Selective Adsorption of Nitrate by a Macroporous Acrylic Anion Exchange Resin: Effect of the Competing Anions

A novel macroporous anion exchange resin (NDP-5) has been successfully developed for selectivity removing nitrate utilizing the acrylic cross-linked polymer skeleton. The process of the nitrate adsorption onto NDP-5 resin follows the Freundlich model, the pseudo-first-order and the pseudo-second-order kinetic models well. Compared to the commercial resin D213, NDP-5 resin displays more preferable adsorption ability toward NO 3 − from the model solution at the presence of the competing anion (Cl−, HCO 3 − or SO 4 2− ) at much greater levels. The contrastive experiment results showed that SO 4 2− with the divalent negative charges has a small effect on the sorption selectivity of NDP-5 resin functionalized with triethylamine at the exchange sites. The equilibrium adsorption capacity of NDP-5 resin is 3.2 times higher than that of D213 at initial concentration with the molar ratio of 1/30 (NO 3 − /SO 4 2− , N/N). Batch and column adsorption demonstrated concentrations of equivalence ratio that nitrate sorbed on NDP-5 resin could result in its conspicuous decrease. These observations pointed out that NDP-5 resin is a promising adsorbent for nitrate selective removal from the model solution. Keywords: Selectivity, nitrate, acrylic, resin, competing anions.