Comparative evaluation of ibuprofen removal by UV/H2O2 and UV/S2O82− processes for wastewater treatment

• The UV/H2O2 and UV/PS can effectively remove IBF.
• The second-order rate constants of IBF with SO4− and HO were determined.
• Higher inhibitory effects of HCO3− and EfOM on SO4− compared to HO were found.
• The UV/PS shows higher mineralization efficiency for the EfOM than the UV/H2O2.
• Production yield of a harmful intermediate (4-IBAP) was determined in both processes.

This study evaluates the UV/H2O2 and UV/S2O82− (UV/PS) processes as alternative methods for the removal of ibuprofen (IBF) from wastewater destined for treatment and reuse. The second-order rate constants of IBF with HO and SO4− were determined as kHO/IBF=5.57×109M-1s-1 and kSO4-/IBF=1.32×109M-1s-1. The IBF removal rate was higher in the UV/PS process than in the UV/H2O2 process for deionized water, while a higher IBF removal rate was seen with the UV/H2O2 process than with the UV/PS process for wastewater effluent. The suppression of IBF removal in wastewater effluent was verified by investigating the effects of background water quality using synthetic solutions (HCO3−, Cl−, NO3−, SO42−, humic acid, and fulvic acid); HCO3− and organic compounds showed stronger inhibitory effects on the UV/PS process than on the UV/H2O2 process. A mineralization test on the effluent organic matter (EfOM) revealed a higher efficiency for the UV/PS process than the UV/H2O2 process. A toxic by-product test showed a notably higher production yield of 4-isobutylacetophenone (4-IBAP) with the UV/PS process ηUV/PSIBF→IBAP=0.23 than with the UV/H2O2 process ηUV/H2O2IBF→IBAP=0.019, even though 4-IBAP was removed by both processes.