Efficient Degradation of Pendimethalin via Photo-Catalytic Ozonation Over Ni/Mg@TiO2 Nanocomposites

The amplifying use of chemical herbicides have led to an accumulation of toxic layers on the domestic crops. These chemical through irrigational practices wash these chemicals into water bodies making it difficult to preserve an acceptable water quality. The most commonly used herbicide which protects the crops against a broad range of unwanted herbs is pendimethalin. Advanced oxidative processes are comprehended to be most efficient techniques compared to the classic waste water treatment methods. In this work we have separated pendimethalin from one of the paddy fields around Vizianagaram, Andhra Pradesh, using liquid-liquid extraction process over ionic liquids and then mineralised using photo-catalytic ozonation over Ni/Mg@TiO2. The catalytic nano composites have been prepared using simple sol-gel method and characterised using various analytical techniques such as BET, SEM, EDX, TEM and PXRD. We achieved complete mineralisation of the target herbicide within a span of 2.5 h with major value added products identified during pendimethalin degradation which are, 5,6-dimethyl-2-(pentan-3-ylamino)cyclohex-4-ene-1,3-dione (DCHO), 3-((4,5-dimethyl-2,6-dioxocyclohex-3-en-1-yl)amino)pentanedioic acid (DOAP), 3-((1-carboxy-4-methyl-1,3-dioxohexan-2-yl)amino)pentanedioic acid (COAP), 2-methylbutanoic acid (MBA), 3-nitropentanedioic acid (NPA), and oxalic acid (OA). The by products were separated using GC-MS at given time. The catalytic nanoparticles showed high recyclability and efficiency for 7-consecutive cycles at a wavelength of 254 nm.