Investigating the Photocatalytic Potential of Nickel Oxide (NiO) Nanoparticles for the Degradation of Thiamethoxam Insecticide and Process Optimization Using Response Surface Methodology (RSM) Desirability Factor

Thiamethoxam, a prevalent neonicotinoid insecticide in agriculture, presents both benefits and environmental risks. Its effectiveness in pest control is offset by bioaccumulation and persistence, potentially contaminating surface and groundwater. Bee colony incidents prompted regulatory shifts in Slovenia, highlighting the necessity for rigorous environmental and safety assessments. Recent findings of thiamethoxam in drinking water underscore concerns about its resilience through water treatment processes. This paper introduces research focused on the production of Nickle Oxide nanoparticles (NiO, NPs) through co-precipitation techniques, with the aim of exploring their potential for photocatalytic degradation.Theformation of NiO NPs was conformed through a range of characterization methods, including SEM, EDX, FTIR, XRD and UV/Vis analyses. The FTIR spectra showed distinctive bands at 1030 cm^{− 1}, 823 cm^{− 1}, and 650 cm^{− 1}, owing to the stretching of NiO bonds and intrinsic stretching vibrations. The band gap calculated forNiO nanoparticles was found to be 3.2 eV.Analysis of SEM images demonstrated that NiO exhibits a semi-spherical morphology, and its average crystallite size was found to be 35.67 nm determined using Debye-Scherrer equation. The point of zero charge (PZC) of NiO NPs was at the pH level of 7.1.Theeffectiveness of the NiOphotocatalyst was verified by assessing its performance in the degradation of thiamethoxam. Under optimal conditions, the photocatalytic degradation achieved remarkable results, with thiamethoxamshowing degradation rates of 95%. The degradation of thiamethoxam processes followed first-order reaction, with rate constants of 0.0184 s^{− 1}. Among the response surface methodology (RSM) models considered, the polynomial quadratic model stands out as the most suitable one, displaying the highest desirability factor and featuring significant terms. This model boasts an R² value of 0.9720an adjusted R-squared (adj R²) value of 0.9569.