New Anion-Exchange Resin Based on Crosslinked PVOH Containing Tertiary Amino Groups

Abstract

A new anion-exchange resin was prepared by reacting poly(vinyl alcohol) (PVOH), as a substrate, with a mixture of triethanolamine hydrochloride, as a reactive additive bearing tertiary amine groups and as an acid-liberating salt; along with a melamine formaldehyde pre condensate, as a cross linker, reinforcing and binding agent. Factors affecting the extent of reactions and/or interactions among the reactants used were studied, such as time and temperature of reaction, as well as reactant molar ratios. Water-insoluble tertiary amine containing cross linked PVOH anion-exchange resin having an amino content of 117 mEq/100 g was synthesized and characterized by determining its strength as well as durability. The potentiometric curve of the prepared resin revealed that it was a weak base anion-exchanger having a strength, pKb, of 8.64. The resin lost about 1% of its capacity during the first 5 cycles of the durability test, after which the capacity remained constant. The resin obtained was used for the removal of permanganate and chromate anions as well as some anionic dyes (acid, reactive, and direct) from aqueous solutions of different pH. It was shown that: (1) the extent of removal was remarkably enhanced on decreasing the pH from 11 to 3, and (2) at a pH value of 3, the resin is very effective in the removal of the anions studied, except that of the direct dye.