phthalic, tartaric, hydrochloric, hydrobromic, nitric, sulphurous, phosphoric and pyrophosphoric acids. |
