Fast removal of methylene blue and Hg(II) from aqueous solution using a novel super-adsorbent containing residues of glycine and maleic acid.

The alternate cyclo-copolymerization of diallylammonioethanoate [(CH=CHCH)NCHCO] and maleic acid in the presence of a cross-linker afforded a novel pH-responsive resin (90% yield). The resin has turned out to be a super-adsorbent for methylene blue (MB) removal with a q of 2101 mg g. The adsorption of the dye followed pseudo second-order kinetics with an energy of activation (E) of 31.5 kJ mol. The process showed an extraordinarily fast adsorption rate owing to faster film diffusion; the resin (250 mg) was able to trap 78 and 99.4% MB from its 3000 mg L solution (100 mL) within 3 and 30 min, respectively. Equilibrium constants from Langmuir nonlinear isotherm model in the range 288-328 K gave ΔG ΔH, and ΔS values of ≈ -25 kJ, -13 kJ and 39.5 J mol K, respectively. Immobilization mechanism was discussed using FTIR, SEM, and Elovich kinetic model. The presence of the chelating glycine residues was exploited for the removal of Hg(II) ions; the q was determined to be 263 mg g. The resin also removed MB and Hg(II) simultaneously from industrial wastewater with remarkable efficacy. The very impressive performance along with efficient recycling conferred the resin a top position among many sorbents.