Modified Graphene Oxide As Effective Adsorbent For The Removal Of Cu²⁺ And Cd²⁺ From Aqueous Solution

The pollution caused by heavy metals and their compounds are known as heavy metal pollution. With the over-exploitation of metal minerals, some industries, such as chemical industry, manufacturing industry and smelting, have been developed rapidly. However, the development of economic also caused serious environmental pollution. The heavy metal wastewater, caused by process of manufacture and livelihood, has been one of main sources of water pollution, soil pollution and air pollution in the environment. It is hard to microbial degradation after the heavy metals were discharged into natural water, the heavy metals not only destroy living environment of aquatic organisms, but also destroy the ecological environmental by the enrichment, containing the precipitation process, adsorption, and food chain. Ultimately, heavy metals harm the healthy development of human beings.In this paper,graphene oxide（GO） was synthesized through Hummer’s method, the adsorbents DTC-GO and TC-GO were obtained by the modification of graphene oxide. The adsorption capacity for heavy metal ions of DTC-GO and TC-GO were evaluated by the removal of Cu²⁺ and Cd²⁺ from aqueous solution.Effect of several factors, including the p H, contact time and temperature were investigated by batch experiment.The adsorption kinetics and adsorption isotherm were also investigated in the paper.The results show DTC-GO and TC-GO exhibit excellent adsorption capacity for Cu²⁺ and Cd²⁺. The optimun p H values for Cu²⁺ and Cd²⁺were 7.0 and 6.8, respectively, and the effect of p H on adsorption capacity of TC-GO was weaker than DTC-GO. With the increasing of temperature, both the adsorption capacities of DTC-GO and TC-GO were higher than before, it indicated the adsorption processes of modified GO were endothermic process. The adsorption kinetics study indicates the adsorption kinetics of Cu²⁺and Cd²⁺ all could be well described by pseudo-second-order kinetic model. The adsorption isotherms were investigated by Langmuir, Freundlich and Dubinin-Radushkevich isotherm models, the datas indicated adsorption processes of DTC-GO and TC-GO for Cu²⁺ and Cd²⁺ were well-described by Langmuir modelisotherm. The Qmax of DTC-GO for Cu²⁺ adsorption is 107.3(mg g^-1) and for Cd²⁺ adsorption is 101.2(mg g^-1). The Qmax of TC-GO for Cu²⁺ adsorption is 156.5(mg g^-1)and for Cd²⁺ adsorption is 151.5(mg g^-1).