Enhanced removal of profenofos from water/wastewater via photocatalytic adsorption using biosynthesized TiO₂ nanoparticles: a comparative study with Fenton process

Abstract

This study compared the efficacy of combined adsorption–photocatalytic process using biosynthesized TiO 2 nanoparticles with the Fenton process in removing profenofos. Characterization techniques such as BET, XRD, and SEM were employed to characterize the biosynthesized nanoparticles. Batch tests were conducted to analyze the effects of different parameters on the adsorption process. The characterization of the TiO 2 nanoparticles derived from guava leaves showed an increased BET surface area of 13.002 m 2 g –1 compared to commercially available TiO 2 . Under optimal conditions of pH 6, 110 min contact time, 1.5 g L –1 adsorbent dosage, and 9 mL L –1 H 2 O 2 concentration, nanoparticles exhibited high initial removal efficiency of 98.6 ± 0.65% for pesticide from wastewater. The reusability study showed that TiO 2 nanoparticles can retain more than 81% of pesticides over the five cycles, and this decline in removal capacity may be due to the saturation of adsorption sites. The TiO 2 nanoparticles had a point of zero charge at 6.7, facilitating efficient pesticide removal below this pH value. Adsorption isotherm studies favored the Freundlich model ( R 2 = 0.993), indicating multilayer adsorption of profenofos on TiO 2 nanoparticles. A strong agreement with a pseudo-second-order (PSO) kinetic model ( R 2 = 0.996), as well as similar fits to the Dubinin-Radushkevich isotherm and Elovich kinetic models, suggested chemisorption mechanisms in the adsorption processes. Guava leaf-based biosynthesized TiO 2 nanoparticles exhibited superior performance in removing profenofos compared to the Fenton process, indicating a more environmentally friendly and efficient method for OPPs remediation.