Reactor model development: The removal performance of ferrous-catalysed photo-oxidation process by examining the reaction parameters

The removal performance of the ferrous catalysed photo-oxidation process was investigated through the examination of major process parameters including pH levels and dosages of ferrous (Fe²⁺) and hydrogen peroxide (H₂O₂). A common used herbicide, alachlor, was used as a target compound in the degradation process. In the study, alachlor was found to be effectively degraded by hydroxyl radicals (HO{radical dot}) which were generated by UV/Fe²⁺/H₂O₂ in the oxidation process. It was interesting to find that the pattern of reaction kinetics of alachlor varied depending on the initial concentrations of Fe²⁺ and H₂O₂. An optimum H₂O₂ dosage was determined. This was practically useful because the overdose of H₂O₂ would cause the process retardation. The conventional pseudo-first-order kinetics and two-stage first-order kinetics were observed at lower and higher Fe²⁺ concentrations, respectively. Models were proposed and used to stimulate the kinetic process. Thus, design charts were established for determining the reaction time (i.e., reactor sizing) required for predetermined removal performance of alachlor under different concentrations of H₂O₂ and Fe²⁺.