Synthesis of a tertiary amine hydrochloride macroporous resin adsorbent for removal of oxyhalide anions from water: Performance, adsorption mechanism, and toxicity

Abstract

The non-volatility, high solubility, and chemical stability of oxyhalide anions make them difficult to remove from waters. Here we describe the synthesis and characterization of tertiary amine hydrochloride macroporous resins (TAHMR) that show excellent performance for the adsorption of oxyhalide anions. Adsorption capacities were in the order ClO4− > ClO3− > ClO2− > BrO3−, and compared favorably with those from various commercial resins studied. Compared with the common anions in water, TAHMR has better selectivity for ClO4−. Adsorption of ClO4− on TAHMR increased with increasing pH in the range 2.0–4.0, but was independent of pH in the range 4.0–10.0, and was only slightly affected by the presence of HCO3− and HPO42−. The adsorption kinetics followed the pseudo-second order rate model and was fitted well by the Langmuir isotherm with maximum adsorption capacity of 2.74 mmol g−1. Investigations with various spectroscopic techniques and quantum chemistry calculations indicate that adsorption of oxyhalide anions occurs at the nitrogen atoms in the resin. Furthermore, TAHMR resins could be effectively regenerated and reused, and did not show any cytotoxic effects. Thus, TAHMR is a promising adsorbent for practical application in the removal of oxyhalide anions from water.