Tetracycline Degradation Efficiency Research Articles

Activation of peroxydisulfate by MIL-88A(Fe) under visible light toward tetracycline degradation: Effect of synthesis temperature on catalytic performance

Three different MIL-88A(Fe) samples (named as MIL-88A(Fe)-65, MIL-88A(Fe)-95 and MIL-88A(Fe)-125) were synthesized by a one-step hydrothermal method at the different synthesis temperature (65 °C, 95 °C and 125 °C) on the control, and they were adopted as high-efficiency catalysts for peroxydisulfate (PDS) activation to remove tetracycline (TC) from water under visible light irradiation. Various characterization methods (including XRD, BET surface area, UV–vis DRS, PL and XPS) indicate that synthesis temperature affects the crystal facet exposure, specific surface area, band gap energy, energy band position and ≡Fe2+/≡Fe3+ ratio of as-prepared MIL-88A(Fe). Activation of PDS by MIL-88A(Fe)-95 sample showed the highest efficiency for TC degradation under visible light mainly due to the photo-generated electrons on the conduction band of MIL-88A(Fe)-95 are more likely to be captured by O2 and PDS to produce reactive oxygen species. As-synthesized MIL-88A(Fe)-95 catalyst is stable and can be efficiently reused in the process of activating PDS to degrade TC. More importantly, TC degradation efficiency in real water matrices by MIL-88A(Fe)-95/PDS oxidation system is significantly higher than that in distilled water because bicarbonate ions in selected real water bodies can promote PDS activation, suggesting good practicability of this oxidation process. Mechanism analysis verifies that 1O2, O2•−, SO4•−, and •OH participate in TC degradation. This work laid a foundation for further developing the synthesis conditions to synthesize high-performance MIL-88A(Fe) applied in PS-AOPs.

ZnWO4 nanorod-colloidal SnO2 quantum dots core@shell heterostructures: Efficient solar-light-driven photocatalytic degradation of tetracycline

Zinc tungsten oxide (ZW) and colloidal SnO2 quantum dots (CS) were synthesized individually by hydrothermal and wet chemical methods. ZW-CS core@shell nanorods were prepared using a sonochemical method for the enhanced photocatalytic activity of tetracycline (TC) degradation. ZW-CS core@shell nanorods were systematically characterized by structural, morphological mapping and optical techniques. All characterization techniques were synchronized to confirm the construction of core@shell nanorods. Optical absorption studies indicate an increased light-capturing efficiency along with a reduced bandgap from 3.56 to 3.23 eV, which is further supported by photoluminescence. Mapping analysis from SEM and HR-TEM evidence the presence of elements as well as a core@shell nanostructure. The optimized sample of ZW-CS 1.0 shows improved photocatalytic degradation of TC under stimulated solar light. The TC degradation efficiency by ZW-CS 1.0 core@shell nanorods was about 97% within 2 h. The formation of core@shell nanorod structure might be the reason for the better photocatalytic tetracycline degradation performance.

Visible-light enhanced peroxymonosulfate activation on Co3O4/MnO2 for the degradation of tetracycline: Cooperation of radical and non-radical mechanisms

Advanced oxidation processes (AOPs) dominated by SO4·- species have drawn mainly attentions for the removal of persistent pollutions. Nevertheless, single radical underutilizes the oxidizing capacity of reactive oxygen species and possesses poor adaptability to the environment compared with the cooperation of radical and non-radical. Herein, a Co3O4/MnO2 heterojunction catalyst is synthesized and used to peroxymonosulfate (PMS) activation for the degradation of tetracycline (TC) via non-radical cooperates with radical under visible irradiation. The optimized 10-Co3O4/MnO2 (10-CMO) composite catalyst exhibits 99.4% TC degradation efficiency within 60 min, and theapparent rate constant is 0.1353 min−1, which is 6.77 and 45.10 times higher than that of in 10-CMO/PMS and 10-CMO/Vissystems, respectively. The PMS acts as an electron accepter and induces the non-radical pathways accelerating TC degradation. After 5 cycles, the 10-CMO catalyst can still remove 93.7% TC with low Co (0.06 mg/L) and Mn (0.20 mg/L) ions leakage. The reactive species trapping experiments and electron paramagnetic resonance analysis demonstrate that the 1O2, h+ and SO4·- species dominate the TC degradation. Theoretical calculation results further reveal the probable PMS activation mechanism and the superiority of heterojunction for the PMS activation. This work shows great potential for pollutions control with visible-light-assisted PMS activation in presence of catalyst.

Sustainable self-powered degradation of antibiotics using Fe3O4@MoS2/PVDF modified pipe with superior piezoelectric activity: Mechanism insight, toxicity assessment and energy consumption

Using clean energy from the environment to treat organics is a sustainable approach to alleviate the energy shortage and environmental pollution. Water flow energy in pipelines is overlooked due to the lack of efficient energy-converting material. Herein, a novel Fe3O4 @MoS2/PVDF modified pipe was prepared and used for self-powered piezocatalytic degradation of organics in the pipeline. The degradation efficiency of tetracycline, Rhodamine B, ciprofloxacin and oxytetracycline can reach 92.5 %, 90.9 %, 85.9 % and 69.2 %, respectively, at an ultralow flow rate. The energy consumption of this water treatment system was only 12.7 % of that of ultrasonic systems. The theoretical calculation and characterization results indicated that the ultrahigh piezocatalytic efficiency was derived from the coupling effect of Fe3O4/MoS2 and PVDF. EPR results showed that ∙O2-, ∙OH, and h+ were the main active species in degrading organics. The results of the toxicity assessment showed that ecotoxicity could be reduced or even eliminated.

Silica enhanced activation and stability of Fe/Mn decorated sludge biochar composite for tetracycline degradation

In this study, SiO2-composited biochar decorated with Fe/Mn was prepared by co-pyrolysis method. The degradation performance of the catalyst was evaluated by activating persulfate (PS) to degrade tetracycline (TC). The effects of pH, initial TC concentration, PS concentration, catalyst dosage and coexisting anions on degradation efficiency and kinetics of TC were investigated. Under optimal conditions (TC = 40 mg L−1, pH = 6.2, PS = 3.0 mM, catalyst = 0.1 g L−1), the kinetic reaction rate constant could reach 0.0264 min−1 in Fe2Mn1@BC-0.3SiO2/PS system, which was 12 times higher than that in the BC/PS system (0.00201 min−1). The electrochemical, X-ray diffractometer (XRD), Fourier transform infrared spectrum (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis showed that both metal oxides and oxygen-containing functional groups provide more active sites to activate PS. The redox cycle between Fe(II)/Fe(III) and Mn(II)/Mn(III)/Mn(IV) accelerated the electron transfer and sustained the catalytic activation of PS. Radical quenching experiments and electron spin resonance (ESR) measurements confirmed that surface sulfate radical (SO4•−) play a key role in TC degradation. Three possible degradation pathways of TC were proposed based on high-performance liquid chromatography coupled with high-resolution mass spectrometry (HPLC-HRMS) analysis, the toxicity of TC and its intermediates was analyzed by bioluminescence inhibition test. In addition to the enhanced catalytic performance, the presence of silica also improved the stability of the catalyst, as confirmed by cyclic experiment and metal ion leaching analysis. The Fe2Mn1@BC-0.3SiO2 catalyst, derived from low-cost metals and bio-waste materials, offer an environmentally friendly option to design and implement heterogenous catalyst system for pollutant removal in water.

Efficient activation of persulfate by Ti3C2 MXene QDs modified ZnFe2O4 for the rapid degradation of tetracycline

Mxene-based catalysts with specific interfacial characteristics are beneficial for photocatalytic applications. Herein, Ti3C2 MXene modified ZnFe2O4 nanocomposite materials were prepared for photocatalysis. The morphology and structure of the nanocmposites were characterized by scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), which revealed that Ti3C2 MXene as quantum dots (QDs) was uniformly distributed on the ZnFe2O4 surface. The Ti3C2 QDs modified ZnFe2O4 catalyst (ZnFe2O4/MXene-15%) under visible light achieved 87% degradation efficiency of tetracycline within 60 min when coupled with persulfate (PS) system. The initial solution pH, PS dosage and co-existing ions were found to be the main factors affecting the heterogeneous oxidation process, while quenching experiments showed that O2•- is the main oxidizing species in the removal of tetracycline in ZnFe2O4/MXene-PS system. In addition, the cyclic experiments suggested that ZnFe2O4/MXene had good stability and thus it may have practical applications in industry.

Boosting photocatalytic degradation efficiency of tetracycline by a visible-light-activated NiMoO4/g-C3N4 heterojunction photocatalyst in the water environment

Semiconductor photocatalytic technology is one of the potential ways to eliminate antibiotic pollution in the water environment. In this study, NiMoO4/g-C3N4 (NMCN) heterojunction photocatalyst was fabricated via an ultrasonic-assisted hydrothermal route. The synthesized monomer and heterojunction photocatalyst samples were characterized in terms of crystal structure, elementary composition, morphology, optical properties, and so on. Upon visible light irradiation, the prepared 30NMCN sample displayed prominent photocatalytic degradation efficiency (89%) of tetracycline within 3 h, which was 1.48 and 2.02 times of NiMoO4 and g-C3N4, respectively. In addition, the 30NMCN sample showed outstanding recyclability after multiple tetracycline photocatalytic degradation processes. Ultimately, the mechanism of the enhanced tetracycline degradation performance over NMCN photocatalysts was elucidated. The meliorative photocatalytic performance was ascribed to the expansion of the light-harvesting range and the alteration of migration pathways of photogenerated charge carriers.

Construction of a N−Mo−O bond bridged MoO2/Mo-doped g-C3N4 Schottky heterojunction composite with enhanced interfacial compatibility for efficient photocatalytic degradation of tetracycline

To improve the photocatalytic performance of g-C3N4 (CN), mechanical activation (MA) treatment of precursor followed by calcination was developed to construct a N−Mo−O bond bridged MoO2/Mo-doped CN (MA-MoO2/Mo-CN) Schottky heterojunction composite, which was used as a visible light-driven photocatalyst for degrading tetracycline (TC). The as-prepared MA-MoO2/Mo-CN with strong interfacial interaction showed excellent photocatalytic performance and structural stability, with 92.3% of TC degradation efficiency within 90 min and maintaining over 90% of degradation efficiency after five consecutive cycles. The enhanced photocatalytic performance can be ascribed to that MA treatment induced the improvement of surface area and the formation of N vacancies and N−Mo−O bonds, which served as a bridge to connect Mo-CN and MoO2 for constructing a Schottky barrier. These provided more reactive sites and effectively enhanced migration efficiency of interface electrons, separation efficiency of photogenerated carriers, and light absorption capacity. In addition, the mechanism of photocatalytic degradation of TC and its possible degradation pathway were investigated. This research provides an environmentally friendly and feasible method for producing highly active precious metal-free photocatalysts with excellent migration and separation efficiency of photoexcited charge carriers.

Photocatalytic degradation of tetracycline by N-CQDs modified S-g-C3N4 nanotubes and its product toxicity evaluation

In this study, to improve the electron-hole pairs separation rate and enhance the antibiotic wastewater treatment efficiency, the sulfur doped g-C3N4 (SCN) nanotubes were modified with nitrogen-doped carbon quantum dots (N-CQDs) derived from pig manure by a simple solvothermal method, and SCN/N-CQDs composite photocatalyst was synthesized. SCN with hexagonal tubular structure has strong light scattering ability and abundant active sites. At the same time, the modification of N-CQDs extended the visible light response range, accelerated the separation of electron-hole pairs, and realized the efficient photocatalytic degradation of tetracycline (TC). The SCN/N-CQDs-1 showed the best photocatalytic performance, and degradation rate of TC could reach to 79.11% after 90 min of visible light irradiation, much higher than the degradation efficiency of pure SCN (58.33%). Among them, the generation of hole, hydroxyl radicals and superoxide radicals play an important role in the efficient degradation of TC. Furthermore, the intermediates produced during the degradation process were detected by ultra-performance liquid chromatography-mass spectrometry (HPLC − MS), and the possible TC degradation pathways were investigated. The repeatability and practicability of SCN/N-CQDs are proved by five cycle experiments. In addition, compared with the original toxicity, the inhibition rate of Escherichia coli (E. coli) colony growth was reduced by 91.315% after 90 min photodegradation. The results of biotoxicity analysis showed that SCN/N-CQDs leaching solution and its photodegradation wastewater did not produce biotoxicity to E. coli.

Guest Molecule Insertion-Optimized d-Band Center Position in MoS2 with Improved Sulfite Activation Ability Inspired by Sulfite Oxidase.

As a prospective member in the family of advanced oxidation processes (AOPs), heterogeneous sulfite activation shows low cost and high safety for poisonous organic pollutants' degradation. To obtain an efficient sulfite activator, sulfite oxidase (SuOx), a molybdenum-based enzyme that can prompt oxidation and activation of sulfite, inspired us greatly. Based on the structure of SuOx, MoS2/BPE (BPE = 1, 2-bis-(4-pyridyl)-ethylene) is synthesized successfully. In MoS2/BPE, the BPE molecule is inserted between the MoS2 layers as a pillar and the N atom links with Mo4+ directly. MoS2/BPE shows excellent SuOx mimic activity. Theoretical calculation implies that BPE insertion optimizes the d-band center position of MoS2/BPE, which regulates the interaction between MoS2 and *SO42-. This prompts •SO4- generation and organic pollutants' degradation. At pH 7.0, its tetracycline degradation efficiency achieved is 93.9% in 30 min. Furthermore, its sulfite activation ability also endows MoS2/BPE with excellent antibiofouling performance because •SO4- can kill the microorganisms in water effectively. This work develops a new sulfite activator based on SuOx. The connection between structure and SuOx mimic activity and sulfite activation ability is clarified in detail.

Highly efficient LaFeO3/Bi2WO6 Z-scheme nanocomposite for photodegradation of tetracycline under visible light irradiation: Statistical modeling and optimization of process by CCD-RSM

The major problems of the semiconductor nanomaterials in the photocatalytic applications for degradation of organic contaminants are fast recombination of photogenerated electron-hole pairs and low visible light harvesting. Therefore, we tried to resolve these drawbacks by coupling LaFeO3 nanoparticles with Bi2WO6 nanoflakes and constructing of binary Z-scheme heterojunction through the facile solvothermal synthesis approach. The photocatalytic activity of the LaFeO3/Bi2WO6 heterojunction was studied through degradation of tetracycline (TC) upon visible light irradiation. The effects of experimental parameters, including LaFeO3/Bi2WO6 dosage, initial concentration of TC, visible light irradiation time, and solution pH on the photocatalyst performance of binary nanocomposite were analyzed by response surface methodology. The results of analysis of variance confirmed that these parameters have a significant effect on the TC degradation efficiency. The value of the first-order kinetic rate constant for removal of TC using LaFeO3/Bi2WO6 was calculated 0.1291 min−1, which was 20 and 10 times higher than pure LaFeO3 and Bi2WO6, respectively. Besides, LaFeO3/Bi2WO6 was shown the excellent photocatalytic stability after 4 cycles. Furthermore, the photocatalytic pathway for photodegradation of TC by binary LaFeO3/Bi2WO6 nanocomposite was proposed according to the trapping experiments of active species and the results were signify that the h+ and .OH are the predominant reactive species for the photodegradation of TC. Overall, we believe that current novel research opens a promising route for the preparation of highly efficient LaFeO3/Bi2WO6 photocatalyst and its usage for wastewater treatment.

Preparation of Porous Ti/RuO2-IrO2@Pt, Ti/RuO2-TiO2@Pt and Ti/Y2O3-RuO2-TiO2@Pt Anodes for Efficient Electrocatalytic Decomposition of Tetracycline

Electrocatalytic oxidation (ECO) has attracted attention because of its high efficiency and environmental friendliness in water treatment. The preparation of anodes with high catalytic activity and long service lifetimes is a core part of electrocatalytic oxidation technology. Here, porous Ti/RuO2-IrO2@Pt, Ti/RuO2-TiO2@Pt, and Ti/Y2O3-RuO2-TiO2@Pt anodes were fabricated by means of modified micro-emulsion and vacuum impregnation methods with high porosity titanium plates as substrates. The scanning electron microscopy (SEM) images showed that RuO2-IrO2@Pt, RuO2-TiO2@Pt, and Y2O3-RuO2-TiO2@Pt nanoparticles were coated on the inner surface of the as-prepared anodes to form the active layer. Electrochemical analysis revealed that the high porosity substrate could result in a large electrochemically active area, and a long service life (60 h at 2 A cm-2 current density, 1 mol L-1 H2SO4 as the electrolyte, and 40 °C). The degradation experiments conducted on tetracycline hydrochloride (TC) showed that the porous Ti/Y2O3-RuO2-TiO2@Pt had the highest degradation efficiency for tetracycline, reaching 100% removal in 10 min with the lowest energy consumption of 167 kWh kg-1 TOC. The reaction was consistent with the pseudo-primary kinetics results with a k value of 0.5480 mol L-1 s-1, which was 16 times higher than that of the commercial Ti/RuO2-IrO2 electrode. The fluorospectrophotometry studies verified that the degradation and mineralization of tetracycline were mainly ascribed to the •OH generated in the electrocatalytic oxidation process. This study thus presents a series of alternative anodes for future industrial wastewater treatment.

Role of holes in microwave-induced catalyst Co3O4 for efficient high-concentration tetracycline degradation

Microwave-induced catalytic is a potential organic wastewater treatment technology. In this work, a new type of microwave-induced catalyst Co3O4 was synthesized and used to remove tetracycline (TC) under microwave (MW). The results have shown that the spherical Co3O4 exhibited impressively high catalytic activity with 100 mg·L-1 TC degradation efficiency of 100 % under MW at 800 W within 30 min. Importantly, Co3O4 catalyst displayed excellent stability with the degradation efficiency. The electron-hole pairs were generated under MW in the presence of Co3O4, which was confirmed by electron paramagnetic resonance and active species scavenging experiments. Part of the electrons (e-) was captured by oxygen vacancies produced under MW, and holes (h+) acted as the main active species for participating in the degradation process of TC. This work indicated the effect of MW for the separation of electrons and holes and provides new ideas for the mechanism of microwave-induced catalytic degradation.

Novel g-C3N4/BiVO4 heterostructured nanohybrids for high efficiency photocatalytic degradation of toxic chemical pollutants

Novel heterostructured hybrid catalysts are essential for the efficient photocatalytic removal of organic pollutants from wastewater generated by the pharmaceutical and textile industries. In this study, novel g-C3N4/BiVO4 nanohybrid catalysts were prepared using a solvothermal technique, and examined their structural and optical properties using different characterizations. The X-ray diffraction analysis confirmed the monoclinic crystal phase of BiVO4. Field emission scanning electron microscopy (FESEM) images revealed that g-C3N4 sheets anchored on the surface of BiVO4 nanospheres. X-ray photoelectron spectroscopy (XPS) analysis confirmed the oxidation states of g-C3N4/BiVO4 composite sample. UV–Vis DRS spectroscopy analysis revealed that the composite (2.08 eV) sample had a reduced bandgap compared to other samples. The photocatalytic properties of the prepared samples were tested in the presence of organic methylene blue (MB) and antibiotic tetracycline (TC) pollutants under visible light illumination. The hybrid composite catalyst exhibited enhanced photocatalytic degradation efficiency of MB (88%) and TC (89%) pollutants at elevated rate constants of 0.0128 and 0.01174 min−1, respectively. The improved catalytic performance of the composite catalyst is due to the heterojunctions between g-C3N4 and BiVO4 that successfully reduced the rate of charge carrier recombination in the catalyst system. Scavenger experiments revealed that O2●— and h+ radicals played a main role in the degradation of the chemical pollutants. The developed g-C3N4/BiVO4 heterostructured catalyst is a suitable candidate for removing contaminants from industrial wastewater because of its facile fabrication and exceptional photocatalytic activity under visible light irradiation.

Synthesis of porous (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O high entropy oxide catalysts for peroxymonosulfate activation toward tetracycline degradation

The porous (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O high entropy oxide was synthesized by a facile solution combustion method. The X-ray diffraction (XRD) patterns showed that a rock-salt phase (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O nanocrystalline was successfully constructed after heat treatment above 800 °C. A porous microstructure with high specific surface area was determined by scanning electron microscope (SEM) and N2 adsorption analysis, respectively. The (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O high entropy oxide displayed excellent peroxymonosulfate (PMS) activation which could fully degrade the tetracycline (TC) within 24 min. Moreover, the effect of PMS concentration, the high entropy oxide dosage, pH value, temperature and coexisting anions on the degradation efficiency of TC was systematically studied. According to free radical quenching experiments and electron paramagnetic resonance studies, the possible mechanism of TC degradation over the (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O/PMS system was proposed. This work provided a research basis for the use of high entropy oxide for PMS activation in environmental treatment.

Efficient degradation of tetracycline by a novel nanoconfinement structure Cu2O/Cu@MXene composite

In order to solve the problem of easy aggregation of copper oxides in environmental remediation, it is an effective method to confine copper oxides to suitable substrates. Herein, we design a novel Cu2O/Cu@MXene composite with a nanoconfinement structure, and it can effectively activate peroxymonosulfate (PMS) to produce .OH for degradation tetracycline (TC). Results indicated that the MXene with extraordinary multilayer structure and surface negativity could fix the Cu2O/Cu nanoparticles in the layer spaces and suppress the agglomeration of nanoparticles. The removal efficiency of TC reached 99.14 % within 30 min, and the pseudo-first-order reaction kinetic constant was 0.1505 min−1, which was 3.2 times that of Cu2O/Cu alone. The outstanding catalytic performance attributed that the MXene based on Cu2O/Cu@MXene could promote the adsorption of TC and electron transmittal between Cu2O/Cu nanoparticles. Furthermore, the degradation efficiency of TC was still over 82 % after five cycles. In addition, based on the degradation intermediates provided by LC-MS, two specific degradation pathways were proposed. This study provides a new reference for suppressing the agglomeration of nanoparticles, and broadens the application of MXene materials in the field of environmental remediation.

Activation of peroxymonosulfate by CoP@Co2P heterostructures via radical and non-radical pathways for antibiotics degradation

In recent years, peroxymonosulfate (PMS)-based advanced oxidation process have been raised widely attention due to the efficient the degradation of antibiotics. However, the low efficiency in PMS activation is still a challenge for practical application. Designing the catalysts which can activate PMS towards hybrid of radical and non-radical pathways may be a promising approach. Herein, CoP@Co2P heterostructure catalyst has been constructed by a convenient calcination method. Characterizations and theoretical calculations confirm the electron transfer process between CoP and Co2P interface, which forms the electron-deficient Co2P and electron-rich CoP. Thus, Co2P oxidizes PMS to produce 1O2, and CoP reduces PMS to produce SO4•-, which mediates both the radical and the non-radical reaction for tetracycline (TC) degradation. Besides, the TC degradation efficiency by CoP@Co2P-3/PMS system was 4.53 and 5.37 times than CoP/PMS and Co2P/PMS system, respectively, and the mineralization rate of TC reached 84.7% after 60 min. CoP@Co2P-3/PMS system still displayed outstanding catalytic performances with the coexistence of anions in natural water, indicating the excellent stability of the catalysts. Besides, three possible degradation pathways of TC were proposed and CoP@Co2P/PMS oxidation system was very efficient at detoxifying TC.

Novel 0D/2D Ag0/BiSbO4 nanosheets with remarkably enhanced photocatalytic activity under simulated sunlight: Strong interfacial interaction, DFT calculation and degradation mechanism study

Herein, a novel 0D/2D Ag0/BiSbO4 heterojunction was successfully synthesized via a simple in-situ light deposition method. Under simulated sunlight irradiation, the photocatalytic degradation efficiency of TC (tetracycline) over the optimal Ag0/BiSbO4 heterojunction can reach 90.5 % within 60 min, which is nearly 18 times higher than that of pristine BiSbO4. Theoretical calculation further demonstrates that an IEF (internal electric field) directing from Ag to BiSbO4 can be formed when they are in close contact, which can automatically drive the photoinduced electrons migration from the CB of BiSbO4 to Ag0, efficiently fostering the separation of charge carriers. On the basis of ESR result, the deposition of Ag0 on the surface of BiSbO4 nanosheets can greatly boost the generation of superoxide and hydroxyl radicals. Quenching experiment validates superoxide radical plays dominated role in the photocatalytic degradation process. This work gives a valuable reference in investigating strong interfacial effect of metal/semiconductor photocatalyst.

The removal of antibiotic, antibiotic resistant bacteria and genes in persulfate oxidation system via activating by antibiotic fermentation dregs derived biochar

To reduce the adverse effects of antibiotics and antibiotic resistance genes (ARGs) in the environment, nitrogen-doped biochar (NLBH), derived from lincomycin fermentation dregs (LFD), was employed as an activator in a persulfate (PDS) oxidation system. The system was evaluated for its ability to degrade tetracycline (TC), inactivate antibiotic resistant bacteria (ARB) and remove ARGs. The degradation efficiency of TC in the NLBH/PDS system (70.1%) was higher than that in the pristine biochar/PDS system (10.3%). It was confirmed that the defects and edge pyridinic nitrogen generated in the nitrogen doping process were the reactive sites for PDS activation. According to electron paramagnetic resonance (EPR) and radical quenching experiments, the major mechanism for PDS activation was a non-radical pathway dominated by singlet oxygen (1O2). Radical pathways involving sulfate (SO4·-) and hydroxyl radicals (·OH) were also at play in the NLBH/PDS system, but their role was minor. TC was principally degraded by hydroxylation, demethylation, and decarboxylation, and within 90 min, the NLBH/PDS system effectively inactivated 71.5% of ARB (Pseudomonas sp. HLS-6). Intracellular ARGs (iARGs; sul1, sul2) and intI1 had log reduction efficiencies of 2.73–4.04 and 2.70, respectively, whereas, extracellular ARGs (sul1 and sul2) and intI1 accumulated noticeably by 1.52–4.18-and 4.92-log, respectively. This work highlights a promising alternative technique for the removal of antibiotics, ARB and iARGs in future advanced wastewater treatment systems.

Z-scheme NiFe LDH/Bi4O5I2 heterojunction for photo-Fenton oxidation of tetracycline

Designing an efficient catalyst for photo-Fenton organic contaminant degradation has been an important subject intended to solve the related environmental deterioration and enormous energy crises. However, the rapid cycle of Fe3+/Fe2+ in a wide pH range based on photo-Fenton reaction is still challenging. Here, we prepare highly effective and stable Z-scheme NiFe LDH/Bi4O5I2 heterogeneous Fenton catalyst for tetracycline (TC) photodegradation. The optimized NiFe LDH/Bi4O5I2 composite (NFBOI-35) reaches more than 95% TC degradation efficiency in Fenton system under visible light irradiation. Excellent stability, low metal ions leaching concentration and wide pH applicability distinguish make NFBOI-35 be a potential candidate for TC elimination. The improved photo-Fenton performance is mainly attributed to the construction of Z-scheme heterojunction and the accelerated decomposition of H2O2, which realizes the remarkable synergy effect between photocatalysis and Fenton reaction. This work would be beneficial to design Z-scheme catalyst for photo-Fenton organic contaminants degradation and other solar energy application.