Tetracycline Concentration Research Articles

Fabrication of MoS2@Fe3O4 Magnetic Catalysts with Photo-Fenton Reaction for Enhancing Tetracycline Degradation

Tetracycline (TCs) is widely used in the treatment of human and animal infectious disease. TCs gives rise to a growing threat to the human health and environment protection due to its overuse. Therefore, it is important to remove TCs contaminants from waste effluents. In this work, MoS2@Fe3O4 catalytic material was fabricated by the simple hydrothermal method, which was applied in the photo-Fenton system to degrade TCs. The crystal structure, surface morphology, elemental composition, chemical state, electrochemical properties, and separability of MoS2@Fe3O4 catalytic materials were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), conventional and high-resolution transmission electron microscopy (TEM/HRTEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and vibrating sample magnetometry (VSM). Furthermore, MoS2@Fe3O4 could degrade 98.6% of TCs within 60 min under the optimum reaction conditions (the catalyst dosage of 3 g/L, H2O2 concentration of 5 mmol/L, the initial TCs concentration of 50 mg/L, and the initial pH of 5), which was a significant increase compared with pure Fe3O4. MoS2 can accelerate the Fe3+/Fe2+ cycle through electron transfer from Mo4+ to Fe3+, resulting in the improvement in the degradation efficiency of TCs. The quenching and electron paramagnetic resonance (EPR) results showed that OH• and photogenic hole h+ was the main active species in the photo-Fenton system. What is more, MoS2@Fe3O4 catalytic materials had remarkable stability and reusability, and can be handily regained via magnetic separation technology in a real scenario.

Smartphone-assisted hydrogel sensing platform based on double emission carbon dots for portable on-site tetracycline detection.

Innovative double-emission carbon dots (DE-CDs) were synthesized via a one-step hydrothermal method using fennel and m-phenylenediamine (m-PD) as precursors. These DE-CDs exhibited dual emission wavelengths at 432 and 515nm under different excitations, making them highly versatile for fluorescence-based applications. The fluorescence of the DE-CDs was efficiently quenched by tetracycline (TC) through the inner filter effect (IFE), allowing for the construction of a sensitive dual-response fluorescent sensor. This sensor demonstrated a strong exponential correlation with TC concentrations in the range 0.99-118μM, achieving a low detection limit of 53.4nM, which is appropriate for environmental monitoring. To further enhance its practicality, a smartphone-integrated fluorescent hydrogel film sensing platform was developed. This portable and user-friendly system enabled rapid, on-site TC detection in water samples, combining high sensitivity with convenience for real-world applications. The integration of the DE-CD-based sensor into a hydrogel platform addressed the challenge of translating laboratory precision into field-ready tools. This study revealed the potential of DE-CDs as a robust and efficient solution for bridging the gap between laboratory-based analysis and portable, on-site environmental monitoring.

Preparation and Characterization of MIL‐53(Al)‐(NH2)@PANI for Tetracycline Removal

ABSTRACTThe growing global demand for water and persistent shortages have underscored the importance of wastewater treatment from industrial and urban sources. Among various approaches, the use of adsorbent materials, particularly metal–organic frameworks (MOFs), has gained significant attention over the past decade due to their exceptional adsorption properties. This study presents a rapid, water‐based synthesis method for MIL‐53(Al)‐(NH2) and its surface modification using polyaniline (PANI). The modified MOFs, MIL‐53(Al)‐(NH2)@PANI, were utilized for the removal and photocatalytic degradation of tetracycline from aqueous solutions. Optimal operational conditions were determined to include an adsorbent dosage of 0.12 g/L, an initial tetracycline concentration of 30 mg/L, a reaction time of 30 min, and a solution pH of 2.5. Kinetic analyses revealed that the adsorption process conforms to the Pseudo‐second‐order kinetic model, with the surface modification by PANI significantly enhancing the adsorption efficiency. The proposed mechanism for photocatalytic degradation involves the generation of reactive radical species, including h+, ˙OH, and ˙O2−, under sunlight irradiation, which synergistically improves the removal efficiency. This study highlights the potential of MIL‐53(Al)‐(NH2)@PANI as an effective adsorbent and photocatalyst for the treatment of antibiotic‐contaminated water, offering a sustainable solution to water pollution challenges.

Antibiotic Pollution Level and Ecological Risk Assessment of Township Wastewater Treatment Plants

Due to the abuse of antibiotics, a large amount of antibiotics has been entering wastewater treatment plants （WWTPs）, but the pollution of antibiotics in township WWTPs has not attracted much attention. To understand the contamination level and removal characteristics, and the risks to aquatic organisms and human health, samples collected from the inlet and outlet of 15 township WWTPs were investigated. The results showed that tetracyclines （TCs） had the highest concentration in the inlet and outlet waters, in which the concentrations of TC and oxytetracycline （OTC） reached （4 943.69±4.31） ng·L-1 and （3 907.81±52.04） ng·L-1. As for antibiotic removal, the A/O and A2/O processes had a better antibiotic removal capacity than those of the MBR process. Ecological risk assessment showed that TCs and fluoroquinolones （FQs） had a higher risk to aquatic organisms. However, sulfonamides （SAs） would pose a low risk to aquatic organisms. Although antibiotics pose a risk to aquatic organisms, the risk to human health is negligible. The results of this study could provide support for the upgrading of township WWTPs and the formulation of regional antibiotic discharge standards in the future.

The Comparison of the Clinical Efficacy and Drug Tissue Distribution of Furazolidone and Tetracycline-quadruple Therapy in Helicobacter pylori Eradication : A Randomized Controlled Trial.

Helicobacter pylori ( H. Pylori ) is considered a main causative organism of gastric ulcers, gastric cancer and duodenal ulcers. The current treatment relies on a combination of antimicrobial agents and acid suppressant agents, but the eradication effect is not satisfactory. To clarify the concentration of antibiotics at the lesion site, we investigate the clinical efficacy and drug tissue distribution of the combination therapy of furazolidone and tetracycline in eradicating H. Pylori. Patients with H. pylori infection (n = 60) were randomized to either group A or B. Bismuth potassium citrate capsules 220mg, omeprazole enteric-coated capsules 20mg, amoxicillin capsules 1000mg, each twice per day, and furazolidone tablets 500mg were administered to group A. Group B was treated with bismuth potassium citrate capsules 220mg, omeprazole enteric-coated capsules 20mg, amoxicillin capsules 1000mg, and tetracycline tablets 500mg each twice per day for 2 weeks. The serum and gastric juice, gastric antrum, gastric horn, and gastric body samples were taken under a gastroscope on the 14th day. The antimicrobial concentrations in serum and tissue samples were determined by high-performance liquid chromatography. In the negative group of furazolidone, the concentrations of gastric antrum, gastric body, and gastric angle were significantly higher than those in the positive group ( P = 0.017, 0.015, and 0.028). The concentrations of furazolidone in gastric fluid, gastric antrum, gastric angle, and gastric body were ∼421 times, 82 times, 17 times, and 51 times higher than those in serum, respectively. The concentrations of tetracycline in the serum and gastric angle of the tetracycline negative group were significantly higher than those in the positive group ( P = 0.036 and 0.042), and the tetracycline concentrations in the gastric horn and gastric body were about 4 and 6 times higher than those in the serum, respectively. The concentration of amoxicillin in group B was higher than that in group A, especially in serum, gastric juice, gastric angle, and gastric body ( P < 0.05). Furazolidone is mainly concentrated and sequentially distributed in gastric juice, gastric antrum, and gastric body tissue, and tetracycline is mainly distributed in serum, gastric angle, and gastric body, whereas amoxicillin is mainly distributed in serum, gastric juice, gastric angle, and gastric body. Improving the concentration and tissue distribution of antibacterial drugs in the human gastric mucosa is the key to ensuring the ideal eradication rate of quadruple therapy.

An environmentally friendly chitosan-loaded BiOCOOH/BiYO3 photocatalyst for efficient photocatalytic degradation of tetracycline.

In this work, the photocatalyst BiOCOOH/BiYO3/Chitosan (CS) was prepared by using CS as the carrier and adsorbent. The performance of the material was studied through the photocatalytic degradation of tetracycline (TC) in water. Theoretical calculations and experiments demonstrate that the formation of BiOCOOH/BiYO3 heterojunctions improves the separation of photogenerated carriers and the absorption of visible light by the material. The introduction of CS improves the difficulties in material recovery, demonstrating exceptional degradation ability for TC under the action of adsorption and photocatalysis. Adsorption kinetics studies indicate that the adsorption of TC by BiOCOOH/BiYO3/CS fits the pseudo-second-order model better, while the adsorption at different concentrations of TC is more suitably described by the Freundlich isotherm model. The synthesis of BiOCOOH/BiYO3/CS was confirmed by the analysis of XRD, XPS, and FTIR. UV-vis DRS showed that the synthesis of BiOCOOH/BiYO3/CS broadened the range of light absorbed by the material. The testing results of PL and transient photocurrent density indicate that BiOCOOH/BiYO3 exhibits a higher efficiency in separating photogenerated charge carriers. After 5cycles of reuse, the degradation efficiency can still reach 90% of the initial efficiency, indicating that CS-based photocatalytic composite catalysts have practical application potential in the field of water pollution treatment.

Unlocking the potential of simultaneous organics oxidation and nitrate reduction over an S-scheme magnetic CoFe2O4@g-C3N4 heterojunction under visible light irradiation: Performance and mechanism

In this study, a novel S-scheme CoFe2O4@g-C3N4 (CF@GCN) heterojunction was prepared via a simple hydrothermal method and its visible-light-driven catalytic potential was evaluated in terms of tetracycline (TC) oxidation and nitrate reduction simultaneously. A series of characterizations validated the effective fabrication of CF@GCN, exhibiting remarkable photocatalytic potentials. In the separated system of TC and nitrate, a nearly 100% removal of TC was observed in 60 min under the optimal conditions (pH = 5.0, Catalyst dosage = 0.4 g/L, TC concentration = 5.0 mg/L). The quenching experiments emphasized the concurrent participation of both non-radical species (h+) and radical species (O2•− and HO•) in TC degradation. Meanwhile, more than 96% of nitrate removal was observed in 90 min under the optimal conditions (pH = 3.0, Catalyst dosage = 0.4 g/L, nitrate concentration = 100 mg/L, in the presence of formic acid). In the combined system, both TC oxidation and nitrate reduction occurred simultaneously and the efficiency of TC oxidation was lower compared to the individual system. The novel S-scheme composite has demonstrated exceptional potential in enhancing the reusability and stability of the catalyst, even after five cycles of trials. A detailed mechanistic pathway for TC oxidation and nitrate reduction was proposed, relying on the identification of reactive species and intermediates. In general, our findings propose a promising method with synergistic properties for the simultaneous oxidation of organics and reduction of nitrate in wastewater over an S-scheme heterojunction.

Aero-TiO2 three-dimensional nanoarchitecture for photocatalytic degradation of tetracycline

One of the biggest issues of wide bandgap semiconductor use in photocatalytic wastewater treatment is the reusability of the material and avoiding the contamination of water with the material itself. In this paper, we report on a novel TiO2 aeromaterial (aero-TiO2) consisting of hollow microtetrapods with Zn2Ti3O8 inclusions. Atomic layer deposition has been used to obtain particles of unique shape allowing them to interlock thereby protecting the photocatalyst from erosion and damage when incorporated in active filters. The performance of the aero-TiO2 material was investigated regarding photocatalytic degradation of tetracycline under UV and visible light irradiation. Upon irradiation with a 3.4 mW/cm2 UV source, the tetracycline concentration decreases by about 90% during 150 min, while upon irradiation with a Solar Simulator (87.5 mW/cm2) the concentration of antibiotic decreases by about 75% during 180 min. The experiments conducted under liquid flow conditions over a photocatalyst fixed in a testing cell have demonstrated the proper reusability of the material.

A ratiometric fluorescent probe based on water-soluble CsPbX3 (Br/I) perovskite nanocrystals for sensitive detection of tetracycline.

Adual supersaturation recrystallization method was employedto synthesize water-stable, highly sensitive cesium-leadhalide perovskite nanocrystals(CsPbBr3 PNCs). The PNCs exhibited excellent water stability, a significant photoluminescence quantum efficiency of 83.03%, along with a narrow full width at half maximum (FWHM) of 20nm. Following iodide ion treatment, the fluorescence emission peak of CsPbBr3 PNCs can be tuned from 520 to 681nm, causing a color transition from green to red. Within the 0-300μM range, the red shift showed a linear correlation with I- concentration, achieving a detection limit as low as 0.40μM. It is worth noting that excessive iodide ions could have allowed PNCs to exhibit dual emission with maximum wavelengths of 520 and 681nm. A ratiometric perovskite nanoprobe was constructed with the green emission peak as an internal standard and the red emission peak as the response signal. The probe demonstrated a strong linear correlation with tetracycline concentrations ranging from 0 to 8μM, with a detection limit of 88.60nM (S/N = 3). This research offers valuable insights into the design and development of ratiometric perovskite sensors capable of detecting in aqueous solutions, while also emphasizing the importance of rapidly establishing hydrogen-bonding networks when analyzing such detection systems.

Application of CuFe2O4/CuS as a new green magnetic nanocomposite in adsorption of tetracycline from aqueous solutions: mathematical models of thermodynamics, isotherms, and kinetics

In current study, a novel adsorbent of CuFe2O4/CuS magnetic nanocomposite (MNC) was constructed via a green approach for tetracycline (TC) removal. The leaf extract of the Alhagi pseudalhagi plant was employed as a green reductant agent. The features of the nanocomposite were characterized using XRD, FTIR, FESEM, TEM, BET, and VSM. Batch studies were conducted to assess the impact of parameters, including pH (3.0–9.0), adsorbent dosage (0.025–2 g/L), TC concentration (5–100 mg/L), and temperature (5–50 °C) on the TC adsorption efficiency. The antibiotic was fully removed at pH 7.0, nanocomposite dose of 1.5 g/L, time of 200 min, and TC content of 5 mg/L. Based on the thermodynamic study, the TC adsorption onto the CuFe2O4/CuS MNC occurred spontaneously and was primarily driven by physical interactions (physisorption). Positive values of ∆H° (enthalpy change) and ∆S° (entropy change) demonstrated that the adsorption process is naturally endothermic, and the degree of dispersion improves with rising temperature. Adsorption kinetics was well fitted by the pseudo-second-order model. The isotherm studies showed that TC can be removed by the adsorbent at a maximum of 31 mg/g. Overall, CuFe2O4/CuS MNC exhibited notable efficacy and cost-effectiveness (reusability: 5 times) for the TC adsorption from water.

Residues of Tetracycline, Erythromycin, and Sulfonamides in Beef, Eggs, and Honey from Grocery Stores in Knoxville, Tennessee, USA: Failure of Cooking to Decrease Drug Concentrations.

This study evaluated the concentrations of tetracycline, erythromycin, and sulfonamide in beef, eggs, and honey products sold at grocery stores and whether standard cooking to 160 °F (71 °C) reduced the concentrations of antimicrobials spiked into the evaluated food products. In June 2021, the concentrations of selected antimicrobials in 65 samples (8 beef, 48 eggs, 9 honey samples) purchased from grocery stores within Knoxville, Tennessee, were measured using enzyme-linked immunosorbent assays. The Kruskal-Wallis test was used to assess the differences in the median tetracycline concentrations across food types, while the Mann-Whitney test was used to compare the erythromycin residue concentrations between beef and honey. Linear regression was used to analyze whether standard cooking at 160 °F (71 °C) reduced antimicrobial concentrations. Detectable tetracycline concentrations were found in all beef (8/8, 100%), eggs (46/48, 96%), and honey (9/9, 100%) samples, with median concentrations of 7.73, 5.62, and 13.13 µg/kg, respectively. Honey had significantly higher tetracycline concentrations than eggs (p = 0.002). Detectable erythromycin concentrations were found in beef (5/8, 63%) and honey (9/9, 100%), with median concentrations of 0.14 µg/kg for beef and 0.48 µg/kg for honey. None of the antimicrobial concentrations found in the beef and egg products exceeded the U.S. FDA's maximum residue limits (MRL). Sulfonamide concentrations were undetectable in the beef and egg products. The concentrations of tetracycline, erythromycin, and sulfonamide spiked into the food products did not change significantly in response to cooking to 160 °F (71 °C). The antimicrobial concentrations found in the selected commercial food products were below the MRL, and cooking appeared to not reduce the spiked antimicrobial concentrations in the evaluated food products.

Synthesis and Characterization of CaO nanoparticles from Periwinkle shell for the Treatment of Tetracycline-contaminated Water by Adsorption and Photocatalyzed Degradation

Due to the ever-increasing discharge of antibiotic residues into different water bodies, there is a significant need to improve existing water treatment methods. In this study, we synthesized calcium oxide nanoparticles from periwinkle shells using the sol-gel method for applications in the adsorption and photodegradation of tetracycline from wastewater. The nanoparticles were characterized using FTIR, UV-Visble spectroscopy, XRD, SEM-EDX, TEM, BET and TGA/DTA. The nanostructure produced showed strong crystalline, optical, structural and surface properties. With an average crystallite size of 25 nm, particle size of 2.09 nm, BET surface area of 582.68 m2/g, specific surface area of 90.08 m2/g, bandgap of 4.8 eV and other properties that supported their functionality as adsorbent and photocatalyst for the removal of tetracycline residue from water. The adsorption experiment gave a maximum efficiency of about 80% while the photodegradation catalysed by the nanoparticles indicated efficiency up to 97%. Both adsorption and photodegradation showed strong dependency on pH, tetracycline concentration, catalyst load and concentration of KI. Response surface analysis and subsequent experimental validation indicated that degradation approaching 100% for tetracycline is feasible under optimum conditions involving concentration = 500 ppm, time = 50 min, catalyst load = 1.25 g and KI concentration = 0.25 M. Computational calculations gave results that are in good match with experimental data and further proved that the degradation is limited by adsorption and is majorly controlled by oxidation facilitated by O2*.

Electrochemical paper-based sensor based on molecular imprinted polymer and nitrogen-doped graphene for tetracycline determination

In this work, an electrochemical paper-based analytical device (ePAD) based on molecular-imprinted polymer (MIP) and nitrogen-doped graphene (NG) was developed for sensitive electrochemical detection of tetracycline in wastewater. The NG was in-situ synthesized on the paper-based screen-printed carbon electrode (pSPCE) by potentiostatic method to improve the conductivity of the sensor. Subsequently, the MIP were electropolymerized on NG using o-phenylenediamine (oPD) as a functional monomer and tetracycline (TC) as template molecule by cyclic voltammetry (CV) to deliver the specific recognition of TC. The electrode modification process was highly controllable, and the detection efficiency was improved. The electrochemical properties of MIP/NG/ePAD were evaluated by CV, differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the fabricated ePAD sensor showed a good linear relationship with TC concentration ranging from 5 × 10−9 to 1 × 10−5 mol/L with a correlation coefficient (R2) of 0.995 and a detection limit of 3.29 × 10−9 mol/L. The ePAD sensor was successfully applied to TC detection in real water samples with satisfied recoveries from 94.0 % to 106.9 %. The low-cost, portable, high specificity, and reliable ePAD sensor proposed here has promising potential for application in point-of-care testing (POCT) in environmental monitoring.

The removal mechanism of tetracycline by environmentally friendly modified sepiolite activated peroxymonosulfate

Sepiolite (SEP), a naturally abundant and environmentally friendly clay mineral, possesses various active sites and a large specific surface area. In this work, peroxymonosulfate (PMS) was activated to remove tetracycline (TC) using modified Sepiolite (MSEP), which was synthesized by ball milling and calcination techniques. According to the findings, MSEP efficiently stimulated PMS to produce 1O2 and ·OH radicals for the degradation of TC, with 1O2 being a key component of this process. The findings demonstrated that the carbonate on the MSEP surface encouraged the production of singlet oxygen. (1O2). Under the conditions of pH 6.5, 0.2 g/L MSEP, 2 mmol/L PMS and 25 °C, a 10 mg/L TC concentration was reduced by 93.3 % after 30 min. The presence of Cl− and NO3− did not inhibit TC degradation, while HCO3− promoted it, and H2PO4− exhibited an inhibitory effect. This work offers a novel method for using clay minerals to activate PMS and degrade organic contaminant without secondary pollution.

Post-vulcanization combined with magnetic modification of sulfonated biochar as heterogeneous fenton catalyst for tetracycline degradation

Although the Fenton reaction has shown remarkable effectiveness in degrading antibiotic contamination in water bodies, its strict pH dependence has limited its wide practical application. In this study, a novel magnetic biochar material with dual functions of adsorption and catalysis was successfully synthesized by carbonization of the shell of blue flower blue with concentrated sulfuric acid through sulfide and magnetic modification. The innovation of this material is its ability to overcome the recycling limitations of traditional catalysts while achieving efficient reactions in the pH range of 3–11. In particular, the introduction of sulfur promotes a stable cycle of Fe(II)/Fe(III) in the material, thereby enhancing its catalytic properties. The porous structure of the sulphonated jacaranda hull and its successful loading of sulfur and iron were revealed by SEM, FTIR, XRD, and XPS analysis. The experimental results showed that under the conditions of S-Fe3O4@JSS dosage of 0.2 g/L, hydrogen peroxide concentration of 10 mM, initial pH value of 5, and initial tetracycline concentration of 50 mg/L, the optimal degradation rate of tetracycline was as high as 85.85 %. The mechanism analysis shows that hydroxyl radical plays a key role in this reaction system because S-Fe3O4@JSS not only releases Fe(II) but also catalyzes hydrogen peroxide with the introduction of surface acidic sites and sulfur elements, which increases the free radical yield and accelerates the tetracycline degradation process. This study provides a new efficient and stable method to solve the problem of antibiotic pollution treatment in water.

Treatment performance of different units in the anaerobic-anoxic-aerobic process of landfill leachate under antibiotic exposure

ABSTRACT The effectiveness of three different treatment units (anaerobic, anoxic, and aerobic) in A/A/O reactors when treating landfill leachate that contained varying concentrations of tetracycline (TC) was evaluated. The effluent quality, sludge performance, and removal rates of COD, TN, TP, and NH3-N of the reactors were investigated. The results showed that in the three treatment units (anaerobic, anoxic, and aerobic), when the TC dosage was 10 mg/L, the removal rates of NH3-N continued to decrease to 6.9%, 16.3%, and 32.8%, and the removal rates of COD, TN, and TP in the three treatment units reached their maximum values, which were 37.5%, 57.4%, and 69.6%; 21.1%, 37.1%, and 41.0%; 13.0%, 16.2%, and 27.4%, respectively. During the reactor's operation, the heavy metal content in the treatment units initially increased followed by a decrease, especially for Mn and Zn. This was due to the production of more EPS by microorganisms, resulting in more active sites for heavy metal adsorption. In addition, with the increase of TC concentration, TC removal rate was always positively correlated with PN, COD, TN and heavy metals removal rates, and negatively correlated with NH3-N, TP, pH, and PS. Further analysis revealed that TC was toxic to microorganisms, leading to a decrease in biodiversity and microbial community diversity among the three treatment units in the reactor. This article analyzed the treatment effects of different treatment units in leachate under antibiotic exposure conditions, to explore better external conditions for sewage biological treatment facilities.

High fluorescence quantum yield of methionine-doped carbon quantum dots for achieving rapid assay of tetracyclines in foodstuffs

The trace-level detection of tetracyclines (TCs) in food products is essential to ensure food safety and public health. Herein, we prepared the methionine-doped carbon quantum dots (Met-CQDs) using citric acid as the precursor. Met-CQDs exhibited a Gaussian unimodal peak centered at 440 nm in the fluorescent excitation spectrum, along with a remarkable greenish-blue emission and a fluorescent quantum yield of 33.5 %. Furthermore, the presence of TC (the quencher) caused a rapid quenching of the fluorescence of Met-CQDs, accompanying with a color transition from light blue to dark bule as TC concentrations increased. The coloring variation was also detected by the images captured by smartphones and RGB analysis software, facilitating portable detection of TC utilizing Met-CQDs as a fluoroprobe. The findings indicate that the Met-CQDs based fluoroprobe exhibits high selectivity, rapid response (only ∼1 min) according to an “ON-OFF” sensing model. This fluorescence sensing method gave a low detection limit (LOD) of 0.032 μM and excellent linearity for TC in the concentration range of 0.1–500 μM. Also, the smartphone-based fluorescence-visualizing approach displayed good linearity with a LOD of 0.33 μM. The interactions between this fluoroprobe and TC occurred by virtue of both inner filter effect (IFE) and static-quenching principle. The average recovery for TC in the milk, honey, and tap water samples was determined to be 98.46 ± 1.71 % by a fluorometric method. Overall, both fluorometric and RGB approaches demonstrate strong correlation with conventional LC-MS/MS, and thus the as-fabricated Met-CQDs are promising for the preliminary screening of TCs’ residues in food products.

Bacterial communities and tetracycline resistance genes in the soil-rice continuum upon tetracycline exposure

Edible plants are known as key vectors for transmission of antibiotic resistance genes (ARGs) to humans. However, little is known about how antibiotic exposure affects the abundance of ARGs in the soil-rice continuum. This study assessed tetracycline (TC) content, tetracycline resistance genes (TRGs), class 1 integron-integrase gene (intI1), and bacterial communities in the mature soil-rice continuum exposed to varying concentrations of TC (0, 50, 100, and 300 ppm). As TC exposure levels increased, the TC content in rhizosphere soils and roots increased accordingly. However, TC residue was not detected in the grains. Additionally, sample type (rhizosphere soils, roots, and grains) was the key determinant of bacterial communities and TRGs profiles in the soil-rice continuum. The bacterial communities and TRGs profiles in the rhizosphere soils and roots exposed to TC >50 ppm were more dissimilar to those without TC than to those exposed to TC <50 ppm. The abundance of TRGs in the soil-rice continuum increased with the TC concentrations but declined when TC > 50 ppm. This decline was primarily due to changes in the abundance of tetX and tetZ. Variation partitioning analysis revealed that the TRGs profiles in rhizosphere soils is strongly affected by bacterial communities. In contrast, the variation in TRGs profiles in roots was predominantly explained by bacterial communities-TC interactions. However, the changes in TRGs profiles of grains could not be attributed to the bacterial communities, TC, or intI1. This study provides valuable insights into the response of TRGs profiles in the soil-rice continuum to TC exposure.

Enhancing Internal Electric Field of Metal-Free Donor-Acceptor Conjugated Photocatalysts for Efficient Photocatalytic Degradation of Tetracycline and CO2 Reduction.

Constructing alternating donor-acceptor (D-A) units within g-C3N4 represents an effective strategy for enhancing photocatalytic performance through improved charge carrier separation while concurrently addressing energy shortages and facilitating wastewater remediation. Here, a series of D-A-type conjugated photocatalysts (CNBTC-X) are prepared using g-C3N4 as an acceptor unit and different masses of 5-bromo-2-thiophenecarboxaldehyde (BTC) as a donor unit by a one-step thermal polymerization. CNBTC-50 presents higher photocatalytic properties for CO2 reduction coupled with tetracycline (TC) removal than those of g-C3N4, CNBTC-10, CNBTC-30, and CNBTC-70. The introduction of the unique electron-donor-acceptor structure effectively drives the separation and transfer of photoinduced carriers while reducing the internal carrier transfer hindrance. Photocatalytic experiments reveal that the CNBTC-50 photocatalyst achieves up to 94.6% TC removal under visible light irradiation conditions. Compared with that of the pristine g-C3N4, the photocatalytic degradation reaction rate constant of CNBTC-50 is significantly increased by about 3.87 times. The study examines the influence of various reaction parameters on degradation activity, including catalyst concentration, pH, and TC concentration. Additionally, LC-MS is utilized to perform a comprehensive analysis of the intermediates and pathways involved in TC degradation. Furthermore, CNBTC-50 demonstrates remarkable photocatalytic CO2 reduction activity, achieving rates of 20.83 μmol g-1 h-1 (CO) and 9.36 μmol g-1 h-1 (CH4), which are 10.68 and 5.98 times more efficient than those of g-C3N4, respectively. This work aims to offer valuable guidance for the rational design of nonmetal D-A-structured catalysts and effectively integrates reaction systems to couple CO2 reduction with antibiotic removal.

Synergistic degradation and ecotoxicology assessment of tetracycline by II-scheme Cu3BiS3/Bi2Fe4O9 photocatalytic activation of peroxymonosulfate

The increasing reliance on antibiotics in recent years has led to the growing overuse of antibiotics, and tetracycline (TC) is a widely used antibiotic. In this study, a hierarchical configuration system was constructed by combining Cu3BiS3 and Bi2Fe4O9 for the study of photocatalytic activation of persulfate degradation of TC, and its photocatalytic performance on TC was fully evaluated. Results found that Bi2Fe4O9 and Cu3BiS3 formed a type-II heterojunction, which inhibited the complexation of photogenerated carriers and synergized with peroxymonosulfate (PMS) to promote the generation of reactive radicals and thus enhance the photocatalytic effect. Also, in the photocatalytic activation of persulfate systemCu3BiS3/Bi2Fe4O9/PMS/ visible (Vis), the best catalytic performance of 12.5 %Cu3BiS3/Bi2Fe4O9 was achieved when the catalyst injection was 0.3 g/L, the concentration of TC was 20 mg/L, the concentration of PMS was 1 mmol/L, and the pH=6.5, which degraded 97.9 % of TC within 60 min. The 12.5 % Cu3BiS3/Bi2Fe4O9/PMS/ Vis system has a contribution of active substances of SO4•−>O2•−>h+>O12>•OH. Further, the degradation mechanism and pathways of TC by the Cu3BiS3/Bi2Fe4O9/PMS/Vis system was proposed, and it was proved that the system could realize the safe conversion of TC according to the toxicity estimation using software Toxicity Estimation Software Tool (TEST).