Mechanical energy triggered piezo-catalyzation of BiWO nanoplates on ferrate (Fe(VI)) oxidation in alkaline media: Performance and mechanism.

Piezo-electricity, as a unique physical phenomenon, demonstrates high effectiveness in capturing the environmental mechanical energy into polarization charges, offering the possibility to activate the advanced oxidation processes via the electron pathway. However, information regarding the intensification of Fe(VI) through piezo-catalysis is limited. Therefore, our study is the first to apply BiWO nanoplates for piezo-catalyzation of Fe(VI) to enhance bisphenol A (BPA) degradation. Compared to Fe(VI) alone, the Fe(VI)/piezo/BiWO system exhibited excellent BPA removal ability, with the degradation rate increased by 32.6% at pH 9.0. Based on the experimental and theoretical results, Fe(VI), Fe(V), Fe(IV) and •OH were confirmed as reaction active species in the reaction, and the increased BPA removal mainly resulted from the enhanced formation of Fe(IV)/Fe(V) species. Additionally, effects of coexisting anions (e.g., Cl, NO, SO and HCO), humic acid and different water matrixes (e.g., deionized water, tap water and lake water) on BPA degradation were studied. Results showed the Fe(VI)/piezo/BiWO system still maintained satisfactory BPA degradation efficiencies under these conditions, guaranteeing future practical applications in surface water treatment. Furthermore, the results of intermediates identification, ECOSAR calculation and cytotoxicity demonstrated that BPA degradation by Fe(VI)/piezo/BiWO posed a diminishing ecological risk. Overall, these findings provide a novel mechanical energy-driven piezo-catalytic approach for Fe(VI) activation, enabling highly efficient pollutant removal under alkaline condition.