Removal of Diclofenace Sodium from Aqueous Environments Using Heterogeneous Photocatalysis Treatment

The occurrence, fate and effects of Pharmaceuticals compounds (PhCs) in the environmental system have been attracted special attention in the world as a new emerging contaminants due to their potential impact on humans, animals and microorganisms even at low concentrations. Conventional wastewater treatment technologies, including biological, thermal and physical treatments, are demonstrated to be insufficient for removal of many pharmaceuticals residues from wastewater, due to their low biodegradability and high chemical stability. Advanced oxidation processes (AOPs), are one of the most promising treatment technologies for elimination of such relentless compounds. The current study was focused on the efficacy of various oxidation processes for degradation of diclofenac sodium (DCF) as a one of the most widespread pharmaceuticals present in sewage. The experimental phase was divided into two parts: Photolysis and heterogeneous photocatalysis. Concerning photocatalysis experiments, TiO2 as a catalyst has been used in two forms: (i) as dispersed powder; (ii) immobilized on the surface of blue slabs. Kinetic studies of DCF were accomplished and it’s photoproducts were identified using liquid chromatography coupled with mass spectrometry system (LC-MS). Heterogeneous photocatalysis by using TiO2 dispersed powder shows the fastest extent of degradation with 54.6 min of half-life (t1/2). Nevertheless, the recovery of the suspended catalyst from the treated solution still form a problem after the treatment process. Direct photolysis and photocatalysis using TiO2 immobilized system showed approximately comparable results ( 71 and 79 min respectively), in contrast, the degradation pathway for each process was different which yielded a diversity in the photoproducts in each process. In conclusion, the overall results suggested that using both photolysis and heterogeneous photocatalysis are promising alternative techniques towards protecting the environment from this emerging contaminants.