Preparation of temperature-sensitive Xanthan/NIPA hydrogel using citric acid as crosslinking agent for bisphenol A adsorption

Hydrogels are emerging materials in pollutant treatment due to their high absorbability and environmental friendliness. Herein, a novel temperature-sensitive hydrogel based on xanthan gum (XG) and N-isopropylacrylamide (NIPA) was successfully synthesized in a water system using low-cost citric acid as crosslinking agent. The lower critical solution temperature of the honeycomb macroporous XG/NIPA hydrogels was 40 °C. Meanwhile, the hydrogels had good water-absorption capacity and the swelling degree reached up to 70.1. Using XG/NIPA hydrogels to absorb bisphenol A (BPA), the maximum adsorption capacity was as high as 458 mg/g. The process was a multilayer adsorption and the rate-controlling step is chemisorption. Thus, the temperature-sensitive XG/NIPA hydrogel had great potential in absorbing BPA from aqueous solutions.