Adsorption Characteristics of Chitosan-g-Poly(acrylic acid)/Attapulgite Hydrogel Composite for Hg(II) Ions from Aqueous Solution

Batch adsorption experiments were carried out to remove Hg(II) from aqueous solutions using chitosan-g-poly(acrylic acid)/attapulgite hydrogel composites as adsorbents. The factors influencing the adsorption capacity of the composites were investigated. The results indicate that the adsorption equilibrium of the composites can be achieved within about ten minutes and the equilibrium adsorption capacities of the composites with 10, 30, and 50 wt% of attapulgite content were 785.20, 679.63, and 541.06 mg g−1, respectively. The negative values of ΔG and positive values of ΔH indicate that the adsorption processes are all spontaneous and endothermic.