Preparation of Functionalized Graphene Oxide Composite Spheres and Removal of Cu2+ and Pb2+ from Wastewater

Functionalized graphene oxide was an important candidate for removing heavy metal pollution. However, its difficult separation, low mechanical strength, and secondary pollution were restricted. In our study, polyvinyl alcohol/functionalized graphene oxide macroporous composite spheres (PVA/GO-SH) were prepared by wrapping sulfhydryl-functionalized graphene oxide (GO-SH) in polyvinyl alcohol (PVA) to solve the above problems. The experiments showed that the removal rates of Cu2+ and Pb2+ by 1 g L−1 PVA/GO-SH were 86.59% and 94.7%, and the equilibrium adsorption capacities were 84.42 mg g−1 and 218.62 mg g−1, respectively. The isothermal equation calculation showed that the adsorption was monomolecular layer adsorption. Kinetic and thermodynamic results showed that adsorption follows a second-order reaction kinetic model, and the more high temperature, the more favorable the adsorption. At a flow rate of 2.0 mL min−1, 80 mg L−1 of Cu2+ solution, and 100 mg L−1 of Pb2+ solution could be adsorbed entirely, with volumes of 1960 mL and 2480 mL, respectively. After five adsorption–desorption cycles, the adsorption rate achieved more than 75% of the initial adsorption rate. The composite sphere maintained an excellent spherical shape without damage, which had good stability. In conclusion, PVA/GO-SH has potential practical value.