Mude Zhu,Xueqin Chen,Yi Tang,Sen Hou,Yang Yu,Xiaoyun Fan
Combining piezoelectric effect and persulfate (PS) activation is a newly developed strategy for refractory emerging contaminants removal. In this work, borate SrBi 2 B 2 O 7 (SBBO) is firstly developed as a piezoelectric material to piezo-assisted activation of PS for the removal of sulfadiazine (SDZ) under ultrasonic irradiation (US). SDZ could be efficiently degraded by 85.61 % in the system of PS/SBBO/US with a pseudo-first-order rate constant of 0.0520 min −1 , which is faster than that in the systems of PS/SBBO (0.0210 min −1 ), SBBO/US (0.0041 min −1 ), PS/US (0.0074 min −1 ), and PS/BaTiO 3 /US (0.0120 min −1 ). The excellent degradation performance of the PS/SBBO/US system is mainly attributed to the piezoelectric effect of the SBBO which plays an important role in PS activation and accelerating reaction. Two oxidation processes , radical process (•O 2 - and •SO 4 - ) and non-radical process ( 1 O 2 and electron transfer), exist during the SDZ degradation. The system of PS/SBBO/US also attains excellent removal efficiency in different SDZ contained water bodies. The possible degradation pathways mainly include cleavage of bonds, ring-opening, and hydroxylation process, and the toxicity of intermediates was predicted by T.E.S.T. software. This study provides new insight into piezoelectric catalysis associated with PS activation for SDZ removal.
Mude Zhu,Yi Tang,Xueqin Chen,Biru Liao,Yang Yu,Sen Hou,Xiaoyun Fan
A built-in electric field of the ferroelectric contributes to improving the photoinduced charges separation in the photocatalysis, attracting great attention for the elimination of contaminants from water sources. Herein, a series of Ba 2+ doped Sr 1-x Ba x Bi 2 B 2 O 7 (0 ≤ x ≤ 0.6) were synthesized successfully. Among all samples, Sr 0.5 Ba 0.5 Bi 2 B 2 O 7 showing the most splendid photocatalytic degradation activity, could degrade 94.06% of TC in 30 min, which was about 6.75 and 2.56 times higher than that of the undoped one and BaTiO 3 , respectively. The synergistic effect of a strong built-in electric field and an appropriate oxygen vacancy was responsible for its high efficiency. The sample remained the superior photocatalytic activity under different reaction parameters including temperature, catalyst dosage, pH, initial ions species, and in the presence of humic acid and different types of water bodies. The different quenching and the controlled atmosphere experiments confirmed that e − and h + played an essential role in attacking TC molecular. LC-MS revealed its three degradation pathways including the process of demethylation, hydroxylation, and dehydroxylation. The toxicity of formed degradation products reduced significantly. The work is of great significance to construct more ferroelectric photocatalysts and highlights the potential of ferroelectric catalysts for purifying wastewater.
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 SrBi 2 B 2 O 7 (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 BaTiO 3 (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 •O 2 – 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.
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