Synthesis of a New Nanocomposite Based on Tungsten for Degradation of an Organochloride Pesticide

Nowadays, huge industrialization and uncontrolled growth of population have tremendously caused environmental contamination. Additionally, clean water resources are scarce. Thus, effective treatment of wastewater and its recycling is highly important. Pesticides play a key role in water–food nexus. Incorrect pest management approaches result in water pollution. Imidacloprid (IMI) is an emerging contaminant used as an alternative to carcinogenic organochloride insecticides such as DDT. The wide range of possible applications of IMI in crop pest control, anti-parasitic treatments, and vector control for dengue mosquitoes resulted in the extensive use of this insecticide. Imidacloprid has a great risk for groundwater resources because of its high water solubility (0.58 g/L) and water stability of > 30 days (at pH 5-7). [1] There are various methods available for treating contaminated water, semiconductor-based photocatalysis method is recognized as one of the green technique and as fascinated immense consideration due to its potential utilization of solar energy. [2] In these work, Ternary photocatalysts with visible-light photocatalytic performances, were fabricated for the first time through integration of CoMoO4 and polyaniline (PANI) with WO3. WO3 is recognized to be an important n-type semiconductor photocatalyst with a band-gap varied from 2.4 to 2.8 eV. It is also one of the most promising materials reported so far for the photodegradation of organic pollutants. Cobalt molybdate (CoMoO4), as one of the metal molybdates, has a narrow band gap of 1.94 eV. This p- type semiconductor has been used in various fields of sensors, catalysts, and supercapacitors. Polyaniline (PANI), as a conducting polymer, has been widely used in photocatalytic processes, owing to unique e‒/h+ transportation properties, low band gap, availability of facile synthesis routes, and good chemical stability. This study presents the preparation of tungsten trioxide (WO3) nanoparticles by acidic precipitation using sodium tungstate as a precursor and couples it with small energy gap semiconductors of CoMoO4 and PANI to improve photocatalytic activity. Synthesized nanocomposites were successfully characterized by transmission electron infrared (FTIR) and microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform and different parameters such as photocatalyst amount (80 mg), pesticide concentration (6 ppm), pH (6), radiation time (80 min), and temperature (40 °C) on the percentage of IMI degradation were investigated and optimized. The degradation percent of IMI was carried out using UV-Vis spectrophotometer. The results revealed that nanocomposite successfully prepared and can be applied in remediation reactions.