Energy-efficient pulsed photocatalysis with engineered biochar-ferrite nanocomposites for the reductive degradation of chlortoluron in water

초록

This study investigates the ultraviolet light (UV) activated photocatalytic degradation of a recalcitrant herbicide chlortoluron by using ferrite and biochar-based nanostructured photocatalysts (CuFe2O4/BC, NiFe2O4/BC, CuFe2O4/NiFe2O4/BC, and CuFe2O4/BC/nZVI). The photocatalytic degradation experiments were conducted in a 700 mL reactor equipped with an internally mounted UV lamp. Materials were thoroughly characterized by XRD, XPS, FTIR, SEM, EDX techniques, and UV/Vis-based band gap energy analysis. Characterization results revealed the successful preparation of the composites and the stability of the materials. Experimental results revealed that the ternary ferrites and the ferrites containing nano-ZVI showed a decline in their efficiency as compared with CuFe2O4/BC and NiFe2O4/BC. For the optimized CuFe2O4/BC system, the photocatalytic activity was found to be high (99%) for chlortoluron degradation from water by pulsing the UV light. The important parameters were also optimized to achieve the desired photocatalytic activity. For the optimized system, the parameters were set to pH 7, a catalyst dosage of 0.3 g/L, and a nitrogen atmosphere to extend the lifetime of the hydrated electron (e-aq) by minimizing oxidation. The presence of competitive ions such as NO3−/NO2− and humic acid led to a decline in chlortoluron removal from water, while other conditions remained the same. The pulsed activation process saved energy consumption (83.3%) as compared to traditional continuous UV-based degradation while maintaining the same efficiency, which will be beneficial in large-scale use. Mechanistic evidence for the reductive degradation pathway through systematic scavenger experiments confirmed the dechlorination as the primary degradation. © 2026 Elsevier Ltd

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