Initial Tetracycline Concentration Research Articles

Removal of tetracycline antibiotic from aqueous solution using bimetallic CuCo-ZIFs as an efficient catalyst in the presence of hydrogen peroxide

Antibiotics play an important role in disease treatment; however, they are also a threat to public health and the ecosystem. Therefore, a bimetallic CuCo-ZIFs catalyst was manufactured through the ultrasonic-assisted solvothermal method to activate H2O2 towards the removal of tetracycline (TC) in an aqueous environment, a polluting broad-spectrum antibiotic model. PXRD, SEM, TEM, EDX, TGA, FT-IR, and BET analyses indicated that CuCo-ZIFs cubic crystals were successfully synthesized with high crystallinity, large specific surface area, and ideal thermal stability. Factors affecting the TC removal were investigated, including CuCo-ZIFs dosage, H2O2 concentration, treatment time, initial TC concentration, and reaction temperature. The results showed that the CuCo-ZIFs/H2O2 catalytic system was capable of effectively handling TC, with about 93.9% of TC removed in the presence of 0.3 g.L-1 CuCo-ZIFs, 0.01 mol.L-1 H2O2 at room temperature within 30 min. Conclusively, this study contributes to expanding the application potential of bimetallic CuCo-ZIFs materials to eliminate antibiotic residues in an aqueous environment and inspire research on environmental improvement.

Heterogeneous Fenton system driven by magnetic graphene-like biochar for degrading tetracycline

In this study, a novel catalyst with high efficiency and low cost was synthesized from farmland waste peanut shells by one-step pyrolysis modification method via K2FeO4, and employed for the catalytic degradation of tetracycline (TC). The magnetic potassium ferrate modified graphene-like biochar catalyst (PFGB) exhibited a high porosity, a highly graphitized structure, and a large specific surface area (857.09 m2·g-1) which was almost 30 times higher compared with peanut shell biochar, and were found to contain more functional groups. The formation and distribution of Fe3O4 and Fe0 nanoparticles on the surface/pores of PFGB provided more active sites for promoting adsorption and catalytic degradation reactions, and accelerated Fe(II)/Fe(III) recycle. Under the optimal conditions (pH=3.5, catalyst dosage = 0.5g·L-1, H2O2 concentration = 10mmol·L-1), about 98% of TC were degraded within 90min when the initial concentration of TC was 150mg·L-1, and PFGB could perform effectively over a wide pH range of 3-6. Furthermore, PFGB exhibited the advantages of convenient magnetic separation and strong reusability, maintaining a TC removal rate of ~90% after five cycles of experiments. The results of free radical quenching experiment and electron spin resonance analysis revealed that •OH and 1O2 were the main active species in the radical and non-radical pathways, respectively. This study indicated that PFGB, a catalyst developed for heterogeneous Fenton-like systems, possessed high efficiency, stability and reusability, and could be promising for the removal of TC in wastewater and other polluted waters.

Effective sonophotocatalytic degradation of tetracycline in water: Optimization, kinetic modeling, and degradation pathways

Hybrid advanced oxidation processes (AOPs) are gaining interest in degradation of variety of recalcitrant compounds for water and wastewater treatment, due to possible synergistic effects. The present study systematically evaluated the degradation of tetracycline (TC) with a sonophotocatalytic process combining acoustic cavitation (sonocavitation) and photocatalysis based on N-doped TiO2 catalyst. The TC degradation rate constant was 2.4 × 10−2 min−1, i.e., much higher than individual sonocatalytic (0.5 × 10−2 min−1) and photocatalysis (0.6 × 10−2 min−1) processes at the optimized conditions. The synergy index was 2.14, which reveals a significant improvement in the process performance. Maximum TC degradations of 55.5 ± 1.8 % for photocatalysis, 66.4 ± 1.8 % for sonocatalysis, and 79.5 ± 0.3 % for sonophotocatalysis were observed for 10 mg L−1 initial TC concentration after 90 min of treatment. The photocatalytic experiments were extended further to 210 min to achieve a maximum degradation of 78.9 ± 0.2 % at the optimized condition. Scavenging experiments confirmed that hydroxyl radicals (•OH), electron holes (h+), and superoxide radical anions (O2−•) played a significant role in the degradation of TC. Further, the degradation intermediates for each process were identified and degradation pathways were proposed. Empirical kinetic models based on operational parameters were also developed and validated.

A novel all-solid-state Z-scheme BiVO4/Ag/Cu2O heterojunction: Photocatalytic and photothermal synergistic catalysis of tetracycline under simulated sunlight irradiation

The possible hazards posed by tetracycline (TC) to the environment and public health have made it a critical concern. In this work, the all-solid-state Z-scheme heterojunction BiVO4/Ag/Cu2O nanocomposites (NCs) were synthesized through a hydrothermal approach for the purpose of achieving efficient degradation towards TC. BiVO4/Ag/Cu2O NCs were able to efficiently degrade TC when exposed to simulated sunlight. The results showed that the photocatalytic efficiency was significantly influenced by Cu2O and Ag nanocrystals. The presence of Ag with large light absorption capability facilitated the efficient electron (e-) transfer between BiVO4 and Cu2O nanocrystals, thereby expanding the spectral range of light absorption in BiVO4/Cu2O NCs. Under photocatalytic and photothermal synergistic conditions, BiVO4/Ag/Cu2O NCs with an optimal addition of Ag were able to degrade TC within 60 min at reaction rate constant (k) of 0.04816 min−1. It was discovered that the best-performing photocatalysts (BAC-2) achieved photothermal conversion rates as high as 27.9 %, and they could exhibit outstanding photocatalytic and photothermal efficiency even after six cycles. Furthermore, the results obtained in radical trapping experiments suggested that photogenerated holes (h+), electrons (e-), superoxide radicals (·O2-), hydroxyl radicals (·OH) and singlet oxygen (1 O2) were involved in the photocatalytic degradation of TC. In the context of practical application, the effects of different initial TC concentrations and different irradiation conditions were studied in depth. In addition, the all-solid-state Z-scheme heterojunction mechanism for degrading TC was put forward. This research endeavors to broaden the application scope of all-solid-state Z-scheme heterojunction photocatalysts, with the aim of achieving significantly improved photocatalytic degradation of antibiotic pollutants.

Efficient Removal of Tetracycline from Water by One-Step Pyrolytic Porous Biochar Derived from Antibiotic Fermentation Residue.

The disposal and treatment of antibiotic residues is a recognized challenge due to the huge production, high moisture content, high processing costs, and residual antibiotics, which caused environmental pollution. Antibiotic residues contained valuable components and could be recycled. Using a one-step controllable pyrolysis technique in a tubular furnace, biochar (OSOBs) was produced without the preliminary carbonization step, which was innovative and time- and cost-saving compared to traditional methods. The main aim of this study was to explore the adsorption and removal efficiency of tetracycline (TC) in water using porous biochar prepared from oxytetracycline fermentation residues in one step. A series of characterizations were conducted on the prepared biochar materials, and the effects of biochar dosage, initial tetracycline concentration, reaction time, and reaction temperature on the adsorption capacity were studied. The experimental results showed that at 298 K, the maximum adsorption capacity of OSOB-3-700 calculated by the Langmuir model reached 1096.871 mg/g. The adsorption kinetics fitting results indicated that the adsorption of tetracycline on biochar was more consistent with the pseudo-second-order kinetic model, which was a chemical adsorption. The adsorption isotherm fitting results showed that the Langmuir model better described the adsorption process of tetracycline on biochar, indicating that tetracycline was adsorbed in a monolayer on specific homogeneous active sites through chemical adsorption, consistent with the kinetic conclusions. The adsorption process occurred on the surface of the biochar containing rich active sites, and the chemical actions such as electron exchange promoted the adsorption process.

Utilization of dragon fruit (Hylocereus undatus) peel-derived biochar for the adsorptive removal of tetracycline from aqueous solution

The peel of Hylocereus undatus was employed in the preparation of biochar and firstly applied for tetracycline removal from aqueous solution. Based on different characterization techniques, the material was found to possess a variety of surface functional groups on a porous structure and a pH point of zero charge (pHpzc) of 9.3. Adsorption of tetracycline (TC) was conducted under varying conditions, revealing significant effects of carbonization temperature, solution pH, adsorbent dose, ionic strength, contact time and initial concentration of TC on the biochar adsorption capacity. Kinetic data on TC adsorption were best described using the Elovich kinetic model, with an initial adsorption rate of 167.3 mg g−1 min−1. Isotherm data on adsorption of the desired biochar showed the best fit with the Temkin isotherm model, followed by the Langmuir model, displaying maximum adsorption capacity at 12.4 mg g−1. The electrostatic interactions between the charged biochar surfaces and certain fractions of TC were proposed as the major mechanism, together with H-bonding, pore-filling effect and π–π interaction. This study demonstrates great potential of H. undatus peel as a starting material to prepare an effective and reusable adsorbent in the removal of TC.

Evaluation and optimization of six adsorbents for removal of tetracycline from swine wastewater: Experiments and response surface analysis

The removal of tetracycline antibiotics using adsorbents is becoming an environmentally friendly and cost-effective method. This study systematically analyzed the stability, structure, morphology, and chemical properties of various adsorbents. Batch adsorption experiments (pH, time, temperature, tetracycline concentration, and adsorbent dosage) were conducted to compare the adsorption capacity of the six adsorbents (biochar, activated carbon, montmorillonite, zeolite, chitosan, and polymerized aluminum chloride) for tetracycline removal. The results indicated that montmorillonite had the highest adsorption efficiency, followed by biochar, with chitosan showing the lowest efficiency. At an adsorbent dose of 25 g/L and an initial tetracycline concentration of 120 mg/L, the removal rates of tetracycline by montmorillonite, biochar, and chitosan were 97.6%, 69.3%, and 12.2%, respectively. Furthermore, the removal rate of tetracycline by biochar, following the response surface methodology optimal mode, increased by 5.5%. The Elovich model was better suited to explain the adsorption process of tetracycline compared to the conventional pseudo-first kinetic model and second-order kinetic model. The isothermal adsorption model suggested that both chemisorption and physisorption occurred in all removal processes, in which chemisorption dominated. Tetracycline was efficiently adsorbed through the combined effects of pore filling, electrostatic attraction, π-π interactions, and complexation reactions of surface functional groups. Additionally, montmorillonite demonstrated superior performance as an adsorbent for tetracycline removal from swine wastewater compared to the other adsorbents studied.

Comparative evaluation of α-Bi2O3/CoFe2O4 and ZnO/CoFe2O4 heterojunction nanocomposites for microwave induced catalytic degradation of tetracycline

Two microwave (MW) responsive heterojunction nanocomposite catalysts, i.e., α-Bi2O3/CoFe2O4 (BO/CFO) and ZnO/CoFe2O4 (ZO/CFO), with weight% ratio of 70/30, 50/50, 30/70 were synthesized by sequential thermal decomposition and co-precipitation methods, and used for the degradation of tetracycline (TC) under MW irradiation. The formation of desired catalysts was confirmed through the characterization results of XRD, FT-IR, SEM, VSM, UV-DRS, XPS, BET, etc. Using batch MW experiments, the catalyst dose, pH, initial TC concentration, reaction temperature, and MW power were optimized for TC removal. Under the following reaction conditions: catalyst dose ∼1 g/L, initial TC concentration ∼1 mg/L, temperature ∼90 °C, MW ∼450 W, BO/CFO, and ZO/CFO showed ∼97.55% and 88.23% TC degradation, respectively, after 5 min. The difference in the catalytic response against TC degradation indicated the difference in reflective loss (RL) between these two catalysts. The presence of other competitive anions has affected the removal efficiency of TC due to the scavenging effect. The radical trapping study revealed the significant contribution of TC degradation by hydroxyl radicals in the case of ZO/CFO, whereas for BO/CFO, superoxide (●O2−) and hydroxyl radicals (●OH) both played influential roles. The Z-scheme heterojunction of BO/CFO allowed the formation of ●O2− but the same was inhibited in type-II heterojunction of ZO/CFO due to the valance band position. The dielectric loss, magnetic loss, interfacial polarization, and high electrical conductivity, ‘hotspots’ were produced over the catalyst surface alongside electron-hole separation at heterojunctions, which were responsible for the generation of reactive oxygen species. In addition, Co3+/Co2+ and Fe3+/Fe2+ redox cycles have promoted ●O2− and sulfate radical production during persulfate application. Among the two MW responsive catalysts, BO/CFO could be a potential material for rapidly destroying emerging organic pollutants from wastewater without applying other oxidative chemicals under MW irradiation.

N, S co-doped porous carbon derived from waste medical masks to support LaFexCo1-xO3 as highly effective peroxymonosulfate catalysts for degradation of tetracycline

N and S co-doped porous carbon was prepared by decorating the waste disposable medical masks (WDMM) with thioacetamide (TAA) as the N/S source and then carbonizing at high temperature, which was subsequently incorporated Co-doped LaFeO3 to obtain NSC@LaFexCo1-xO3 catalysts. The resulting catalysts were used to construct an advanced oxidation process (AOP) based on activation of peroxymonosulfate (PMS) to degrade tetracycline (TC) in water. The physicochemical properties of the as-obtained catalysts were characterized and environmental factors affecting the catalytic performances of NSC@LaFexCo1-xO3/PMS were systematically investigated. The results showed that N and S co-doped porous carbon derived from thioacetamide (TAA)-functionalized WDMM at high temperature could be used as good support for LaFexCo1-xO3. The synergistic effects between N/S co-doped carbon and polyvalent metals (Co2+/Co3+ and Fe3+/Fe2+) endowed NSC@LaFexCo1-xO3 with enhanced catalytic performances, in which nearly 100% of TC could be removed by NSC@LaFe0.95Co0.05O3/PMS system within 10 min under the conditions of 0.2 g/L of catalyst dose, 2.5 mmol/L of PMS concentration and 10 mg/L of initial TC concentration. Furthermore, the constructed NSC@LaFe0.95Co0.05O3/PMS system exhibited a wider pH adaptability (3.0 ∼ 10.0), good salt resistance and reusability as well as high mineralization. The mechanisms and possible pathways of TC degradation by NSC@LaFe0.95Co0.05O3/PMS system were proposed and the ecotoxicity of TC and its intermediates was also evaluated. This study demonstrated the feasible transformation of waste masks into porous carbon with high added value for water pollution control and remediation, accomplishing the dual purposes of recycling and resource utilization of waste masks and protecting the environment.

Optimization of cerium-based metal–organic framework synthesis for maximal sonophotocatalytic tetracycline degradation

Wastewater treatment is inevitably required to alleviate the pollution of water resources by various contaminants such as antibiotics. MOFs are novel materials with photocatalytic activities. In this study, sonophotocatalytic degradation of tetracycline (TC) by the Cerium-based MOF (Ce-MOF) is optimized by modification of its synthesis route. Ce-MOF synthesis by room temperature (RT), hydrothermal (HT), and sonochemical synthesis (SC) are studied. TC degradation experiments revealed the superiority of SC synthesis. The interplay of main synthesis parameters, namely, initial ligand concentration, ultrasound (US) power and time on sonophotocatalytic activity of Ce-MOF, were investigated by response surface methodology model (RSM) utilizing the central composite experimental design (CCD). The optimum SC synthesis conditions are an initial ligand concentration of 8.4 mmol/L, a sonication power of 50 amplitude, and a US time of 60 min. The optimally synthesized Ce-MOF was characterized by infrared spectroscopy, FTIR, XRD, FE-SEM, TEM, zeta potential analysis, diffuse reflectance spectroscopy, particle size analysis, Mott-Schottky analysis, photocurrent analysis, electrochemical impedance spectra, and photoluminescence spectroscopy. The findings indicate that the removal efficiency of TC can reach up to 81.75% within 120 min in an aqueous solution containing an initial TC concentration of 120 ppm and 1 g/L Ce-MOF at pH of 7. Mineralization efficiency of the process is 71% according to COD measurements. The Ce-MOF catalyst retained its chemical stability and remained active upon TC degradation which makes it a promising candidate for wastewater treatment.

Boosting photocatalytic performance of cubic Co2SnO4-MnO2@g-C3N5 ternary composites: Analysis of morphology, degradation ability of tetracycline hydrochloride and fragments pathway mechanism

The increasing prevalence of tetracycline contaminants poses a profound threat to biodiversity in both aquatic and terrestrial ecosystems worldwide. To address this issue, the current study presents an innovative degradation approach using a ternary composite photocatalyst of Co2SnO4/MnO2 encapsulated with g-C3N5 synthesized via a hydrothermal method. This research describes the first report on the use of Co2SnO4/MnO2@g-C3N5 heterostructures for the photodegradation of tetracycline hydrochloride. A comprehensive characterization of the nanocomposites was performed using XRD, FTIR, SEM (including EDX and mapping), TEM, BET, XPS, and DRS-UV analyses, which confirmed their crystalline structure and revealed a morphology of Co2SnO4 nanocubes and MnO2 nanorods on the g-C3N5 layers. Photocatalytic experiments under visible light illumination showed that with an optimum catalyst loading of 40 mg/L and an initial tetracycline concentration of 5 μM, the composite achieved a degradation efficiency of 93.22 % within 75 min, following pseudo-first order kinetics. The degradation process was predominantly driven by hydroxyl radicals, as confirmed by scavenger studies. The reusability tests was confirmed the stability of the catalyst, which maintained high efficiency over four cycles. A degradation pathway was proposed based on LC-MS analysis of the reaction intermediates. This study confirms that Co2SnO4/MnO2@g-C3N5 composites (ratio 50:30:20) outperform comparative photocatalysts under similar conditions, providing a viable and environmentally benign solution for tetracycline remediation in wastewater.

A novel xanthan-chitosan based peroxydisulfate controlled-release material for in-situ sustained degradation of tetracycline: Performance, mechanism and application

In situ chemical oxidation (ISCO) is a promising technology to remove the organic pollutants from groundwater on site. In order to ensure the sustainable and long-term treatment performance, the oxidant controlled-release materials (CRMs) are required. In this study, a novel environmentally friendly and low-cost peroxydisulfate CRM (XG/CS-PDS) was synthesized via the mixing and mold method with xanthan, polyvinyl alcohol and chitosan as the binders for the first time. The XG/CS-PDS possessed significantly stable controlled-release properties under different pH and co-anions. 80% PDS in the CRMs could continuously and slowly release within 50 days. The simulation of PDS controlled-release process indicated that the process was controlled by the non-Fickian diffusion. Then the as-prepared CRM was applied to remove tetracycline (TC) from synthesized groundwater with nanoscale zero-valent iron (nZVI) as the PDS activator. The XG/CS-PDS/nZVI system could achieve 100% removal efficiency at different initial TC concentrations (5‐40 mg/L) and had a good anti-interference ability to pH, inorganic co-anions and humic acid. The quenching experiments and electron spin resonance (ESR) revealed that SO4•-, •OH and 1O2 were the main reactive oxygen species (ROS) for the degradation of TC, while SO4•- played the more dominant role. The intermediates and possible degradation pathway of TC were proposed and the toxicity of TC and its intermediates were evaluated. This study provided a new conception for the design of controlled-release material and theoretical strategies for in-situ remediation of groundwater.

Unveiling the photocatalytic application of niobia based n-n heterojunction for degradation of tetracycline: A sustainable approach for water treatment

This study investigates the efficacy of a novel Nb2O5–MoO3 n-n heterojunction as a photocatalyst for the degradation of tetracycline in aqueous solution. The synthesized heterojunction shows remarkable photocatalytic activity attributed to the synergistic effect of niobium pentoxide (Nb2O5) and molybdenum trioxide (MoO3). Various characterization techniques, including X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy etc., were employed to elucidate the structural and morphological features of the heterojunction. The band gap energy and surface area were observed to be 2.55 eV and 32.897 m2/g respectively. The photocatalytic degradation of tetracycline was systematically studied under various experimental conditions, including catalytic dosage, initial tetracycline concentration and wavelength of irradiation light. These results reveal the greater efficiency of Nb2O5–MoO3 heterojunction compared to that of pristine Nb2O5 with a complete degradation achieved in 60 min under visible region with a degradation rate of 4.9 × 102 min−1. Furthermore, the catalyst demonstrates excellent stability over multiple cycles of use.

Adsorptive removal of tetracycline antibiotic by biochars originated in pine leaves (<i>P.kesiya</i>) and rice husk

In this day and age, the excessive use of antibiotics for medical purposes has resulted in antibiotic pollution, which has negative impacts on human health and the environment. Biochars originated in pine leaves (P.kesiya) and rice husk were pyrolyzed to remove tetracycline from aquatic environments. Utilizing physical analysis methods (BET, FT-IR, SEM, and EDX) to determine materialcharacterizations and factors (pH, contact time, initial tetracycline concentration) affecting adsorption efficiency. The adsorption processes of tetracycline onto biochars were fitted by the Langmuir isotherm model. Additionally, the kinetic data of adsorption processes were well-described by the pseudo-second-order model. The maximum adsorption capacities of tetracycline onto biochars originated in pine leaves (P.kesiya) and rice husk were 21,44 and 21,37 mg/g, respectively. Biochars originated in pine leaves (P. kesiya) and rice husk will be potential materials to adsorb antibiotics from aquatic environments.

Combined Effect of Adsorption and Photocatalytic Degradation Using Magnesium Oxide Nano-flowers for Tetracycline Removal

AbstractThe extensive use of antibiotics, including tetracycline (TC), has several negative impacts on ecosystems that need attention. In the present study, magnesium oxide nano-flowers (MgO NFs) were examined as an adsorbent and as a degradation photocatalyst for TC elimination. MgO NFs were characterized by XRD, UV-Vis, PL, SEM, TEM, and FTIR. Optimization of the removal process included varying the treatment time, initial pH, MgO NFs dosage, and testing with different initial TC concentrations. The highest removal efficiency (77.3%) was achieved for 50 mg/L TC using 0.6 g/L of MgO NFs at pH 9. Adsorption removal contributed to 26.0% of this removal, while 51.3% was attributed to photocatalytic removal. A one-way analysis of variance (ANOVA) revealed significant impacts of time, initial pH, MgO NFs dose, and initial TC concentrations on TC removal. Although adding different ions showed strong effects on TC adsorption on MgO NFs, those ions inhibited TC removal by about 5% after photocatalytic degradation. Adsorption data fitted well with the Langmuir isotherm and pseudo-second-order kinetic models, the adsorption process was monolayer on a homogenous surface based on chemical interactions. Based on the Langmuir-Hinshelwood model, t1/2 values ranged from 60.79 to 76.15 min for TC concentrations varying from 10 to 60 mg/L. Bacterial growth inhibition of Escherichia coli (ATCC 25,922) and Bacillus cereus (ATCC 33,019) were reduced after TC treatment. The study evidenced that using MgO NFs in photodegradation is an effective approach for TC removal from water bodies.

Performance test and analysis of tetracycline degradation using a Micro-Nano Bubble system

Antibiotics and organic residues from Tetracycline (TC) and other pharmaceuticals administered to aquatic living organism have negative impacts on aquatic environment by killing-off non-target living organisms and developing antibiotic-resistant bacteria. In this study, Micro-Nano Bubble (MNB) system was used to remove TC residues. MNB system demonstrated good level of degradation efficiency, as resulted in experiment where in time of 100 min, the TC degraded at rate of 82.66% from its initial concentration of TC when the initial concentration was 1 mg/L. When the initial concentration was increased to 10 mg/L, MNB system degraded TC at 64.35% of their initial, this means MNB system demonstrated good level of efficiency for TC removal and indicated that it is more efficient in TC degradation under the conditions of low initial TC concentration and high availability of dissolved oxygen (DO). In the system as the temperature increased there was a significant decrease in DO saturation which was related to the TC complex structure that contain multiple function groups such as amino groups, hydroxyl and carboxyl which possess high strong affinity with oxygen that leads to their adsorption onto bubble surface. This study provides significant insights into the application of MNB system for the removal of organic residues within aquatic ecosystem and underscores the need for further exploration of MNB technology for environmental remediation.

Moving Bed Sequenced Batch Reactor System in Tetracycline Antibiotic Removal from Real Hospital Wastewater

Background: Water contamination by synthetic organic chemicals like antibiotics is a major environmental issue. Tetracycline (TC), an antibiotic in a wide family, is notable. A moving bed sequenced batch reactor (MBSBR) is tested for treating hospital raw wastewater containing TC. Methods: A 35-L pilot system was constructed, with 30 L usable. PVC suspended carriers (Kaldnes K3) with 584.3 m2 /m3 specific surface area made about 70% of the functional volume. The independent variables in this study were hydraulic retention duration (1, 1.5, 2, and 2.5 hours) and starting TC concentration (5, 10, and 15 mg/L). Results: The findings of the study demonstrated satisfactory performance under the conditions of an initial TC concentration of 5 mg/L and an organic load of 350 mg/L. The overall removal efficiencies for TC, chemical oxygen demand (COD), and biological oxygen demand (BOD5 ) were 72.8%, 83%, and 93.9%, respectively. The optimal performance of the system was primarily observed during the initial phase, characterized by a TC concentration of 5 mg/L and a hydraulic retention time (HRT) of 2.5 hours. The experimental results also indicated that the maximum removal efficiency was 1.8 kg COD/m2 .day, as determined by a fitted surface loading rate (SLR). Furthermore, the food-tomicroorganism (F/M) ratio decreased from 0.101 to 0.038 as the HRT increased from 1 to 2.5 hours. Conclusion: The results of the study indicate that the MBSBR exhibits a high level of efficiency in removing TC from hospital wastewater.

Enhanced degradation of tetracycline with zinc-based adenine-derived P, N co-doped carbon via peroxydisulfate activation

In this study, a P, N co-doped carbon with excellent adsorption and peroxydisulfate (PDS) catalytic activity based on zinc-based adenine complex (Zn-Ade) derived has been designed and fabricated via a facile two-step pyrolysis strategy. Under the optimized conditions, the synthesized phosphorus and nitrogen co-doped carbon (PNC-4, 4 is the mass ratio of KH2PO4 to pristine nitrogen-doped carbon) has a high graphitic N and pyrrolic N and exhibited excellent catalytic activity in PDS activation. A small amount of PNC-4 (0.05 g/L) could remove about 92.44 % of TC within 80 min when the initial tetracycline (TC) concentration was 20 mg/L (PDS = 0.1 g/L; initial pH = 5.71), which could be attributed to the accelerated electron transfer and large adsorption capacity of PNC-4. The adsorption of TC on PNC-4 was chemisorption and the maximum theoretical capacity of adsorption (qmax) was 500.577 mg/g. The results of reactive oxygen species (ROS) capture experiments and electrochemical characterization confirmed that TC was oxidized mainly through electron transfer mechanism. Furthermore, the reaction rate constant (k) was significantly positively correlated with the graphitic N and pyrrolic N contents and weakly positively correlated with the defects, respectively. These findings demonstrated that graphitic N and pyrrolic N enhanced PDS activation and oxidized TC via the electron transfer pathway. Finally, the results of toxicity assessment showed that the toxicity of the intermediates were significantly reduced after TC degradation. This study not only propelled the mechanistic understanding of the collaborative contribution of active sites to PDS activation, but also offered a new strategy for the design of bifunctional carbon materials for adsorption and catalysis.

Synthesis of Ag2ZnGeO4/g-C3N4 binary heterostructure: A Z-scheme heterojunction photocatalyst for enhanced tetracycline degradation under visible light

Accumulation of tetracycline was hazardous to human health and ecosystems. Ag2ZnGeO4/g-C3N4 heterojunction photocatalysts were successfully prepared by the wet impregnation method. The morphological structure and optical properties of the photocatalysts were measured by a series of characterization methods. Moreover, Ag2ZnGeO4/g-C3N4 with a loading ratio of 20 % exhibited excellent photocatalytic activity by exploring the Ag2ZnGeO4 loading, catalyst dosage, initial concentration, and initial pH of tetracycline. The degradation efficiency of 20 % Ag2ZnGeO4/g-C3N4 for 10 mg/L TC was 94.29 % at 0.2 g/L catalyst dosage, and the corresponding first-order reaction rate constant reached a maximum of 0.0199 min−1. In addition, according to the results of the trapping experiments, superoxide anion radical was the major active species. Eventually, a possible Z-scheme of the photocatalytic degradation mechanism was proposed. The heterojunction formed between Ag2ZnGeO4 and g-C3N4 could accelerate the transfer and separation of photogenerated carriers, enhancing the photocatalytic activity.

Organic pollutants degradation by a superb MXene-based Z-scheme heterojunction Photocatalyst: Synthesize, delamination process, mechanism and toxicity assessment

In this study, a new CeO2/MXene-TiO2 photocatalyst was created using a simple and economical approach and thoroughly characterized by different techniques, including TEM, XPS, BET, XRD, Raman, and SEM. The focus of this research was to improve the degradation of tetracycline (TC), a commonly used antibiotic with known environmental and health risks. To optimize the degradation process, RSM- CCD method was used to systematically vary key parameters including initial TC concentration, photocatalyst dosage, pH and irradiation time. The trapping experiments were revealed that the hydroxyl (•OH) and superoxide anion (•O2-) radicals played a crucial role in this process. An impressive degradation efficiency of 96.60 % was achieved under optimal conditions, attributed to the Z-scheme electron transfer heterojunction, which enhances the generation and separation of oxidant species. LC-MS analysis was employed to elucidate the photodegradation pathway of TC by identifying the reaction intermediates. This analysis facilitated the proposal of a plausible mechanism for TC degradation. The demonstrated efficacy of the CeO₂/MXene-TiO₂ photocatalyst suggests its potential application in wastewater treatment for the significant degradation of persistent organic contaminants.