The effective adsorption of lead from wastewater has become a significant problem from both environmental and biological viewpoints. In this study, a composite of reduced graphene oxide (RGO) with zeolitic imidazolate framework-67(ZIF-67) was prepared as adsorbent to remove the Pb(II) ions from aqueous solutions. The composite was characterized by various techniques such as SEM, TEM, FTIR, XRD, BET and TGA. The important factors including sorbent weight, contact time, initial lead concentration, pH and temperature were optimized by central composite design (CCD) of response surface methodology (RSM). The maximum adsorption of 99.2% was achieved at the initial lead concentration of 87.5 ppm, adsorbent weight of 38.68 mg, contact time of 46 min and temperature of 47 °C. Different kinetic and isotherm models were evaluated to describe adsorption data. The results showed that kinetic data have better agreement with the pseudo-second-order kinetic model. From isotherm studies, the experimental results exhibited the best matching with the Langmuir isotherm. The outcomes of thermodynamic investigations confirmed that the adsorption process is endothermic and spontaneou
