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•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.
The contagious coronavirus disease-2019 pandemic has led to an increasing number of disposable face masks (DFMs) abandoned in the environment, when they are exposed to the air condition, the broken ...of chemical bond induced aging is inevitably occurred which meantime would cause a drastic decrease of the mechanical flexibility. However, the understanding of between chemical bond change related to aging and its micromechanical loss is limited due to the lack of refined techniques. Herein, the atomic force microscopy (AFM) technique was firstly used to observe the aging process induced by methine of the polypropylene-based DFMs. By comparing the micromechanical properties loss, the influences of humidity and light density on the DFM aging were systematically studied in the early 72 h, and it revealed that the increasing scissions number of the easiest attacked methine (Ct-H) can gradually decrease the micromechanical properties of the polypropylene (PP)-based DFM. Furthermore, the results are also validated by the in- situ FTIR and XPS analysis. This work discloses that an aging process can be initially estimated with the micromechanical changes observed by AFM, which offers fundamental data to manage this important emerging plastic pollution during COVID-19 pandemic.
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•Methine induced DFM aging is directly observed by AFM.•The changes in micro-mechanical properties during aging are quantified by AFM.•The relationship between micromechanical behavior and chemical bond is established.•Competitive formation of unsaturated bonds during aging can be observed.
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•Ba2+ doping induced the OVs generation and enhanced the ferroelectricity.•94.06% of TC can be degraded by SBBO4 in 30 min under visible light irradiation.•The degradation pathway for ...TC was proposed basing on LC-MS and Fukui index.•The toxicity of the degradation product and intermediates decreased.•A mechanism of the synergy of built-in electric field and OVs was clarified.
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 Ba2+ doped Sr1-xBaxBi2B2O7 (0 ≤ x ≤ 0.6) were synthesized successfully. Among all samples, Sr0.5Ba0.5Bi2B2O7 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 BaTiO3, 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.
Combining piezoelectric effect and persulfate (PS) activation is a newly developed strategy for refractory emerging contaminants removal. In this work, borate SrBi2B2O7 (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/BaTiO3/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 (•O2- and •SO4-) and non-radical process (1O2 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.
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•Piezo-promoted PS activation by SBBO exhibited an excellent catalytic performance.•The degradation process existed radical and non-radical process.•The mechanism of piezo-promoted PS activation was clarified.•The possible degradation pathway of sulfadiazine based on LC-MS was proposed.•The toxicity of intermediates was evaluated by T.E.S.T. software.
Ball milling (BM) combined with piezoelectric materials offers a significant potential to realize the energy harvesting in wet surroundings. However, a fundamental understanding of the relationship ...between the imposed force induced built-in electric field and the amount of generated charges under BM is limited due to the complex reaction system and the short lifetime of the free charges. Herein, a BM system consisted of a series of piezoelectric materials Pb2BO3X (X = Cl, Br, I) and different milling balls is conducted to degrade organic pollutants. For Rhodamine B removal, Pb2BO3I possesses the highest rate constant of 0.161 min−1 compared to Pb2BO3Cl and Pb2BO3Br, and it also exhibits an enhanced degradation efficiency for Ciprofloxacin and Norfloxacin, which is 158.3 and 104.2 times than that of conventional piezoelectric material BaTiO3. ZrO2 balls collision under 600 rpm can produce a large force about 64.7 N which is 2.2 and 2.7 times than that of SiO2 balls collision under 600 and 500 rpm, and generate the most charges based on ratio comparison. The stronger force brings out an enlarged built-in electric field for the higher polarization materials to generate more reactive radicals, resulting in a higher degradation efficiency. Such enhanced piezocatalytic system represents a significant step toward novel-form energy harvesting and energy saving.
We demonstrate the first example of three non-centrosymmetric materials, Pb2BO3X (X = Cl, Br, I), can mediate the conversion of mechanical energy to chemical redox reaction through ball milling. The water pollutants, Rhodamine B, Ciprofloxacin and Norfloxacin, could be efficiently decomposed in the presence of Pb2BO3I material. The periodic collision induced by ball milling could produce strong alternating built-in electric field and high free charges separation which enhance the piezocatalytic activity. Display omitted
•Three Pb2BO3X (X = Cl, Br, I) borate materials and ball milling combination for efficient piezocatalysis.•The reaction rate constant k of Pb2BO3I for Ciprofloxacin removal is 158.3 times than that of commercial BaTiO3 under ball milling.•High speed and large density milling balls are benefit to generate reactive species.•Enhanced alternating built-in electric field promotes the charge pairs separation.
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•3-Chromophore asymmetric structures enhanced Cd4BiO(BO3)3 piezoelectric response.•96.2% of CBZ can be degraded by Cd4BiO(BO3)3 in 60 min under ultrasonic vibration.•The degradation ...pathway for CBZ was proposed based on LC-TOF-MS.•The toxicity of the degradation product and intermediates decreased.•A mechanism of the alternating piezoelectric field was clarified.
How to efficiently treat a type of new emerging organic pollutant, carbamazepine (CBZ), with the features of environmental persistence, toxicity, and bioaccumulation, is now posing a challenge to scientists. Piezocatalysis, through the harvesting of mechanical energy, has a high capacity to degrade organic pollutants and is gaining increasing attention. Herein, a novel piezo material Cd4BiO(BO3)3 (CBB) with a 3-chromophore asymmetric structure showing an excellent CBZ degradation activity has been synthesized. The removal efficiency can reach 96.2% in 60 min, which is 4.13 times that of tetragonal phase BaTiO3 (BTO) under the same conditions. The superior catalytic performance can be attributed to the easily polarized 3-chromophore asymmetric structure units of CBB, d10 Cd2+ ion, stereochemically active lone pair of Bi3+, and π-delocalization of BO3, which can generate a very strong internal alternating piezoelectric field under the action of ultrasonic vibration. Driven by this internal electric field force, the excited free charges can be easily separated and transferred to the surface of the material to take part in the redox reactions. Besides, CBB also exhibits high stability and excellent removal efficiency for rhodamine B (Rh B) and tetracycline (TC). Hydroxylation and aldehyde oxidation are the main processes of CBZ degradation. The eco-toxicity of CBZ and its intermediates was evaluated using T.E.S.T. software. This study shows that the easily strongly polarized borate material has a potential application in the piezocatalytic degradation of organic pollutants.
Precisely determining which bonds are more sensitive when plastic aging occurs is critical to better understand the mechanisms of toxic release and microplastics formation. However, the relationship ...between chemical bonds with the active aging sites changes and the aging behavior of plastics at an early age is still unclear. Herein, the mechanical behavior of four polymers with different substituents was characterized by the high-resolution AFM. Young's modulus (YM) changes suggested that the cleavage of C-Cl bonds in PVC, C-H bonds in PE and PP, and C-F bonds in PTFE are the main active aging sites for plastic aging. The aging degree of the plastics followed the order of PVC > PP > PE > PTFE. Two aging periods exhibited different YM change behavior, the free radical and cross-linking resulted in a minor increase in YM during the initiation period. Numerous free radicals formed and cross-linking reaction happened, causing a significant increase in YM during the propagation period. Raman spectroscopy verified the formation of microplastics. This research develops promising strategies to quantitatively evaluate the aging degrees using AFM and establish the relationship between chemical bonds and mechanical behavior, which would provide new method to predict plastic pollution in actual environments.
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•C-X bonds are the main aging active sites of plastics with different substituents.•Plastics with different substituents have different changing trends in Young's modulus during aging.•Micromechanical behavior affects the formation of microplastics.•The effect of chemical bonds on micromechanical properties was investigated.
Piezocatalysts have attracted considerable attention due to their ability to convert natural mechanical energy into chemical energy. However, the inefficient chemical reactions of the free charges ...and the poor mechanical endurance of the powder piezoelectric materials have largely restricted their wide application. Here, by combining piezocatalyst Cu3B2O6 (CBO) and polyvinylidene fluoride (PVDF), a composite membrane CBO/PVDF with superior stability and excellent piezo-performance is prepared for the first time. This composite membrane shows a high efficiency for the degradation of antibiotics and organic dyes under ultrasonication; particularly, the removal efficiency is 33.9 times higher than that of a pure PVDF membrane for amoxicillin degradation, and it maintains a high efficiency after 16 cycling tests. The polarization electric field in the dual piezoelectric composite membrane significantly enhances the redox reaction of the intrinsic free carrier with dissolved oxygen and water molecules to generate reactive oxygen species. The results provide a strategy for combining the borate with the polymer membrane to lead piezocatalysis to real future applications.
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•Three different morphologies of SBTO were obtained by various preparation methods.•SBTO with nanoflower shape exhibited the most excellent piezoelectric activity.•Morphology and ...thickness synergistically promoted catalytic degradation for VLFX.•The energy band theory and screening effect clarified piezo-catalytic mechanism.
Piezoelectric catalytic technology has been widely applied in the removal of contaminants, and now has become a hot research spot for potential practice application. In this study, the piezoelectric performance could be exactly regulated by changing the morphology of the piezo-materials. Via different synthesis methods, series of SrBi2Ta2O9 (SBTO) with different morphology were successfully prepared. The results show that the SBTO synthesized by hydrothermal method (SBTO-HR) owes the nanoflower morphology, exhibiting the most excellent catalytic activity than the solid-state method (SBTO-SS) and molten salt method (SBTO-MS). The degradation efficiency for Venlafaxine (VLFX) is almost 100 % in 20 min, which is 5.46 and 6.59 times that of SBTO-MS and SBTO-SS. The enhanced piezoelectric catalytic performance is attributed to that SBTO-HR nanomaterial with the smaller thickness around 32.0 nm and exposed facet (001) can be easily deformed and polarized under external force which induces a stronger piezoelectric potential to accelerate the separation of electrons and holes. The proposed screening effect and energy band theory further clarified the piezoelectric catalytic mechanism. The TOC removal rate of VLFX could reach 80 %, illustrating the outstanding mineralization ability of SBTO-HR. This work provides a promising strategy for promoting piezoelectric activity by morphology engineering of the piezo-materials.
How to promote the free charges of piezomaterials to take the redox is now a challenging work in environmental remediation. Construction of built internal electric fields is crucial to realize ...efficient charge separation for charge-induced redox reaction. Herein, PbB4O7 (PBO) with lone pair electrons firstly realizes a high piezocatalytic degradation efficiency for removal of dye & Cr(VI) under ultrasound activation. PBO shows more excellent degradation performance than traditional BaTiO3 (BTO), which is 2.08 times, 2.47 times, 2.28 times, and 3.02 times than that of BTO for RhB in the unary system, RhB & Cr(VI) in binary systems, MB in the unary system, and MB & Cr(VI) in binary systems, respectively. Piezoresponse force microscopy confirmed that PBO had excellent piezoelectric property. The varied degradation performance can be assigned to systems exposed to different ions (negative or positive) environment that influence shielding effect. Additionally, the easily polarization of lone pair electrons of the Pb-contained piezomaterial forming a strong alternating built-in electric field under ultrasound that can offer a strong driven force to separate electron and hole pairs, thus producing the superior piezocatalytic activities. The main active species in the unary system and the binary system were determined, and the piezocatalytic degradation mechanism of PBO was analyzed.
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•Lone pair electrons containing PbB4O7 shows high piezocatalytic efficiency.•Different catalytic activity of unary and binary system deduces shielding effect.•Alternating built-in electric field promotes separate of charge pairs.
