Removal Efficiency Of Oxytetracycline Research Articles

Intermittent electrical stimulation removes mixed antibiotics and associated antibiotic resistance genes at low temperatures

Biotechnology has limited effectiveness in terms of removing mixed antibiotics at low temperatures, leading to ecological risks arising from the presence of antibiotics in environmental waters. In this study, the removal of tetracycline (TCs) and sulfonamide (SAs) from antibiotic wastewater was improved by the intermittent electrical stimulation of anaerobic-aerobic-coupled upflow bioelectrochemical reactors (AO-UBERs) at low temperatures. The removal effects of oxytetracycline and tetracycline were 48.6 ± 3.5 % and 71.5 ± 2.9 %, respectively. Under 0.9V, the removal rates of oxytetracycline, tetracycline, and trimethoprim were significantly increased in both the aerobic-cathodic and anaerobic anodic chambers, with a more obvious increase at low temperatures. Compared with the blank control group, the removal efficiency of oxytetracycline, trimethoprim and tetracycline in the electric group was increased by 11.8 ± 2.5 %, 27.8 ± 10.5 % and 11.2 ± 5.8 %. The anaerobic chamber contributed more to the removal of TCs and trimethoprim than the aerobic chamber. Furthermore, electrical stimulation selectively enriched electroactive bacteria (Methylophage and Pleuromonas), drug-resistant bacteria (Proteobacteria), and nitrifying bacteria associated with biodegradation. The abundance of antibiotic-resistance genes is related to the distribution of potential hosts and mobile genetic elements (sul1), and electrical stimulation induces the enrichment of both. This suggests that while potentially effective for treating TCs- and SAs-containing wastewater at low temperatures, AO-UBERs may lead to the accumulation of antibiotic-resistance genes.

Efficient removal of oxytetracycline antibiotic from aqueous media using UV/g-C3N4/Fe3O4 photocatalytic process

Residual pharmaceuticals in the environment are a class of emerging pollutants that endanger human health. Tetracycline's family, including oxytetracycline (OTC), are known as one of the most produced and consumed antibiotics worldwide. The g-C3N4/Fe3O4 nanocomposite with high level of catalytic efficiency features suitable performance in water/wastewater treatment. Therefore, in the present study, this nanocomposite was applied to remove the oxytetracycline from the aqueous environment. In this research study, g-C3N4/Fe3O4 nanocomposite (serving as catalyst) was initially synthesized by a simple hydrothermal method. The effect of key operating parameters such as initial solution pH, dose of catalyst, contact time and initial concentration of OTC in aqueous solutions was investigated under UV irradiation. In addition, COD and TOC tests, the kinetics and the effect of radical scavengers on the applied photocatalytic process were all evaluated. The maximum removal efficiency of OTC (99.8 %) was achieved under the following conditions: neutral solution pH 7; catalyst dose, 0.7 g/L; and an initial OTC concentration of 5 mg/L. The data showed that the kinetics of the reaction followed the first-order model with R2 of 0.9755. The respective COD and TOC efficiency values for the applied photocatalytic process were determined to be 87 and 59 %, respectively. In addition, the lowest removal efficiency of OTC was observed in the presence of tert-butanol radical scavengers, and OH radicals played a main role. The UV/g-C3N4/Fe3O4 photocatalytic process proved to be highly efficient for the removal of OTC antibiotic and could be potentially applied for the removal of other pollutants from aqueous solutions.

Oxygen-vacancies rich CuFe2O4 catalyst as efficient peroxymonosulfate activator for enhanced oxytetracycline degradation: Performance and mechanism

Peroxymonosulfate (PMS) based advanced oxidation methods have gained attention for eliminating antibiotics like oxytetracycline (OTC) from wastewater. This study presents an innovative approach by incorporating oxygen vacancies (OVs) into CuFe2O4 to create OVs-CuFe2O4 materials. Compared to traditional CuFe2O4, OVs-CuFe2O4 offered superior catalytic performance due to its surface-rich OVs promoting rapid conversion of oxygen and efficient metal redox of Fe(Ⅱ)/Fe(Ⅲ) and Cu(Ⅰ)/Cu(Ⅱ). OVs-CuFe2O4/PMS achieved impressive 95.7 % OTC removal in 45 min with a rate constant of 0.107 min−1, which was 3.87 times of CuFe2O4/PMS. The OVs-CuFe2O4/PMS system exhibited a broad pH tolerance range of 3 to 11 with OTC removal efficiency above 89.3 %. The OVs-CuFe2O4/PMS system produced various free radicals and non-radical for OTC degradation. The OVs-CuFe2O4 also has good stability with removal efficiency of 81.9 % at fourth cycle. This research gives a strategy to construct oxygen vacancies enrich catalysts for efficient activation of PMS and treatment of antibiotics wastewater.

Citric acid enhanced oxytetracycline degradation by Fe(Ⅲ)/peracetic acid: Performance, mechanism and influence factors

Citric acid (CA) can effectively complex with Fe(Ⅲ) to improve the solubility of Fe(Ⅲ) and accelerate the reduction of Fe(Ⅲ) to Fe(II), while its use in Fe(Ⅲ)-activated peracetic acid (PAA) system has not been reported so far. Therefore, CA was introduced into Fe(Ⅲ)/PAA system in this study to degrade oxytetracycline (OTC), and the degradation efficiency and mechanism of OTC in this system were systematically investigated. The results showed that the removal efficiency of OTC in Fe(Ⅲ)-CA/PAA system at pH 7.0 could reach 81.5% after 20 min, and the degradation of OTC followed pseudo-first-order kinetic. The addition of CA into Fe(Ⅲ)/PAA system could effectively reduce Fe(Ⅲ) to Fe(Ⅱ) driving the cycle of Fe(Ⅲ)/Fe(Ⅱ) and accordingly enhance the OTC removal in this system. According to the results of electron paramagnetic resonance (EPR) and scavenging experiments, hydroxyl radical (HO•) and organic radicals (CH3C(O)O• and CH3C(O)OO•) played major roles for the degradation of OTC in Fe(Ⅲ)-CA/PAA system. Four possible transformation paths of OTC in this system were proposed, including demethylation, hydroxylation, dehydrogenation and dehydration, based on five detected degradation products. This study provides an idea to improve PAA activation by Fe(Ⅲ) and broadens the practical application of Fe(Ⅲ) in advanced oxidation processes.

High-performance Cu/Mn modified ceramsite as a persulfate activator to degrade oxytetracycline in batch Erlenmeyer flask and continuous-flow fixed-bed column systems: An exploration of its practicability and non-radical mechanisms

Persulfate non-radical oxidation have excellent catalytic capability for degrading specific contaminants in complicated water environments. Nevertheless, the preparation of high-performance activators and their application in actual water treatment in continuous flow mode are still scarce and unsatisfactory. In this work, copper-, manganese-, and copper/manganese-doped ceramsites (Cu–C, Mn–C and Cu/Mn–C), successfully fabricated through a facile impregnation-calcination approach, were characterized and evaluated for their performance to activate potassium peroxydisulfate (PDS) and degrade oxytetracycline (OTC) under different pH, ceramsite dosages, and PDS dosages. Compared with Cu–C and Mn–C, Cu/Mn–C showed the highest OTC degradation rate (0.0264 min−1) via activating PDS with an OTC removal efficiency of 98.2% in 240 min at an initial OTC concentration of 40 mg/L. The removal efficiency of OTC by Cu/Mn–C only decreased to 92.8% after 5 cycles; the activating ability of the used Cu/Mn–C was almost completely recovered through 2 h of calcination at 500 °C. The results of electron paramagnetic resonance and radical quenching suggest that singlet oxygen (1O2) was unveiled to be the dominant reactive oxygen species (ROS) for contaminant degradation, originating from the regrouping of superoxide ions or reduction of active Cu/Mn sites. Synergies between Cu and Mn species to enhance ROS yield were the primary activating mechanisms. Six possible routes of OTC decomposition were inferred. Additionally, Cu/Mn–C behaved excellently in treating an actual wastewater using a continuous flow fixed-bed reactor. It is believed that this novel Cu/Mn–C/PDS system may create a fresh path to design effective and cheap metal-ceramsite hybrid activators for degrading recalcitrant contaminants in the actual application process.

Highly adsorptive removal of oxytetracycline in water environment using polyanion modified alumina nanoparticles

In this study, adsorptive removal of an antibiotic oxytetracycline (OTC) using polyanion poly(2-acrylamide-2-methylpropane sulfonic acid), PAMPs modified α-Al2O3 nanoparticles (PAMNA) was investigated. Surface modification of α-Al2O3 nanoparticles by PAMPs enhanced the removal efficiency of OTC significantly from 35.5 to 90.7 %. The optimum conditions for adsorptive removal of OTC using PAMNA were found to be pH 4, contact time 120 min and adsorbent dosage 20 mg/mL. Under selected conditions, the removal efficiency of OTC using PAMNA was greater than 90 % while the maximum adsorption capacity reached 140.2 mg/g. After three regenerations, the removal efficiencies of OTC were still higher than 75 %. The results of adsorption isotherms of OTC on PAMNA and the surface charge change of PAMNA indicate that both electrostatic and non-electrostatic interactions control OTC adsorption on PAMNA.

Preparation and characterization of activated carbons from Lemon Pulp for oxytetracycline removal.

This study aims to remove oxytetracycline (OTC) that harms the ecosystem, with activated carbon (LPAC) obtained from Lemon Pulp (LP). Characterization and properties of LPAC were analyzed by Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD) and point of zero charge (pHPZC) analyses. BET surface area, pore volume and pHPZC of LPAC produced by carbonization at 400°C and activation with KOH at 800°C were obtained as 1333.01 m2/g, 0.391 cm3/g, and 6.81, respectively. pH, reaction time, initial OTC concentration, and adsorbent amounts were optimized in the adsorption study performed with LPAC with high porosity and micropores. Kinetic evaluation was made with pseudo-first-order, pseudo-second-order, and intra-particle diffusion models and Freundlich, Langmuir, and Temkin equations are used to investigate their isotherms under reaction equilibrium conditions, and also the results were analyzed by statistical method (ANOVA). In pseudo-second-order kinetic and Freundlich isotherm models, where the best results were obtained, R2 values were calculated as 0.999 and 0.995, respectively. Maximum OTC removal efficiency was found as 104.22mg/g. Overall, this research indicates that LPAC for the treatment of water contaminated with antibiotics is environmentally friendly green material.

Cometabolic biotransformation mediates the detoxification of oxytetracycline in Flavobacterium-enriched microbiome

Oxytetracycline (OTC), a widely used antibiotic that is readily detectable in the environment, potentially has a number of negative ecological consequences. The present study revealed the key role of the cometabolic breakdown of OTC in activated sludge microbiomes, which led to a high removal efficiency and detoxification of both OTC and its derivatives. An AS bioreactor was established to treat environmentally relevant levels of OTC. The bioreactor achieved an overall OTC removal efficiency of 94–97% at the steady state, with cometabolic biotransformation as the primary contributor to this ahead of other removal routes such as direct metabolic biodegradation, biosorption, and phosphorolysis. A novel biotransformation pathway for OTC proposed in this study involved dehydration, hydroxylation, ring cleavage, and alcohol dehydrogenation, distinguishing it from previously reported pathways. Although transformation products with potentially higher toxicity than OTC formed during the biotransformation process, the AS microbiome eliminated the overall toxicity of both OTC and its derivatives, as illustrated by both molecular structure-based toxicity simulations and antimicrobial susceptibility testing. Analysis of microbiome sequence data revealed the bacterial populations potentially facilitating cometabolic (e.g., Tolumonas) and direct metabolic (e.g., Flavobacterium) biotransformation. Overall, our study provides new insights into the removal routes and kinetics for OTC in AS microbiomes and the key species that potentially promote OTC transformation and detoxification.

Three-dimensional graphene anchored nZVI hybrid MnO2 as a dissolved oxygen activated Fenton-like catalyst for efficient mineralization of oxytetracycline

This work is dedicated to achieving the high mineralization efficiency of oxytetracycline (OTC) in a dissolved oxygen (DO) activated Fenton-like system by constructing a catalyst with unique catalytic performance. Three-dimensional graphene anchored nZVI hybrid MnO2 (3D-rGO@nZVI/MnO2) with layered and porous structures was synthesized and characterized by field emission scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), Brunner-Emmet-Teller (BET) analysis, X-ray diffraction (XRD) measurement and Raman spectroscopy. The experimental results showed that the removal efficiency of OTC could reach 100.0% with outstanding TOC decrease of 84.0% at natural pH in the 3D-rGO@nZVI/MnO2-DO system. Moreover, negligible harmful intermediates were detected by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) after the reaction in the 3D-rGO@nZVI/MnO2-DO system. Reactive oxygen species (ROSs) detection, electrochemical measurements and X-ray photoelectron spectroscopy (XPS) analysis confirmed that the elimination mechanism of OTC was the unique catalytic degradation caused by the synergism of •OH and 1O2. The unprecedented synchronous generation of •OH and 1O2 by DO activation provides an innovative strategy for further exploration of Fenton-like system toward more effective degradation of organic pollutants.

Evaluating the removal and impacts of combined tetracycline, oxytetracycline, sulfadiazine, and norfloxacin during swine manure storage process at ambient temperatures

Manure storage is widely applied in intensive livestock regions with reporting elevated concentrations of combined veterinary antibiotics (CVAs), which raised serious environmental concerns. Four antibiotics (tetracycline (TC), oxytetracycline (OTC), sulfadiazine (SDZ), and norfloxacin (Norf)) were combined and their removal, fate and impacts on swine manure storage process under ambient temperatures for 90 days were examined. The results showed that temperature level, retention time, and CVAs’ initial concentration significantly affected the biodegradation rates of CVAs and governed its impacts on the storage process stability. The storage temperatures of ≥ 20 °C maximized the removal of CVAs, while it was minimized at 6 °C. The maximum removal efficiency of OTC was 94.8%, while 82.4%, 66.1%, and 61.4% were observed, respectively, for Norf, TC, and SDZ. However, no effective removal performance was achieved after day 60th for Norf and TC. Antibiotics degradation’s half-lives ranged from 26 to 150 d, affected by temperature level and CVAs’ initial concentration. Due to a prolonged storage time, CVAs showed slight negative effects on swine manure's physicochemical properties (pH, COD, VFAs, TAN, and TN). According to the microbial diversity, Clostridium sensu stricto, Leucobacter, Advenella, Corynebacterium, and Turicibacter were the most dominant bacterial community abundance, where their abundance was enhanced by improving CVAs degradation. The recommended swine manure storage temperature was ≥ 20 °C, with at least 60 days of incubation to facilitate the removal of CVAs and unstimulating their relative effects.

Rape Straw Supported FeS Nanoparticles with Encapsulated Structure as Peroxymonosulfate and Hydrogen Peroxide Activators for Enhanced Oxytetracycline Degradation

Iron-based catalysts with high load content of iron sulfide (FeS) were commonly peroxymonosulfate (PMS) and hydrogen peroxide (H2O2) activators to degrade organic pollutants but limited catalytic efficiency and increased risk of ferrous ion leaching restricted their use. Meanwhile, various biomass materials such as straw, peel, and branch have been extensively prepared into biochar for mechanical support for iron-based catalysts; however, the preparation process of biochar was energy-intensive. In this study, FeS nanoparticles modified rape straw composites (RS-FeS) encapsulated with ethylenediaminetetraacetic acid (RS-EDTA-FeS) were successfully presented by in-situ synthesis method for efficiently activating PMS and H2O2 to degrade oxytetracycline (OTC), which was economical and environmentally friendly. The results showed that the modified rape straw can remove OTC efficiently, and the addition of EDTA also significantly enhanced the stability and the reusability of the catalyst. In addition, EDTA also promoted the activation of H2O2 at neutral pH. The OTC degradation efficiency of the two catalysts by PMS was faster than that of H2O2, but H2O2 had a stronger ability to remove OTC than PMS. The highest OTC removal efficiency of RS-FeS and RS-EDTA-FeS were 87.51 and 81.15%. O2•- and 1O2 were the major reactive oxidative species (ROS) in the PMS system. Furthermore, compared with RS-FeS, the addition of EDTA inhabited the generation of O2•- in the PMS system. Instead, O2•- and •OH were the major ROS in the H2O2 system, but 1O2 was also identified in RS-FeS/H2O2 system. RS-EDTA-FeS showed a trend of rising first and then decreasing in recycle test. Instead, the removal rate of OTC by RS-FeS decreased significantly with the increase in reuse times. In the actual wastewater test, the TOC removal of two catalysts active by H2O2 was better than PMS, which was consistent with the test results of OTC, indicating that the two catalysts have application value in the removal of organic pollutants in actual wastewater. This study directly used plant materials as catalysts and omits the preparation process of biochar, greatly reduces the preparation cost and secondary pollution of catalysts, and provides theoretical support for the deepening of advanced oxidation technology.

Simultaneous degradation of antibiotic and removal of phosphate in water by a O3/CaO2 advanced oxidation process

The simultaneous presence of antibiotics and phosphate (P) in wastewater will threaten human health and ecological security. The purpose of this study is to study the simultaneous removal of oxytetracycline (OTC) and P in water by O3/CaO2 advanced oxidation process. With enhancing CaO2 dosage, the degradation efficiency of OTC first improved and then declined, whereas the removal efficiency of P kept increasing. Increasing the amount of O3 increased the removal efficiency of OTC, but had little effect on the removal efficiency of P. With 0.80 g/L CaO2 and 0.50 g/h O3, the removal efficiency of OTC and P reached 98.0 % and 90.5 % respectively. The lower OTC concentration was beneficial to OTC degradation and P precipitation. The P concentration has no effect on OTC degradation, but it would affect itself precipitation. Alkaline environment was conducive to OTC degradation and P removal. ·OH, ·O2−, 1O2 made major contribution to the degradation of OTC, which was verified by ESR technique and free radical capture experiment. During the degradation of OTC and P removal, TOC and COD values decreased, while pH and conductivity showed a downward trend. Based on UV–Vis spectrum, 3D EEMF spectrum and LC-MS analysis, two main degradation pathways of OTC were proposed. Toxicity analysis of intermediates showed that their toxicity was significantly lower than that of OTC. The O3/CaO2 system can be considered as an efficient and prospective method for the simultaneous removal of OTC and P in water.

Visible Light Activated Fe-N-SiO2/TiO2 Photocatalyst: Providing an Opportunity for Enhanced Photocatalytic Degradation of Antibiotic Oxytetracycline in Aqueous Solution

To probe advantages in Fe-N-SiO2/TiO2 nanocomposite system, the visible photocatalytic degradation of the nonbiodegradable antibiotic oxytetracycline (OTC) by unsupported TiO2 and its modified composites by incorporating each of the Fe, N, and SiO2 dopants under a series of conditions were investigated. The structural and optical properties as well as the morphology of the prepared nanocomposites were also characterized applying Fourier transform infrared (FT-IR), X-ray diffraction, photoluminescence spectroscopy, UV-visible diffuse reflectance spectra and field emission scanning electron microscopy/Energy-dispersive X-ray spectroscopy (FESEM/EDX). In order to develop two models portraying appropriate functional relationships between two main responses (OTC removal efficiency and its specific removal rate (SRR)) and four numerical variables (OTC concentration, catalysis loading, initial pH and reaction time), two separate multivariate analysis pathways under response surface methodology (RSM) were taken. The results obtained all came down to the maximum SRR (220 OTC mg OTC removed/g cat. h) found at the maximum catalyst dosage of 1.5 g/l, and acidic pH of 3 after 0.5 h. Furthermore, the Fe-N-SiO2/TiO2 proved a stable photocatalytic activity during three subsequent reusability experiments, shedding light on its reliable potential for future application.

Oxidative removal of oxytetracycline by UV-C/hydrogen peroxide and UV-C/peroxymonosulfate: Process optimization, kinetics, influence of co-existing ions, and quenching experiments

Oxytetracycline (OTC) is a tetracycline group antibiotic with high environmental pollution potential and is resistant to conventional treatment processes. This study provides an environmentally friendly and efficient OTC treatment by ultraviolet (UV)-based advanced oxidation processes. UV irradiation was used for the activation of hydrogen peroxide (HP) and peroxymonosulfate (PMS). In the first stage of the study, control experiments were conducted and the effect of initial pH on the UV/HP and UV/PMS in OTC removal was evaluated. In the following part, variables of the UV/HP and UV/PMS were optimized by the Box-Behnken design. The optimum conditions of the UV/HP process were as follows: 6.5 mg/L initial OTC concentration, 3.50 mM HP dose, and 45.4 min reaction time. The optimum parameters of the UV/PMS process were: 5 mg/L initial OTC concentration, 3.69 mM PMS dose, and 42.75 min reaction time. 72.8 % and 50.96 % OTC removal efficiency were achieved with the validation experiments by the UV/PMS and UV/HP processes, respectively. Kinetic studies showed that Cl− and HCO3− ions have a positive effect whereas SO42− has a negligible effect on the reaction rate of both processes. NO3− has a positive effect on the UV/HP process and a negligible effect on the UV/PMS process. According to the radical scavenging experiments, hydroxyl radicals were dominant in the UV/HP process while in the UV/PMS process both hydroxyl and sulfate radicals were involved. Both processes were effective in OTC removal; however, the UV/PMS process is more efficient and cost-effective.

Enhanced electrochemical oxidation of oxytetracycline on oxygen vacancy-rich MnO@N-doped C anode: Transformation pathway and toxicity assessment

Oxytetracycline (OTC) is a widely used antibiotic found in the environmental systems that may threaten human health. In this study, the degradation of OTC was investigated using an electrochemical oxidation system with oxygen vacancy-rich MnO@N-doped carbon (ov-MnO@NC) electrodes. It is found that nearly 95% of OTC could be degraded within 60 min using the ov-MnO@NC anode. The effects of electrolytes, OTC concentration, ov-MnO@NC dosage, current density and solution pH on OTC degradation were examined. Radical quenching tests and EPR spectra reveal that 1O2, •O2– and •OH all contributed to OTC elimination. A total of 11 transformation products were identified by LC-MS during electrochemical degradation. To assess toxicity, T.E.S.T calculations were performed for each of the transformation compounds. In the flow cytometry test, the reaction solution was tested for cytotoxicity when mixed with transformation products and other reactants at different reaction times. Furthermore, the removal efficiency of OTC at ov-MnO@NC anode maintained over 85% after recycling for four times, demonstrating the considerable durability. Overall, this study provides new insight into the development of metal oxide-based anodes with tuned oxygen vacancies, as well as comprehension of the transformation pathway and potential toxicity of the parent pollutants.

Enhanced removal of oxytetracycline from wastewater using bimetallic Fe/Ni nanoparticles combined with ZIF-8 nanocomposites.

The integration of metal-organic frameworks with other functional materials has recently emerged as a promising approach for creating innovative materials for environmental remediation. Here, a nano-sized iron/nickel (Fe/Ni) functionalized zeolitic imidazolate framework-8 (ZIF-8-Fe/Ni) was fabricated for oxytetracycline (OTC) removal from wastewater. Cyclic voltammetry and amperometric I-t measurements indicated that OTC was degraded by ZIF-8-Fe/Ni. X-ray diffraction spectroscopy (XRD), transmission electron microscopy mapping (TEM-mapping) and X-ray photoelectron spectroscopy (XPS) indicated that Fe/Ni was evenly dispersed throughout ZIF-8 and partially oxidized after reaction with OTC. OTC adsorption isotherms and kinetics best fitted the Langmuir isotherm (R2>0.982) and pseudo-second-order model (R2>0.997), respectively. Reduction kinetics data followed the pseudo-first-order model (R2>0.905), where the apparent activation energy (Ea) was 22.9kJmol-1, demonstrating that OTC degradation was mainly via a chemical process. The practical removal efficiency of OTC from real wastewater by ZIF-8-Fe/Ni was 92.6%, where even after application of ZIF-8-Fe/Ni for 5 consecutive removal cycles, a high OTC removal of 74.9% was maintained. Thus ZIF-8-Fe/Ni exhibited both high removal efficiency and good recyclability.

Photodegradation of oxytetracycline by UV-assisted persulfate and percarbonate processes: kinetics, influencing factors, anion effect, and radical species.

In this study, the performance of ultraviolet (UV)-assisted persulfate (PS) and percarbonate (PC) oxidation processes in oxytetracycline (OTC) removal was investigated. UVC lamps were used for the photolysis process and the effect of operating parameters (initial pH, oxidant dose, initial OTC concentration, UV intensity) on OTC removal efficiency was determined. Control experiments were carried out at pH 5.5 and 32W UV power for 60min by adding a 4mM oxidant with 10mg/L initial OTC concentration. The OTC removal efficiency obtained as a result of only photolysis was 17.3% and the removal efficiency obtained by PS and PC oxidation alone was 18.3% and 12.7%, respectively. The OTC removal efficiencies increased in the combined processes and reached 58.1% and 69.9% for the UV-PS and UV-PC processes, respectively. The reaction rates of the processes were ranked as UV-PC > UV-PS > PS > UV > PC. In the UV-PS and UV-PC processes, the highest removal efficiencies were achieved at alkaline pH values. The OTC removal efficiency was increased with the increase in oxidant dose; however, the efficiency decreased after a certain dose due to the scavenging effect. The removal efficiency also increased as the initial OTC concentration decreased. The UV intensity had a positive effect on OTC removal efficiency. The effect of the water matrix on OTC removal efficiency was investigated while the dominant radical types were determined in UV-assisted processes. The EE/O values for the UV-PS and UV-PC processes were calculated as 211 kWh/m3 and 153 kWh/m3, respectively for 60min of reaction time. Although similar removal efficiencies were obtained with both UV-assisted processes, the UV-PC process steps forward in terms of being a novel, environmentally friendly, more economic, and promising technology for OTC removal.

Photocatalytic Degradation of Oxytetracycline Using Zeolite Imidazole Framework-8 (ZIF-8) as an Effective Catalyst

Antibiotics are a class of organic pollutant in the medical field for hundreds of years. Due to the continuous discharge of antibiotics in the environment, the phenomenon of pseudo-persistence of antibiotics is produced. Therefore, it is necessary to develop an advanced sustainable technology to remove antibiotics from water resources. In this study, Zeolite Imidazole Framework-8 (ZIF-8) was prepared by a simple and rapid method. Oxytetracycline (OTC) degradation was performed using ZIF-8 as a photocatalyst under visible light (VL) (500[Formula: see text]W xenon lamp) irradiation. Under different experimental conditions, ZIF-8 has strong catalytic removal performance for OTC. When the reaction conditions are: OTC concentration of 80 mg L[Formula: see text], ZIF-8 concentration of 1.0[Formula: see text]g[Formula: see text]L[Formula: see text], pH 5.96, the OTC removal rate is more than 90%. Through the detection and analysis of degradation intermediates, the possible degradation pathway of OTC was proposed. This study showed that the OTC removal rate of ZIF-8 could still reach 69% after four times of recycling. The results showed that the ZIF-8/VL system had high OTC removal efficiency and good recyclability.

Schwertmannite catalyze persulfate to remove oxytetracycline from wastewater under solar light or UV-254

Oxytetracycline (OTC) pollution has become an important environmental issue. It is an obvious innovation in the field of OTC degradation to comprehensively explore the effect of Schwertmannite (Sch) catalyzed persulfate to degrade OTC under different light conditions, and apply the optimized parameters to remove OTC from actual aquaculture wastewater. Therefore, the effect of sodium persulfate (PS) on the removal of OTC catalyzed by Sch under solar light and UV-254 irradiation was investigated in this study, and the optimized parameters were applied to the OTC removal from actual aquaculture wastewater. The results showed that when 0.8 g/L Sch was added and the concentration of PS was 350 μmol/L, the removal rate of OTC (40 μmol/L) was 89.8% and 92.3% after 3 h and 6 h reactions in dark conditions, respectively. Furthermore, light significantly enhanced the removal efficiency of OTC. The removal rates of OTC in the Sch + PS + OTC system were 96.8% and 99.1% after 3 h and 6 h reactions under UV-254 irradiation, respectively. In addition, it was shown that light accelerated the removal of total organic carbon (TOC); the TOC removal rates after 3 h and 6 h under UV-254 in the Sch + PS + OTC system were 49.8% and 69.7%, respectively. In actual aquaculture wastewater, the removal rates of OTC after 6 h in the Sch + PS + OTC + UV-254 system were 21.7%, 22.7%, 46.1%, 55.1%, 74.1%, 94.5%, and 98.3%, respectively, when the COD concentrations in wastewater were 10,000 mg/L, 5000 mg/L, 2000 mg/L, 1000 mg/L, 500 mg/L, 200 mg/L, and 100 mg/L. The recovery rate of Sch after the reaction in actual aquaculture wastewater was 70.0–99.8%, and the pH after treatment remained neutral. These findings provide theoretical support for the treatment of OTC-containing wastewater via the advanced oxidation technology catalyzed by Sch.

Two novel and efficient plant composites for the degradation of oxytetracycline: nanoscale ferrous sulphide supported on rape straw waste.

As a biomass waste, rape straw shows a good application prospect in heterogeneous catalyst preparation due to its low-cost and stable structure. In this study, FeS-modified rape straw (RS-FeS) and its biochar (RSBC-FeS) were firstly synthesized to remove oxytetracycline (OTC). The highest OTC removal capacities observed for RS-FeS and RSBC-FeS were 635.66 and 827.80mgg-1. When compared with the adsorption process, the degradation ratios of the total OTC removal capacity observed in the RS-FeS/H2O2 and RSBC-FeS/H2O2 systems were 70.14 and 79.35%. Degradation was the dominant process observed during the removal of OTC. Both radical (SO4•-, •OH, and O2•-) and non-radical (1O2 and Ov) pathways were involved in the degradation process. OTC was degraded into smaller molecules via hydroxylation, dehydration, quinonization, demethylation, decarbonylation, alcohol oxidation, and ring cleavage reaction, indicating two catalysts could efficiently mineralize organic pollutants. The highest total organic carbon removal efficiencies of observed for RS-FeS and RSBC-FeS in swine wastewater were 88.93 and 96.81%, respectively. In addition, OTC removal efficiency of RS-FeS was more than 80% in successive experiments, further suggesting the feasibility of rape straw to Fenton-like catalysts. In this study, FeS nanoparticles were directly loaded on rape straw for the first time. Compared with biochar, FeS-modified rape straw can also degrade OTC efficiently, which provides an eco-friendly, high-efficient, and sustainable strategy for the preparation of catalyst.