Abstract
The photocatalytic removal of Cr(VI) and Pb(II) from different wastewater types using doped TiO2 nanocomposites with reduced graphene oxide added in different ratios (1%, 3%, 5% w/w) and the removal of these ions from their aqueous solutions,were studied using batch adsorption methods. Different types of wastewater from agricultural, domestic and industrial sources were collected from several governorates in Egypt. Some physical characterization technologies, including X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), were used to demonstrate the morphological characteristics of the surface of the synthesized sorbent. The surface area of TiO2@rGO 1% was larger than that of TiO2@rGO 3% or 5%. The nanocomposites showed high removal efficiency of toxic metals in different types of wastewater in the order of: Fe > Mn > Cd > Cr > Zn > Cu > Pb. In addition, some factors, e.g. pH, sorbent dosage, initial metal concentration and contact time, were studied. The results indicated that the maximum removal efficiency was achieved at pH = 2 and 5.5, 150 min contact time and 0.4 g L-1 sorbent dose for Cr(VI) and Pb(II), respectively. Langmuir and Freundlich isotherm studies showed that adsorption obeyed the Langmuir isotherm model. Metal ions were removed following the order of Cr(VI) > Pb(II) according to values of maximum adsorption capacities (q(max)), Langmuir constant (b), separation factor (RL) and Freundlich intensity parameter (1/n).