Sequential impregnation and sol-gel synthesis of Fe-ZnO over hydrophobic silica aerogel as a floating photocatalyst with highly enhanced photodecomposition of BTX compounds from water

Abstract

Benzene, Toluene, and Xylene (BTX) are included in the floating contaminants which originated from the explosion of oil wells. Photocatalytic oxidation of the some oil spill components like Benzene, Toluene, and Xylene can be a proper way to solve this challenge due to its economic saving, usage of free energy, and environmentally friendly. For this purpose, we have synthesized a hydrophobic catalyst of Fe-ZnO nanoparticles inoculated with silica aerogel (SA). Various percentage of hydrophobic silica aerogel (10, 20 and 30%) was added, as support of catalyst, to Fe-ZnO nanoparticles using impregnation method. The impregnation of silica aerogel to Fe-ZnO nanoparticles caused the photocatalytic performance of nanocatalyst was improved through its increased surface area, and also floated active phase (Fe-ZnO) on water. In order to investigate the impact of the synthetic method of nanocomposite on the activity of synthesized nanophotocatalyst, optimum samples (Fe-ZnO over 20% SiO2) were synthesized using the sol-gel method. The synthesized nanophotocatalysts were characterized using PXRD, FESEM, EDX, UV–Vis, Contact Angle, FT-IR, and BET-BJH analyses. Photocatalytic activity of synthesized nanophotocatalyst was evaluated in the degradation of the BTX after 120 min, under visible light irradiation. In addition, the influence of various parameters including the addition of hydrophobic silica aerogel, pH, catalyst loading, benzene concentration, and reusability was studied on the photodegradation efficiency of Fe-ZnO/SA (20%). The most photocatalytic activity was observed in the optimum condition involving pH = 5, catalyst loading = 1 g/L, and benzene concentration = 5% V/V.