Elucidating Synergistic Effect of In-Situ Hybrid Process Towards Paraquat Abatement

Abstract

Presence of non-biodegradable organic compounds, mainly pesticides in water bodies peril humans as well as aquatic life. Paraquat (PQ) is one such widely used Class II herbicide associated with Parkinson’s disease. Herein, pristine TiO2 (PT), as well as metal (Fe-PT, Ni-PT) and nonmetal (C-PT, S-PT), modified TiO2 was synthesized using hydrothermal treatment for mineralization and degradation of PQ. The crystallite size from XRD exhibited the prepared catalysts to be nanomaterials while FESEM confirmed the nanorod formation. Moreover, morphological analysis established the occurrence of doping in PT. Through optical properties, reduction in band gap from 3.2 eV to 2.4 eV was found which was accompanied by decrease in electron-hole recombination rate. Further, nanocomposites were investigated for PQ removal with S-PT depicting 93% degradation under solar radiations followed by Fe-PT degrading 87% PQ indicating that with optimum doping levels and proper reduction of band gap, TiO2 can be made more enthusiastic towards degradation and remediation process. Further, hybrid process employing photocatalysis and photo-Fenton simultaneously was utilised by synthesising Fe-S-PT, a codoped catalyst. This codoped Fe-S-PT resulted in a sharp decrement of 47% in processing time which is attributed to the presence of OH˙ and e−. Moreover, a degradation mechanism for Fe-S-PT was proposed along with the evaluation of extent of mineralization taking place. Lately, intermediates formed during the process were identified. Overall, study is extremely significant towards providing a practical and economical solution for PQ degradation using hybrid process within 80 mins at the benign pH of 6.3.