In Situ Piezoelectric Regulation of Lewis Acid Sites in Vanadate to Boost the Long-Term Generation of Hydroxyl Radicals for the Purification of Arsenic-Containing Acidic Mine Wastewater.

内容摘要

Self-Fenton processes show potential for treating acidic mine drainage (AMD), yet their efficacy is limited by inefficient conversion of in situ generated hydrogen peroxide (H2O2) to hydroxyl radicals (·OH), crucial for oxidizing highly mobile trivalent arsenic (As(III)). Here, we engineered Lewis acid sites on iron vanadate (FeVO4) and leveraged piezocatalysis to dynamically boost both the sustained generation and subsequent activation of H2O2 into ·OH under acidic conditions. Under ultrasonic excitation, FeVO4 achieved a remarkable ·OH generation rate of 334.26 μmol g-1 h-1 at pH 3.0. This system oxidized 80.14% of As(III) and concurrently adsorbed 19.14% of the resulting pentavalent arsenic (As(V)), leading to a total arsenic removal of 15.34% within 3 h. Intriguingly, the presence of As(III) accelerated ·OH production by 3-4 fold, attributed to the facilitated redox cycling of Fe sites at the FeVO4 surface. Mechanism studies confirm that Lewis acid sites are pivotal for adsorbing and activating O2 and H2O2, while piezoelectric polarization optimizes their electronic state to promote efficient ·OH formation and its diffusion into bulk solution for As(III) oxidation. This work demonstrates a novel, external-oxidant-free strategy for long-term ·OH yield via in situ piezoelectric regulation of Lewis acidity, offering a sustainable avenue for the remediation of AMD.