Effect of water constituents on the photocatalytic degradation of sulfaclozine in the UV/TiO2, and UV/TiO2/K2S2O8 systems. Comparison with UV/K2S2O8.
Résumé
While the TiO2-based photocatalystic degradation of micro-pollutants in ultra-pure water is usually very efficient, the presence of natural constituents of water such as bicarbonate ions, chloride ions, phosphate ions, dissolved organic matters etc can dramatically affect the process.
In this context, this work deals with the degradation of sulfaclozine, in the presence and in the absence of the main natural constituents of water in three different systems: UV/TiO2, UV/K2S2O8 and UV/TiO2/K2S2O8. Here persulfate of potassium was added to the photocatalytic system to reduce the rate of electron-hole recombination and generate reactive sulfate radicals. A comparison will be done with the system UV/K2S2O8.
The results showed that (bi)carbonate and phosphate ions have an enhancing effect on the degradation rate of sulfaclozine in the UV/TiO2 and UV/TiO2/K2S2O8 systems while they have no effect in the UV/K2S2O8 system. In the presence of humic substances an inhibitory effect was observed in the UV/ K2S2O8 system and no significant effect was identified in the UV/TiO2 and UV/TiO2/K2S2O8 systems. Moreover, chloride ions enhanced the adsorption of sulfaclozine on the surface of TiO2.
In this work the results observed will be discussed as well as the reactivity of radicals, OH° and SO4°- , towards sulfaclozine.