Photodegradation of thiophanate-methyl under simulated sunlight by utilization of novel composite photocatalysts

Abstract

This work aimed to investigate the influence of modified titanium(IV) oxide by different nanosized particles on photocatalytic capacity to decompose the chosen organic pollutant under simulated sunlight. For that purpose, rutile-phased titanium(IV) oxide (r-TiO2) was decorated with iron vanadate (FeVO4/r-TiO2) and vanadium-substituted goethite (Fe1-xVxOOH/r-TiO2). The obtained composites were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X ray powder diffraction, Brunauer-Emmett-Teller, Fourier transform infrared spectroscopy - attenuated total reflec-tance and ultraviolet-visible diffuse reflectance spectroscopy techniques. Both synthesized photocatalysts showed higher photoactivity than the base r-TiO2 for the degradation of the target contaminant - thiophanate-methyl (2.5 h vs. 5 h). During the tests, parameters like the irradiation time, catalysts amount, and pesticide concentration were systematically investigated. Furthermore, photocatalysts were applied in multicycle degradation tests for examining their effectiveness during exploitation time. Monitoring of the removal rate was performed both by UV/visible spectrometry and high-performance liquid chromatography (HPLC). In order to prove completion of fungicide degradation chemical oxygen demand was measured in the course of the photocatalytic experiment. The final concentration of the observed contaminant in treated samples was under the prescribed legislative level. The fabricated materials displayed great reliability, durability and photocatalytic activity repre-senting good potentials for implementing this process in real wastewater treatment plants.