Carboxymethyl chitosan-kaolinite composite hydrogel for efficient copper ions trapping

The qualified sorbents for removing heavy metals from wastewater, which possess high adsorption capacity, low cost and the ability of rapid separation and regeneration, are urgently needed. Herein, we reported a kind of carboxymethyl chitosan-kaolinite composite hydrogel with excellent mechanical properties, low cost and high Cu2+ removal efficiency. This polyampholyte hydrogel was well designed and prepared through a simple Schiff base reaction. Due to the remarkable mechanical strength, the composite hydrogel could be fast separated, easily regenerated and highly reused. The adsorption capacities for Cu2+ were reaching up to 206 mg g(-1) attribute to the existence of the large number of active groups. The adsorption could be conducted in a wide pH range of 2.5 to 6 and the equilibrium fast reached in 300 min due to its excellent water penetration for highly accessible to metal ions. These results indicated that carboxymethyl chitosan-kaolinite composite hydrogel were effective adsorbents for trapping Cu2+ from wastewater, which would provide a new idea for removal of heavy metal ions.