Degradation Of Tc Research Articles

DBD plasma assisted synthesis of Ce-MIL-88B(Fe) with electron-rich CUSs and mixed-valent bimetallic sites for enhanced photo-Fenton performance

Iron-based metal-organic frameworks (Fe-MOFs) are regarded as a kind of prospective catalysts for photo-Fenton process. However, high cost, rate-limiting Fe(III)/Fe(II) circulation and limited metal sites greatly restricted the application of Fe-MOFs in photo-Fenton system. Ce-MIL-88B(Fe) was synthesized with mixed-valent bimetallic sites and tunable coordinated unsaturated metal sites (CUSs) using dielectric barrier discharge (DBD) plasma with waste PET. The incorporation of Ce altered the structure and the electron aggregation, as well as induced structural defects. Ce substitution in Fe-MOFs induced the regulation of the ratio of Fe ions and formation of electron-rich CUSs, which were beneficial for the rapid adsorption and activation of H2O2, thus enhancing the photo-Fenton performance. The effect of reaction conditions on TC degradation was investigated by response surface methodology (RSM) combined with Box-Behnken design (BBD). This study demonstrates a new perspective on the construction of bimetallic MOFs for the photo-Fenton system.

ZIFs@MIL-101/urea-derived magnetic FeCo nitrogen-rich carbon as an effective and stable catalyst for peroxymonosulfate activation

High efficiency and stability are key issues in heterogeneous metal catalytic materials/peroxymonosulfate (PMS) systems during wastewater degradation. However, catalytic materials that are difficult to recover and metal leaching can cause secondary contamination of water bodies. Herein, we designed the magnetic FeCo nitrogen-rich carbon (FeCo-NC) obtained by layer-by-layer encapsulation, followed by urea encapsulation of in situ grown MOF-in-MOF and carbonization. The CoFe2O4 crystalline nature of FeCo-NC was confirmed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and selected angle electron diffraction (SAED) results, which is responsible for the magnetic properties of FeCo-NC. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) present that the material's morphology transforms from dodecahedral ZIF-67 to spindle-shaped ZIF-67@MIL-101 and then to octahedral FeCo-NC. Compared with FeCo-C and ZIF-67@MIL-101, the removal efficiency of FeCo-NC was maintained at 78.6 % after 10 consecutive cycles, with only a 17 % loss of raw material. The Fe and Co leaching amounts in the FeCo-NC/PMS system were approximately 0.6 and 0.1 mg/L, respectively, much lower than China's Fe and Co emission standards. FeCo-NC characterization and TC degradation results demonstrated that magnetic CoFe2O4 nanoparticles formed on the surface or inside the FeCo-NC could effectively inhibit metal (Fe and Co) loss and be easily regenerated in multiple degradation cycles. The mechanism and degradation routes in the FeCo-NC/PMS/ TC system, including the radical/nonradical pathways, Fe/Co valence change, and electron transfer, were further investigated by electron paramagnetic resonance experiments, electrochemical analyses, in situ Raman spectroscopy, and HPLC–MS experiments.

Enhanced tetracycline degradation using UV/Fenton/titanium dioxide (TiO2) hybrid process

TiO2 was synthesized using neem leaf extract as soft bio template and Titanium (IV) isopropoxide (C12H28O4Ti) as a precursor. Morphological properties revealed well crystalline anatase phase of 19.8 nm size for the biotemplated TiO2 (B-TiO2) compared to 24.2 nm of the non-templated TiO2 (N-TiO2). TEM revealed a nano sheet-like structure for the B-TiO2 and it exhibited a larger SBET surface area (35.45 m2/g) and average pore diameter (5.74 nm) compared to the N-TiO2 (19.72 m2/g) and (2.028 nm) respectively. XPS results showed carbon peaks indicating small bio-carbon doping on the lattice of the TiO2, which can promote charge transfer upon light excitation during photocatalyst reactions. The results of the photoluminescence study indicate reduced PL intensity of the B-TiO2 which signifies the suppression of recombination of charge carriers or electron-hole pairs in the B-TiO2. The photocatalytic activity was assessed by the photodegradation of tetracycline (TC: 50 mg/L) under UV irradiation and the B-TiO2 was employed as a photocatalyst. In the absence of UV light, B-TiO2 catalyst slightly removed TC due to limited active species. However, the degradation of TC increases significantly due to the synergetic effect of the UV/Fenton/B-TiO2 hybrid system. Moreover, the biotemplate exposes the surface of the B-TiO2 which permits improved utilization of all surface-active sites. Quenching experiments were also performed via scavengers, results confirmed that hydroxyl radicals, superoxide radicals and electrons are the key reactive species in the TC degradation. The effects of influential parameters such as B-TiO2 dosage, TC concentration, pH, and Fe2+ to H2O2 molar ratio were also investigated, in addition, the catalyst is stable, as it achieved > 80 % TC degradation efficiency after five reuse cycles.

Efficient photocatalytic degradation of tetracycline and its derivatives by green recyclable PAN/Bi2WO6/Cu2O nanofiber membrane

The use of tetracycline antibiotics in industry, healthcare, animal husbandry, agriculture, and aquaculture has resulted in excessive concentrations in a variety of aquatic environments. In this work, PAN/Bi2WO6/Cu2O nanofibrous membranes (PBC ENMs) with photocatalytic degradation performance were successfully prepared using electrostatic spinning technique, and the morphology of catalysts and PBC ENMs were characterised by SEM, BET and UV–Vis. The results demonstrated that the prepared nanofibrous membranes could achieve 97.05 % photocatalytic degradation of TC under visible light, and the degradation efficiencies of its derivatives, chlortetracycline (CTC) and oxytetracycline (OTC), reached 90.87 % and 85.12 %, respectively. Free radical trapping experiments and mechanistic analyses showed that·O2– is the main active factor in the degradation process. The highest degradation rate of 97.05 % was achieved at initial pH = 7.2.PBC ENMs adsorbed above 87.5 % after six cycles of the experiment. The highest degradation rate of 97.05 % was achieved at initial pH = 7.2 PBC ENMs adsorbed above 87.5 % after six cycles of the experiment. Based on the above advantages, the preparation process of PBC ENMs is simple, low-cost and has good catalytic effect, which provides a simple and efficient treatment means for the treatment of TC wastewater and has a broad application prospect.

Synthesis of a novel Bi19Cl3S27/Bi2MoO6 Z-type heterojunction for efficient photocatalytic removal of tetracycline antibiotic and Cr(VI): Intermediate toxicity and mechanism insight

Novel Bi19Cl3S27/Bi2MoO6 (BCS/BMO) Z-type heterojunctions were synthesized using a straightforward hydrothermal method. Benefiting from the large specific surface area (62.41 m2/g) and the effective separation of photogenerated carriers facilitated by the Z-scheme heterojunction, the BCS/BMO exhibited remarkable improved photocatalytic tetracycline degradation and Cr(VI) reduction efficiency in comparison to BCS, BMO, and their physical mixture. Specifically, the photocatalytic degradation rate constants for TC and Cr(VI) are 0.0209 and 0.0218 min-1, respectively, which are 16.08 and 15.57 times those of BCS, 1.74 and 1.31 times those of BMO, and 2.4 and 1.73 times those of the physical mixture. Additionally, based on density functional theory (DFT) calculations and empirical data, three potential photocatalytic pathways of tetracycline were presented. This study presents a novel approach for designing and synthesizing high-efficiency Z-scheme photocatalysts for the degradation of TC and the reduction of Cr(VI) in wastewater.

Mn doping and ZnS nanoparticles modification on Bi2MoO6 to achieve an highly-efficient photocatalyst for TC degradation

Environmental pollution presents significant challenges to both human production and daily life. Photocatalytic technology offers a promising solution for environmental remediation, and Bi2MoO6 is widely recognized as an excellent visible light photocatalyst for the degradation of organic pollutants. Nevertheless, the high recombination rate of photogenerated charge carriers in Bi2MoO6 limits the number of charge carriers available for photocatalytic reactions, resulting in reduced photocatalytic efficiency. To overcome this limitation, we designed and synthesized a composite photocatalyst (30% ZnS/Mn0.08-Bi2MoO6). Mn-doped Bi2MoO6 nanosheets (Mn-Bi2MoO6) were prepared through a simple coprecipitation method, and ZnS nanoparticles were introduced to modify the surface, forming a ZnS/Mn-Bi2MoO6 composite photocatalyst. Experimental results demonstrated that the photocatalytic degradation rate of tetracycline using the 30% ZnS/Mn0.08-Bi2MoO6 composite increased 11.1 times and 3.7 times compared with pure Bi2MoO6 and ZnS, respectively. The formation of ZnS/Mn-Bi2MoO6 heterojunction was confirmed through XRD, XPS, SEM, and TEM analyses. Furthermore, photoelectrochemical measurements, including photocurrent, EIS, and PL, indicated that Mn doping and the ZnS nanoparticle modification significantly improved the separation and transfer efficiency of photogenerated charge carriers. DFT calculations and experimental results revealed the photocatalytic mechanism of the 30% ZnS/Mn0.08-Bi2MoO6 composite. This study provides valuable theoretical and technical insights into photocatalyst modification.

Cu‐Doped 0D Bi2WO6 Nanoparticles for Efficient Visible‐Light‐Driven Photocatalytic Tetracycline Degradation

AbstractBismuth‐based photocatalysts have been widely employed in the photocatalytic degradation of organic pollutants in wastewater. However, the lack of rational structural design and the slow generation of active free radicals have hindered its efficiency. Here, we stabilized Bi2WO6 nanoparticles by wrapping them with hydroxyl groups, introduced metal Cu doping, and underwent an annealing process to construct Cu‐BiNP nanocatalysts with exposed active sites. Under visible light irradiation, 0.03Cu‐BiNP achieved a 94.5% TC degradation efficiency, which is 15.8 times higher than the rate of bulk BiWO. The 0D structure endows Cu‐BiNP with ample opportunities for O2 adsorption and activation, and Cu atomic doping reduces the bandgap and increases the oxygen vacancy, promoting the generation of active oxygen species. This work demonstrates the rapid charge separation and activation of O2 to generate active oxygen species by 0D bismuth‐based nanocatalysts in photocatalytic oxidation reactions, providing a scalable nanocatalyst platform for TC photocatalytic degradation.

Exploring the formation of S-scheme heterojunctions in CuFe2O4/Bi2MoO6 porous cubes for photocatalytic removal of tetracycline

Exploring highly active and noble metal-free photocatalysts for the efficient photocatalytic degradation of antibiotics is of great significance. The CuFe2O4 nanostructured cube is synthesized by using a self-sacrificial template strategy, and two-dimensional Bi2MoO6 nanosheets are grown on the surface of CuFe2O4 through a solvothermal method to construct CuFe2O4/Bi2MoO6 S-scheme heterostructure. The CuFe2O4/Bi2MoO6 composite material exhibits eminent photocatalytic activity for the degradation of TC under simulated sunlight, with the optimal ratio CFO/BMO-2 achieving a degradation rate of 98.54 % within 30 min (initial concentration of TC: 50 mg L−1). In addition, CFO/BMO-2 also has excellent magnetic recyclability and cycling ability. Rice cultivation tests demonstrate that the biotoxicity of TC is effectively removed. Density functional theory calculations and in-situ irradiated X-ray spectroscopy deeply reveal the mechanisms of charge separation and transfer of S-scheme heterojunctions in CuFe2O4/Bi2MoO6. The construction of S-scheme heterojunctions promotes the separation of photo-induced charge carriers and improves photocatalytic degradation performance by retaining holes and electrons with strong redox ability. The work provides a practicable method for constructing efficient spinel photocatalysts to drive wastewater treatment reactions, and the constructed magnetically recyclable photocatalysts have certain practical application potential.

Unraveling the mechanism and the key role of amorphous structure C-O-Fe in tetracycline degradation by activation of persulfate in lotus leaf-based red mud-modified biochar

In the present study, red mud modified lotus leaf biochar was synthesized using a low-cost and concise method. The experimental results showed that when RM-HBC=0.4 g/L, PDS=4 mM, pH=5.0, the RM-HBC-PDS system exhibited the best degradation effect on TC, with the highest removal rate of 98.61 %, the highest degradation kinetics of 0.0229 min−1. Advanced characterization and density functional theory have demonstrated that the emergence of the C-O-Fe structure led to the redistribution of the surface charge of RM-HBC. This charge redistribution caused the electrons on the surface of RM-HBC to transfer from C to Fe through the C-O-Fe structure, forming an electron-rich center centered on Fe. The C-O-Fe structure facilitated the transformation of the Fe valence state within the RM-HBC while transmitting electrons, thus maintaining the regeneration of Fe(II). This further promoted the adsorption and activation ability of RM-HBC for PDS, thereby improving the degradation effect of TC in the system. XRD detection showed that the Fe3O4 crystal strength in RM-HBC after the reaction was significantly enhanced. This was due to the C-O-Fe present on the surface of RM-HBC in the process of degradation of TC, which accelerated sustained electron transfer at C-O-Fe, leading to structural fracture, recombination, and ultimately the formation of Fe3O4 crystals. Intermediate detection and toxicity prediction showed that the toxicity of TC was significantly reduced. All the above results confirmed that this study not only achieved the efficient treatment of antibiotic wastewater but also realized the rational utilization of lotus leaf and red mud resources.

Synergistic activation of peroxymonosulfate for tetracycline hydrochloride degradation with SrTiO3/Ti3C2Tx photocatalyst

Peroxymonosulfate (PMS) is a promising technology for increasing the oxidation capacity and promoting the production of active species in the photocatalytic system. SrTiO3, a material with a perovskite crystal structure in a cubic form, can activate PMS on its surface and generate non-radical 1O2. Herein, SrTiO3/Ti3C2Tx (ST) composites were successfully synthesized using a hydrothermal method based on SrTiO3 materials. The photocatalytic activation of PMS resulted in the degradation of tetracycline hydrochloride (TC-HCl), with the ST-10 (10 wt% SrTiO3/Ti3C2Tx) composite showing the highest efficiency in TC removal and rapid degradation kinetics, achieving complete TC removal within 10 min. The synergistic interaction between the two components in ST-10 significantly enhanced the activation of peroxymonosulfate (PMS), leading to an increased production of free radicals. The larger specific surface area and presence of –OH groups in the composite material facilitated the adsorption and chemical bonding of PMS molecules, thereby improving their overall performance. Quench experiments and electron paramagnetic resonance analysis identified •SO4−, •OH, •O2– and 1O2 as the primary active species responsible for the degradation of TC. Additionally, the degradation pathway of TC was elucidated through mass spectrometry analysis. This study provides valuable insights for the development of effective photocatalysts as promising PMS catalysts in environmental applications.

Construction of floating photothermal-assisted S-scheme heterojunction with enhanced photocatalytic degradation of tetracycline: Insights into mechanisms, degradation pathways and toxicity assessment

Inspired by ecological floating beds to treat water pollution through photosynthesis, we employed a combination of calcination and hydrothermal methods to construct a photothermal-assisted photocatalysis system based on a floating monolithic porous mesh of g-C3N4 (MPMCN) loaded with the excellent photothermal material Bi2MoO6 (BMO), forming a BMO/MPMCN S-scheme heterojunction. This approach improved the utilization efficiency of solar light by BMO/MPMCN, minimized heat loss, and enhanced the overall temperature of the material during the reaction process, thereby accelerating interfacial electron transfer. The unique floating structure confers a larger specific surface area to BMO/MPMCN, providing more reaction sites for TC pollutants and efficiently removing TC contamination from water. BMO/MPMCN degradated 99.3% of TC after 90 min of photothermal reaction, and exhibited good recyclability and reusability. Structural and performance characterizations of the material were carried out using techniques such as XRD, TEM, electrochemical testing, and ESR. Furthermore, the corresponding band structure and S-scheme electron transfer mechanism of the BMO/MPMCN heterojunction were deduced through the combination of in-situ XPS and UPS. The possible degradation pathways of TC and the ecological toxicity changes of intermediate products were analyzed. Finally, a mechanistic model for the photothermal-assisted photocatalytic degradation of TC in water by the BMO/MPMCN S-scheme heterojunction was established, providing a novel approach for the practical application of photocatalysis technology.

S-scheme 2D/2D B-doped N-deficient g-C3N4/ZnIn2S4 heterojunction for efficient H2 production intergrated with tertracycline degradation under visible-light illumination

A novel S-scheme 2D/2D boron-doped nitrogen-deficient g-C3N4/ZnIn2S4 (BDCNN/ZnIn2S4) heterojunction was successfully fabricated via the in-situ assembly of ZnIn2S4 onto BDCNN in an oil bath. To assess the quality and characteristics of the synthesized photocatalysts, a comprehensive range of characterizations were conducted. The innovative S-scheme 2D/2D BDCNN/ZnIn2S4 heterojunction, equipped with a deliberately established inter-built electric field, facilitates rapid electron transfer and enhanced separation efficiency of photo-induced carriers. Consequently, this heterojunction demonstrates remarkable enhancements in both H2 production and TC degradation under visible-light illumination (λ > 420 nm). The optimized BDCNN/ZnIn2S4 heterojunction exhibited impressive photocatalytic performance, achieving a promising H2 evolution rate of 2378.8 μmolg−1h−1 and a high degradation efficiency exceeding 90 % (k = 0.021 min−1) for TC. This noteworthy improvement in photocatalytic performance is primarily attributed to the synergistic effects of boron-doping and nitrogen-defects within BDCNN, coupled with the unique S-scheme photocatalytic mechanism inherent to the BDCNN/ZnIn2S4 heterojunction. Overall, this study introduces a groundbreaking approach for constructing 2D/2D g-C3N4-based heterojunctions that exhibit exceptional visible-light photocatalytic capabilities, thereby offering significant potential for various photocatalytic applications.

Silk fibroin protein and graphene synergistically boosting the reactive oxygen species generation of PU/AgI photocatalytic membrane for tetracycline sustained removal

Solar-light driven organic pollutants degradation by the recyclable photocatalytic membrane materials emerges as a promising technology for sewage purification. However, low generation of reactive oxygen species severely constraints their photocatalytic activity. Herein, we introduce a novel hydrophilic PU/SF/GO/AgI composite photocatalytic membrane fabricated via adding silk fibroin (SF) and graphene oxide (GO) for TC removal. By visible light irradiation, the PU/SF/GO/AgI membrane with 66.7 wt% SF and 0.05 wt% GO degrades TC with 7-fold increase in comparison with the PU/AgI membrane. The enhance photocatalytic activity is primarily attributed to its efficient generation of reactive oxygen species facilitated by the improved hydrophilicity and boosted charge separation. FTIR and electrochemical results demonstrate that the SF and GO with rich surface oxygen-containing groups contribute to the formation of Ag-O bonds for accelerating charge migration and separation. Significantly, the improved hydrophilicity of PU/SF/GO membrane can not only provide rich binging sites for AgI loading, but also be benefitted to attract small molecules for facilitating to reactive oxygen species generation. As a result, •O2−, •OH and H2O2 concentrations produced in PU/SF/GO/AgI membrane system reaches up to 53.20 μmol g−1 h−1, 7.89 μmol g−1 h−1 and 16.52 μmol, respectively, 6.7, 15.4 and 5.1-times higher than PU/AgI membrane system. Meanwhile, under LED irradiation of 12 h, TC degradation efficiency by the dynamic membrane reactor equipped with PU/SF/GO/AgI can reach up to 53 % and achieve 41 % TOC removal, exceeding the pure PU/AgI and those of reported membrane materials. This work proves that tuning hydrophilicity and charge migration of PU membrane can enhance their photocatalytic activity and recyclability, which offers an effective strategy for constructing sustained solar-light driven photocatalytic membrane system.

Co-regulation of microstructure and intrinsic groups in carbon nitride to achieve high-efficient pollutant degradation under visible light: Roles of N species

Owing to the drawback of the lower separation and shorter lifetime of carriers in carbon nitride (CN), this study reported that the CN composites with different morphologies and the N species were successfully synthesized through the regulation of intrinsic functional groups. Results showed that the formed tubular structure in 1D CN nanotubes (1D CNNTs) could intensify the utilization of visible light (Vis) because of the multiple diffraction or scattering of light, bridge the mass transfer distance and provide more active sites. Meanwhile, 1D CNNTs showed excellent TC degradation rates (0.3777 min-1) under Vis, which were 13, 630 and 6-36 times higher than these of two-dimensional CN nanosheets, three-dimensional CN microspheres and reported CN based catalysts, respectively. The analysis of active species showed O2·- and h+ were the main active species for TC degradation. The degradation pathways and comprehensive toxicities of TC were also comprehensively analyzed. Theoretical calculation exhibited that the introduction of N vacancy and -NHx groups effectively accelerating separation of carriers, prolonging carrier lifetime and enhancing the adsorption ability and relative electron transfer of O2 to the production of O2·-. In addition, the prepared catalysts presented better stability and anti-interference ability. Therefore, this study would provide a new view for regulation of intrinsic functional groups in CN to achieve efficient pollutant degradation under Vis.

Carbon quantum dots assemblies integrated with spatial confined Co nanoparticles for antibiotic degradation via peroxymonosulfate activation

Heterogeneous Co-based materials are well-known for their exceptional catalytic properties in activating peroxymonosulfate (PMS) for the degradation of antibiotic pollutants. However, the potential applications of these materials are often hindered by significant Co nanoparticle aggregation and ion leaching. In this study, a carbon quantum dot-mediated self-assembly strategy was used to fabricate three-dimensional porous sponge-like Co@CDs-x (x represents the calcination tempeatures) catalysts with spatially confined Co nanoparticles. Among the samples, Co@CDs-900 exhibited a remarkable 97.8 % removal efficiency of TC in 11 minutes, with an apparent rate constant of 0.313 min−1. The exceptional performance of Co@CDs-900/PMS can be attributed to its large specific surface area, unique porosity, and abundant catalytically active sites, which generate ample reactive oxygen species for TC degradation. The catalyst demonstrated good degradation capabilities across a wide pH range of 3–11 and various organic pollutants such as tetranitrophenol, oxytetracycline, ciprofloxacin, methyl orange, and rhodamine B. Moreover, Co@CDs-900 maintained high activity even after the 5th cycle due to its magnetic property and spatial confinement effect, preventing catalyst loss and ion leaching during recycling tests. The degradation mechanism involved both free-radical and non-free radical pathways, with SO4•− and 1O2 identified as the primary reactive oxygen species. The degradation intermediates of TC were identified and a plausible degradation pathway was proposed. Toxicity assessment revealed that the Co@CDs-900/PMS system effectively reduced the toxicity of TC post-degradation. This study presents an effective approach for developing sponge-like CDs assemblies with spatially confined metal nanoparticles for activating PMS in antibiotic degradation.

Zn-Al@LDH infused hydrochar as cathode catalyst for upgrading tetracycline degradation and hospital wastewater treatment: A synergy of Fenton-like and bio-electrochemical systems

The present investigation proposed a “Bio-electro-Fenton like (BEFL)” approach for the treatment of antibiotic (tetracycline, TC) containing wastewater. The system is modified using a uniquely developed cathode catalyst Zn-Al@layered double hydroxide (LDH) supported by low-cost carbonaceous material hydrochar (i.e., Zn-Al@LDH/HC), derived from anaerobic digestate and electrocoagulation sludge (waste materials). The result revealed nearly 96.90 ± 0.25 % removal of 10 mg/L of TC as well as about 89.50 ± 0.45 % abatement of total organic carbon (TOC) during 240 min of treatment time using Zn-Al@LDH/HC based BEFL system. Simultaneously, the chemical oxygen demand (COD) abatement in the anodic chamber (with glucose as substrate having COD of 1000 mg/L) was observed to be 85.16 ± 0.50 %. In-situ hydrogen peroxide (46.2 ± 1.2 mg/L as mean 4 h concentration) generation capability of the Zn-Al@LDH/HC was responsible for the outstanding performance of BEFL system. Additionally, the BEFL was also proficient in generation of bioelectricity (1141 ± 25 mA/m2) via the microbial activity in the anodic chamber. Further, the technology was extended for TC degradation in presence of surfactants and real hospital wastewater to depict the effect of real field conditions on the performance of as-synthesized waste derived catalyst. Intermediate products formed, the mechanism of TC degradation, and the phytotoxicity assessment were also illustrated to confirm the negligible toxicity of the treated effluent. Overall, deriving the catalyst from waste materials would reduce the scale-up cost of the proposed technology, enhance environmental sustainability, and contribute to circular economy.

Fe-N-coordinated graphene-like honeycomb porous carbon as an extremely effective catalyst for catalytic oxidation

In this study, Fe/N co-doped graphene-like honeycomb porous carbon (Fe-NC)was produced and used for the activating PMS to degrade TC. The Fe-NC catalyst has shown high activity in the TC degradation by activated PMS, with an efficiency of up to 94 % in 30 min. while the blank catalyst without N and Fe doping exhibited the lowest performance with 47.3 % TC degradation. Moreover, other operational factors of Fe-NC catalysts were also investigated to evaluate its catalytic activity. The burst experiments and electron paramagnetic resonance (EPR) experiments demonstrated that free radical paths (O2·-) and non-free radical paths (1O2) coexist inside the Fe-NC/PMS system. The experiment results and degradation mechanism analysis revealed that N species(Pyridine N, Graphite N,Fe-Nx) and iron species (Fe0) were possible to be the active species of catalysts. Furthermore, Fe-NC/PMS system was investigated for possible pathway of TC degradation by liquid mass spectrometry (LC-MS), and the presence of intermediates was analyzed for toxicity magnitude by ECOSAR software.

Synergistic photocatalysis for bacteria inactivation and organic pollutant removal by S-scheme heterojunction InVO4/Bi5O7I: Performance evaluation and mechanism investigation

The low efficiency of charge carrier separation is a major limitation hindering the application of photocatalytic technology. Constructing S-scheme heterojunction photocatalysts not only effectively promotes the separation of charge carriers, but also maximizes the oxidative and reductive capabilities of the two monomers. In this study S-scheme heterogeneous InVO4/Bi5O7I photocatalyst was synthesized by hydrothermal method combined with calcination. The optimal sample 20 % InVO4/Bi5O7I can completely deactivate Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in 30 min, remove 20 mg/L TC 76.0 % in 60 min and 20 mg/L BPA 93.0 % in 90 min. Intermediate products of TC and BPA degradation were detected using LC-MS, and possible degradation pathways were proposed. The photocurrent and electrochemical impedance spectroscopy (EIS) tests confirm that InVO4/Bi5O7I exhibits excellent photocurrent intensity and photocarrier migration ability, which are crucial reasons for the enhancement of the photocatalytic performance of the InVO4/Bi5O7I composite. Capture experiments indicate that OH, O2−, h+ and e−are reactive species. EPR further confirms the generation of OH and O2−. Combined with Kelvin probe force microscopy (KPFM) and band structure analysis, it is proposed that InVO4/Bi5O7I has an S-scheme charge transfer mechanism.

Self-assembly preparation of 3D nanorestricted domain catalysts based on carbon nanotube wires and in-depth analysis of tetracycline degradation performance, mechanism, and toxicology

In this study, the 3D intertwined tubular structure of carbon nanotube sponge (CNTS) was utilized to intersperse MIL-53(Fe) onto the nanofragments of CNTS. For the preparation of a novel composite catalyst, MIL-53(Fe)@CNTS, nanorestricted domain growth was combined with self-assembly regulation to realize the ordered growth of MIL-53(Fe) in the space of CNTS. The catalyst exhibited excellent activation performance for PMS within a wide pH range. The maximum removal of tetracycline (TC, 20 mg/L) was as high as 96.7 % within 90 min, and the maximum degradation rate constant (K) was as high as 0.1648 min−1. The performance of the catalyst was directly correlated with the number of domain-limited assemblies. Synchrotron radiation results and DFT theoretical calculations confirmed that the overall catalytic performance of MIL-53(Fe) was greatly improved after the nanorestricted domain assembly in CNTS. The TC degradation system involved radical–oxidative and nonradical pathways. The intermediates of the reaction system were identified by HPLC-MS, and several possible degradation pathways during the TC reaction were proposed. The toxicity degree of the intermediate monomers was analyzed in conjunction with the TEST program, and their effects on the biological environment were predicted. Combined with the toxicity prediction of the TC degradation pathways, the post-reaction degradation solution was used for practical biotoxicity assessment. The effects of the real solution before and after degradation on the ecotoxicity of different organisms were also determined. In conclusion, the composite catalyst MIL-53(Fe)@CNTS synthesized by precise assembly using the nanorestricted domain strategy has promising applications in pollutant degradation and environmental remediation.

Accurate construction of Cd/CdS/g-C3N4 heterojunction interface for efficient photocatalytic tetracycline degradation and Cr6+ reduction

With the increasing attention paid to environmental issues and the rapid development of photocatalytic environmental remediation technology, it is of great significance to develop catalysts with efficient photocatalytic environmental remediation capabilities. Graphite phase carbon nitride and its heterojunction are ideal choices for photocatalytic environmental remediation. Accurately constructing stable and well contacted heterogeneous interfaces is an effective means to improve catalytic efficiency. Herein, stable Cd/CdS/CN heterojunction interface was successful constructed by an in-situ synthesis method. Cd/CdS/CN photocatalysts exhibits excellent environmental remediation potential, capable of removing 88 % of high concentration TC (40 mg/L) within 60 min, and reducing over 96 % of Cr(VI) (50 mg/L) within 25 min under visible light, with good cycling stability. In addition, the reaction mechanism and TC degradation pathway of the composite photocatalyst with good photocatalytic activity were analyzed in depth. The experimental results confirmed that the synergistic effect of Z-Scheme heterojunction and Ohmic junction significantly improved the separation and migration of photogenerated carriers in the system, and maintained a high redox ability. This work provides a new reference for constructing CN based heterojunction photocatalysts with close contact.