Degradation Of Oxytetracycline Research Articles

The Degradation of Aqueous Oxytetracycline by an O3/CaO2 System in the Presence of HCO3-: Performance, Mechanism, Degradation Pathways, and Toxicity Evaluation.

This research constructed a novel O3/CaO2/HCO3- system to degrade antibiotic oxytetracycline (OTC) in water. The results indicated that CaO2 and HCO3- addition could promote OTC degradation in an O3 system. There is an optimal dosage of CaO2 (0.05 g/L) and HCO3- (2.25 mmol/L) that promotes OTC degradation. After 30 min of treatment, approximately 91.5% of the OTC molecules were eliminated in the O3/CaO2/HCO3- system. A higher O3 concentration, alkaline condition, and lower OTC concentration were conducive to OTC decomposition. Active substances including ·OH, 1O2, ·O2-, and ·HCO3- play certain roles in OTC degradation. The production of ·OH followed the order: O3/CaO2/HCO3- > O3/CaO2 > O3. Compared to the sole O3 system, TOC and COD were easier to remove in the O3/CaO2/HCO3- system. Based on DFT and LC-MS, active species dominant in the degradation pathways of OTC were proposed. Then, an evaluation of the toxic changes in intermediates during OTC degradation was carried out. The feasibility of O3/CaO2/HCO3- for the treatment of other substances, such as bisphenol A, tetracycline, and actual wastewater, was investigated. Finally, the energy efficiency of the O3/CaO2/HCO3- system was calculated and compared with other mainstream processes of OTC degradation. The O3/CaO2/HCO3- system may be considered as an efficient and economical approach for antibiotic destruction.

Construction of surface-rich MoS2 nanoflowers decorated on 2D layered MXene nanohybrid heterostructure for highly efficient and rapid degradation of oxytetracycline

In this study, we successfully developed a hybrid architecture referred to as MoS2@MX, involving the integration of MoS2 layered onto MXene using a straightforward co-precipitation method. This innovative hybrid photocatalyst exhibited remarkable efficiency in removing oxytetracycline (OTC) molecules from aqueous solutions under visible-light irradiation. During the photocatalytic process, both MoS2 and MX played distinct yet complementary roles. MoS2 facilitated efficient electron transfer, while MX contributed to the generation of radicals. This unique collaboration resulted in a noteworthy 99 % oxidation efficiency for OTC degradation within a brief 60 min of visible light exposure in an aqueous environment. The radicals 1O2 and •OH were identified as the principal drivers behind OTC degradation, underscoring the vital role of the hybrid material. Mechanistically, the degradation of OTC involved several key steps, including C–H bond cleavage, de-carboxylation, C–N bond oxidation, and de-chlorination. Importantly, the MoS2@MX hybrid composite demonstrated remarkable stability, maintaining a noteworthy photocatalytic efficiency of 89 % for targeted OTC removal after undergoing five consecutive cycles. In conclusion, this study emphasizes the potential of the MoS2@MX hybrid material as an effective agent for degrading organic OTC compounds within aquatic environments. The hybrid's multifaceted roles and exceptional performance suggest promising applications in sustainable water treatment.

Potential mechanism of biochar enhanced degradation of oxytetracycline by Pseudomonas aeruginosa OTC-T

Extensive use of oxytetracycline (OTC) and the generation of its corresponding resistance genes have resulted in serious environmental problems. Physical-biological combined remediation is an attractive method for OTC degradation because of its high remediation efficiency, stability, and environmental friendliness. In this study, an effective OTC-degrading strain identified as Pseudomonas aeruginosa OTC-T, was isolated from chicken manure. In the degradation experiment, the degradation rates of OTC in the degradation systems with and without the biochar addition were 92.71–100 % and 69.11–99.59 %, respectively. Biochar improved the tolerance of the strain to extreme environments, and the OTC degradation rate increased by 20.25 %, 18.61 %, and 13.13 % under extreme pH, temperature, and substrate concentration conditions, respectively. Additionally, the degradation kinetics showed that biochar increased the reaction rate constant in the degradation system and shortened the degradation period. In the biological toxicity assessment, biochar increased the proportion of live cells by 17.63 % and decreased the proportion of apoptotic cells by 58.87 %. Metabolomics revealed that biochar had a significant effect on the metabolism of the strains and promoted cell growth and reproduction, effectively reducing oxidative stress induced by OTC. This study elucidates how biochar affects OTC biodegradation and provides insights into the future application of biochar-assisted microbial technology in environmental remediation.

Oxygen-enriched vacancy spinel Mn-Co oxides by deep thermal reduction for enhanced antibiotics degradation efficiency

In this research work, flower-like MnCo2O4.5 was synthesized by introducing a short-chain surfactant as a surface-active agent. This structure was utilized as a precursor, and a gas atmosphere pyrolytic deep reduction strategy was employed to construct a sea urchin-like catalyst (DTR-Vo-MCO) with abundant oxygen vacancies. A series of characterizations were conducted to reveal the catalyst's microstructure and crystal phase composition. DTR-Vo-MCO achieved more than 90% degradation of OTC within 10 min, and the efficiency was 1.5 times that of Vp-MCO. The substantial presence of oxygen defects on the DTR-Vo-MCO surface expedited charge transfer processes, resulting in a remarkable enhancement of PMS activation efficiency. Electron paramagnetic resonance spectroscopy (EPR) and radical quenching experiments indicated that the contributions of radicals to oxytetracycline (OTC) degradation were in the order of 1O2 > SO4•– > O2•– > •OH. 1O2 and SO4•– played dominant roles in OTC degradation. The possible oxytetracycline degradation pathways were proposed based on LC-MS analysis. In summary, this work presents an efficient method for a highly oxygen-deficient catalyst, expanding the application of binary transition metal materials in environmental remediation.

A flower-like heterojunction for highly photocatalytic treating oxytetracycline based on chrome-based metal-organic frameworks decorated BiOCl nanosheet

The widespread use of antibiotics poses significant risks to both human health and the environment. Among various approaches, photocatalysis has emerged as a promising method for addressing the issue of antibiotic residues. BiOCl, a semiconductor photocatalyst, has attracted attention due to its distinctive structure. However, the limited light utilization efficiency of its ultraviolet light responsiveness remains a challenge. In this study, we developed a heterojunction by decorating BiOCl with metal-organic frameworks (MOFs) MIL-100(Cr), referred to MIL-100(Cr)/BiOCl (MB), to efficiently treat the antibiotic oxytetracycline (OTC) under visible light irradiation. Various analytical techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy, were used to verify the formation of the MB heterojunction. The interaction between MIL-100(Cr) and BiOCl in the MB heterojunction substantially enhances the responsiveness to visible light, increases the specific surface area, facilitates the separation and transfer of charged carriers, and ultimately results in a significant enhancement in visible light-driven photocatalytic performance for OTC degradation. This study explores the application of narrow/wide band gap nanomaterials-based nanocomposites in environmental remediation by constructing heterojunctions.

Enhanced activation of persulfate by magnetic NiFe2O4@CuO coupled with ultrasonic for degradation of oxytetracycline: Activation mechanism and degradation pathway

Coupled advanced oxidation processes (AOPs) based on ultrasound and transition metal-activated persulfate (PS) have attracted considerable attention for the degradation of antibiotics. NiFe2O4@CuO composites with core–shell structure were prepared by hydrothermal-freeze-drying-synchronous pyrolysis and coupled with ultrasound to degrade oxytetracycline (OTC) via activated PS. The coupled oxidation process (15-NFO@CuO/US/PS) can substantially enhance the degradation rate of OTC due to the synergistic effects from both ultrasonic and metal activation. X-ray photoelectron spectroscopy reflects that the synergistic interaction between the metals on the 15-NFO@CuO surface can effectively enhance the redox cycling process of metal ions and promote PS activation. Free radical quenching experiments and electron paramagnetic resonance spectroscopy (EPR) identified and confirmed the presence of sulfate radicals (SO4•−), hydroxyl radicals (•OH), and superoxide radicals (O2•−). In addition, the degradation pathways and intermediates of OTC were proposed based on liquid chromatography-mass spectrometry (LC-MS) and three-dimensional excitation-emission matrix (3D-EEM) analysis.

Oxytetracycline degradation and antidermatophytic activity of novel biosynthesized MoS2 photocatalysts

The presence of environmental contamination poses a significant threat to life on our planet. Oxytetracycline, an antibiotic with a broad spectrum of effectiveness, demonstrates resistance to biodegradation, potentially resulting in an ecological hazard. In this study, we synthesized both pure and biosynthesized Molybdenum Disulfide (MoS2) nanoparticles using extracts from the bark of Ficusreligiosa L (FR) and leaves of ZiziphusjujubeL (ZJ). These nanopartices were characterized by various analytical methods to assess their efficiency in photocatalytic degradation of oxytetracycline (OTC) and their antidermatophytic activity. X-ray diffraction patterns revealed that the prepared MoS2 catalysts typically exhibited hexagonal phase structure with crystalline size of approximately 13, 6, and 4 nm. Both pure and biosynthesized MoS2 nanoparticles displayed a nanoflake-like morphology with a spherical size distribution. BET surface area analyses exhibited an increase in surface area for biosynthesized MoS2 nanoparticles from 79 to 121 m2g−1. Optical absorption revealed a red shift in band gap energy, decreasing from 2.37 to 2.03 eV for biosynthesized MoS2 nanoparticles. The biosynthesized MoS2:FR nanoparticles exhibited remarkable OTC degradation with 99 % achieved within 100 min along with strong antifungal activity (Minimum Inhibitory Concentration - MIC of 12.5 µg/mL, Minimum Fungicidal Concentration - MFC of 25 µg/mL). These biosynthesized MoS2 catalysts are promising for water treatment purposes.

S doping in CoOHS modified hollow fiber membranes boosting electron transfer between activated PMS and pollutants in a continuous flow reactor

The surface-sulfurized CoAl-LDH (CoOHS) modified hollow fiber membranes (HFM@(PDA/PEI)@CoOHS) demonstrated excellent peroxymonosulfate (PMS) activation for oxytetracycline (OTC) degradation, with high removal efficiency and detoxification capacities, thanks to the coexistence of S-doping species, flower-like microstructures, and hollow fiber membrane support. Meanwhile, the hollow tube morphology of HFM@(PDA/PEI)@CoOHS is easily separated for recycling. With the combination of competitive radical quenching experiments, EPR, and electrochemical analysis, the 1O2 and enhanced electron transfer can be accounted for OTC oxidation. Therein, S doping species are able to promote the Co(III)/Co(II) redox cycle by forming more metastable catalyst/PMS* complexes to enhance electron transfer between OTC and PMS* complexes. A continuous flow reactor with hollow fiber membranes was used to evaluate the OTC removal in practice. Using computational fluid dynamics (CFD), the flow within the modified hollow fiber membrane was modeled. Additionally, HFM@(PDA/PEI)@CoOHS is recyclable after 5 cycles with a degradation efficiency of 86.17%. This research paves the way for an innovative strategy for designing continuous flow reactors functioning as PMS activators, opening up possibilities for practical applications in organic pollutant removal.

Construction of an interpenetrating manganese residue-derived FeC2O4/CuC2O4 composite with enhanced charge transfer in photo-Fenton reactions via mechanical activation pre-anchoring strategy

The low rates of charge separation and migration and the pronounced photo-corrosion of FeC2O4 significantly limit its environmental applications. Strengthening the charge transfer rate by constructing a tight bimetallic interface is an attractive method. Herein, a novel interpenetrating manganese residue (MR)-derived FeC2O4/CuC2O4 (MAMR-FeCuOx) composite with intimate interface was constructed via mechanical activation (MA) pre-anchoring and liquid-phase deposition-photo-reduction strategy, and was used as a photo-Fenton catalyst for efficient degradation of oxytetracycline (OTC) under visible light irradiation. The Cu2+ was uniformly dispersed and anchored on the surface of MR after MA pretreatment and an interpenetrating structure was formed through the liquid-phase deposition-photo-reduction process. MAMR-FeCuOx displayed excellent photo-Fenton catalytic performance and stability with a 99% OTC removal rate within 10 min, which is 20.87 times higher than that of FeC2O4, and maintained over 96% OTC removal rate even after ten consecutive cycles. These enhanced catalytic performances and stability can be attributed to the formation of an interpenetrating structure with the intimate interface between FeC2O4 and CuC2O4 induced by MA pretreatment, which promoted electronic interactions between Fe and Cu for effectively reducing the charge transfer barriers. This improved the utilization rate of visible light, the interface electron migration, and the separation efficiency of photogenerated charge carriers. This study provides new insights into the valorization of solid waste and the development of stable and efficient FeC2O4-based catalysts.

B-N bonds between SrBi2B2O7 and humic acid composites enhance polarized electric field for efficient piezocatalytic degradation of oxytetracycline in water

Constructing a chemical bond between the catalysts’ interfaces can establish a fast electron diffusion path and improve interfacial charge transport, thus produce a high efficiency in the catalytic field. We innovatively incorporate the humic acid (HA) and SrBi2B2O7 (SBBO) to degrade oxytetracycline (OTC) under ball milling (BM), the degradation efficiency of OTC for SBBO/HA under BM is 93.17 % and its pseudo-first-order kinetic constant is 0.0434 min−1, being 1.41 times than the sum of rate constant for HA (0.00826 min−1) and SBBO (0.0225 min−1), and 5.26 times than that for BaTiO3 (0.00825 min−1), illustrating their outstanding synthetic effect of SBBO and HA on piezoelectric degradation of OTC. The mechanism of enhanced piezoelectric activity was attributed to the B-N bond which enhances the local polarized electric field improving electron transfer and contributes to the generation of •O2– and •OH. The possible degradation pathways involving bonds cleavage, ring-opening, and dehydroxylation process were proposed based on LC-MS and Fukui index calculation. The toxicity of intermediates generated during the piezoelectric catalysis was predicted and investigated by T.E.S.T. software and mung bean growth. This study provides a new technology of enhancing piezoelectric catalytic activity by combining HA, SBBO and BM and clarifies the mechanism in detail.

Effect of Mn2+ substitution on catalytic properties of Fe3-xMnxO4 nanoparticles synthesized via co-precipitation method

Mn-substituted magnetite samples Fe3-xMnxO4 (x = 0.0; 0.02; 0.05; 0.1; 0.15; 0.2; 0.25) were synthesized using the co-precipitation method. X-ray diffraction patterns confirmed the formation of pure, well-crystallized manganese ferrite with a cubic spinel structure. The crystallites size increases sharply for the minimum degrees of substitution, with a subsequent tendency to decrease with the growth of manganese ions content. The catalytic properties of Fe3-xMnxO4 were investigated for the degradation of oxytetracycline (ОТС) and inactivate E. coli. There is a correlation between particle size and catalytic activity. The Fe2.95Mn0.05O4 sample exhibited the highest catalytic activity in the destruction of OTC. The effect of electromagnetic heating (EMH) on the catalytic properties of iron oxides were investigated. The Fe2.9Mn0.1O4 sample with electromagnetic heating achieved 100 % efficiency in decomposing 5 mg/L of OTC. Fe3-xMnxO4 samples reduce the number of Gram-negative bacteria E. coli at concentrations of 104 and 106 CFU/mL. Electromagnetic heating experiments demonstrated high performance, achieving inactivation of 6 logs of E. coli in the presence of Fe2.98Mn0.02O4 and Fe2.95Mn0.05O4 catalysts within 135 minutes. Studies on ecotoxicity have shown that Daphnia magna is a sensitive bioindicator of residual H2O2 concentration. An increase in the Mn2+ content in the synthesized catalysts resulted in a decrease in the toxicity of purified water. The study suggests that Mn-substituted magnetite catalysts are effective materials for catalytic decomposition of OTC and inactivation of E. coli bacteria.

Facile construction of 2D Ni2P/Bi12O17Cl2 composite to reinforce photocatalytic degradation performance of antibiotics in water

Utilizing highly efficient and stable photocatalysts to remove residual organic pollutants in wastewater has been deemed to be a promising and green technique for environmental management. Herein, novel 2D Ni2P/Bi12O17Cl2 composites have been prepared by a facile deposition-precipitation method, and the structure, morphology, optical, photo-electrochemical and photoluminescence properties were characterized particularly. Oxytetracycline (OTC), phenol and methyl orange (MO) were selected as target pollutants to evaluate the photocatalytic performance of the Ni2P/Bi12O17Cl2. Under visible light illumination (λ > 420 nm), the Ni2P/Bi12O17Cl2 photocatalyst possesses outstanding photocatalytic properties for the degradation of OTC, phenol and MO than those of Bi12O17Cl2. The enhanced photocatalytic activity of the Ni2P/Bi12O17Cl2 is attributed to Ni2P acting as photogenerated electrons trappers to reinforce photoinduced charges separation. Furthermore, the Ni2P/Bi12O17Cl2 photocatalyst owns outstanding stability. This study might shed light on the enhanced photocatalytic capacities of bismuth oxyhalide by means of embellishing transition metal phosphides in environment remediation fields.

Multi-channel charge transfer in self-supporting B-g-C3Nx/Bi2S3/CdS dual S-scheme heterojunction toward enhanced photothermal-photocatalytic performance

Improving the charge separation efficiency of catalysts is a significant challenge in photocatalysis. To solve this problem, we design a three-dimensional self-supported B-g-C3Nx/Bi2S3/CdS dual S-scheme heterojunction photocatalytic system mimicking natural photosynthesis to achieve multi-channel rapid charge transfer. The dual S-scheme heterojunction induces double interface electric fields on the surface of ultra-thin B-g-C3Nx nanosheets, which can drive charge carriers to migrate directionally along multiple channels and suppress carrier recombination through spatial separation of electrons and holes. Furthermore, the three-dimensional interconnected open framework of B-g-C3Nx/Bi2S3/CdS enhances light absorption, touching off intense photothermal effects and near-field temperature rise, thereby improving the chemical reaction kinetics. Benefiting from the efficient charge separation and near-field temperature rise, the B-g-C3Nx/Bi2S3/CdS exhibits a photocatalytic oxytetracycline degradation rate of 98.7% and H2 evolution rate of 4.78 mmol g−1 h−1. This work provides new insights into the construction of efficient S-scheme photocatalysts with multiple-channel charge transfer characteristics.

Molten salt-assisted synthesis of carbon polyhedra with self-grown carbon nanotubes on the surface for boosting peroxymonosulfate activation

Despite attempts made to use carbon nanotubes (CNTs) as metal-free catalysts for peroxymonosulfate (PMS) activation recently, the challenge remains in the preparation of carbon nanotubes by an in-situ method. In this paper, basing a novel molten salt-assisted method with heat treatment, cobalt (Co) and nitrogen (N) co-doped carbonaceous polyhedrons with self-catalyzed-grown CNTs on the surface (CNT@CoNC-x) were synthesized and employed to activate PMS to degradation oxytetracycline (OTC) in the aqueous phase. Such a unique structure, the three-dimensional carbon matrix with Co and N co-doped in the CNT@CoNC-x, not only confirmed the control of the active sites by the simple method, but also promoted the interaction between metal nanoparticles and CNTs. It is beneficial to accelerate the decomposition of PMS, which in turn improves the degradation efficiency of OTC. A two-stage kinetics of OTC degradation was studied and the apparent rate constant (k0∼5min) of the CNT@CoNC-5 catalyst is 66.97 L/g min−1, which increased 25.46 times greater than that of the CoNC catalyst obtained by calcining ZIF-67 directly. CNT@CoNC-5 catalysts exhibited good environmental resistance and recyclability.

Mediated electron transfer process in α-MnO2 catalyzed Fenton-like reaction for oxytetracycline degradation

In Fenton-like oxidation, the catalyst directly influences the reaction mechanism for the degradation of pollutants from water. Here, a α-MnO2 catalyst (OAm-1) was synthesized via a self-assembly method with the assistance of a surfactant. OAm-1 possessed a large specific surface area of 221 m2/g, abundant mesoporous structures and a large proportion of Mn(III). Further characterization exhibited that OAm-1 had abundant oxygen vacancies and excellent reducibility and conductivity. The adsorption and catalytic ability of OAm-1 were studied in the degradation of oxytetracycline (OTC) via the activation of hydrogen peroxide (H2O2). Through the radical quenching experiments, electron resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) analysis, Mn(III) of OAm-1 was proved to be the active sites for the chemisorption of OTC. Systematic electrochemical experiments and analysis have shown that a process of electron transfer mediated by OAm-1 occurred between the pollutant and H2O2 during a Fenton-like reaction. This work experimentally verifies the electron transfer process dominated nonradical mechanism over α-MnO2, which is helpful for understanding the catalytic mechanism of the Fenton-like oxidation.

Bimetallic Fe:Co metal–organic framework (MOF) with unsaturated metal sites for efficient Fenton-like catalytic degradation of oxytetracycline (OTC) antibiotics

Fe:Co MIL-88B nanorods with abundant unsaturated metal centers have been synthesized via a rapid microwave-assisted solvothermal process and used as a Fenton-like catalyst for oxytetracycline (OTC) degradation. The bimetallic Fe:Co MOFs outperformed their monometallic counterparts in catalytic degradation in both alkaline and acidic environments, with the highest catalytic activity in the alkaline pH region. The synthesis time, temperature, and bimetal ratios were essential in creating MOFs with high catalytic activity. Acid-base titration clearly revealed the resulting MOFs to possess high acidity, although no acid solution was used in the synthesis. The acidity arises probably from the charge imbalance in the mixed substitutions of Fe(III) and Co(II) in the MIL-88B topology under rapid synthesis, which leads to the metal centers having incomplete coordination and thus are very active. These highly active metal centers can catalyze hydrogen peroxide into reactive radicals to degrade OTC efficiently with 50 mg/L OTC being degraded completely within 90 min at pH 8, and 0.125 g/L catalyst loading. The obtained catalysts also displayed high stability and reusability. The metal ions leaching of the catalysts are less than 1.0 ppm in the fresh use and decrease to less than 0.1 ppm after 4 cycles, while still sustaining the catalytic activity over 90 % of its initial efficiency. This work demonstrates the use of mixed metals in synthesizing MOFs to achieve highly active, broad pH, Fenton-like catalysts that may be useful for advanced oxidation and environmental remediation.

Boron-doped biochar-nano loaded zero-valent iron to activate persulfate for the degradation of oxytetracycline

Oxytetracycline has posed a serious environmental nuisance, and seeking environmental decontamination materials is the priority task to deal with antibiotic water contamination. Herein, boron-doped biochar loaded nano zero-valent iron composites (nZVI/BBC) were fabricated as activators of PDS for oxidative degradation of oxytetracycline hydrochloride (OTC), and the main removal mechanism was explored in detail. The results showed that Boron-doped biochar with borate ester structure (BC2O) and degree of defects are the main active sites for improving PDS activation properties. BBC could effectively prevent nZVI agglomeration and reduce nZVI passivation. The effects of calcination temperature of BBC, loading ratio and dosage of nZVI/BBC, PDS concentration, initial solution pH, pollutant concentration, and interfering ions on OTC removal by nZVI/BBC were also systematically investigated, and the optimal reaction conditions were screened: 10 wt% loading of nZVI in the composite, 1 g/L dosage of nZVI/BBC, 1 mM dosage of PDS and solution pH= 5. The cycling test showed that the removal rate of OTC by nZVI/BBC decreased from 95.3% to 70.2% after five cycles, indicating that there is excellent stability of this material. Among them, the catalyst of 10%nZVI/BBC displayed the optimal PDS activation performance, owing to the synergistic adsorption-double oxidation system, BBC as well as nZVI. The free radical quenching experiment and free radical trapping experiment proved that the degradation of OTC mainly followed the free radical pathway and SO4•− and •OH were the primary active species in the catalytic system. This study provides a practical reference for the treatment of actual antibiotic wastewater.

Construction of Z-scheme NiO/BiOBr heterojunction for facilitating photocatalytic degradation of oxytetracycline and 2-mercaptobenzothiazole

Z-scheme NiO/BiOBr heterojunction was prepared by mechanical ball milling method and applied for the photodegradation removal of oxytetracycline (OTC) and 2-mercaptobenzothiazole (MBT). The Z-scheme electron transport pathway optimizes the separation of photogenerated carriers, thereby significantly increasing the generation capacity of reactive oxygen species (ROS). The photocatalytic degradation experiments demonstrate that the optimized OTC and MBT removal efficiency of NiO/BiOBr (NBOB) composites could reach 72.6% (120 min) and 97.7% (9 min), respectively. Photoluminescence (PL) spectra and PL decay curves indicate that NBOB-2 composites exhibit low photoinduced electron-hole recombination rate and accelerated electron separation efficiency. In addition, ESR spectra confirm that the Z-scheme NiO/BiOBr heterojunction can generate a larger quantity of ROS species. The possible photodegradation pathways and toxicity analysis for the OTC and MTB photodegradation intermediates are elucidated by HPLC-MS measurement and T.E.S.T. application. The manuscript provides a reference for the macro-preparation of bismuth-based photocatalysts with superior performance and high stability.

Micronano-bubble ozonation as an efficient pretreatment technology for raw oxytetracycline production wastewater discharged to biological treatment

Efficient high-strength antibiotic production wastewater treatment is a significant challenge that restricts sustainable pharmaceutical industry development. A novel ozone micronano-bubble (MNB) treatment system has been firstly developed to enhance oxytetracycline (OTC) degradation primarily by ozone and singlet oxygen. For practical applications employing pretreatment combined with biological treatment for raw OTC production wastewater, it is necessary to clarify the treatment performance (including the removal of parent OTC, toxicity, and organic fraction), and the potential impact on following bioprocesses. In this study, three pretreatment technologies (i.e., MNB ozonation, conventional ozonation, and thermal hydrolysis) were developed to treat real raw OTC production wastewater and were comprehensively compared. Conventional ozonation requires treatment time of over 14 h for complete removal of OTC and toxicity. Under the high-temperature operating condition (85°C), thermal hydrolysis achieves the shortest treatment time (3 h) for complete OTC removal from production wastewater without toxic substance generation. Nevertheless, the hydrolysis products and high-concentration dissolved organic matter (DOM) cannot undergo further transformation. Despite the formation of some toxic oxygen-rich transformation products, these products can be rapidly degraded to innoxious substances with lower molecular weights within 8 h via MNB ozonation. In addition, MNB ozonation can promote a 30.0% organic fraction transformation to produce more methane (584.0 mL) during the anaerobic inhibition tests than thermal hydrolysis (356.0 mL). Consequently, MNB ozonation technology is more conducive to combination with biological post-treatment. This study demonstrates the promising application potential of MNB ozonation as an efficient pretreatment technology for OTC production wastewater, and provides comprehensive insight into different pretreatment technologies to obtain an optimal treatment strategy for practical applications.

Effect of municipal sludge-based biochar produced at different pyrolysis temperatures on humification and oxytetracycline degradation of pig manure composting

This study explored the influence of pyrolysis temperatures on the properties of municipal sludge-based biochar (MSB) and evaluated the impact of MSB on humification and oxytetracycline (OTC, a broad-spectrum antibiotic) degradation in pig manure composting. Three types of MSB were produced from sewage sludge pyrolyzed at 300 °C, 500 °C, and 700 °C, respectively. Results indicated that pyrolysis temperature adjusted the formation sequence of the functional groups in MSB, and higher pyrolysis temperatures enriched the aromaticity of the biochar and augmented the concentrations of humic precursor compounds. The MSB addition to pig manure composting enhanced the peak temperature and prolonged the thermophilic phase. Moreover, the MSB addition significantly increased the HI (humic acid/fulvic acid) values (1.6–2.57) compared with the control (1.28), with a more pronounced effect observed at higher biochar pyrolysis temperatures. Furthermore, the MSB reduced the half-life of OTC degradation (1.47–2.44 d) during composting, accelerating its degradation compared with the control (2.66 d). The study demonstrated that the MSB provided a substantial amount of humic precursor materials into the composting process while also expediting the degradation of organic matter, thereby enhancing the humification process. Moreover, the extended duration of the thermophilic phase accelerated the degradation of OTC and shortened its half-life. Notably, the MSB at 700 °C had the best performance compared with other MSBs.