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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. [ABSTRACT FROM AUTHOR]

A polyampholytic superabsorbent polymer (PASAP), sodium alginate-g-(polyacrylic acid-co-allyltrimethylammonium chloride) (SA-g-(PAA-co-PTM)), was prepared by free-radical graft copolymerization and characterized. The polymer exhibited pH-dependent swelling behaviors with extremely high swelling ratios, and was saline tolerant. The dye adsorption properties of SA-g-(PAA-co-PTM) were investigated using methylene blue (MB) as a cationic dye model. It was found that its dye adsorption capacity was significantly affected by the TM content in PASAP and pH of dye solution. The dye adsorption kinetics and isotherm obey the pseudo-second-order kinetic model and the Langmuir isotherm model, respectively, and the adsorption process is chemisorption in nature. In addition, SA-g-(PAA-co-PTM) exhibited high MB adsorption capacities in a wide pH range and reusability in at least five adsorption-desorption cycles, indicating its great application potentials as the adsorbent for dye removals from effluents.

A polyampholytic superabsorbent polymer (PASAP), sodium alginate-g-(polyacrylic acid-co-allyltrimethylammonium chloride) (SA-g-(PAA-co-PTM)), was prepared by free-radical graft copolymerization and characterized. The polymer exhibited pH-dependent swelling behaviors with extremely high swelling ratios, and was saline tolerant. The dye adsorption properties of SA-g-(PAA-co-PTM) were investigated using methylene blue (MB) as a cationic dye model. It was found that its dye adsorption capacity was significantly affected by the TM content in PASAP and pH of dye solution. The dye adsorption kinetics and isotherm obey the pseudo-second-order kinetic model and the Langmuir isotherm model, respectively, and the adsorption process is chemisorption in nature. In addition, SA-g-(PAA-co-PTM) exhibited high MB adsorption capacities in a wide pH range and reusability in at least five adsorption-desorption cycles, indicating its great application potentials as the adsorbent for dye removals from effluents. [ABSTRACT FROM AUTHOR]