Degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in real-field soil by an integrated visible-light photocatalysis and solvent migration system with p-n heterojunction BiVO4/Bi2O3

Highly sensitive photoelectrochemical biosensing detection of early cardiac injury enabled by novel self-assembled Bi2O3/MgIn2S4 photoelectrode coupled with ZnSnO3 quencher

The development of photoelectrochemical (PEC) biosensors plays a critical role in enabling timely intervention and personalized treatment for cardiac injury. Herein, a novel approach is presented for the fabrication of highly sensitive PEC biosensor employing Bi2O3/MgIn2S4 heterojunction for the ultrasensitive detection of heart fatty acid binding protein (H-FABP). The Bi2O3/MgIn2S4 heterojunction, synthesized through in-situ growth of MgIn2S4 on Bi2O3 nanoplates, offers superior attributes including a larger specific surface area and more homogeneous distribution, leading to enhanced sensing sensitivity. The well-matched valence and conduction bands of Bi2O3 and MgIn2S4 effectively suppress the recombination of photogenerated carriers and facilitate electron transfer, resulting in a significantly improved photocurrent signal response. And the presence of the secondary antibody marker (ZnSnO3) introduces steric hindrance that hinders electron transfer between ascorbic acid and the photoelectrode, leading to a reduction in photocurrent signal. Additionally, the competition between the ZnSnO3 marker and the Bi2O3/MgIn2S4 heterojunction material for the excitation light source further diminishes the photocurrent signal response. After rigorous repeatability and selectivity tests, the PEC biosensor exhibited excellent performance, and the linear detection range of the biosensor was determined to be 0.05 pg/mL to 100 ng/mL with a remarkable detection limit of 0.029 pg/mL (S/N = 3).

Review of thermal treatments for the degradation of dioxins in municipal solid waste incineration fly ash: Proposing a suitable method for large-scale processing

Dioxin degradation is considered essential for the environmentally sound management of municipal solid waste incineration fly ash (MSWIFA). Among the many degradation techniques, thermal treatment has shown good prospects owing to its high efficiency and wide range of applications. Thermal treatment is divided into high-temperature thermal, microwave thermal, hydrothermal, and low-temperature thermal treatments. High-temperature sintering and melting not only have dioxin degradation rates higher than 95 % but also remove volatile heavy metals, although energy consumption is high. High-temperature industrial co-processing effectively solves the problem of energy consumption, but with a low fly ash (FA) mixture, and the process is limited by location. Microwave thermal treatment and hydrothermal treatment are still in the experimental stage and cannot be used for large-scale processing. The dioxin degradation rate of low-temperature thermal treatment can also be stabilized at higher than 95 %. Compared to other methods, low-temperature thermal treatment is less costly and energy consumption with no restriction on location. This review comprehensively compares the current status of the above-mentioned thermal treatment methods and their ability to dispose of MSWIFA, especially the potential for large-scale processing. Then, the respective characteristics, challenges, and application prospects of different thermal treatment methods were discussed. Finally, based on the goal of low carbon and emission reduction, three possible approaches for improvement were proposed to address the challenges of large-scale processing of low-temperature thermal treatment, namely, adding a catalyst, changing the FA fraction, or supplementing with blockers, providing a reasonable development direction for the degradation of dioxins in MSWIFA.

NaNbO3/ZnO piezocatalyst for non-destructive tooth cleaning and antibacterial activity

Tooth discoloration and plaque formation are serious issues for dental healthcare professionals across the world. Although traditional hydrogen peroxide-based cleaning methods are efficient, they can cause enamel demineralization, periodontal irritation, and toxicity. Also, these treatments are time-taking. Here, we present a noninvasive, safe, and simple tooth cleaning approach by using the piezoelectric phenomenon. After 6 h of vibrations, contaminated teeth can be significantly cleaned by the NaNbO₃/ZnO binary nanocomposite. Moreover, the NaNbO₃/ZnO binary nanocomposite-based piezocatalysis tooth cleaning procedure causes far less harm to enamel and biological cells in comparison to hydrogen peroxide-based cleaning methods. To evaluate its functionality, organic dyes were degraded by piezoelectric effect of NaNbO₃/ZnO binary nanocomposite under ultrasonic irradiation. The piezoelectric potential of NaNbO₃/ZnO was found to be 3.75 V. The binary nanocomposite’s antibacterial activity was proven to be efficient against Escherichia coli with the inhibitory zone of 21 mm and complete removal of bacteria.

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NaNbO₃/ZnO binary nanocomposite was synthesized by hydrothermal method

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NaNbO₃/ZnO binary nanocomposite was evaluated as a piezocatalyst

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The formation of p-n heterojunction enhances the catalytic activity

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NaNbO₃/ZnO binary nanocomposite can be used for non-destructive tooth cleaning

Novel strategies for 2,8-dichlorodibenzo-p-dioxin degradation using ternary Au-modified iron doped TiO2 catalysts under UV-vis light illumination

Polychlorinated dibenzo-p-dioxins (PCDDs), characterized by their extreme toxicity, high persistency and bioaccumulation, regard as one of the most concerned environmental pollutants on the priority list. In this study, microwave-hydrothermal and photoreduction methods were adopted for fabrication of ternary Au@Fe/TiO₂ composites for removal of 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) under UV-Vis light irradiation. The acquired materials were characterized and analyzed by XRD, TEM, XPS, UV-Vis DRS, PL, etc. As a result, the 1%Au@1%Fe/TiO₂ exhibited much higher photocatalytic activity that 96.3% of 2,8-DCDD was removed within 160 min with respect to that of Fe/TiO₂ (3.0 times) and TiO₂ (5.5 times). It revealed the active substances might be produced, which were verified by ESR analysis. In a comparison, the 1%Au@1%Fe/TiO₂ also exhibited high activity in that 97.2% of 2,8-DCDD was removed within 240 min under an anoxic atmosphere. The 1%Au@1%Fe/TiO₂ systems were all pH-dependent that 2,8-DCDD could be fully degraded in neutral conditions. The results of repeatability on 1%Au@1%Fe/TiO₂ showed that the sample was high stability. Fe doping improved the charge separation of TiO₂ and Au modification improved the activity via SPR effect and Mott-Schottky barrier. The degradation mechanisms and pathways were proposed and discussed in detail. The current work develops a new approach on photocatalytic oxidation and reductive dechlorination of dioxins and may open a new opportunity to extend the application range of TiO₂ catalysts.

White rot fungus Pleurotus pulmonarius enhanced bioremediation of highly PCDD/F-contaminated field soil via solid state fermentation

This study was performed to evaluate the use of white rot fungus, Pleurotus pulmonarius, to treat polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in contaminated soil using solid state fermentation (SSF). The soil was collected from a long-closed pentachlorophenol plant in southern Taiwan. The non-sterilized soil with a total PCDD/F concentration of 14,000 ± 2400 ng I-TEQ kg^-1 was mixed directly with the solid fungal inocula at dry w/w ratio of 1:1.4 (ratio-adjusted test) and incubated at 26 ± 2 °C in a controlled environment. The highest PCDD/F decomposition was observed during the mycelium colonization. Pearson correlation coefficient (r) studied during this period (35 days) indicated that laccase had no significant correlation (r = -0.53), while manganese peroxidase had a strong positive correlation (r = 0.88) with PCDD/F decomposition efficiency. After 72 days, the more toxic congeners, tetra- and penta-CDD/Fs were removed to non-detectable levels. Meanwhile, the removal efficiencies of hexa-, hepta-, and octa-CDD/Fs were >80%, >97%, and >90%, respectively. The simultaneous degradation of low and high chlorinated DD/Fs suggested that overall removal was nonspecific. The overall PCDD/F removal was 96%, and the residual concentration (276 ng I-TEQ kg^-1) was below the regulatory control limit (1000 ng I-TEQ kg^-1). In conclusion, this study shows that P. pulmonarius via SSF can successfully remediate the PCDD/F-contaminated field soil. Furthermore, this SSF technique overcame the well-known intractability of PCDD/F biodegradation in non-sterilized soil, making it promising for actual field application.

Recent advances in the removal of persistent organic pollutants (POPs) using multifunctional materials:a review

Persistent organic pollutants (POPs) have gained heightened attentions in recent years owing to their persistent property and hazard influence on wild life and human beings. Removal of POPs using varieties of multifunctional materials have shown a promising prospect compared with conventional treatments. Herein, three main categories, including thermal degradation, electrochemical remediation, as well as photocatalytic degradation with the use of diverse catalytic materials, especially the recently developed prominent ones were comprehensively reviewed. Kinetic analysis and underlying mechanism for various POPs degradation processes were addressed in detail. The review also systematically documented how catalytic performance was dramatically affected by the nature of the material itself, the structure of target pollutants, reaction conditions and treatment techniques. Moreover, the future challenges and prospects of POPs degradation by means of multiple multifunctional materials were outlined accordingly. Knowing this is of immense significance to enhance our understanding of POPs remediation procedures and promote the development of novel multifunctional materials.

Effectively enhanced photodegradation of Bisphenol A by in-situ g-C3N4-Zn/Bi2WO6 heterojunctions and mechanism study

In our work, a series of in-situ g-C₃N₄-Zn/Bi₂WO₆ heterojunctions were synthesized by a two-step solvothermal method followed with calcination process, using dicyanamide as the precursor for g-C₃N₄. C₃N₄-Zn/BWO heterojunctions were of gossypine shape, and both C₃N₄ and Zn were finely distributed into BWO nanosheets, forming a hierarchical structure. C₃N₄-Zn/BWO with 2.0 g of precursor addition and calcined at 520 °C exhibited effectively enhanced photodegradation for typical organic contaminant BPA, degrading 93% within 120 min, and implied a maximum rate constant k of 0.0211 min^-1, indicating synergistic effect of C₃N₄ and Zn components in C₃N₄-Zn/BWO heterojunction. The enhancement of photocatalysis was due to quick carriers' separations via Z-scheme system and enlarged specific surface area of as-synthesized C₃N₄-Zn/BWO heterojunction. Main reactive oxidation species were detected to be h⁺ and O₂^-, and nine intermediates were confirmed via anlysis of LC-MS/MS. This study provided an alternative strategy to design novel photocatalysts containing multicomponents for higher photocatalytic activity.

Bi spheres SPR-coupled Cu2O/Bi2MoO6 with hollow spheres forming Z-scheme Cu2O/Bi/Bi2MoO6 heterostructure for simultaneous photocatalytic decontamination of sulfadiazine and Ni(II)

Environmental problem on the coexistence of organic pollutants and heavy metals in surface waters has become increasingly serious. Few relative researches have focused on their simultaneous decontamination. Herein, a ternary plasmonic Z-scheme Cu₂O/Bi/Bi₂MoO₆ heterojunction was synthesized via two-step route followed by a wet-impregnation, where Bi spheres coupled with Cu₂O particles were anchored on the surface of Bi₂MoO₆ with hollow microflower spheres. The composites were characterized via various measurements. The excellent photocatalytic activity of Cu₂O/Bi/Bi₂MoO₆ displayed in single sulfadiazine (SDZ) oxidation or Ni(II) reduction, and their simultaneous removal. The degradation pathway for SDZ was investigated via LC-MS and Gaussian theory. DFT and FDTD calculations confirmed the electronic structural characteristics in the Cu₂O/Bi/Bi₂MoO₆ heterostructure and the induced electric field enhancement around nearly touching Bi spheres. A possible photodegradation mechanism of the as-prepared photocatalyst was elucidated via combining scavenger experiments with EPR technique. The results suggested h⁺, •O₂^- and •OH all participated in SDZ oxidation, which verified that Z-Scheme electron transfer was major manner in Cu₂O/Bi/Bi₂MoO₆, while •O₂^- and e^-acted on Ni(II) reduction. The improved photocatalytic activity of Cu₂O/Bi/Bi₂MoO₆ could be ascribed to the unique Z-scheme electron transfer among Cu₂O, Bi and Bi₂MoO₆, particularly SPR and local electric field near Bi spheres.

Photocatalytic degradation of bisphenol A over a ZnFe2O4/TiO2 nanocomposite under visible light

A ZnFe₂O₄-TiO₂ nanocomposite combining p-type ZnFe₂O₄ and n-type TiO₂ was successfully fabricated. The ZnFe₂O₄-TiO₂ nanocomposite greatly enhanced the bisphenol A (BPA) photodegradation under visible light irradiation at 465 ± 40 nm. Loading TiO₂ with 1 wt% of ZnFe₂O₄ produced high photocurrent and low charge transfer resistance. The photodegradation rate of BPA by ZnFe₂O₄-TiO₂, which was highly dependent on the water chemistry including pH, anions, and humic acid, was 20.8-21.4 times higher than that of commercial TiO₂ photocatalysts. Chloride and sulfate ions enhanced BPA photodegradation mostly due to the production of more radical species; whereas nitrate, dihydrogen phosphate, and bicarbonate ions decreased the photodegradation rate of BPA due to the scavenge of hydroxyl radicals. The photoactivity and recyclability of ZnFe₂O₄-TiO₂ in lake water was also assessed. A near complete BPA removal from lake water was observed under visible light irradiation. Furthermore, >90% of photocatalytic activity toward BPA degradation was achieved in 5 cycles of continuous addition of BPA to the lake water. The BPA degradation intermediates were identified by HPLC/MS/MS and possible reaction pathways were proposed. Results clearly demonstrate the excellent visible-light-sensitive photocatalytic degradation of BPA over ZnFe₂O₄-TiO₂ composite which has a great application potential for the decomposition of emerging contaminants in impaired waters.