Comparative study on photocatalytic treatment of diclofenac: slurry vs. immobilized processes

Abstract

a b s t r a c tThe applicability of different photocatalytic systems for the treatment of pharmaceuticals in water was investigated. Slurry (UV-A/TiO 2 (s) and UV-A/TiO 2 (s)/H 2 O 2 ) and immobilized (UV-A/TiO 2 (i)/H 2 O 2 ) processes were compared regarding the removal of diclofenac (DCF) and total organic content, as well as the improvements in biodegradability and toxicity. The applied response surface modeling revealed the significance of TiO 2 dosage and concentration of H 2 O 2 , while pH was less influential within the studied range. Although UV-A/TiO 2 (i)/H 2 O 2 was somewhat less effective in comparison with UV-A/ TiO 2 (s)/H 2 O 2 process (88.8% and 99.1% of DCF removal, respectively), the immobilized system enabled photocatalyst reuse. In comparison with air dried and thermally reactivated, chemically reactivated photocatalyst provided better performance through four consecutive runs.