Photocatalytic Degradation of Alachlor over Titania-Reduced Graphene Oxide Nanocomposite: Intrinsic Kinetic Model and Reaction Pathways

An intrinsic kinetic model based on a proposed reaction photomechanism explicitly dependent on the volumetric rate of photon absorption (VRPA) has been performed and analyzed for the photocatalytic degradation of alachlor in water. A titania-reduced graphene oxide nanocomposite (HBK TiO2-rGO) was used as the photocatalyst. The proposed degradation pathway was elucidated addressing H* - abstraction, HO* substitution, C-C scission, C-N bond scission, and dealkylation reactions. A suitable kinetic model has successfully been validated by fitting the obtained experimental data to reproduce the evolution of alachlor photodegradation at different HBK-rGO loadings. After simplification, the proposed kinetics were adjusted to a reasoned simplified model of 1-2 parameters, showing very good fitting between predicted and experimental values, as denoted by the resulting lower root-square-mean errors. Finally, the synthesized nanocomposite addressed very good stability and durability applied to the degradation of alachlor by photo-oxidation along six consecutive cycles of reuse.

Automated summary

An intrinsic kinetic model based on the volumetric rate of photon absorption has been successfully validated for photocatalytic degradation, with a proposed simplified model showing excellent fitting with experimental values. The synthesized nanocomposite exhibited good stability and durability in the degradation of alachlor by photo-oxidation over six consecutive cycles of reuse.