Performance of TiO₂ Photocatalytic Nanomaterial in Removal of Lead from Sanitary Landfill Leachate Using Sunlight

Abstract

The worldwide increase in population, industrialization, and urbanization results in the increase of Municipal Solid Waste (MSW). Most of the countries have adopted sanitary landfilling as the best method for disposal of their MSW. One of the major pollution problems caused by the sanitary landfill is landfill leachate, which is generated as consequences of infiltration of water into landfills and squeezing of the waste due to self-weight. Landfill leachate contains variety of compounds such as organic matter, heavy metals, and inorganic salts. The treating of these recalcitrant compounds by conventional ways makes it quite difficult, because of its high chemical stability and low biodegradability. In recent years, semiconductor photocatalysis has gained focus on treatment of heavy metals, organic, and inorganic matter by nanosized ZnS, ZnO, CdS, TiO₂, and Fe₂O₃. Among all these semiconductor nanomaterials, TiO₂ has received more popularity because of its low-cost, nontoxic, chemical stability, and photostable properties. In the present study, the degradation of lead in aqueous solution was investigated by using photocatalytic TiO₂ under natural sunlight. The parabolic trough collector is used as solar photoreactor, which brings chemical reagents and solar photons into contact with the photocatalyst. The characterization of TiO₂ is conducted by Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The influencing parameters (pH, contact time, photocatalytic dosage, and concentration of an aqueous solution) on lead removal efficiency was studied and optimized by Response Surface methodology (RSM). The results indicated that at pH 7, with adsorbent dosage 0.35 g/l, with initial concentration 27.5 mg/l, and irradiation time 42.5 min can successfully remove lead up to 99.3%. The characterization study of TiO₂ confirms that the selected photocatalytic TiO₂ is anatase which is spherical in shape. The crystallite size is approximately 19 nm and specific surface area of 120.32 m²/gm.