Tetracycline Research Articles

The Surface Confinement of FeO Assists in the Generation of Singlet Oxygen and High-Valent Metal-Oxo Species for Enhanced Fenton-Like Catalysis.

Transition metal compounds (TMCs) have long been potential candidate catalysts in persulfate-based advanced oxidation process (PS-AOPs) due to their Fenton-like catalyze ability for radical generation. However, the mechanism involved in TMCs-catalyzed nonradical PS-AOPs remains obscure. Herein, the growth of FeO on the Fe3O4/carbon precursor is regulated by restricted pyrolysis of MIL-88A template to activate peroxymonosulfate (PMS) for tetracycline (TC) removal. The higher FeO incorporation conferred a 2.6 times higher degradation performance than that catalyzed by Fe3O4 and also a higher interference resistance to anions or natural organic matter. Unexpectedly, the quenching experiment, probe method, and electron paramagnetic resonance quantitatively revealed that the FeO reassigned high nonradical species (1O2 and FeIV═O) generation to replace original radical system created by Fe3O4. Density functional theory calculation interpreted that PMS molecular on strongly-adsorbed (200) and (220) facets of FeO enjoyed unique polarized electronic reception for surface confinement effect, thus the retained peroxide bond energetically supported the production of 1O2 and FeIV═O. This work promotes the mechanism understanding of TMCs-induced surface-catalyzed persulfate activation and enables them better perform catalytic properties in wastewater treatment.

Effective degradation of tetracycline under visible light by microwave-assisted reflux synthesis of ZnO/MoS2/rGO ternary nanocomposites

ZnO@MoS2 and conducting rGO based ternary nanocomposites were synthesized by a bottom-up microwave-assisted reflux method and effectively investigated for the photocatalytic degradation of tetracycline hydrochloride (TCH) antibiotic. The XRD, EDAX and XPS results corroborates the formation of nanostructure composite with high phase purity. The ZnO nanorods are well grafted on the curled configuration of layered MoS2 and thin surfaced rGO sheets as visualised from HR-TEM analysis. Upon addition of rGO, there is a significant decrease in the bandgap and improved visible light response in the ternary nanocomposites is elucidated by UV–visible Diffuse Reflectance Spectroscopy (UV-DRS) analysis. The suppression in photo-induced electron/hole pair recombination and allowing easy charge transport of ZnMG-50 were evidenced from photoluminescence (PL) and photo-electrochemical impedance (photo-EIS) spectroscopy. From BET and BJH analysis, the enhancement in surface area and pore volume by loading of rGO (SBET = 264.794 m2/g and 0.548 cm3/g). The optimized ZnMG-50 nano-photocatalyst possess a superior photocatalytic performance with higher removal efficiency of 92.18 % was achieved at pH level 10, catalyst dosage 40 mg and TCH concentration 20 ppm within 180 min under illumination. The degradation process compiles a pseudo-first order reaction with a kinetic rate constant of 0.01365 min−1. The nonstop generation of hydroxyl (˙OH) and superoxide (O2˙-) reactive species were beneficial for free electrons in the active participation, which remains as a core factor in the degradation process. The detailed study on ZnMG-50 nanocomposite substantiated to be an efficient noble metal-free synthetic catalyst for enhanced photocatalytic degradation of antibiotics.

CdIn2S4/self-assembled g-C3N4 composite material with boosted photocatalytic degradation performance: The significance of morphology and structure

The influence of morphology on the photocatalytic performance of catalysts is a critical aspect that merits further exploration. This study successfully synthesized a series of CdIn2S4/self-assembled g-C3N4 photocatalysts with varying morphologies and structures via an in-situ deposition approach. The unique combination of g-C3N4′s surface curvature and the radial-spreading layers significantly contributed to the superior photocatalytic activity observed in the optimal sample. This sample achieved an impressive 91.3 % degradation of methyl orange within 30 min and an 81.6 % degradation of tetracycline hydrochloride in 120 min. These degradation rates surpassed those of pristine g-C3N4 by factors of 13.12 and 1.14, respectively. The findings of this research offer a promising strategy for designing highly active heterojunction photocatalysts tailored for pollutant removal and guiding the uniform deposition of CdIn2S4.

Degradation of tetracycline under a wide pH range in a heterogeneous photo bio-electro-fenton system using FeMn-LDH/g-C3N4 cathode: Performance and mechanism

The widespread use of antibiotics and the inefficiency of traditional degradation treatments pose threats to the environment and human health. Previous studies have reported the potential of bio-electro-Fenton (BEF) processes for antibiotic removal. However, some drawbacks, such as a strict pH range of 2–3 and iron sludge generation, limit their large-scale application. Thus, to overcome the narrow pH range of traditional BEF processes, a photo-BEF (PBEF) system was established using a novel FeMn-layered double hydroxide (LDH)/graphitic carbon nitride (g-C3N4) (FM/CN) composite cathode. The performance of the PBEF system was investigated by degrading tetracycline (TC) under low-power LED lamp irradiation. The results indicated that the pH range of the PBEF system could be expanded to 3–11 using an FM/CN cathode, which exhibited a TC removal efficiency of 63.0%–75.9%. The highest TC removal efficiency was achieved at pH 7. The efficient mineralization of TC by the PBEF system can be high, up to 67.6%. In addition, the TC removal mechanism was discussed in terms of reactive oxygen species, TC degradation intermediate analyses, and density functional theory (DFT) calculations. Strong oxidative hydroxyl radicals (·OH) were the dominant reactive oxidizing species in the PBEF system, followed by ·O2− and h+. Three pathways of TC degradation were proposed based on the analysis of intermediates, and the reactive sites attacked by electrophilic reagents were explored using DFT modeling. In addition, the overall toxicity of TC degradation intermediates effectively decreased in the PBEF system. This work offers deep insights into the TC removal mechanisms and performance of the PBEF system over a wide pH range of 3–11.

Fluorescent Sensors for Tetracycline Detection in Aqueous Medium: A Mini-Review.

Tetracycline (TC) is a commonly used antibiotic in human therapy and animal husbandry. Public concerns about TC residues inflated due to their negative impact on the environment, food, and human health concerns. To ensure human health and safety, there is a need for fluorogenic chemosensors that can easily detect TC antibiotics with high selectivity and sensitivity in the aqueous medium. This mini-review discusses the progress and achievements in several fluorometric antibiotic tetracycline detection methods. Fluorogenic chemosensors for tetracycline antibiotics with easy-to-use, high selectivity, and sensitivity have been essentially required to regulate food safety and secure human health and safety. Moreover, we gave more attention to the practical applicability of chemosensors for tetracycline antibiotics in food and water quality assessment. This article starts with a section that constitutes an overview of the problems of antibiotics and the typical features of traditional techniques of antibiotic detection. It then goes on to describe up-to-date optical methods for the selective detection and efficient removal of TC. These methods involve a variety of platforms, like tetraphenylethylene polymers, metal complexes, self-assembled CuNCs, and hydrogel. The article also discusses the practical applicability of chemosensors for tetracycline antibiotics in food and water quality.

Seeking the adsorption of tetracycline in water by Fe-modified sludge biochar at different pyrolysis temperatures.

The composite material SBC-Fe-x with sludge and Fe3+ was developed by different calcination temperatures (600, 700, and 800 °C) for the removal of tetracycline (TC). The adsorption rates of SBC-Fe-600, SBC-Fe-700, and SBC-Fe-800 were 77.5%, 89%, and 91%, respectively. Furthermore, the Langmuir model indicated that the maximum adsorption capacity of SBC-Fe-700 (157.93 mg/g) was three times greater than that of SBC-Fe-600. The conclusions were confirmed by a series of characterizations that SBC-Fe-700 showed a larger specific surface area, well-developed pore structure, rich oxygen-containing functional groups and a high degree of graphitization. The results of pH experiments indicated the broad applicability of SBC-Fe-700 for TC adsorption. In addition, SBC-Fe-700 suggested outstanding performance in different water environments. This work produced a feasible adsorbent for the removal of TC, and a new direction for sludge resource utilization was proposed.

INVESTIGATION OF THE EFFICIENCY OF NON-STEROIDAL ANTI-INFLAMMATORY VETERINARY MEDICINAL PRODUCT IN THE COMPLEX TREATMENT OF DISEASES OF THE MUSCULOSKELETAL SYSTEM OF PIGS

The article presents the results of clinical trials of a non-steroidal anti-inflammatory veterinary drug when administered to fattening piglets with clinical signs of musculoskeletal diseases. For the treatment of the diseases, piglets of the experimental (I) and control (II) groups received an antimicrobial drug based on the tetracycline antibiotic. The animals of the experimental group were additionally administered orally with drinking water the test non-steroidal anti-inflammatory drug based on acetylsalicylic, ascorbic and citric acids, in the recommended dosage by the manufacturer. Blood for laboratory tests was selected from piglets before and after the use of drugs. Studies of hematological and biochemical parameters were conducted according to generally accepted methods. The therapeutic efficiecy of the drug and its effect on the morphofunctional state of the body was evaluated by comparing the statistically processed data obtained before and after treatment, as well as in comparison with the indicators of animals of the control group. The analysis of hematological parameters of piglets during the experiment showed a decrease in the number of leukocytes in the animal’s blood after the use of drugs. The normalization of the leukogram was also noted by reducing the relative number of rod-nuclear neutrophils. In particular, this indicator decreased by 17.4% in group I piglets, and by 12% in group II piglets. It is noted that the clinical response to therapy was faster and more pronounced in animals, which used a non-steroidal anti-inflammatory drug in combination with an antimicrobial drug than in piglets, which were treated only by antibiotic. According to the results of biochemical studies, it was found that the content of urea in the serum of animals of both groups before the use of drugs exceeded more than 3 times the upper limit of physiological values for a given age group of piglets. After therapy with the drugs a significant decrease in the urea content in the blood serum of groups 1 and 2 animals was noted by 3.42 and 2.98 times, respectively. It is established that the activity of marker enzymes of the liver physiological state (ALT, AST) in the serum of group I piglets after complex treatment with the studied drugs was slightly reduced and was within the physiological values. In the serum of group II animals, which were treated only with antimicrobial drug, ALT activity increased by 12,0 %, and AST – by 38,6 %, compared to the initial data, and exceeded the limit of physiological values. An increase in the content of iron by 37.4 % in the blood of group I piglets, compared to the period before drug administration, was noted. No adverse reactions and negative phenomena were detected during the use of the test drug, and the drug was well tolerated. According to the clinical condition of the experimental group animals and the results of laboratory tests it was established that the use of non-steroidal anti-inflammatory drugs based on acetylsalicylic, ascorbic and citric acids simultaneously with antimicrobial therapy led to a faster improvement in the state of the musculoskeletal system. Observation during the month of the piglet’s clinical conditions confirmed the safety of the drug in the recommended dosage and method of administration in the combined treatment of inflammatory processes of the musculoskeletal system.

Efficiency and Mechanistic Insights of Photocatalytic Decomposition of Tetracycline and Rhodamine B utilizing Z-scheme g-C3N4/SnWO4 Heterostructures under Visible Light Irradiation

The hydrothermal approach was used in the design and construction of the SnWO4 (SW) nanoplates anchored g-C3N4 (gCN) nanosheet heterostructures. Morphology, optical characteristics, and phase identification were investigated. The heterostructure architect construction and successful interface interaction were validated by the physicochemical characteristics. The test materials were used as a photocatalyst in the presence of visible light to break down the antibiotic tetracycline (TC) and the organic Rhodamine B (RhB). The best photocatalytic degradation efficiency of TC (97%) and RhB (98%) pollutants was demonstrated by the optimized 15 mg of gCNSW-7.5 in 72 and 48 minutes, respectively, at higher rate constants of 0.0409 and 0.0772 min–1. The interface contact between gCN and SW, which successfully enhanced charge transfer and restricted recombination rate in the photocatalyst, is responsible for the enhanced performance of the gCNSW heterostructure photocatalyst. In addition, the gCNSW heterostructure photocatalyst demonstrated exceptional stability and reusability over the course of four successive testing cycles, highlighting its durable and dependable function. Superoxide radicals and holes were shown to be key players in the degradation of contaminants through scavenger studies. The charge transfer mechanism in the heterostructure is identified as Z-scheme mode with the help of UV-vis DRS analysis. Attributed to its unique structural features, and effective separation of charge carriers, the Z-scheme gCNSW-7.5 heterostructure photocatalyst exhibits significant promise as an exceptionally efficient catalyst for the degradation of pollutants. This positions it as a prospective material with considerable potential across various environmental applications.

Ce-Doped Nanosheet as Visible Light Photocatalyst for the Photocatalytic Degradation of Tetracycline Hydrochloride

Ce-Doped Nanosheet as Visible Light Photocatalyst for the Photocatalytic Degradation of Tetracycline Hydrochloride

Synergistic Engineering of Energy Band Alignment and Interfacial Electric Field Distribution over Bi-bismuth-Based Hetero-nanofibers for Boosting Visible-Light-Driven Photocatalytic Ammonia Synthesis and Antibiotic Removal.

Synergistic engineering of energy band alignment and interfacial electric field distribution is essential for photocatalyst design but is still challenging because of the limitation on refined regulation in the nanoscale. This study addresses the issue by employing surface modification and thermal-induced phase transformation in Bi2MoO6/BixOyIz hetero-nanofiber frameworks. The energy band alignment switches from a type-II interface to a Z-scheme contact with stronger redox potentials and inhibited electron traps, and the optimized built-in electric field distribution could be reached based on experimental and theoretical investigations. The engineered hetero-nanofibers exhibit outstanding visible-light-driven photocatalytic nitrogen reduction activity (605 μmol/g/h) and tetracycline hydrochloride removal rate (81.5% within 30 min), ranking them among the top-performing bismuth series materials. Furthermore, the photocatalysts show promise in activating advanced oxidants for efficient organic pollutant degradation. Moreover, the Bi2MoO6/Bi5O7I hetero-nanofibers possess good recycling stability owing to their three-dimensional network structure. This research offers valuable insights into heterojunction design for environmental remediation and industrial applications.

Synthesis and Characterization of WO3/BiVO4/Graphene Ternary Nanocomposites for the Photodegradation of Methlyene Blue and Tetracycline

In this study, a hydrothermal method was employed to synthesize the ternary nanocomposites comprising WO3/BiVO4/Graphene, all driven by visible light. The characteristics of these nanocomposites were interpreted through techniques such as UV–Vis, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and photoluminescence spectroscopy (PL). The enhanced performance of the composite, attributed to its heightened capability for separating charge carriers, outperformed that of the individual semiconductor components. The PL results validated the composite's improved charge separation. The nanocomposites have weaker PL peaks, indicating slower e−/h+ recombination. The balanced concentrations of the mixed semiconductors in the composite affected both PL intensity and photodegradation efficiency. The photocatalytic degradation of methylene blue (MB) and tetracycline (TC) was observed by nanocomposites. The heterogeneous nanocomposite WOBV/G-5 with 0.03 mg graphene content has a better photocatalytic activity for both MB (63 %) and TC (80 %) than other concentrations. It has also been investigated using TOC and COD analysis. Moreover, zeta potential analysis and pH analysis have been done to check the conductivity of optimized photocatalyst. Additionally, to check the stability of WOBV/G-5 photocatalyst, recyclability test that shows 58 % degradation rate after five cycles and analysis of XRD after recyclability have also been performed. Role of active species (h+, O2−, and OH.) was observed by using different scavengers (EDTA, BQ, and IPA) in trapping experiment that plays a vital role in photocatalytic degradation process.

Microsphere structure enhances the photocatalytic performance of TiO2-CdS heterojunction

Herein, a novel TiO2 microsphere structure (TMS) was reported for the first time, formed through the self-assembly of TiO2 nanocone monomers. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis revealed that the microsphere structure substantially boosted the growth density of TiO2 nanocone monomers, facilitating CdS loading. Photocurrent characterization revealed that CdS/TMS heterojunction (CTMS) exhibited a heightened photocurrent response than that of our previously reported CdS/TiO2 nanocone arrays (CTNC), suggesting that the microsphere structure enhanced photon absorption and electron-hole pair transmission channels for TiO2-CdS heterojunctions per unit area. Photocatalytic degradation experiments of tetracycline (TC) demonstrated that CTMS exhibited superior performance, achieving the degradation of 84.9 % of TC within 45 min, high than that of our previously reported CTNC (69.9 %). First-order kinetic fitting indicated that the degradation kinetic constant of CTMS (0.042 min−1) was 1.45 times higher than that of our previously reported CTNC (0.029 min−1).

Enhanced Photocatalytic Degradation of Tetracycline by Magnetically Separable g-C3N4-Doped Magnetite@Titanium Dioxide Heterostructured Photocatalyst

Residual drug pollutants in water environments represent a severe risk to human health, so developing a cheap, environmentally friendly, and effective photocatalyst to deal with them has become a hot topic. Herein, a magnetically separable Fe3O4@TiO2/g-C3N4 photocatalyst with a special heterojunction structure was fabricated, and its photocatalytic performance was assessed by degrading tetracycline (TC). Compared to Fe3O4@TiO2, the synthesized Fe3O4@TiO2/g-C3N4 exhibited superior TC degradation performance, which was primarily ascribed to the heterojunction formed between TiO2 and g-C3N4 and its ability to enhance the visible light absorption capacity and reduce the photoinduced electron/hole recombination rate. Moreover, a free radical capture experiment further confirmed that·O2− and h+ are the predominant components in the TC degradation reaction. Under UV–Vis irradiation, the TC degradation rate escalated to as high as 98% within 120 min. Moreover, Fe3O4@TiO2/g-C3N4 was demonstrated to be easily recovered by magnetic separation without any notable loss even after five cycles, showing exceptional stability and reusability. These findings indicate that Fe3O4@TiO2/g-C3N4 is a promising photocatalyst for environmental remediation that may provide a sustainable approach to degrading antibiotic pollutants in wastewater.

Construction of Z‐scheme 1T/2H‐MoS2/CdS for improving photocatalytic degradation of antibiotic residues

Abstract1T/2H‐MoS2/CdS composite was effectively prepared by a two‐step hydrothermal method, which greatly improved the photocatalytic degradation efficiency of tetracycline hydrochloride and photocatalytic cycle stability compared with pristine 1T/2H‐MoS2. The highest photodegradation efficiency of 70.8% is achieved when the molar ratio of 1T/2H‐MoS2 to cadmium sulfide is 1:4. The capture experiment indicates that hydroxyl radical (⋅OH) and superoxide radical (⋅O2−) play a role in the photocatalytic degradation process. A Z‐type heterojunction may be formed on the 1T/2H‐MoS2/CdS composite based on a series of analyses, which improves the photocatalytic performance effectively via expanding the range of light response and promoting the separation of photogenerated electrons and holes. This work provides an alternative to constructing novel Z‐scheme photocatalysts with high performance in the absence of noble metals.

Molten salt induced strong interaction between Co3O4 and montmorillonite for the promoted peroxymonosulfate activation toward tetracycline degradation

Cobalt-based materials exhibit great premises for activating peroxymonosulfate (PMS) toward water remediation. Generally, active Co species are anchored on the surface of supports to improve the utilization efficiency, yet the stability of the catalyst is difficult to resolve due to the weak interaction between the active species and the support. Herein, a molten salt method is employed to reinforce the interfacial interaction between Co3O4 and montmorillonite (Mt) support. The use of molten Na3PO4 can mitigate the dehydroxylation process of Mt, and thus the electronic structure of Co3O4 NPs can be regulated by the surface hydroxyl species more efficiently. Consequently, the prepared Co3O4/Mt displays an enhanced CoII/CoIII ratio, and the degradation of tetracycline (TC) could reach 99% in 7 min by the PMS-based advanced oxidation process. Meanwhile, the TC removal efficiency can still reach 96% after 8 cycles, and the Co ion leaching is over 10 times lower as compared with the catalyst prepared not using the molten salt. This study highlights the significance of the molten salt method for enhancing the strong interfacial interaction, which is crucial to regulating the nature of supported catalysts, and provide satisfactory Co-based catalyst for PMS activation toward TC degradation.

Metal–Organic Framework Fe-BTC as Heterogeneous Catalyst for Electro-Fenton Treatment of Tetracycline

This study explores the use of the iron-containing metal–organic framework (MOF), Basolite®F300, as a heterogeneous catalyst for electrochemically-driven Fenton processes. Electrochemical advanced oxidation processes (EAOPs) have shown promise on the abatement of recalcitrant organic pollutants such as pharmaceuticals. Tetracyclines (TC) are a frequently used class of antibiotics that are now polluting surface water and groundwater sources worldwide. Acknowledging the fast capability of EAOPs to treat persistent pharmaceutical pollutants, we propose an electrochemical Fenton treatment process that is catalyzed by the use of a commercially available MOF material to degrade TC. The efficiency of H2O2 generation in the IrO2/carbon felt setup is highlighted. However, electrochemical oxidation with H2O2 production (ECO-H2O2) alone is not enough to achieve complete TC removal, attributed to the formation of weak oxidant species. Incorporating Basolite®F300 in the heterogeneous electro-Fenton (HEF) process results in complete TC removal within 40 min, showcasing its efficacy. Additionally, this study explores the effect of varying MOF concentrations, indicating optimal removal rates at 100 mg L−1 due to a balance of kinetics and limitation of active sites of the catalysts. Furthermore, the impact of the applied current on TC removal is investigated, revealing a proportional relationship between current and removal rates. The analysis of energy efficiency emphasizes 50 mA as the optimal current, however, balancing removal efficiency with electrical energy consumption. This work highlights the potential of Basolite®F300 as an effective catalyst in the HEF process for pollutant abatement, providing valuable insights into optimizing electrified water treatment applications with MOF nanomaterials to treat organic pollutants.

Conjugating HA bundles with ZIF-8 for catalytic degradation of tetracycline and antibacterial capacity

The overused of antibiotics had led to major environmental issues and drug-resistant bacteria, which inevitably harmed the environment and public health. In this work, in order to obtain environmentally friendly bi-functional materials to combat with residual antibiotics and bacterial contamination, ZIF-8, a typical Zn based zeolitic imidazolate framework (ZnZIF) with excellent chemical stability, was conjugated to hydroxyapatite nanowire bundles (HAnBs) by a simple in-situ synthesis. The obtained ZnZIFs@HAnBs was characterized by SEM, EDS, XPS, FT-IR, XRD and BET. The effects of catalysts, catalyst dosage, TC initial concentration, PMS concentration and pH on TC degradation were investigated. Notably, ZnZIFs@HAnBs (94.0 %) exhibited excellent degradation effect of tetracycline (TC) within 15 min, which was 1.7 and 5.2 times than that of ZIF-8 (55.9 %) and HAnBs (18.1 %) under optimal conditions, respectively. Moreover, after recycling 10 times, the degradation rate still more than 86.8 %. The degradation mechanism was confirmed by free radical quenching experiment coupling with electron paramagnetic resonance (EPR), and the 1O2 and O2•- were the major reactive oxygen species in TC degradation. Furthermore, it presented excellent antibacterial activity (95.0 %) against E. coli and S. aureus, which was attributed to the synergistic effect of sustained release of Zn2+ and phosphate in ZnZIF@HAnBs. In summary, an eco-friendly bi-functional materials of HA nanowire bundles could be synthesized by simple strategy, and it could be applied in the fields of environmental remediation, as well as in treatment of antibiotic and bacterial pollution.

Fabrication of 2D/2D InVO4/BiVO4 Heterojunction with Synergistic Effects for Enhanced Photocatalytic Degradation and Photoelectrochemical Applications

In this work, we report a novel 2D/2D InVO4/BiVO4 heterojunction nanocomposite constructed through a simple hydrothermal approach. The morphological analysis demonstrated that BiVO4 nanoflakes to be anchored on the surface of InVO4 nanosheets. The InVO4/BiVO4 heterojunction nanocomposite displayed increased light absorption promoting their visible light harvesting. The photoactivity of the prepared InVO4/BiVO4 heterojunction was explored for the degradation of tetracycline (TC) under light treatment. InVO4/BiVO4 heterojunction exhibited superior photocatalytic activity than that of bare InVO4 and BiVO4. The as-prepared InVO4/BiVO4 heterojunction photoanodes achieved a higher photocurrent density of 60 μA/cm2 under illumination in 0.5 M Na2SO4 electrolyte. The enhanced photoelectrochemical performance is attributed to the synergistic effect and interface formation between InVO4 and BiVO4 and can effectively promote the charge separation and transfer of photoinduced carriers in heterojunction.

Analysis of Antibiotics in Milk from Smallholder Farmers from Kenya Shows Traces Above the Recommended Maximum Residue Limits

Antimicrobial resistance (AMR) is rising globally and is likely to cause more deaths because of antibiotic-resistant microbial infections and antibiotic residues in animal foods and products as a result of misuse of antibiotics in dairying. Thus, we determined the presence and quantities of sulfonamide, tetracycline, and beta-lactam drug residues in milk sampled in Nyandarua, Meru, and Kiambu counties in Kenya using the Charm TRIO® test kit and liquid chromatography (LC) coupled to the triple quadrupole mass spectroscopy (MS) (LC-MS/MS). The TRIO® test kit showed dicloxacillin as the most prevalent at 9.3%, followed by penicillin and cloxacillin at 3.7% each, and nafcillin at 0.9% among the beta-lactams. Among the tetracyclines, demeclocycline and tigecycline were the most prevalent at 10.3% each, followed by oxytetracycline at 9.3%, chlortetracycline at 7.5%, and doxycycline at 3.7%, while sulfaquinoxaline was the only sulfonamide drug detected at 4%. The LC-MS/MS detected the presence of all the tested β-lactam and tetracycline antimicrobial traces and all sulfonamide drugs except sulfamerazine in all three counties. All the tetracycline antibiotics recorded between 3 and 10.5% of antibiotic residues above the recommended Maximum Residue Levels (MRLs) in milk across all three counties, with beta-lactam antibiotics recording between 2 and 33.3%, indicating their misuse in the three counties. Sulfaquinoxaline was the only sulfonamide detected in milk samples above the recommended MRLs, indicating sulfonamides are less used in those counties. Therefore, it is important to enforce a regulatory framework to control antibiotic use in livestock to minimize potential health risks related to their traces in the foods.

β-NaGdF4:Yb,Er@CdS/MWCNTs photocatalysts with efficient interfacial energy migration for full-spectrum light-driven antibiotic degradation: Construction and DFT insight

Currently, upconversion nanoparticles (UCNPs) based photocatalysts have been extensively developed to improve solar energy utilization. However, the mechanisms underlying interfacial energy migration of upconversion photocatalyst remain unclear. Herein, a promising composite photocatalyst with complementary properties is designed by integrating β-NaGdF4:Yb3+/Er3+ (NGFYE), CdS and multi-walled carbon nanotubes (MWCNTs). The morphology, structure and chemical properties of NGFYE@CdS/MWCNTs ternary photocatalyst are characterized. In addition, the existence of Förster resonance energy transfer process in NGFYE@CdS/MWCNTs photocatalysts, i.e., the migration of excitation energy from Er3+−4S3/2 excitation level and higher excitation level (e.g., Er3+−2H11/2) to CdS nanoparticles, was further confirmed by density functional theory (DFT) calculations. The optimized NGFYE@CdS/MWCNTs photocatalyst presents 71.65 % and 35.29 % degradation of tetracycline hydrochloride (TCH) and ciprofloxacin (CIP) under λ ≥ 800 nm irradiation for 3 h, respectively. This work not only illustrates the interfacial energy migration mechanism between NGFYE and CdS, but also provides insights for the rapid construction of heterojunction materials with efficient energy transfer interfaces.