A Novel Anion Exchanger Composed of Formate Hydrotalcite for Sorptive Recovery of Phosphorus

Abstract

Feasibility of a renewable sorbent for phosphorus was determined by testing the anion-exchange ability of hydrotalcite, which holds formate ions in its interlayer. The formate hydrotalcite, successfully prepared by reacting raw hydrotalcite with a formic acid/1-propanol solution, exhibited high performance for phosphorus removal and collection based on a stoichiometric anion-exchange principle. It was estimated that the collected orthophosphate ions existed as poly-anion forms of HPO4 2– and PO4 3– with a ratio of 67.6:32.4 in the interlayer after the sorption. The formate hydrotalcite is also able to revert to the starting hydrotalcite after the sorption, when treated with Na2CO3 aqueous solution, demonstrating that it can be an attractive alternative to the conventional chloride or nitrate hydrotalcite as an anion exchanger.