Morphology-dependent piezoelectric decontamination of organoarsenicals on BaTiO3: The governing roles of TiO2 precursor and reaction mechanism tailored by surface chemistry

Abstract

Organoarsenicals and phenols are main contaminants with the characteristics of high toxicity and anti-degradation in aquaculture wastewater. Herein, we aim to explore the piezoelectric decontamination of organoarsenicals on BaTiO3, with the main focus on the TiO2 precursor with different morphological shape, crystal structure and surface chemistry. Our findings elucidated the great morphology-dependent BaTiO3 reactivity for piezoelectric degradation of typical organoarsenicals, roxarsone (ROX) and arsanilic acid (ASA). Hollow BaTiO3 sphere was prepared with the TiO2 precursor co-exposed by low-energy non-polar {101} and high-energy polar {001} facets, and exhibited the highest piezoelectric reactivity. The released high-toxicity As3+/5+ were strongly adsorbed onto BaTiO3 by forming the Ti-As bond, thus in-situ avoiding secondary pollution from organoarsenicals in one-single process. Rendered by the in-situ formed Ti-As surface ligand on spent BaTiO3, a much superior piezoelectric reactivity was further measured for other pollutants degradation. Based on a series of experimental measurements, the bulk-free radical-mediated reaction mechanism was proposed, in comparison with the surface-bound radical-mediated pathway. This study provides a new chance for piezoelectric water purification rendered by the finely regulated surface chemistry of solid catalyst.