Accelerated mineralization of the drug Diclofenac via Fenton reactions in a concentric photo-reactor

The complete mineralization of concentrated solutions of Diclofenac (2-[(2,6-dichlorophenyl) amino] benzene-acetic acid) sodium salt C14H10Cl2NO2Na was carried out in a concentric cylindrical immersion photoreactor in batch mode operation. Irradiation with a lamp emitting light at 254 nm (400 W) achieved total mineralization of Diclofenac solutions (0.062 mM or TOC 20 mg C l−1) in times under an hour. The mineralization was carried out via Fenton photo-assisted treatment. A determination of the solution parameters was carried out to optimize the time of the Diclofenac pretreatment, the type and intensity of the light source, the effect of the concentrations of Fe-ions and the oxidant added in solution and the reactor recirculation rate. Diclofenac disappearance was monitored by high liquid pressure chromatography (HPLC). Concomitantly, the aromatic and aliphatic intermediates were also monitored under low-energy (36 W) light irradiation at 366 nm in order to be able to detect the intermediates by HPLC in the minute time scale. The decrease of the chemical oxygen demand was followed during Diclofenac degradation. The activation energy for the mineralization of Diclofenac was determined to be 4.02 Kcal mol−1.