Diazinon pesticide photocatalytic degradation in aqueous matrices based on reductive agent release in iodide exciting under UV Irradiation

Regarding the cost-effective degradation of diazinon (DIZ), the present study was conducted to develop and UV/iodide process in a photo catalyst reactor. CCD modeling applied and the results shows that the highest R-squared value (adjusted R-squared: 0.9987), the lowest P-value (2.842 e − 10), the lowest AIC (14.54), and the most insignificant lack-of-fit (0.73) belonged to the second-order model. Based on second-order model, the stationary points for time, iodide: DIZ (molar ratio %), DIZ concentration, and pH were 6.99 min, 80.15% iodide: DIZ (molar ratio %), 3.34, mg L⁻¹, and pH 7.34 (− log₁₀[H⁺]), respectively. The maximum reduction efficiency of 97.22% was obtained at the experimental conditions. The LC–MS analyses from optimal condition implied that all the DIZ molecules and its intermediates breaking to simple compounds during 15 min of processing. The data shown UI process reduced the BOD and COD levels by about 66% and 86.29% within 80 min of photoreaction, respectively. Furthermore, in kinetic investigation, with the increase in DIZ concentration, kₒbₛ and rₒbₛ increased and secondly, the conventional and PCBR reactor kₒbₛ increased by about respectively 17% and 50% with an increase in DIZ concentration from 5 to 15 mgL⁻¹. Additionally, when the DIZ concentration increase from 5 to 15 mg L⁻¹, rₒbₛ increased in the conventional and PCBR reactors respectively about 4.9 and 6 times. Figure-of-merit EEₒ changed from 12.66–17.41 to 7.26–10.15 kWhm³ for the conventional reactor, and 8.66–13.61 to 5.24–8.12 kWhm³ in PCBR, when the DIZ concentration increasing from 5 to 15 mg L⁻¹. Consequently, in the PCBR reactor, the energy consumption reduced by 14% at 5 mg L⁻¹ DIZ concentration and by 60% at 15 mg L⁻¹ DIZ concentration. Also, total cost of the system (TCS) decreases from 4.52 to 1.46 $ in conventional reactor and 1.47 to 0.42 $ in PCBR reactor when the DIZ concentration increase from 5 to 15 mg L⁻¹.