Cross-linked chitosan microspheres: An efficient and eco-friendly adsorbent for iodide removal from waste water

Abstract

Radioactive iodine from the nuclear wastes was the significant environmental pollution, causing the health concern. Cross-linked chitosan microspheres (CM) by emulsion polymerization were investigated and proposed as the green and efficient adsorbents to treat iodine wastes via I− and -NH2 attraction. The I127 anions (instead of the radioactive iodine) adsorbed by CM were promising according to adsorbent dosage, pH, co-existing anions and recyclability analyzations through FTIR, SEM, BET and TGA. From pH 4 to 10, CMs maintained the I− adsorption efficiency no less than 95%. The maximum adsorption capacity of I− was up to 0.8792 mmol/g relative to the initial 2 mmol/L I− at pH 5 during 40 min adsorption, well-fitting with Freundlich isotherm model and pseudo-second order kinetic model. Moreover, the CMs after five regenerations maintained almost the same adsorption efficiency, and performed the differently competitive-adsorbed behavior. The CMs thus were prospective adsorbents for the iodide removal from waste water.