Degradation Of Chlortetracycline Research Articles

Spatial Confinement of Co Nanoparticles in N-Doped Carbon Nanorods for Wastewater Purification via CaSO3 Activation.

Spatial confinement of organic pollutants and reactive oxygen species (e.g., SO4•- and •OH) with ultrashort lifetime inside the scale of chemical theoretical diffusion could provide a greatly promising strategy to overcome the limitation of mass transfer in the heterogeneous Fenton-like oxidation process. Herein, we first reported spatial confinement of cobalt nanoparticles in N-doped carbon nanorods (Co-NCNRs), by encapsulating Co nanoparticles into N-doped carbon nanorods, in activating CaSO3 for antibiotic degradation. Compared to Na2SO3 and NaHSO3, CaSO3 could slowly and persistently discharge SO32- due to its low solubility, thus avoiding the depletion of the generated SO3•- and •OH under the high concentration of sulfite ions. Fully physical characterizations confirmed that the 3D hydrogel was mostly transformed into the nanorod structure of Co-NCNRs at 550 °C. Co atoms were successfully nanoconfined into N-doped carbon nanorods, which contributes to mass transfer and prevents the agglomeration of Co nanoparticles, thus enhancing its catalytic activity and stability in activating CaSO3 for water decontamination. The catalytic performance, kinetic research, influences of inorganic anions, pH, and degradation mechanism of chlortetracycline degradation catalyzed by the Co-NCNRs/CaSO3 system have been studied in detail. This work not only proposed a facile method for synthesis of nanoconfined catalyst but also provided an excellent Co-NCNRs/CaSO3 system for wastewater treatment.

Mitigating Tetracycline antibiotic contamination in chicken manure using ex situ fermentation system

Excessive use of tetracycline antibiotics in poultry farming results in significant concentrations of these drugs and tetracycline resistance genes (TRGs) in chicken manure, impacting both environmental and human health. Our research represents the first investigation into the removal dynamics of chlortetracycline (CTC) and TRGs in different layers of an ex situ fermentation system (EFS) for chicken waste treatment. By pinpointing and analyzing dominant TRGs-harboring bacteria and their interactions with environmental variables, we've closed an existing knowledge gap. Findings revealed that CTC's degradation half-lives spanned 3.3–5.8 days across different EFS layers, and TRG removal efficiency ranged between 86.82% and 99.52%. Network analysis highlighted Proteobacteria and Actinobacteria's essential roles in TRGs elimination, whereas Chloroflexi broadened the potential TRG hosts in the lower layer. Physical and chemical conditions within the EFS influenced microbial community diversity, subsequently impacting TRGs and integrons. Importantly, our study reports that the middle EFS layer exhibited superior performance in eliminating CTC and key TRGs (tetW, tetG, and tetX) as well as intI2. Our work transcends immediate health and environmental remediation by offering insights that encourage sustainable agriculture practices.

Natural pyrite-stimulative periodate activation: efficiency and mechanism study.

Natural pyrite (NP) is an alternative catalyst for wastewater purification via advanced oxidation processes (AOPs). However, the activation performance and mechanism of periodate (PI) by NP have not yet been revealed. Herein, this work examines the activation performance of NP towards PI and its application in the degradation of antibiotic wastewater. Interestingly, 95.69% of chlortetracycline (CTC) was degraded by NP within 20min via PI activation. Besides, NP shows effective degradation of various pollutants such as rhodamine B (65.81%), sulfamethoxazole (89.04%), and sodium butylxanthate (99.77%) within 20min. The active species quenching experiment suggested that the active species , , 1O2 and the active complex of PI bonded with NP surface participated in CTC degradation. In addition, Fe(II) on NP surface is the main active site for PI activation, while Sn2- species accelerates the reduction of Fe(III) to Fe(II) and promotes sustained PI activation. This work provides new ideas for the application of NP in environmental pollution control.

A magnetically reusable Ce-MOF/GO/Fe3O4 composite for effective photocatalytic degradation of chlortetracycline.

Herein, we report a novel 1/GO/Fe3O4 photocatalyst, comprising Ce(BTB)(H2O) (MOF-1, H3BTB = 1,3,5-benzenetrisbenzoic acid), graphene oxide (GO), and iron oxide (Fe3O4) for photocatalytic degradation of chlortetracycline (CTC). This design enables the effective transfer of electrons from the MOF to GO, thereby reducing the photoelectron-hole recombination rate. Therefore, the optimized 1/GO/Fe3O4 photocatalyst with H2O2 shows the highest photocatalytic activity toward CTC. The kinetic constant is 5.4 times that in the system of MOF-1 and hydrogen peroxide, which usually acted as efficient electron acceptors to improve the photocatalytic performance of MOFs. More importantly, light absorption is extended from the ultraviolet to the visible region. Furthermore, 1/GO/Fe3O4 can be quickly recycled under an applied magnetic field and displays outstanding stability and reusability. According to the radical trapping experiments and electron paramagnetic resonance results, hydroxyl radicals, superoxide radicals, and holes all contribute to excellent photocatalytic activity. The possible catalytic mechanism of 1/GO/Fe3O4 is tentatively proposed. This work aims to explore the synergistic effect between metal-organic frameworks (MOFs) and GO, and provide a theoretical basis for MOF-based composites to remove antibiotic contaminants in the environment.

Confined PbO2 nanoparticles in carbon nanotubes on boron-doped diamond substrate for highly efficient chlortetracycline degradation

Realizing highly efficient catalysis with high stability in complex chemical environments remains a major challenge for advanced oxidation processes. Here, confined lead dioxide (PbO2) nanoparticles in carbon nanotubes (CNTs) on boron-doped diamond (BDD) substrate is designed and fabricated as a heterogeneous catalyst for antibiotic treatment, achieving ultra-efficient degradation of chlortetracycline (CTC) with high reaction rate and stability. The maximum degradation rate of CTC reaches 98.8 % in 120 min, and it remains 91.0 % after ten cycles, which are significantly higher than that proposed by the contrast catalysts. The excellent degradation performance of this heterogeneous catalyst is mainly attributed to three factors: (i) the prepared PbO2 nanoparticles with an average size of 5 nm are confined in CNTs, providing more active sites and higher electron transfer rate; (ii) secondary pollution and catalyst deactivation of PbO2 are avoided by protecting CNTs; (iii) BDD shows strong capacity for mineralizing organic compounds related to the high oxygen evolution reaction potential. This finding provides a novel strategy for advanced oxidation processes in environmental remediation.

Sulfite activation by Jahn-Teller-driven oxygen vacancies Cu-Mn composite oxide for chlortetracycline degradation

Copper-manganese composite metal oxides (CuMnOy) were prepared by hydrolysis-driven oxidation-reduction method and used to activate sulfite to degrade chlortetracycline hydrochloride (CTC) for the first time. The Jahn-Teller ions Mn3+ and Cu2+ exist in CuMnOy, which form a solid electric charge transport redox system and ensure the continuous generation of reactive oxygen species (ROS). Through the systematic study of the experimental parameters such as sulfite concentration, catalyst metal molar ratio, catalyst amounts and initial pH, the optimal degradation rate of CTC could reach 91.74% within 10 min and 94.46% after 30 min. The major reactive radicals were determined by radical quenching experiments and electron paramagnetic resonance (EPR) trapping techniques, and it was confirmed that SO4•- and •O2- played a nonnegligible role in the process of degrading CTC. Density functional theory (DFT) calculations show that higher Fukui indices (f- and f0) of CTC sites are more vulnerable to free radical attack. CuMnOy has low CTC degradation intermediate toxicity, high catalytic performance, good anti-interference ability, reusability and stability, and possesses decent application potential in the actual water treatment field.

Activation of peroxymonosulfate by biochar in-situ enriched with cobalt tungstate and cobalt: Insights into the role of rich oxygen vacancies and catalytic mechanism

The development of low-cost, stable, and recyclable multiphase catalysts in advanced oxidation process is essential for efficient degradation of antibiotics. In this study, a BC-Co-W-700 catalyst was used to activate peroxymonosulfate (PMS) for chlortetracycline (CTC) degradation. The catalyst was prepared using reclaimed biomass material as a matrix. The biochar-based catalyst possessed abundant active sites and realized the in-situ growth of Co and CoWO4. The BC-Co-W-700/PMS achieved 100% degradation of CTC (20 mg/L) within 18 min. Quenching and electron paramagnetic resonance experiments were conducted to investigate the reactive oxygen species (ROS) in the BC-Co-W-700/PMS system. The identified ROS in this system included 1O2, O2−, SO4−, and OH. Abundant ROS endowed the system with strong degradation performance, applicability, and anti-interference ability. The catalytic mechanism of BC-Co-W-700/PMS system was comprehensively investigated using a combination of electrochemical experiments and theoretical calculations. The in-situ pyrrolic N formed by biochar had a strong adsorption capacity for CTC, allowing pollutants to quickly adsorb to the catalyst surface. This greatly shortened the distance required for the catalytic reaction. The introduction of W led to abundant oxygen vacancies on BC-Co-W-700, causing the catalyst to produce a large amount of 1O2. Furthermore, the oxygen vacancies provided a high concentration of electrons for the conversion of Co3+/Co2+. In addition, CTC degradation pathways were analyzed using density functional theory calculations, and the toxicity of the intermediates was evaluated using the quantitative structure–activity relationship combined with experiments. The green catalyst synthesis method proposed in this paper could provide a new approach for the efficient degradation of antibiotics in wastewater.

Biodegradation mechanism of chlortetracycline by a novel fungal Aspergillus sp. LS-1

Chlortetracycline (CTC), a widely used typical tetracycline antibiotic, has raised increasing concerns due to its potential health and environmental risks. Biodegradation is considered an effective method to reduce CTC in environment. In this study, a strain Aspergillus sp. LS-1, which can efficiently degrade CTC, was isolated from CTC-rich activated sludge. Under optimal conditions, the maximum removal efficiency of CTC could reach 95.41%. Temperature was the most significant factor affecting the degradation efficiency of LS-1. The 19 products were identified in the CTC degradation by strain LS-1, and three degradation pathways were proposed. All the degradation pathways for CTC exhibited ring-cleaving, which may accelerate the mineralization of CTC. To gain more comprehensive insights into this strain, we obtained the genome of LS-1, which had high GC content (50.1%) and completeness (99.3%). The gene annotation revealed that LS-1 contains some vital enzymes and resistance genes that may carry functional genes involved in the CTC degradation. In addition, other antibiotic resistance genes were found in the genome of LS-1, indicating that LS-1 has the potential to degrade other antibiotics. This study provides a more theoretical basis for the investigation of CTC degradation by fungi and new insights into the biodegradation of CTC.

Peroxymonosulfate activation by Co@TiO2 for high-efficiency organic removals

Here we demonstrated that the Co doped anatase titanium dioxide (Co@TiO2) prepared by a facile wet chemical method could activate peroxymonosulfate (PMS) for efficiently degrading a wide range of refractory organic pollutants. The characterization results demonstrated that the doped Co replaced partial Ti while did not bring obvious structural change. The Co@TiO2/PMS system can efficiently remove about 100 % chlortetracycline (CTC) within 40 min and 100 % Rhodamine B (RhB) within 15 min. The Co@TiO2/PMS/CTC system maintained a good catalytic performance over a wide pH range from 3 to 11 and the removal efficiency of CTC improved with increasing pH. The Co@TiO2/PMS system had a good anti-interference ability, which was free from interference by inorganic ions (such as H2PO42-, NO3- and SO42-, etc.) and HA, and also in the different real water matrixes and refractory organic pollutants. Quenching experiments and electron spin resonance (EPR) measurements confirmed that the system had a typical radical process as hydroxyl radical (•OH), sulfate radical (SO4•−) and superoxide radical (O2•−) were the main reactive species for the degradation of CTC. Furthermore, the Co@TiO2 also showed excellent stability and low metal leaching during long-term use because of the excellent chemical and physical stability of TiO2.

Investigation of degradation and transformation product formation during the UV/H2O2-based oxidation process for chemicals of emerging concern

This study aimed to optimize the ultraviolet (UV)/hydrogen peroxide (H2O2) process for degrading chemicals of emerging concern (CECs), such as caffeine (CAF), atenolol (ATL), acetaminophen (ACT), and chlortetracycline (CTC). The CECs used in this study were chosen because they are used in various industries, affect water bodies, and are difficult to degrade using conventional oxidation and biological processes. The individual degradation results revealed that the CAF degradation rate increased from 23 ± 2%–80 ± 4% as the UV/H2O2 dose increased from 1 to 10 mg·L−1. Similarly, the ATL, ACT, and CTC degradation rates increased from 59.23 ± 2%, 34.21 ± 1.9%, and, 41.36 ± 2.3%–91.24 ± 3%, 68.12 ± 3%, and 91.93 ± 3.1%, respectively. The complex feed water analysis results revealed that CTC had a higher degradation rate than the other targeted contaminants owing to its higher degradation potential. The rate of reaction results revealed that the degradation of these CECs followed the pseudo-first-order reaction, with R2 > 0.95 in all cases. liquid chromatography with tandem mass spectrometry (LC–MS/MS) was used to identify the degradation products, and the results revealed the presence of low-molecular-weight organic products due to oxidation. The organic products were formed because of the hydroxylation and demethylation of intermediates and photoproducts, which caused a ring opening and generated several low-molecular-weight carboxylic acids before complete mineralization. These results illustrate that the UV/H2O2 process had some significant effects on the complex mixture. However, CTC exhibited a relatively high degradation rate, which is believed to have inhibited the degradation of other chemicals.

Laccase-Based Self-Amplifying Catalytic System Enables Efficient Antibiotic Degradation for Sustainable Environmental Remediation.

Antibiotic contamination poses potential risks to ecosystems and human health. Laccase (LAC) has emerged as a promising biocatalyst for the oxidation of environmentally toxic contaminants with high catalytic efficiency; however, its large-scale application is hindered by enzyme costs and dependency on redox mediators. Herein, a novel self-amplifying catalytic system (SACS) for antibiotic remediation that does not require external mediators is developed. In SACS, a natural mediator-regenerating koji with high-activity LAC, derived from lignocellulosic waste, initiates the chlortetracycline (CTC) degradation. Subsequently, an intermediate product, CTC327, identified as an active mediator for LAC via molecular docking, is formed and then starts a renewable reaction cycle, including CTC327-LAC interaction, stimulated CTC bioconversion, and self-amplifying CTC327 release, thus enabling highly efficient antibiotic bioremediation. In addition, SACS exhibits excellent performance in producing lignocellulose-degrading enzymes, highlighting its potential for lignocellulosic biomass deconstruction. To demonstrate its effectiveness and accessibility in the natural environment, SACS is used to catalyze in situ soil bioremediation and straw degradation. The resulting CTC degradation rate is 93.43%, with a straw mass loss of up to 58.35% in a coupled process. This mediator regeneration and waste-to-resource conversion in SACS provides a promising route for environmental remediation and sustainable agricultural practices.

Efficient Degradation of Chlortetracycline by Graphene Supported Cobalt Oxide Activated Peroxydisulfate: Performances and Mechanisms

Cobalt oxide has good catalytic activity for peroxydisulfate (PDS) activation but poor stability and is vulnerable to inactivation because of agglomeration. In this work, the chlortetracycline (CTC) degradation by peroxydisulfate (PDS) catalysis using the reduced graphene oxide support cobalt oxide (Co3O4/rGO) composite catalyst was investigated. It was found that 86.3% of CTC was degraded within 120 min in the Co3O4/rGO-800/PDS system. The influences of catalyst dosage, PDS concentration, solution pH, and reaction temperature were systematically explored. The excellent removal performance of CTC could be attributed to the synergistic effect between adsorption and catalytic degradation. ≡Co2+ and surface functional groups played as active sites to catalyze PDS, and the circulation of ≡Co2+/≡Co3+ was achieved. Moreover, Co3O4/rGO-800 showed satisfactory reusability after three cycles. This research can provide useful information for the development of efficient PDS catalysts and facilitate insights into CTC degradation mechanism.

In-situ constructed indirect Z-type heterojunction by plasma Bi and BiO2-X–Bi2O2CO3 co-modified with BiOCl@Bi–MOF for enhanced photocatalytic efficiency toward antibiotics

Currently, the chemical properties of metal–organic frameworks (MOFs) can be fully exploited by combining inorganic semiconductors with MOFs to improve their narrow light absorption range and high carrier separation efficiency. Therefore, in this paper, indirect Z-type multicomponent Bi/BiO2-X–Bi2O2CO3/BiOCl@Bi–MOF heterojunction with plasma Bi and BiO2-X–Bi2O2CO3 co-modified with BiOCl@Bi–MOF were successfully prepared through combining hydrothermal and photodeposition methods using BiOCl@Bi–MOF composites as active carriers. The ability to remove chlortetracycline (CTC) with Bi/BiO2-X–Bi2O2CO3/BiOCl@Bi–MOF was investigated by modulating the factors, such as photodeposition time, presence or absence of MOF structure, different water source, and different inorganic salts. In the CTC degradation experiments, the optimized Bi/BiO2-X–Bi2O2CO3/BiOCl@Bi–MOF-10-0.3 composite showed the best photocatalytic degradation efficiency (94.6%) within 90 min of full-spectrum light illumination. Its corresponding first-order kinetic rate constant (0.0315 min−1) was 2.5 and 1.6 times higher than those of MOF-free structural composites Bi/BiO2-X–Bi2O2CO3/BiOCl-10-0.3 and BiOCl@Bi–MOF, respectively. The increased photocatalytic activity is attributed to the synergistic effect between the MOF structure, metal Bi, BiO2-X–Bi2O2CO3, and BiOCl@Bi–MOF carrier. By combining the results of active species capture experiments, electron spin resonance techniques (EPR), and photoelectrochemical experiments, we have deduced a possible indirect Z-type heterojunction photocatalytic mechanism between Bi, BiO2-X–Bi2O2CO3 and BiOCl@Bi–MOF. The possible photocatalytic degradation pathways and products of CTC were deduced by combining liquid chromatography-mass spectrometry (LC-MS). This work supplies valuable guidance for preparing metal nanoparticles/semiconductor/MOFs with an indirect Z-type heterojunction photocatalyst for the repair of natural CTC wastewater.

Degradation of Oxytetracycline and Chlortetracycline by Fenton Process

In this study, degradation of oxytetracycline (OTC) and chlortetracycline (CTC) was investigated by Fenton process. In experimental studies conducted for this purpose, different values of pH, Fe2+ concentration, H2O2 concentration and reaction time were tested as important parameters for the Fenton process and optimum conditions for OTC and CTC removal were determined. For both antibiotics, the optimum values of the parameters in the Fenton process were the same, and these values were found to be 3 for pH, 20 mg/L for Fe2+ concentration, 25 mg/L for H2O2 concentration, 5 min for reaction time. Under these optimum conditions, OTC degradation was 100%, CTC degradation was 99.68%, chemical oxygen demand (COD) removal efficiency for oxytetracycline (O-COD) was 89.6%, COD removal efficiency for chlortetracycline (C-COD) was 88.5%. These results show that the Fenton process is an effective method that can be used for OTC and CTC degradation.

Efficient degradation of chlortetracycline in water by ultrasound activation of flexible ZnCoO doped PVDF membranes with high β phase

Piezo-catalysis technology is considered an emerging technology to remove organic pollutants from wastewater. In this study, a ZnCoO@PVDF membranes with high-voltage electrical properties was prepared for the piezo-catalytic degradation of chlortetracycline (CTC) in wastewater. The entry of Co into the main lattice of ZnO changes the electrical properties of ZnO. The d33 test shows that Co increases the piezoelectric coefficient of ZnO by 6.5 times. Under ultrasonic conditions, the Zn0.8Co0.2O@PVDF membranes exhibit the best piezo-catalytic activity, with a degradation rate constant of 0.2027 mM−1, which is 34.94 times higher than that of pure PVDF. At the same time, the doping of Zn0.8Co0.2O caused the change of the crystal form of PVDF, the β phase with piezoelectric properties increased significantly, and the piezoelectric coefficient increased from 27.3 pC/N of PVDF to 44.7 pC/N. Multiple by-products and degradation pathways were identified using LC-MS, and two main degradation pathways were proposed based on density functional theory (DFT) calculations. The toxicity of CTC and its by-products was estimated using Toxicity Estimation Software Tool (TEST) software, which further confirmed the reduction of environmental risk after piezoelectric catalytic degradation. This study provides new insights into the efficient piezo-catalytic treatment of antibiotic wastewater.

Facile synthesis of Fe-doped Zn-based coordination polymer composite with enhanced visible-light-driven activity for degradation of multiple antibiotics

We developed the novel Fe-doped Zn-based coordination polymer (CP) composites (Fe@Zn-CP-n, n = 1–3) with superior visible-light-driven photocatalytic activity. Herein, the Fe@Zn-CP composites were prepared using a newly designed Zn-CP {[Zn(3-padpe)(1,3-BDC)]·H2O}n using mixed ligands 4,4′-bis(3-pyridylformamide)diphenylether (3-padpe) and 1,3-benzenedicarboxylic acid (1,3-H2BDC) and FeSO4 by a facile approach at room temperature. The degradation of several tetracyclines (TCs), such as chlortetracycline (CTC), tetracycline hydrochloride (TC), and oxytetracycline (OTC) under visible-light irradiation were used to assess the photocatalytic performance. The generated ideal Fe@Zn-CP-2 composite showed high photocatalytic activity under visible light irradiation, for which the removal rate of antibiotics were 90.60% for CTC in 100 min, 90.00% for TC in 100 min, and 87.70% for OTC in 30 min, respectively. The superior photocatalytic performance was attributed to the Fe–O bond formation which expanded the optical absorption range and significantly increased the separation effectiveness of photogenerated charges. These properties enhanced the photoactivity of Fe@Zn-CP-2 for photocatalytic reaction under visible light irradiation. Additionally, the Fe@Zn-CP-2 showed excellent photostability and recycleability. The detailed intermediates and pathway of CTC degradation were also illustrated. According to the quenching studies and electron spin resonance (ESR) spectra characterization, the main species involved in the photocatalytic reaction were the radicals h+ and O2–. In addition, the possible photocatalytic reaction mechanisms were deeply discussed. This work offers fresh insight into the design of CP-based photocatalytic materials and demonstrates the broad application potential of Fe@Zn-CP composites in environmental remediation.

Nitrogen−doped−CQDs/schwertmannites as visible−light−responsive Fenton catalysts for the degradation of chlortetracycline and related cytotoxicity

The heterogeneous photo−Fenton method is a promising technology for wastewater treatment based on the development of efficient catalysts through which the inefficient Fe(III)/Fe(II) cycles and low utilization of H2O2 are optimized. In this work, viable heterogeneous photo−Fenton catalysts (NCS) are synthesized by in situ compounding nitrogen−doped carbon quantum dots (N−CQDs) with schwertmannite (SCH). Specifically, the NCS catalysts exhibit greatly enhanced capacity for chlortetracycline (CTC) degradation, in comparison with those of the pristine SCH and N−CQDs, with a remarkable efficiency of 95.12% at a wide pH range (3.0–7.0). In particular, this allows an efficient Fe(III)/Fe(II) conversion due to the fast electron transport capability provided by N−CQDs, coupled to an excellent structural stability of the catalysts. Main active species including •OH, •O2− and 1O2 are identified in the degradation process, and a possible degradation mechanism is tentatively proposed. In addition, related cytotoxicity of CTC degradation intermediates is verified via co−culturing with E. coli. This study provides a new strategy to overcome the disadvantages of photo−Fenton processes and develop new technologies for advanced water treatment.

Efficient, fast and robust degradation of chlortetracycline in wastewater catalyzed by recombinant Arthromyces ramosus peroxidase

Chlortetracycline (CTC), a widely used antibiotic, is recalcitrant and ubiquitous in the environment. Enzymatic degradation of CTC is an economical and efficient bioremediation method. In this work, recombinant Arthromyces ramosus peroxidase (rARP) at a concentration of 3.13 × 10−9 M was used to catalyze rapid degradation of CTC in water. The second-order rate constants of rARP showed up to 62-fold catalytic efficiency of horseradish peroxidase (HRP) toward CTC. The degradation half-life of CTC at the concentrations of 2 and 40 mg L−1 in wastewater under the rARP catalysis was, respectively, 5.3 and 5.7 min at 25 °C, and 2.7 and 3.1 min at 40 °C, which were up to 15-fold and 111-fold faster than HRP and laccase, respectively, but use of 3 % the amount of rARP as HRP. rARP catalyzed degradation of CTC at 2–40 mg L−1 in wastewater completed in 20–24 min, and its catalytic efficiency varied within only 2-fold at 25–40 °C. rARP showed only 2–3-fold discrepancy of catalytic efficiency among pH 5.0, 7.5 and 9.0. CTC under rARP catalysis underwent demethylation and oxidation to form nontoxic N-dedimethyl-9-hydroxy-CTC. The high catalytic efficiency of rARP agreed with a short distance between rARP's δN-His56 and CTC's dimethylamine N as indicated by docking simulation. rARP is a useful enzyme for CTC bioremediation.

Spindle-like MIL101(Fe) decorated with Bi2O3 nanoparticles for enhanced degradation of chlortetracycline under visible-light irradiation.

Improving the photocatalytic performance of metal–organic frameworks (MOFs) is an important way to expand its potential applications. In this work, zero-dimensional (0D) Bi2O3 nanoparticles were anchored to the surface of tridimensional (3D) MIL101(Fe) by a facile solvothermal method to obtain a novel 0D/3D heterojunction Bi2O3/MIL101(Fe) (BOM). The morphology and optical properties of the as-prepared Bi2O3/MIL101(Fe) composite were characterized. The photocatalytic activity of the synthesized samples was evaluated by degrading chlortetracycline (CTC) under visible-light irradiation. The obtained BOM-20 composite (20 wt % Bi2O3/MIL101(Fe)) exhibits the highest photocatalytic activity with CTC degradation efficiency of 88.2% within 120 min. The degradation rate constant of BOM-20 toward CTC is 0.01348 min−1, which is 5.9 and 4.3 times higher than that of pristine Bi2O3 and MIL101(Fe), respectively. The enhanced photocatalytic activity is attributed to the formation of a Z-scheme heterojunction between Bi2O3 and MIL101(Fe), which is conducive to the rapid separation of photogenerated carriers and the enhancement of photogenerated electron and hole redox capacity. The intermediate products were analyzed by liquid chromatography–mass spectrometry (LC–MS), and a possible photocatalytic degradation path of CTC was proposed. This work provides a new perspective for the preparation of efficient MOF-based photocatalysts.

Coupling the bioanode and S-scheme CuO/CdS quantum dots photocathode for chlortetracycline degradation: Performance, mechanism and microbial community

The quantum dots (QDs) modified S-scheme CuO/CdS photocathode was fabricated and integrated with a bioanode in the bio-photoelectrochemical system (BPES) for chlortetracycline (CTC) degradation under simulated solar irradiation using NaHCO3 as buffer. The S-scheme CuO/CdS QDs heterojunction was demonstrated by work function calculation and electron spin-resonance spectroscopy (ESR) test. The optimized CuO/CdS QDs photocathode exhibited great photocatalytic activity toward CTC degradation, due to its unique small-size effect, efficient light absorption, and efficient carriers separation and transfer. Results of ESR test demonstrated that hydroxyl (·OH), superoxide (·O2-) and carbonate radicals (·CO3-) could be produced by the photocathode, and they all contributed to CTC degradation. The degradation rate of CTC by BPES was 1.29 times that of the unilluminated system (86.8% vs 67.1%), and the maximum current density was 2.3 times (3.42 vs 1.48 A/m2). The dominant bacterial species in the CTC degradation of BPES were Pseudomonas and Acinetobacter. Possible mechanism and pathways of CTC degradation were proposed. This study advances the development of BPESs for antibiotics degradation.