Solar assisted green photocatalysis for deducing carbamate insecticide from agriculture stream into water reclaiming opportunity

Abstract

‘Ultraviolet’ and ‘Solar’ wastewater treatment units are used augmented with nanocrystals of magnetite, Fe2O3, which were previously synthesised via a cost-efficient co-perception route. The nanocrystals produced were used as a Fenton reagent source for the oxidising carbamate pesticide in aqueous solution through a combination of natural abundant solar radiation as well as artificial UV source. System parameters were examined and the optimal operating conditions were investigated to maximise the system yield. The objective optimisation was attained using a Box-Behnken factoring design (BBD) based on Response Surface Methodology, RSM. A mathematical model was developed and the maximal removal efficiency reached to 84.1% within 15 min of reaction time. Furthermore, the chemical oxygen demand was then investigated and it was oxidised and deduced to 57%. Analysis of the experimental data revealed that a second-order reaction model is best described the reaction kinetics. The calculated thermodynamic parameters suggested that the non-spontaneous nature of oxidation at high temperature was corroborated by positive Gibbs free energy change ∆G• and negative entropy, ∆S• values. Also, the negative values of enthalpy, ∆H•, indicated that the reaction was exothermic. The low activation energy barrier (−35.85 kJ/mol) indicated that the reaction proceeds at a low energy level.