Enhanced peroxydisulfate activation by photo-piezocatalysis based on zinc-aluminum layered double hydroxide for imidacloprid removal: Combined radical with nonradical pathways

The residual imidacloprid (IMI) insecticide in the environment has become a potential risk to ecological safety and human health, encouraging an efficient, sustainable and environment friendly approach for its removal. In this study, zinc-aluminum layered double hydroxide (ZA) is applied in the photo-piezocatalytic (VL-Pi) process to activate PDS (ZA/PDS/VL-Pi) for the degradation of IMI. The degradation ratio of ZA/PDS/VL-Pi process for IMI reaches 90.6% with a reaction rate constant of 0.021 min-1, which is 205 and 29 times higher than that of ZA and ZA/PDS processes, respectively. This significant enhancement can be attributed to the stimulation of high current by VL-Pi that generated electrons (e-) and holes (h+) on ZA for PDS activation, resulting in efficient separation of e-/h+ pairs, and the production of more reactive oxygen species (1O2 and •OH). Furthermore, by combining DFT calculation with experimental tests, degradation pathways of IMI and toxicity of the intermediates are elucidated, demonstrating the substantial detoxification of IMI. Moreover, the ZA/PDS/VL-Pi process functions well over a wide pH range from 3.0 to 9.0 and in various natural water matrices. This work is dedicated to opening up a new field for the application of photo-piezoelectric catalysis by utilization of green energy in environmental remediation.