On the degradation of glyphosate by photocatalysis using tio2 /biochar composite obtained from the pyrolysis of rice husk

Abstract

In this study, titanium dioxide (TiO2 ) nanoparticles are immobilized onto rice husk biochar (RHB), as a porous support, for the photodegradation of glyphosate under UV light irradiation. The TiO2 /RHB composites are prepared by pyrolysis and the sol-gel method. The SEM, XRD, EDX, and FT-IR results confirm the graphene structure of RHB and the formation of 10.61 nm TiO2 nanoparticles on the catalyst support. The effects of operating conditions, including catalyst dosage (3 g L−1, 5 g L−1, 10 g L−1, and 20 g L−1 ) and different illumination conditions (9 W lamp, 2 × 9 W lamps), on the removal of glyphosate from aqueous solutions were investigated. The photodegradation efficiency of 15 mg L−1 of commercial glyphosate was up to 99% after 5 h of irradiation at pH 3.0, with a TiO2 /RHB dosage of 10 g L−1 . However, the mineralization efficiency under this condition was lower than the decomposition efficiency of glyphosate, proving the partial degradation of glyphosate into AMPA and other metabolites after 5 h of reaction.