Adsorption and photocatalysis for methyl orange and Cd removal from wastewater using TiO(2)/sewage sludge-based activated carbon nanocomposites

Nanocomposite TiO(2)/ASS (TiO(2) nanoparticle coated sewage sludge-based activated carbon) was synthesized by the sol-gel method. The changes in surface properties of the TiO(2)/ASS nanocomposite were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence. The prepared TiO(2)/ASS nanocomposite was applied for simultaneous removal of methyl orange dye (MO) and Cd(2+) from bi-pollutant solution. The factors influencing photocatalysis (TiO(2) : ASS ratios, initial pollutant concentrations, solution pH, nanocomposite dosage and UV irradiation time) were investigated. The results revealed that high removal efficiency of methyl orange dye (MO) and Cd(2+) from bi-pollutant solution was achieved with TiO(2)/ASS at a ratio (1 : 2). The obtained results revealed that degradation of MO dye on the TiO(2)/ASS nanocomposite was facilitated by surface adsorption and photocatalytic processes. The coupled photocatalysis and adsorption shown by TiO(2)/ASS nanocomposite resulted in faster and higher degradation of MO as compared to MO removal by ASS adsorbent. The removal efficiency of MO by ASS adsorbent and TiO(2)/ASS (1 : 2) nanocomposite at optimum pH value 7 were 74.14 and 94.28%, respectively, while for Cd(2+) it was more than 90%. The experimental results fitted well with the second-order kinetic reaction.