Higher Degradation Research Articles

Construction of Ternary Heterostructured NaNbO<sub>3</sub>/Bi<sub>2</sub>S<sub>3</sub>/ Ag Nanorods with Synergistic Pyroelectric and Photocatalytic Effects for Enhanced Catalytic Performance

The removal of dyes and pathogens from contaminated water remains a significant challenge. In the present study, NaNbO3 and NaNbO3/Bi2S3 powders were prepared by a simple hydrothermal method, and then the noble metal Ag was successfully deposited on NaNbO3/Bi2S3 by photoreduction to constitute the NaNbO3/Bi2S3/Ag ternary nanorods heterostructure. With continuous visible light irradiation and controlled temperature variation (25-55 °C), the monomeric NaNbO3 could degrade 73.3% of Rhodamine B (RhB) and inactivated 46% of Salmonella while the ternary complex NaNbO3/Bi2S3/Ag showed a higher RhB degradation efficiency of 94.9% as well as an higher sterilization efficiency of 82%. In addition, after four replicate experiments, NaNbO3/Bi2S3/Ag still had a high degradation efficiency. Compared with NaNbO3 monomer, NaNbO3/Bi2S3/Ag possessed stronger catalytic ability. The improvement of catalytic activity could be attributed to the efficient separation of pyroelectric and photocatalytic electrons and holes through the formation of NaNbO3/Bi2S3/Ag heterostructural nanorod. Keywords: Ternary heterostructures; Nanocomposites; Pyroelectricity; RhB solution degradation; Salmonella sterilization

Synthesis of biomass-based BiOI@Hydrochar heterogeneous catalyst and investigation of its activity in sonocatalytic process

Innovative studies in recent years to remove pollutants discharged into water resources through various means are critically important for protecting existing water resources. An important part of these studies is heterogeneous catalysis-based AOPs, where new generation composite materials are used and high organic pollutant degradation has been achieved. This study used the solvothermal approach to produce a BiOI@BH sonocatalyst doped with hydrochar (BH). A variety of analysis techniques, including XRD, FESEM, EDS, FTIR, DRS, and BET surface analysis, were used to assess changes in the physico-chemical properties of the BiOI@BH structure in comparison to BiOI. Both the adsorption and sonocatalytic degradation processes for the methylene blue aqueous solution were found to be more successful with the BiOI@BH structure. The following order of oxidative species activity was observed in sonocatalytic degradation: •OH > h+ > O2•–. Recovery studies showed that the decrease in the efficiency of the catalyst after 5 cycles in MB degradation was 10 %. It was determined that the MB degradation efficiency increased significantly with the use of persulfate oxidant at pH> 5. Finally, MB solution (20 mg L−1) was degraded by 99 % in the presence of 5 mM persulfate and 0.5 g L−1 BiOI@BH at 90 min

Synergistic photocatalytic performance of MoO3:Cu/g-C3N4 heterojunction semiconductor for efficient crystal violet dye degradation: A sustainable approach for environmental remediation

A heterojunction semiconductor of MoO3:Cu in conjunction with g-C3N4 was fabricated using a green synthesis approach facilitated by leaves extract of Murraya paniculata. Numerous methods of characterisation, including XPS, FTIR spectroscopy, XRD, BET, HR-TEM, FE-SEM, EDAX, and UV–visible spectrophotometry were employed to analyse the materials. The results from XRD and HRTEM indicated the highly crystalline nanoparticles with a mean particle size of 5.42 nm for MoO3 nanomaterials with doping of 5.62 nm Cu particles. The two-dimensional g-C3N4 sheeted structure acted as a translucent layer, facilitating self-assembly on the spherical MoO3:Cu nanoparticles, thereby promoting efficient charge flow and enhancing the photodegradation capability of the heterojunction semiconductor. XPS analysis confirmed the presence of Mo, Cu, N, O, and C in the fabricated heterojunction. UV–Visible and PL spectra demonstrated the efficient suppression of exciton annihilation in the heterojunction semiconductor. Remarkably, the heterojunction exhibited a high photocatalytic degradation performance of 97 % for the photodegradation of Crystal violet (CV) dye. Additionally, the effects of pH and dose of catalyst on photodegradation, as well as the recyclability of the catalyst, were evaluated. Kinetic analysis revealed a pseudo first-order reaction with 0.617 min−1 rate constant, while scavenger experiments confirmed the involvement of h+ and .O2− as active species in the degradation process.

UVA light assisted activation of sulfite by metal–organic framework-derived FeOx@C catalyst for organic degradation: Formation and role of non-radical species

Advanced oxidation processes (AOPs) based on sulfite (S(IV)) activation are gaining recognition as a promising Fenton-like strategy, primarily due to their ability to generate potent radicals (e.g., SO4− and HO). However, the existence and role of a non-radical-driven oxidation pathway in the S(IV)-mediated degradation of contaminants remain under debate. Herein, a magnetic iron-carbon composite (FeOx@C) was fabricated using the MOF-templated method and utilized as a stable photocatalyst to activate S(IV) under UVA light, achieving >93.6 % degradation of 20 μM ofloxacin (OFL) with a high degradation rate constant of 0.073 min−1 within 45 min. The catalyst’s porous carbon structure facilitated the transport of substrates to active sites and shortened the diffusion distance between reactive species and contaminants. Adsorbed S(IV) donated one electron to photo-generated holes and exposed Fe(III) sites with the formation of SO5−, which then followed two distinct pathways to produce radicals (SO4−) and non-radicals (Fe(IV) and 1O2) responsible for OFL degradation. By leveraging the synergy of both radicals and non-radicals, this innovative oxidative system showcased robust anti-interference capacities and exceptional performance in degrading contaminants from complex water matrices. This study provides new insights into the significant role of non-radical species in S(IV)-mediated decontamination processes.

Biodegradation of bisphenol-A in water using a novel strain of Xenophilus sp. embedded onto biochar: Elucidating the influencing factors and degradation pathway

Bisphenol-A (BPA) is an emerging hazardous contaminant, which is ubiquitous in the environment and can cause endocrine disruptor and cancer risks. Therefore, biodegradation of BPA is an essential issue to mitigate the associated human health. In this work, a bacterial strain enables of degrading BPA, named BPA-LRH8 (identified as Xenophilus sp.), was newly isolated from activated sludge and embedded onto walnut shell biochar (WSBC) to form a bio-composite (BCM) for biodegradation of BPA in water. The Langmuir maximum adsorption capacity of BPA by WSBC was 21.7 mg g−1. The free bacteria of BPA-LRH8 showed high BPA degradation rate (∼100 %) at pH 5–11, while it was lower (＜20 %) at pH 3. The BCM eliminated all BPA (∼100 %) at pH 3–11 and 25–45 °C when the BPA level was ≤ 25 mg L−1. The spectrometry investigations suggested two possible degradation routes of BPA by Xenophilus sp. In one route, BPA (C15H16O3) was oxidized to C15H16O3, and then broken into C9H12O3 through chain scission. In another route, BPA was likely hydroxylated, oxidized, and cleaved into C9H10O4P4, which was further metabolized into CO2 and H2O in the TCA cycle. This study concluded that the novel isolated bacteria (BPA-LRH8) embedded onto WSBC is a promising and new method for the effective removal of BPA and similar hazardous substances from contaminated water under high concentrations and wide range of pH and temperature.

Periodate activation and pH regulation using ball-milled metal-oxide-mineral-biochar composite for removal of antibiotics from contaminated water

The inclusion of mineral salts in carbon activators are beneficial for advanced oxidation processes (AOPs). Herein, we present the application of ball-milled biochar with phosphate salt for periodate (IO4−) activation and degradation of antibiotics in contaminated water. Physical characterization results showed that the catalyst is infused with Mg3(PO4)2 and ball-milling increased the specific surface area to 216 m2 g−1 from 46 m2 g−1 while reducing the particle size to less than 1.0 μ. The optimized system successfully eliminated >99% of diclofenac while maintaining the pH of the reaction medium to circumneutral levels. Scavenger and ESR experiments revealed the degradation is triggered by O2•–, 1O2 and •OH species within the system. Electrochemical studies confirmed electron transfer during diclofenac degradation. The reported system demonstrated high degradation efficiency under both neutral and acidic pH conditions. Based on the by-product analysis, the degradation pathway of diclofenac was elucidated. Further, the toxicity assessment for the identified intermediates showed minimum toxicity of the degraded products. This mineral-biochar composite exhibited promising performance in eliminating other antibiotic substances. Therefore, the present finding highlights the importance of raw materials selection for producing mineral-biochar composite that provide new insights into IO4− activation for antibiotic removal by maintaining the natural pH.

High acidity organic waste degradation and the potential to bioremediation of heavy metals in soil by an acid-tolerant Serratia sp.

Highly acidic citrus pomace (CP) is a byproduct of Pericarpium Citri Reticulatae production and causes significant environmental damage. In this study, a newly isolated acid-tolerant strain of Serratia sp. JS-043 was used to treat CP and evaluate the effect of reduced acid citrus pomace (RACP) in passivating heavy metals. The results showed that biological treatment could remove 97.56% of citric acid in CP, the organic matter in the soil increased by 202.60% and the catalase activity in the soil increased from 0 to 0.117Ug-1. Adding RACP into soil can increase the stabilization of Cu, Zn, As, Co, and Pb. Specifically, through the metabolism of strain JS-043, RACP was also involved in the stabilization of Zn and Pb, and Residual Fraction in the total pool of these metals increased by 10.73% and 10.54%, respectively. Finally, the genome sequence of Serratia sp. JS-043 was completed, and the genetic basis of its acid-resistant and acid-reducing characteristics was preliminarily revealed. JS-043 also contains many genes encoding proteins associated with heavy metal ion tolerance and transport. These findings suggest that JS-043 may be a high-potential strain to improve the quality of acidic organic wastes that can then be useful for soil bioremediation.

Ranitidine degradation in layered double hydroxide activated peroxymonosulfate system: impact of transition metal composition and reaction mechanisms.

Ranitidine, a competitive inhibitor of histamine H2 receptors, has been identified as an emerging micropollutant in water and wastewater, raising concerns about its potential impact on the environment and human health. This study aims to address this issue by developing an effective removal strategy using two types of layered double hydroxide (LDH) catalysts (i.e., CoFeLDH and CoCuLDH). Characterization results show that CoFeLDH catalyst has superior catalytic properties due to its stronger chemical bond compared to CoCuLDH. The degradation experiment shows that 100% degradation of ranitidine could be achieved within 20min using 25mg/L of CoFeLDH and 20mg/L of peroxymonosulfate (PMS). On the other hand, CoCuLDH was less effective, achieving only 70% degradation after 60min at a similar dosage. The degradation rate constant of CoFeLDH was 10 times higher than the rate constant of CoCuLDH at different pH range. Positive zeta potential of CoFeLDH made it superior over CoCuLDH regarding catalytic oxidation of PMS. The catalytic degradation mechanism shows that sulfate radicals played a more dominant role than hydroxyl radicals in the case of LDH catalysts. Also, CoFeLDH demonstrated a stronger radical pathway than CoCuLDH. XPS analysis of CoFeLDH revealed the cation percentages at different phases and proved the claim of being reusable even after 8 cycles. Overall, the findings suggest that CoFeLDH/PMS system proves to be a suitable choice for attaining high degradation efficiency and good stability in the remediation of ranitidine in wastewater.

Low Carbon Development Strategy in the Rambat Menduyung Mangrove Forest Area of West Bangka

Indonesia is committed to reducing carbon emissions through low-carbon development. Mangrove ecosystems have a high carbon storage value that can support this development. There is a problem of high mangrove degradation caused by economic activities. One of the sectors causing mangrove degradation is the mining sector in the province of Kepulauan Bangka Belitung. Low-carbon development strategies in mangrove areas are needed to support the increase of sustainable economic activities such as capture fisheries, aquaculture, and mangrove conservation. The objective of this research is to calculate the potential value of sustainable economic activities and develop a low-carbon development strategy in the Rambat Menduyung Mangrove Area. The methods used in this research are economic benefit analysis, benefit transfer analysis of carbon emission factors, and strategy analysis using interpretative structural modeling with Exsimpro software. The results of research suggest that potential economic activities that support low carbon development in mangrove areas, namely mangrove conservation, capture of marine biota, and blood clam production, produce economic benefits of IDR105,723,552,069/year. Prioritizing low-carbon development strategies by improving protection and law enforcement policies and increasing institutional capacity and community participation supported by adequate infrastructure from stakeholders, namely DKP West Bangka, KPHP Rambat Menduyung, and Belo Laut Village Government.

Low Carbon Development Strategy in the Rambat Menduyung Mangrove Forest Area of West Bangka

Indonesia is committed to reducing carbon emissions through low-carbon development. Mangrove ecosystems have a high carbon storage value that can support this development. There is a problem of high mangrove degradation caused by economic activities. One of the sectors causing mangrove degradation is the mining sector in the province of Kepulauan Bangka Belitung. Low-carbon development strategies in mangrove areas are needed to support the increase of sustainable economic activities such as capture fisheries, aquaculture, and mangrove conservation. The objective of this research is to calculate the potential value of sustainable economic activities and develop a low-carbon development strategy in the Rambat Menduyung Mangrove Area. The methods used in this research are economic benefit analysis, benefit transfer analysis of carbon emission factors, and strategy analysis using interpretative structural modeling with Exsimpro software. The results of research suggest that potential economic activities that support low carbon development in mangrove areas, namely mangrove conservation, capture of marine biota, and blood clam production, produce economic benefits of IDR105,723,552,069/year. Prioritizing low-carbon development strategies by improving protection and law enforcement policies and increasing institutional capacity and community participation supported by adequate infrastructure from stakeholders, namely DKP West Bangka, KPHP Rambat Menduyung, and Belo Laut Village Government.

Surface water area dynamics of the major lakes of Ethiopia (1985–2023): A spatio-temporal analysis

Ethiopian lakes face multiple ecosystem threats from human and natural factors, including climate change. The long-term dynamics of water surface area in many lakes remain unknown. This study presents the first comprehensive account of major Ethiopian lakes’ long-term water surface area dynamics, providing essential information for prioritizing hydrological conservation strategies. We extracted the time-series water surface area of the lakes from Landsat images in the Google Earth Engine (GEE), using the Modified Normalized Water Index (MNDWI) and machine learning (Random Forest) methods. Random Forest (RF) outperformed MNDWI across many lakes, especially when water body spectral characteristics became complex. A comparison of the results with the Joint Research Center (JRC) Global Surface Water Mapping Layers showed a good agreement. Long-term water surface area dynamics showed both common and distinct trends. Common trends included: (a) similar recession and expansion periodicities despite lakes being in different climatic zones, (b) an increase in the inter-annual variability of water area after 2000, and (c) a common abrupt point in time (2000/2001). Distinct trends included: (i) long-term decline in five lakes (Abiyata, Langano, Shalla, Chamo, and Hayq), (ii) expansion in three lakes (Ziway, Hawassa, and Abaya), and (iii) non-homogeneous long-term trends in two lakes (Tana and Hardibo). These common and distinct trends show the interplay of climate phenomena and lake-specific factors. Climate factors govern inter-annual lake area change (decreasing/increasing) and recession and expansion cycle periods. The magnitudes of changes and recovery rates after each change cycle vary based on lake-specific factors. We recommend prioritizing conservation efforts for lakes with high water storage degradation risks, as indicated by significant water loss over the historical period and persistent long-term declining trends. This includes Abiyata, Chamo, Shalla, Langano, Hayq, and Hardibo, in order of priority.

Delineating acetaminophen biodegradation kinetics and metabolomics using bacterial community.

Acetaminophen [N-(4-hydroxyphenyl) acetamide, APAP]is an extensively and frequently consumed over-the-counter analgesic and antiphlogistic medication. It is being regarded as an emerging pollutant due to its continuous increment in the environment instigating inimical impacts on humans and the ecosystem. Considering its wide prevalence in the environment, there is an immense need of appropriate methods for the removal of APAP. The present study indulged screening and isolation of APAP degrading bacterial strains from pharmaceuticals-contaminated sites, followed by their molecular characterization via 16SrRNA sequencing. The phylogenetic analyses assigned the isolates to the genera Pseudomonas, Bacillus, Paracoccus, Agrobacterium, Brucella, Escherichia, and Enterobacter based on genetic relatedness. The efficacy of these strains in batch cultures tested through High-performance Liquid Chromatography (HPLC) revealed Paracoccus sp. and Enterobacter sp. as the most promising bacterial isolates degrading up to 88.96 and 85.92%, respectively of 300mg L-1 of APAP within 8days of incubation. Michaelis-Menten kinetics model parameters also elucidated the high degradation potential of these isolates. The major metabolites identified through FTIR and GC-MS analyses were 4-aminophenol, hydroquinone, and 3-hydroxy-2,4-hexadienedioic. Therefore, the outcomes of this comprehensive investigation will be of paramount significance in formulating strategies for the bioremediation of acetaminophen-contaminated sites through a natural augmentation process via native bacterial strains.

Postindustrial Jute Waste as a Support for Nano-Carbon Nitride Photocatalyst: Influence of Chemical Pretreatment.

Non-woven jute (NWJ) produced from carpet industry waste was oxidized by H2O2 or alkali-treated by NaOH and compared with water-washed samples. Changes in the structure of the NWJ, tracked by X-ray diffraction (XRD), showed that both chemical treatments disrupt hydrogen bond networks between cellulose Iβ chains of the NWJ fibers. Thereafter, nano-carbon nitride (nCN) was impregnated, using a layer-by-layer technique, onto water-washed jute samples (nCN-Jw), NaOH-treated samples (nCN-Ja) and-H2O2 treated samples (nCN-Jo). Analysis of the Fourier transform infrared spectroscopy (FTIR) spectra of the impregnated samples revealed that nCN anchors to the water-washed NWJ surface through hemicellulose and secondary hydroxyl groups of the cellulose. In the case of chemically treated samples, nCN is preferentially bonded to the hydroxymethyl groups of cellulose. The stability and reusability of prepared nCN-jute (nCN-J) samples were assessed by tracking the photocatalytic degradation of Acid Orange 7 (AO7) dye under simulated solar light irradiation. Results from up to ten consecutive photocatalytic cycles demonstrated varying degrees of effectiveness across different samples. nCN-Jo and nCN-Ja samples exhibited declining effectiveness over cycles, attributed to bond instability between nCN and jute. In contrast, the nCN-Jw sample consistently maintained high degradation rates over ten cycles, with a dye removal percentage constantly above 90%.

Photocatalytic performance of Co3O4/Na-Alginate nanocomposite for the dynamic removal of direct red 31 dye: Degradation and mechanical pathways

<p>This study examines the use of Co3O4 nanocomposite as a photo-catalyst in aqueous solution for photocatalytic degradation of dyes under UV. It has been observed that substrate concentrations, catalyst, pH, oxidant present and temperature, effect on dye degradation. The characterization of synthesized Co3O4 NPs and Co3O4/Na-Alg NC was done by UV-Visible, SEM, XRD and FTIR. Co3O4 NPs and Co3O4/Na-Alg NC were found to be 23 nm and 10 nm in size. The synthesized Co3O4/NaAlg NC were employed to degrade Direct Red 31 dye by optimization of experimental conditions. The highest degradation (68.24%) was attained at optimal conditions. TOC and COD were evaluated to check proficiency of this process. It was found that percentage reduction in TOC and COD was 66.7% and 65.2%. The generation of non-toxic products was validated by Direct Red 31 dye degradation route. The study concluded that the synthesized nanocomposites could be chosen for dyes-containing wastewater remediation. Because it is economical and environmentally beneficial, the produced Co3O4/Na-Alg NC is strongly advised for dye degradation.</p>

Assessment of Management Practices to Prevent Soil Degradation Threats on Lithuanian Acid Soils

An assessment of soil characteristics pertaining to their suitability for agricultural use in general is necessary to reverse the declining trend of soil quality and to ensure sustainable agriculture. The aim of this study was to determine the soil resistance (SRI) and degradation indices (SDI) under different agrotechniques and to find out whether management-induced changes are large enough to reduce soil degradation. The study was based on the comparison of physicochemical data of 3 long-term experiments conducted in the western part of Lithuania. Changes in soil properties over the past 20 years (1999–2019) have been determined. The most commonly used measures in Lithuania, such as soil liming, manuring, residue maintenance, and tillage, were selected for the analysis. The analysis carried out showed that the soil, which was fertilized with manure, had a higher value of soil quality parameters compared to natural Retisol: organic matter (by 0.53 percentage points), total nitrogen (by 0.04 percentage points), and the available amounts of phosphorus (by 69 mg/kg) and potassium (by 6.6 mg/kg). The assessment of the relative annual change in SOC content revealed that long-term soil manuring has significant SOC sequestration capability. Among the soil management techniques examined, it appeared that the greatest relative annual change (0.47 g kg−1yr−1) in SOC content was noted in manured soil. The results indicate that the higher degradation, and resistance values were observed in acid soil (pH 4.2), where liming was applied, indicating greater sensitivity to degradation. Based on analyzed indices, the agricultural practices ranked as: manuring > residue management > reduced tillage > liming. The lowest SRI values were obtained for low level of nutrients (from −0.11 to 0.89), organic carbon (from −0.72 to −0.49), and pH (from −0.25 to –0.1), indicating that these properties are more sensitive to applied agricultural practices compared to others. All these findings provide information for promoting better soil management, soil protection, land use planning, and the planning of remedial measures, especially in the most afflicted areas.

Red mud/steel slag three-dimensional electrochemical system for the removal of organic pollutant with Na2S2O3 as electrolyte: Contribution of •OHads

The dynamic changes in the iron redox cycle (Fe2+/Fe3+) played a crucial role in the electro-Fenton degradation of organic pollutants. The synthesis of composite particle electrodes RMSSx:y from a mixture of steel slag (SS) and red mud (RM) was applied in a three-dimensional electrochemical system for the remediation of hydrochloric tetracycline (TCH) in wastewater, utilizing Na2S2O3 as an electrolyte. Further, some investigations were conducted to determine the effects of RM/SS, electrolyte, particle electrode dosage, cell voltage, and pH on TCH degradation efficiency. Under optimal conditions such as 8 g/L RMSS5:5 particle electrodes, a cell voltage of 4 V, an initial pH of 3, and 6 mM Na2S2O3 electrolyte, the degradation rate of TCH in wastewater was 98.3 %. Meanwhile, its total organic carbon (TOC) was reduced by 88 % within 60 min. Cyclic experiments with consistently high degradation efficiency demonstrated the stability of the particle electrode RMSS5:5. The practical applicability of RMSS5:5 was further confirmed through its successful treatment of various industrial wastewaters, including dyeing (DW), chemical (CW), and pharmaceutical (PW) effluents, achieving chemical oxygen demand (COD) removal rates of 67.8 %, 67.6 %, and 65.0 % respectively. The enhancement of TCH degradation through the utilization of Na2S2O3 as the electrolyte was primarily attributed to the complexation and reduction effects exerted by S2O32- ions. These effects prevented the leaching and precipitation of iron ions, facilitated the reduction of Fe (III), and consequently enabled •OHads to play a dominant role in the degradation process. These findings demonstrated the potential of RMSS5:5 in efficiently degrading emerging contaminants, thereby offering an innovative approach for utilizing SS and RM as functional materials in electro-Fenton processes.

Facile fabrication of chitosan/bone/bamboo biochar beads for simultaneous removal of co-existing Cr(VI) and bisphenol a from water

Heavy metal Cr(VI) and organic BPA have posed harmful risks to human health, aquatic organisms and the ecosystem. In this work, Chitosan/bone/bamboo biochar beads (CS-AMCM) were synthesized by co-pyrolysis and in situ precipitation method. These microbeads featured a particle size of approximately 1 ± 0.2 mm and were rich in oxygen/nitrogen functional groups. CS-AMCM was characterized using XRD, Zeta potential, FTIR, etc. Experiments showed that adsorption processes of CS-AMCM on Cr(VI) and BPA fitted well to Langmuir model, with theoretical maximum capacities of 343.61 mg/g and 140.30 mg/g, respectively. Pore filling, electrostatic attraction, redox, complexation and ion exchange were the main mechanisms for Cr(VI), whereas for BPA, the intermolecular force (hydrogen bond) and pore filling were involved. CS-AMCM with adsorbed Cr(VI) demonstrated effective activation in producing ·OH and ·O2 from H2O2, which degraded BPA and Cr(VI) with the removal rates of 99.2% and 98.2%, respectively. CS-AMCM offers the advantages of low-cost, large adsorption capacity, high catalytic degradation efficiency, and favorable recycling in treating Cr(VI) and BPA mixed wastewater, which shows great potential in treating heavy metal and organic matter mixed pollution wastewater.

ZIF-67-derived monolithic bimetallic sulfides as efficient persulfate activators for the degradation of ofloxacin

In this study, we successfully synthesized ZIF-67 material on three-dimensional (3D) nickel foam (NF) substrate by co-precipitation method, and then fixed CoSx on NF by hydrothermal vulcanization method to form CoSx/NF. The optimized CoSx/NF can effectively activate peroxymonosulfate (PMS) and improve the degradation efficiency of ofloxacin (OFL). The effects of PMS dosage, reaction temperature, initial pH and co-existing ions on the degradation effect of OFL were investigated in detail. CoSx/NF (1 piece 2 × 2 cm) and PMS (1 mM) in an aqueous solution (pH = 7) degraded 85 % of OFL (20.0 mg/L) within 45 min. This favorable degradation performance is mainly attributed to the enhanced electron transfer capability introduced by the bimetallic material. In addition, CoSx/NF still maintained high degradation effect and stable structure after 5 cycles. Quenching experiments further revealed that radicals •OH and 1O2 play a major role in degrading OFL. In addition, the degradation pathway, ecotoxicity evaluation and degradation mechanism of OFL were comprehensively investigated. In summary, the CoSx/NF catalyst proved to be a highly efficient, stable and recyclable heterogeneous composite, and opened up the possibility of using Metal-organic framework (MOF) derivatives in fields such as wastewater treatment.

Construction of polarized 2D/2D g-C3N4/BiOCl nanosheet dual piezoelectric Z-scheme heterojunction and its efficient charge separation mechanism

A multi-electric field synergistic strategy based on heterojunction construction and polarization engineering enhances carrier separation and migration, achieving excellent piezoelectric photocatalytic performance of g-C3N4 based materials. Here, through the in-situ growth of BiOCl nanosheets (BOCs) on g-C3N4 nanosheets (GCNs), a 2D/2D Z-scheme GCNs/BOCs heterojunction was successfully fabricated, and its outstanding piezo-photocatalytic property was demonstrated. Compared to individual BOCs and GCNs, the high degradation rate (97.64 %) of rhodamine B (RhB) can be achieved over the optimal composite (GCNs/BOCs-50) after 50 min irradiation. Inspiringly, the polarized GCNs/BOCs-50 composite degraded RhB almost completely within 30 min under the simultaneous light irradiation and ultrasound, which reduced the photocatalytic time by 40 %, and its k reached 0.1410 min−1 (12.59 and 2.48 times that of BOCs and GCNs). This work is of great significance for designing a novel heterojunction photocatalysts using polarized ferroelectric materials.

Enhanced visible light utilization of BiOI/BiOBr/Bi composite catalytic materials for photocatalytic degradation of TC and reduction of Cr(Ⅵ)

The rational design and construction of semiconductor photocatalytic materials are important significance for efficient utilization of solar energy and enhancement of photocatalytic activity. In this study, composite photocatalytic materials modified with Bi0 on the surface of BiOI/BiOBr heterojunction were successfully constructed based on the current mature electrostatic spinning technology by using solvothermal and in-situ reduction methods. The successful preparation of BiOI/BiOBr/Bi composites was confirmed by a series of characterization methods. The composite photocatalyst was applied to the degradation of pollutants, and by adjusting the addition ratio of different substances, it was found that the photocatalytic composites prepared with the addition of 0.125 mmol NaBH4 and the ratio of I/Br of 3:1 showed the best performance. The degradation efficiency of the catalyst for tetracycline hydrochloride (TC) at 10 mg/L reached 98.4 % after 180 min of visible light irradiation, and the high degradation performance of the material was maintained after five cycles. Meanwhile, the reduction efficiency of the material for Cr(VI) was 98.2 % after 100 min of visible light irradiation. Free radical trapping experiments demonstrated that photogenerated holes (h+) and superoxide radicals (•O2−) are the main active substances for photocatalytic degradation of TC. Due to the partial reduction of Bi0, the absorption of the catalyst in the near-infrared region was enlarged, which enhanced the photothermal effect of the whole material and further improved the catalyst activity.