Polydopamine-Chitosan modified TiO2 nanoparticles for temperature-response removal of diclofenac sodium under visible light irradiation

Abstract

BackgroundDiclofenac sodium is a kind of classic pharmaceutical and personal care product which has a potential risk to aqueous environment and food chain. The aim of the study is to realize the removal of diclofenac sodium in an energy-efficient and eco-friendly way. MethodTiO2 nanoparticles were modified with aminopropyltriethoxysilane and then were grafted with polydopamine and chitosan sequentially through Schiff-base reaction to realize spatiotemporal coagulation and degradation of diclofenac sodium under visible light irradiation, which was rare reported before. ResultsThe polymer layer of modified TiO2 nanoparticles became swelling and outstretching with cooling the temperature from 313.15±0.2 to 293.15±0.2 K, which led to the exposure of the TiO2 nanoparticle surface and the photocatalysis of which was activated. Photoelectrons migrated to the surface of which due to the protonation of TiO2 nanoparticles in acidic aqueous milieu and reacted with OHˉ forming •OH at the presence of oxygen and the photocatalytic efficiency of which was improved. It further reacted with diclofenac sodium and the coagulant could be directly reused at least twenty times without rinse process in this work, which has a significantly application potential considering future benefits.