Improved permselective membranes, the process of producing them, and the applications of these membranes

摘要

Anionic and cationic permselective membranes for use in the electrodialytic demineralization of water are made by impregnating cellulosic parchment paper with an acidic aqueous solution comprising a salt containing a N-methylolamide group, formaldehyde and a phenol having at least two nuclear hydrogen atoms at which addition of formaldehyde can occur and drying the impregnated paper at a temperature of at least 120 DEG C. Exchangeable ionic groups are thus deposited in the paper and some cellulose molecules therein become cross-linked. The salt may be hydroxymethylcarbamylmethyl - trimethyl ammonium chloride, hydroxymethylcarbamylmethylisoquinolinium or - pyridinium chloride, methylolcarbamidomethyl - pyridinium chloride, acetamidomethylol sodium sulphonate or the chloride of mixed coal-tar bases quaternized with methylolchloracetamide. The phenol may be hydroxy-benzene and/or o- and/or m- and/or p-cresol or resorcinol. The pH of the solution is, preferably, brought to a value between 2.4 and 2.5 by adding hydrochloric acid. Specifications 733,100, 750,220, 750,238 and 813,607 are referred to.ALSO:Anionic and cationic permselective membranes are made by impregnating cellulosic parchment paper with an acidic aqueous solution comprising a salt containing a N-methylolamide group, formaldehyde and a phenol having at least two nuclear hydrogen atoms at which addition of formaldehyde can occur and drying the impregnated paper at a temperature of at least 120 DEG C. Exchangeable ionic groups are thus deposited in the paper and some cellulose molecules therein become cross-linked. The salt may be hydroxymethylcarbamylmethyltrimethyl ammonium chloride, hydroxymethylcarbamylmethyl - isoquinolinium or - pyridinium chloride, methylolcarbamidomethyl - pyridinium chloride, acetamidomethylol sodium sulphonate or the chloride of mixed coal-tar bases quaternized with methylol chloroacetamide. The phenol may be hydroxybenzene and/or o- and/or m- and/or p-cresol, or resorcinol. The pH of the solution is, preferably, brought to a value between 2.4 and 2.5 by adding hydrochloric acid. Specifications 733,100, 750,220, 750,238 and 813,607 are referred to.