B-N bonds between SrBi2B2O7 and humic acid composites enhance polarized electric field for efficient piezocatalytic degradation of oxytetracycline in water

[Display omitted] •The B-N bonds were formed between SBBO and HA under BM.•93.17 % of OTC can be piezoelectric degradation by SBBO/HA in 60 min.•A mechanism of B-N bond enhancing polarized electric field was clarified.•The degradation pathway for OTC was proposed basing on LC-MS and Fukui index.•The toxicity of the degradation product and intermediates decreased. Constructing a chemical bond between the catalysts’ interfaces can establish a fast electron diffusion path and improve interfacial charge transport, thus produce a high efficiency in the catalytic field. We innovatively incorporate the humic acid (HA) and SrBi2B2O7 (SBBO) to degrade oxytetracycline (OTC) under ball milling (BM), the degradation efficiency of OTC for SBBO/HA under BM is 93.17 % and its pseudo-first-order kinetic constant is 0.0434 min−1, being 1.41 times than the sum of rate constant for HA (0.00826 min−1) and SBBO (0.0225 min−1), and 5.26 times than that for BaTiO3 (0.00825 min−1), illustrating their outstanding synthetic effect of SBBO and HA on piezoelectric degradation of OTC. The mechanism of enhanced piezoelectric activity was attributed to the B-N bond which enhances the local polarized electric field improving electron transfer and contributes to the generation of •O2– and •OH. The possible degradation pathways involving bonds cleavage, ring-opening, and dehydroxylation process were proposed based on LC-MS and Fukui index calculation. The toxicity of intermediates generated during the piezoelectric catalysis was predicted and investigated by T.E.S.T. software and mung bean growth. This study provides a new technology of enhancing piezoelectric catalytic activity by combining HA, SBBO and BM and clarifies the mechanism in detail.