First highly efficient degradation and dechlorination of herbicides by photocatalytic hydrogenation: Advanced reduction processes (ARP) approach

The widespread use of phenylurea herbicides (PUHs) such as chlorotoluron (CHL) has caused important environmental and human health concerns due to their persistence, bioaccumulation and resistance to conventional wastewater treatments. Until now, the degradation and transformation of PUHs have been the subject of numerous research. Adsorption, microbial degradation, chemical oxidation, biodegradation, and radical-based advanced oxidation processes (AOPs) have all been shown to be effective in the removal of PUHs. These methods do have some serious disadvantages, though, including poor kinetics, the production of hazardous byproducts, and high costs of treatment. On the other hand, ARPs could be an effective alternate to degrade impurities and yield non-harmful byproducts unlike AOPs and other approaches.

In this paper, we have studied the degradation of a phenylurea herbicide (CHL) contaminant in an aqueous environment by the first highly effective process based on UV based sulfite (S), palladium on activated carbon (Pd-C), and hydrogen gas (H₂) (UV/S/Pd-C/H₂) using an ARP approach. The developed process provides CHL's complete reduction within 1 hour of treatment along with >90% dechlorination at ambient temperature. Also, we observed excellent resistance of the reaction system to the presence of inorganic anions, and the system performed well across a wide pH range.

Funding informationThe authors gratefully acknowledge financial support from the National Science Centre, Warsaw, Poland, for project OPUS nr UMO-2021/41/B/ST8/01575.