Preparation of SA-g-(PAA-co-PDMC) polyampholytic superabsorbent polymer and its application to the anionic dye adsorption removal from effluents

A pH-responsive polyampholytic superabsorbent polymer (SAP), sodium alginate-g-(polyacrylic acid-co-polymethacryloxyethyltrimethyl ammonium chloride) (SA-g-(PAA-co-PDMC)), was prepared by the free-radical-induced graft copolymerization. The structure of the SAP was characterized by FTIR, XRD and SEM. The synthesis conditions were optimized to achieve an SAP with the highest swelling ratio. The anionic dye adsorption properties of the achieved SAP were characterized using Food Yellow 3 (FY3) as a model dye. The effects of DMC amount and pH of the dye solution on the adsorption capacities were determined. The adsorption kinetics, isotherm, thermodynamics, desorption and reusability of the SAP were studied respectively. The maximum adsorption capacity and removal efficiency of SA-g-(PAA-co-PDMC) SAP reached up to 654.87 mg/g and 98.23%, respectively, which are among the highest values of solid adsorbents in FY3 adsorption. Compared with the traditional polyanion SAPs, the SAP prepared in the present work can be expended to the simultaneous removal of both cationic and anionic dyes.