Preparation of graphene oxide/organo-modified bentonite composites and their adsorption on Cd(Ⅱ)

Graphene oxide/organo-modified bentonite(GO/OM-Bent) composites were prepared by the synthesis of GO, Bent and cetyltrimethyl ammonium bromide (CTAB), then the composites were used to treat Cd(Ⅱ)-containing wastewater at a concentration of 10 mg·L^-1. The effects of GO content in GO/OM-Bent composite, pH value, GO/OM-Bent composite dosage, reaction time, initial concentration of cadmium and coexisting ions on adsorption of Cd(Ⅱ) by GO/OM-Bent composite were investigated by batch test. The adsorption results of GO/OM-Bent composites are balanced at 120 min with the best effect on Cd(Ⅱ) adsorption under the optimal condition:the pH value is 6, the mass fraction of GO is 30wt%, the GO/OM-Bent composite dosage is 200 mg·L^-1; Under the same conditions, the adsorption capacity of GO/OM-Bent composite is 12.01 mg·g^-1 and 5.39 mg·g^-1 higher than that of OM-Bent and GO, respectively; the pseudo-second-order kinetics model can well describe the adsorption process and the adsorption isotherm conforms to the Langmuir model. At 303 K, the maximum adsorption capacity of GO/OM-Bent composite on Cd(Ⅱ) could be reached 133.33 mg·g^-1. The results of desorption test shows that the adsorption efficiency of Cd(Ⅱ) remains as high as 83.5% after 5 cycles of adsorption-desorption, indicating that GO/OM-Bent composite has good cyclic regeneration performance.