Adsorption behaviors of ammonium nitrogen by an amphoteric hydrogel

摘要

An amphoteric hydrogel was prepared by cross-linking graft copolymerization of dimethyl-diallylammonium chloride and acrylic acid onto soluble starch. The adsorption behaviors of ammonium nitrogen (NH4+-N) by the amphoteric hydrogel were discussed in this study. The effects of various experimental parameters on NH4+-N removal, including pH, the dose of absorbent, the temperature, the adsorption time, and the initial concentration of NH4+-N, were investigated. The result indicated that the amphoteric hydrogel showed a fast adsorption rate and high adsorption capacity for NH4+-N in a pH range from 4 to 8. The adsorption process was exothermic according to the value of thermodynamic parameters. The adsorption process fits the pseudo-second-order kinetic model best. To this hydrogel, it was seen that the Freundlich adsorption isotherm model fits the adsorption data better. The adsorption capacity could reach to 33.98 mg/g. The hydrogel showed the potential use for removal of NH4+-N in water treatment and fishing industry.