Photoassisted degradation of pentachlorophenol in a simulated soil washing system containing nonionic surfactant Triton X-100 with La–B codoped TiO2 under visible and solar light irradiation

Abstract

A novel method to remediate soil washing contaminants was developed through the utilization of La–B codoped TiO2 (La–B–TiO2) nanoparticle in the photocatalysis of a simulated complex system containing hydrophobic pentachlorophenol (PCP) and nonionic surfactant Triton X-100 (TX-100) under visible and solar light irradiation. The photocatalyst synthesized by the sol–gel hydrothermal process exhibited excellent visible light photocatalytic activity and a modified surface. The investigation of the adsorption kinetics and isotherms showed that the distribution of PCP between the catalyst surface and the bulk solution significantly depended on the initial TX-100 concentration (CTX-0). The formed superficial reactive monolayer at CTX-0 ranging from 0.023 to 0.23mM by the dramatic hydrophobic interactions between the TX-100 moiety and hydrophobic sites on the La–B–TiO2 could remarkably capture the target pollutant. The PCP implanted into the hydrophobic space could be removed effectively in the photocatalysis process induced by visible and solar light, ascribing to the facile availability of PCP to the photo-yielded oxidative radicals on the La–B–TiO2 surface. Additionally, the preferential decomposition of the incorporated PCP, rather than the TX-100, facilitated the removal of the target contaminant and the recycling of the surfactant, which is beneficial to the practical application of this technique under mild and natural light sources.