Ultrasonic-assisted synthesis of TiO2/MWCNT/Pani nanocomposite: Photocatalyst characterization and optimization of efficient variables in the degradation of benzene via RSM-CCD

Abstract

Nowadays, volatile organic compounds (VOCs) are the primary cause of rising contamination in groundwater, surface water, and wastewater. On the other hand, photocatalysis technology is among the best ways to treat wastewater because of its ability to rapidly mineralize a range of pollutants into non-toxic chemicals using sunlight as an energy source and its ecological friendliness. Herein, the TiO2/MWCNT/Pani nanocomposite was synthesized by combining ultrasonic and in-situ polymerization methods to decompose benzene, a prevalent and harmful VOC. The nanocomposite was characterized by XRD, FTIR, BET, SEM, and UV–Vis analysis. The response surface methodology (RSM), based on Central Composite Design (CCD), was used to investigate and optimize the effects of the independent factors on photocatalytic degradation, including initial benzene concentration, catalyst dosage, pH, and light irradiation time. The optimal conditions (benzene concentration = 700 mg. L−1, pH = 6, irradiation time = 80 min, and photocatalyst dosage = 1.5 g. L−1) resulted in maximum benzene degradation (84.90%). Trapping test and EPR analysis were also utilized to detect reactive species, and the findings indicated that the breakdown of benzene through photocatalysis is caused by the presence of hydroxyl radicals (•OH) and superoxide radicals (•O2−). Furthermore, the kinetics of the reaction and the stability of the nanocomposite (4 cycles) were examined. Finally, the results of this study provide convincing evidence for using TiO2/MWCNT/Pani as highly efficient and promising photocatalysts for removing benzene from aqueous solutions.