Preparation of Anion Exchangers Derived from Melamine Sponge and Its Adsorption Characteristics of Nitrate Ion

Abstract

Preparation of anion exchangers using melamine sponge (MS) and adsorption of nitrate ion was investigated. Carbonized melamine sponge was prepared at 500°C with ZnCl₂ impregnation (Z6) to develop the pore structure. Z6 was further treated by CH₃I to introduce quaternary nitrogen onto the carbon surface and referred to as Z6-Q. Based on the result of X-ray photoelectron spectroscopy (XPS), Z6-Q contained more quaternary nitrogen than MS and Z6. Adsorption of nitrate ion on Z6-Q reached an equilibrium state the most quickly among the prepared samples. Adsorption kinetic curves indicated that the rate-limiting process was diffusion inside the pore for the adsorption of nitrate ion. In the adsorption of nitrate ion ranging 0.1–0.7 mmol/g, Z6-Q released equimolar chloride ion, suggesting that Z6-Q could have anion exchange sites to adsorb nitrate ion.