Oxidation of sulfamethazine by TiO2 photocatalysis

Pharmaceuticals cover a wide range of different compounds and are used to cure disease and fight infection both in humans and in animals. Their occurrence in the environment has become an issue of great importance in the last decade. Sulfonamides are synthetic antimicrobial agents derived from sulfanilic acid. They are widely prescribed to treat human and animal infections and are used as food additives in livestock production. Major source of their release into environment is their incomplete removal from the wastewater treatment plants. Over the past few decades, advanced oxidation processes (AOPs) are widely applied in wastewater treatment for the removal of organic pollutants. In that sense AOPs can be used as effective way for pharmaceuticals removal from the wastewaters. The aim of this work is to study photocatalytic oxidation of aqueous solution of sulfamethazine by sol-gel TiO2 film. Sol-gel TiO2 film was immobilized on the inner surface of borosilicate glass tube (photoreactor). HPLC-ESI(+)-MS Agilent 1200 was used to monitor sulfamethazine and the appearance of transformation products. For chromatographic analysis polar embedded C18 Synergy Fusion column (4 μm, 150 x 2.0 mm, Phenomenex) was used. The analysis was performed using 0.1% formic acid in water and 0.1% formic acid in acetonitrile in gradient elution mode. Inorganic anions (NO3-, SO42-, C2O42-) were quantified by ion chromatography on a Dionex DX600 using precolumn AG19 (4x50 mm, Dionex) and column AS19 (4x250 mm, Dionex). In addition to that the extent of mineralization was evaluated by measuring changes in total organic carbon on Shimadzu TOC analyser.