Engineering TiO2 supported CTAB modified bentonite for treatment of refinery wastewater through simultaneous photocatalytic oxidation and adsorption

• DOI: 10.1016/j.jwpe.2021.102239
• Publication Date: 2021-08-04T10:43:17Z
• Authors: Ihtisham Ulhaq; Waqas Ahmad; Imtiaz Ahmad; Muhammad Yaseen; Muhammad Ilyas
• Keywords: 13. Climate action; 0211 other engineering and technologies; 02 engineering and technology; 7. Clean energy; 6. Clean water

Abstract This study reports the removal of hydrocarbon pollutants from petroleum refinery wastewater by simultaneous photo-catalytic oxidation and adsorption using TiO2 loaded on Cetyl-trimethyl Ammonium bromide modified Bentonite clay (TiO2/CTAB-Bt). The synthesized CTAB-Bt and hybrid TiO2/CTAB-Bt were characterized by XRD, SEM, EDX, and FTIR techniques. The adsorption efficiency of CTAB-Bt was investigated using model refinery wastewater containing phenol, benzene, toluene, and naphthalene (100 ppm each). Under the optimum conditions of 0.8 g/100 mL CTAB-Bt adsorbent dosage, 40 °C, and 120 min contact time, maximum adsorption of hydrocarbons (94%) was attained. The adsorption followed pseudo-first-order kinetics and best fitted with the Langmuir isotherm model. Enthalpy (ΔH°), Gibbs free energy (ΔG°) and entropy (ΔS°) data of the system revealed that the adsorption process was endothermic, spontaneous and feasible. Through simultaneous photocatalytic oxidation under UV light irradiation and adsorption using TiO2/CTAB-Bt, the maximum removal (93%) of hydrocarbons from the model wastewater was achieved under milder conditions of 1100 mg/500 mL of TiO2/CTAB-Bt, 30 °C temperature and 60 min contact time. In the case of real refinery wastewater, CTAB-Bt realized 92% decrease in the COD via adsorption at 40 °C in 120 min, while simultaneous photocatalytic oxidation and adsorption achieved 94% decrease in COD at 30 °C in 60 min. The reaction products of photocatalytic oxidation of refinery wastewater were analyzed by GC–MS analysis. This study reports a new and interesting strategy of photocatalytic oxidation and adsorption for the remediation of hydrocarbon pollutants from refinery wastewater using CTAB-Bt.