Role of the radical promoter systems on the degradation of an antipeleptic drug using HO and SO4- species

The aim of this work was to determine whether the effectiveness of hydroxyl and sulfate radicals to degrade carbamazepine (CBZ) in aqueous solution is a function of the radical generator system used. For this purpose, an in-depth analysis was conducted of CBZ degradation by UV radiation, UV/H2O2, UV/S2O82−, Fe2+/H2O2, Fe2+/S2O82−, UV/Fe2+/H2O2 and UV/Fe2+/S2O82−. Results obtained show that CBZ can be degraded by direct photolysis but that the effectiveness is very low, with a quantum yield near zero. CBZ can be effectively degraded by UV/H2O2 and UV/S2O82- systems, with percentages close to 100%. CBZ degradation was 1.26- to 2.0-fold faster with SO4 - radicals than with HO radicals. In contrast, CBZ degradation was 1.1- to 1.7-fold more effective with the Fe2+/H2O2 versus Fe2+/S2O82- system when the Fenton process was applied. CBZ removal from water was most effective with UV/Fe2+/H2O2 and UV/Fe2+/S2O82− systems, attributable to the additional generation of HO radicals resulting from the reduction in Fe3+. A slight decrease in percentage degradation was observed with all systems when wastewater was the aqueous matrix, mainly due to the presence of organic and inorganic species that may act as radical scavengers (Cl-, NO2-, NO3- and SO42−). Finally, the highest percentage mineralization was obtained with the UV/Fe2+/H2O2 system in deionized water.