PHOTOCATALYTIC DEGRADATION OF PROFENOFOS BY ELECTROSPUN TITANIUM (IV) DIOXIDE NANOFIBERS WITH UV AND VUV IRRADIATION

Abstract

The photolytic and photocatalytic degradation of profenofos, an organophosphate pesticide, in aqueous solutions under UV, VUV, UV/TiO2, and VUV/TiO2 systems in both Deguss-P25 nanoparticles and synthesized electrospun TiO2/PVP composite nanofibers were investigated. The experiments were performed at 10 mg/L of profenofos, pH 7 (unbuffered), room temperature (25 ºC ± 3), 30 min of reaction time and dose of TiO2 of 0, 0.05, 0.1, and 0.2 g/L. Photodegradation performances of profenofos including removal efficiency, kinetic rate and mineralization were in the order: VUV/TiO2 > VUV > UV/TiO2 > UV. Particularly, the VUV/TiO2 system in both P25 and nanofibers showed the highest removal efficiency for 98% and 97%, respectively, indicating that the presence of titania photocatalyst could significantly improve the removal of profenofos in aqueous solution. Increasing of titania (both Deguss-P25 and nanofibers) significantly enhanced removal efficiency, kinetic rate and mineralization of profenofos under UV and VUV radiation due to more active sites on titania surface area, where the photocatalysis reaction occurred, and more formation hydroxyl radicals in the system. The kinetic rate results indicated that the degradation kinetic of profenofos by photolytic process followed first kinetic model and kinetic of profenofos by photolytic process followed pseudo-first kinetic model, and the results showed that photocatalytic degradation with Deguss-P25 had similarly resulted to TiO2 nanofibers. Reusability of TiO2 had been investigated for ten consecutive cycles, and the results revealed that TiO2 nanofibers had more reusability than P25. Due to easy separation, readily easy reusable, eco – friendly solid photocatalyst, high activity, long-term stability, and insignificant loss in adsorption performance, TiO2 nanofibers present appropriate properties to be a catalyst for photocatalytic purification of organophosphate pesticides in water sources and would be attractive to develop a real scale application.