Chlortetracycline Research Articles

Comprehensive Study on Amino‐Modified Salix Wood Powder Membranes: Preparation, Adsorption Mechanism and Desorption Conditions for Efficient Chlortetracycline Removal

The wastewater of Chlortetracycline (CTC) poses a threat to the balance of aquatic ecosystems, promoting the formation and dissemination of antibiotic‐resistant bacterial strains in the aquatic environment. Moreover, such pollution can directly or indirectly affect human health through water sources, exacerbating the issue of antibiotic resistance. In response to this pollution challenge, Amino‐modified salix wood powder membrane(ASPPM) was prepared by phase transition and wet spinning techniques, aimed at removing CTC from water bodies. Adsorption experiment results show that the ASPPM maximum adsorption capacity for CTC is 458.99 mg/g. In the desorption process, the highest desorption rate of ASPPM for CTC was 79.65%. By fitting pseudo‐first‐order and pseudo‐second‐order kinetic models, it is found that the adsorption process of ASPPM on CTC is predominantly chemical adsorption. By fitting three isotherm models, it is found that the adsorption behavior of ASPPM on CTC is more in accordance with the Freundlich isotherm model, indicating multilayer adsorption on heterogeneous surfaces. The preparation of ASPPM study not only transforms renewable biomass materials into effective tools for environmental purification but also offers a cost‐effective new approach for sustainable environmental management, expanding the application of biomass materials in the field of environmental protection.

Quaternary Ammonium Salt-Derived Carbon Dots for Antibacterial Efficacy and Tetracycline Sensing

Bacterial infections pose a significant threat to global health, necessitating the development of novel antibacterial materials. Tetracycline antibiotics (CTC, OTC, TC) are low-cost and widely abused in recent years. However, they were easily absorbed by the human body and long-term exposure to tetracycline could contribute to some adverse reactions and diseases. So there is a need for novel antimicrobial agents and a rapid, sensitive detection method of tetracycline antibiotics. In this study, we synthesized three carbon dots (CDs1, CDs2, CDs3) from quaternary ammonium salts via a hydrothermal method. Antibacterial assays against Staphylococcus aureus and Escherichia coli demonstrated their potent antibacterial activity with minimum inhibitory concentrations(MIC) determined as 39 μg/mL, 78 μg/mL, and 9.8 μg/mL, respectively. Notably, CDs3 exhibited the highest antibacterial effectiveness, attributed to its smaller size and higher chlorine content compared toCDs1 and CDs2. Additionally, CDs1, characterized by its high fluorescence quantum yield and stability, demonstrated remarkable specificity and robust anti-interference capabilities in detecting tetracycline antibiotics, including chlortetracycline (CTC), oxytetracycline (OTC), and tetracycline (TC). Leveraging the internal filtration effect mechanism, CDs1 exhibited detection limits of 0.18 μmol/L for CTC, 0.15 μmol/L for OTC, and 0.13 μmol/L for TC, respectively. The effectiveness of this detection method was further confirmed through validation in real milk samples, confirming the practical utility of CDs1 in food safety testing. The low toxicity of carbon dots were synthesized using a simple one-step hydrothermal method, which was fast, cost-effective, and easy to achieve large-scale production. Our findings underscore the potential of CDs derived from quaternary ammonium salts, demonstrating promising performance in antibacterial applications and providing insights into food safety testing methodologies.

Upcycling of steel slag to activate persulfate for the degradation of chlortetracycline hydrochloride: Performance and mechanism

ABSTRACT Steel slag has great potential as an Fe-based heterogeneous Fenton-like catalyst because of its high iron content and low cost. However, the iron compounds are often encapsulated by calcium or silicon compounds in the steel slag. Herein, steel slag powder was acid-modified with salicylic acid to remove some Ca–Si compounds and thus expose more iron active sites. The results showed that the calcium content significantly decreased from 36.33 to 20.54% after modification, and more transition metals of Fe and Mn with catalytic activities were exposed simultaneously. During the activation of peroxysulphate, the conversion of Fe(Ⅱ) to Fe(Ⅲ) occurs and large amounts of •OH and 1O2 are produced as the main reactive oxygen species. The removal rates of CTC and TOC are 93.42 and 46.05%, respectively, and a degradation process may also be inhibited by CO32−, H2PO4−, and humic acid (HA). The degradation pathways of CTC mainly include both dechlorination and demethylation. In addition, salicylic acid-modified steel slag shows good repeated usability, and its removal ability is maintained at higher than 80% after four times of recycling. This study provides a new idea for designing an efficient and cheap catalyst to treat organic wastewater.

N-doped silicon QDs: facile synthesis and application as sensor for discrimination and selective detection of oxytetracycline, tetracycline, and chlortetracycline in foods.

Nitrogen-doped silicon quantum dots (N-SiQDs) with a quantum yield of up to 37.8% were simply synthesized using inexpensive and readily available silica as the silicon source. Based on the internal filter effect (IFE), both oxytetracycline (OTC) and tetracycline (TC) can effectively and rapidly quench the fluorescence of N-SiQDs at 380nm. However, interestingly, the accompanied formation of a new complex of OTC with N-SiQDs could emit fluorescence at 505nm, resulting in a gradualcolor change of the sensor from blue to yellow under the irradiation of 365nm UV lamp. Thus, a visual semi-quantitative detection of OTC was realized. In contrast, based on the aggregation-induced luminescence (AIE) effect, chlortetracycline (CTC) linearly enhanced the fluorescence intensity of N-SiQDs, which can effectively reduce other interfering signals, and can significantly improve the sensitivity and selectivity. Hence, a low limit of detection of 47nM for CTC was obtained. On account of the three distinctly different phenomena and mechanisms of N-SiQDs sensor exhibited towards OTC, TC, and CTC, a novel sensing method for discriminating and selectively measuring OTC, TC, and CTC in food was developed.

Coated oregano essential oil and cinnamaldehyde compounds supplementation improves growth performance, enhances immune responses, and inhibits cecal Escherichia coli proliferation of broilers.

Plant essential oils are unstable due to high volatility and easy oxidation, while microencapsulation provides a potentially effective strategy for increasing the stability of natural essential oils and preserving their function. This study examined the effects of feeding coated oregano essential oil and cinnamaldehyde (COEC) compounds on growth, immune organ development, intestinal morphology, mucosal immune function, and the cecal microbiota populations of broilers. Three hundred one-day-old male Arbor Acres broiler chicks were organized into 5 groups: 1) negative control fed basal diet alone (NC), 2) positive control receiving basal diet plus 50mg/kg of chlortetracycline (CTC), 3) basal diet plus 150mg/kg COEC (COEC150), 4) plus 300mg/kg COEC (COEC300), and 5) plus 450mg/kg COEC (COEC450). The supplement trial was continued for 42 d. The results showed that CTC, COEC300, and COEC450 treatments decreased the feed conversion ratio of broilers both in the starter and whole experiment phases, increased the height of jejunal villi at 21 d and the number of goblet cells and IgA-producing cells at 21 or 42 d compared with NC group (P < 0.05). Members of the COEC300 treatment group had a higher thymus weight index and jejunum length index than birds of NC or CTC groups at 21 d (P < 0.05). CTC and all COEC treatments decreased malondialdehyde content in jejunal mucosa at 42 d (P < 0.05). The population of Escherichia coli (E. coli) in the cecal digesta at 21 d was lower in the CTC, COEC300, and COEC450 treatment groups compared with the NC group (P < 0.05). In contrast to the CTC group, COEC supplementation dose-dependently accelerated body weight gain, improved jejunal morphology, decreased malondialdehyde content in jejunal mucosa, increased numbers of jejunal goblet cells and IgA-producing cells, and decreased the E. coli population in cecal digesta at 21 or 42 d (P < 0.05). Thus, we concluded that feeding broiler chickens with 300 or 450mg/kg in antibiotic-free diets can improve growth performance, enhance immune responses, and inhibit the proliferation of cecal pathogenic bacteria.

Z-Scheme Ag2S-Ag-In2O3 Heterostructure with Efficient Antibiotics Removal under Natural Sunlight.

The widespread distribution of antibiotics in natural waters is a great threat to human health. Photocatalytic degradation is an environmentally friendly technology to remediate antibiotic-polluted waters, driven by endless solar energy. Herein, a Z-scheme Ag2S-Ag-In2O3 heterostructure photocatalyst is prepared to remove antibiotics under environmental conditions. Under natural sunlight (light intensity: ∼78 mW/cm2) irradiation, the optimal Ag2S-Ag-In2O3 (10-ASAIO) exhibits considerable performance for decomposing diverse antibiotics, including norfloxacin (NOR), tetracycline hydrochloride, sulfisoxazole, ciprofloxacin, chlortetracycline hydrochloride, and ofloxacin. The NOR photodegradation rate constant of 10-ASAIO reaches 0.025 min-1, which is 12.50, 5.00, and 6.25 times higher than that of In2O3 (0.002 min-1), Ag-In2O3 (0.005 min-1), and Ag2S-In2O3 (0.004 min-1), respectively. This performance of the 10-ASAIO photocatalyst for decomposing NOR under natural sunlight exceeds most of the previously reported photocatalysts under a xenon lamp. Particularly, due to the intermittency of natural sunlight, a light-emitting diode (LED) lamp (light intensity: 5.1 mW/cm2) is also used as a light source, and 72.20% of NOR can be degraded with irradiation for 12 h. The effects of many water characteristics (water bodies, coexisting inorganic anions, pH, and humic acid) on the degradation performance of 10-ASAIO have been investigated, which exhibits stable degradation efficiency in variable aquatic environments. A 10-ASAIO catalyst-coated frosted glass sheet is fabricated to settle the problem of recovery of powder photocatalysts, and the immobilized catalyst shows outstanding activity and stability to decompose NOR. The photocatalytic mechanism and pathway of degrading NOR over 10-ASAIO have also been systemically investigated and proposed. The ecotoxicity (phytotoxicity and biotoxicity) of the 10-ASAIO photocatalyst and treated NOR solution have been tested by their toxic effects on cabbage seeds and Staphylococcus aureus (S. aureus). This work provides a feasible photocatalytic system for environmental pollutant remediation under natural sunlight or an LED lamp.

Biosurfactant-mediated transport of tetracycline antibiotics in saturated porous media: Combined effects of the chemical properties of contaminants and solution chemistry conditions

The mobility of tetracycline antibiotics (TCs) in saturated aquifers is possibly affected by the presence of biosurfactants, which are widespread in the aquatic/soil environments. This study investigated the mobility characteristics of various tetracyclines—specifically tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC)—within quartz sand columns in the presence of rhamnolipid, a common biosurfactant. Exogenous rhamnolipid significantly inhibited the transport of the three TCs over the pH range of 5.0–9.0 (e.g., the mass of retained TC, OTC, and CTC increased from 32.6 %, 26.9 %, and 39.2 % (in the absence rhamnolipid) to 39.4 %, 38.9 %, and 51.7 % (in the presence of rhamnolipid), respectively). This observation could be attributed to the bridging effects of this biosurfactant. Specifically, the hydrophilic head of rhamnolipid molecules is likely associated with the surfaces of sand grains through surface complexation and/or hydrogen bonding interactions. Accordingly, the hydrophobic moieties of the deposited rhamnolipid molecules (i.e., the aliphatic chains) interact with the hydrophobic groups of TCs molecules via hydrophobic interactions. Interestingly, the extent of the inhibitory effect on CTC mobility was greater than that on OTC and TC, which was related to the different hydrophobic characteristics of the three antibiotics. Furthermore, the inhibitory effect of rhamnolipid on the transport of TCs diminished as the pH of the background solution increased. This observation was attributed to the weakened bridging effects, resulting from the reduced deposition of the biosurfactant on the sand surfaces. Additionally, the cation-bridging mechanism involved in the retention of TCs in the addition of rhamnolipid when the background electrolyte was Ca2+ (i.e., Ca2+ ions served as bridging agents between the deposited rhamnolipid molecules and TCs). The insightful findings enhance our understanding of the critical roles of biosurfactants in influencing the environmental dynamics and ultimate fate of conventional antibiotic pollutants within groundwater systems.

Polymers Enhance Chlortetracycline Hydrochloride Solubility

Chlortetracycline hydrochloride (CTC) is a broad-spectrum tetracycline antibiotic with a wide range of antibacterial activities. Due to low solubility, poor stability, and low bioavailability, clinical preparation development is limited. We sought to improve these solubility and dissolution rates by preparing solid dispersions. A hydrophilic polymer was selected as the carrier, and a solid dispersion was prepared using a medium grinding method, with samples characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), and particle size distribution (PSD). To maximize CTC solubility and stability, different polymer types and optimal drug-to-polymer ratios were screened. The solubility of optimized povidone K30 (PVPK30) (1/0.75, w/w)-, hydroxypropyl-β-cyclodextrin (HP-β-CD) (1/2, w/w)-, and gelatin (1/1, w/w)-based solid dispersions was 6.25-, 7.7-, and 3.75-fold higher than that of pure CTC powder, respectively. Additionally, in vitro dissolution studies showed that the gelatin-based solid dispersion had a higher initial dissolution rate. SEM and PS analyses confirmed that this dispersion had smaller and more uniform particles than PVPK30 and HP-β-CD dispersions. Therefore, successful solid polymer dispersion preparations improved the CTC solubility, dissolution rates, and stability, which may have potential as drug delivery systems.

Effective removal of tetracycline antibiotics from water by in-situ nitrogen-doped porous biochar derived from waste antibiotic fermentation residues

This study explored the utilization of waste oxytetracycline fermentation residue (OFR), abundant in nitrogen and organic matter, to prepare in-situ nitrogen-doped porous biochar (activated OFR derived biochar, AOBC) through a coupled pyrolysis process, and investigated the removal of tetracycline antibiotics (TCs) from water with the prepared AOBCs. The physicochemical characterization results showed the characterizations of abundant nitrogen functional groups, high specific surface area (1960.38 m2/g), and the high microporosity (61.6%) for AOBCs. At 25 ℃, the maximum adsorption capacity calculated by Langmuir model of AOBC-3-600 for tetracycline hydrochloride (TC), chlortetracycline hydrochloride (CTC), oxytetracycline hydrochloride (OTC), and doxycycline hydrochloride (DOC) reached 473.00, 293.28, 220.61, and 282.72mg/g, respectively. The superior fit of the pseudo-second-order and Langmuir models indicated that the adsorption mechanism involved both the physical effect (pore filling) and chemical interactions (electrostatic attraction, hydrogen bonding, π-π interaction, and Lewis acid-base interaction). Environmental risk assessments substantiated the absence of residual oxytetracycline and antibiotic resistance genes in the prepared biochar, indicating its application safety. This research provides a sustainable route to simultaneously treat the antibiotic contamination in water and rationally utilize antibiotic fermentation residues.

Enhanced piezo-photocatalytic activity of ZnS/Fe2O3: Benefit from type I junction and weak water flow-induced piezoelectric polarization

Photocatalysis is considered to be a sustainable and less polluting environmental purification technology, however, the limited photogenerated charge separation efficiency and light absorption hinder its large-scale application. Encouragingly, piezocatalysis is proposed as an emerging and appealing strategy to drive the migration and separation of photoinduced carriers. Nevertheless, the source of piezocatalysis is usually derived from high energy-consuming ultrasonic vibration. Herein, we realize superior piezo-photocatalytic chlortetracycline hydrochloride degradation performance stimulated by low-frequency water flow-driven piezoelectric polarization of I-type ZnS/Fe2O3 junction. The integration of Fe2O3 is beneficial to extend the light absorption from ultraviolet region to visible range and boost the charge separation efficiency of ZnS/Fe2O3. Meanwhile, the piezoelectric polarization triggered by weak water flow further promotes the directional separation of photogenerated carriers. With all these merits, the optimized ZnS/Fe2O3 shows a piezo-photocatalytic chlortetracycline hydrochloride (CTC) degradation rate of 73.2 % within 20 min, which is 2.8 and 2.1 times that of Fe2O3 and ZnS, respectively, and 17.4-fold and 1.1-fold that of single stirring and light, respectively. This work provides a feasible guidance for designing efficient piezo-photocatalysts for in-situ purification of wastewater in natural environmental with effective visible light responsiveness and sensitivity to weak mechanical stress.

Efficient photocatalytic degradation of tetracycline and its derivatives by green recyclable PAN/Bi2WO6/Cu2O nanofiber membrane

The use of tetracycline antibiotics in industry, healthcare, animal husbandry, agriculture, and aquaculture has resulted in excessive concentrations in a variety of aquatic environments. In this work, PAN/Bi2WO6/Cu2O nanofibrous membranes (PBC ENMs) with photocatalytic degradation performance were successfully prepared using electrostatic spinning technique, and the morphology of catalysts and PBC ENMs were characterised by SEM, BET and UV–Vis. The results demonstrated that the prepared nanofibrous membranes could achieve 97.05 % photocatalytic degradation of TC under visible light, and the degradation efficiencies of its derivatives, chlortetracycline (CTC) and oxytetracycline (OTC), reached 90.87 % and 85.12 %, respectively. Free radical trapping experiments and mechanistic analyses showed that·O2– is the main active factor in the degradation process. The highest degradation rate of 97.05 % was achieved at initial pH = 7.2.PBC ENMs adsorbed above 87.5 % after six cycles of the experiment. The highest degradation rate of 97.05 % was achieved at initial pH = 7.2 PBC ENMs adsorbed above 87.5 % after six cycles of the experiment. Based on the above advantages, the preparation process of PBC ENMs is simple, low-cost and has good catalytic effect, which provides a simple and efficient treatment means for the treatment of TC wastewater and has a broad application prospect.

Determination of Tetracycline Group Antibiotics Residues in the Tigris River and Agricultural Lands Fed by Tigris River and Reduction of Unconscious Use of Antibiotics

The recent increase in environmental pollutants is contaminating important natural resources and causing irreversible damage. Due to the limitations of traditional treatment techniques, studies on the problem of micro pollutant contamination of water resources have increased significantly. Antibiotics used in medicine and veterinary medicine cause significant pollution of water resources as residues of these contaminants remain unchanged in the aqueous environment. This has recently been recognised as a global environmental health threat. The ecosystem is vulnerable to residues of these contaminants from agriculture and aquaculture. In this study, the presence of tetracycline group antibiotics, the most commonly used in veterinary medicine, was determined in the Tigris river. This is the first study to date in which antibiotics from the tetracycline group have been identified in the Tigris river. Water samples were taken from 16 different points (80 samples) along the river. Sampling points were grouped as abattoirs, livestock markets, farmland, cafes and bridges near settlements. The samples were analysed for the presence of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC). With a concentration range of 0.037 to 1.756 ng/L, oxytetracycline was found in 14 of the 16 sites. A concentration of 0.004–0.014 ng/L of tetracycline was found in five samples. Chlortetracycline was found in six samples, with concentrations ranging from 0.015 to 0.097 ng/L. According to the study, the tetracycline family of antibiotics was found in the water samples, and oxytetracycline was present in the highest concentrations in most of them.

Ratiometric fluorescence sensing and discrimination of tetracycline analogs by using coumarin-embedded Eu-MOF nanosensor

As widely used antibiotics, tetracycline residues exist in food and environmental media, which pose certain hidden dangers and negative effects on public health. Therefore, the sensing and discrimination of tetracycline analogs (TCs) have great significance for improving food safety and preventing environmental pollution. Herein, a 7-hydroxycoumarin-3-carboxylic acid-embedded Eu-MOF (HC@Eu-MOF) material was constructed and then developed for the detection of TCs. Upon addition of TCs, the synthesized sensor displays opposite fluorescence changes at two different wavelengths due to the simultaneous presence of the inner filter effect (IFE) and the antenna effect (AE), and achieves a stable ratio signal response within 90 s. In addition, six important tetracycline analogs, including chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TC), metacycline (MC), doxycycline (DC) and demeclocycline (DMC) can be discriminated with 100 % accuracy through the principal component analysis even in extremely complicated mixtures. Further, a smartphone-assisted portable device was applied for visual sensing of TCs. The as-developed platform possessed the characteristics of simple synthesis, fast response, high sensitivity, and high stability, which further lays a further foundation for the on-site visual detection and discrimination of TCs in real samples.

In vitro versus cryo-induced capacitation of bovine spermatozoa, part 3: Compositional and molecular changes to the plasma membrane

The aim of this study was to assess the level of membrane cryodamage through the levels of selected capacitation and apoptosis-associated proteins, together with compositional membrane changes in capacitated (CAP), cryopreserved (CRYO) and non-capacitated bovine spermatozoa (CRTL). Sperm kinetic parameters were analyzed by the computer assisted sperm analysis (CASA) while the capacitation patterns were examined with the chlortetracycline (CTC) assay. In the case of DNA integrity, sperm chromatin structure assay and aniline blue staining were used. For the quantification of fatty acid content gas chromatography was performed. Using Western blotting the expression of capacitation (protein kinase C – PKC; phospholipases A2 and Cζ – PLA2, PLCζ; soluble adenylyl cyclase 10 – sAC10) and apoptosis-associated (apoptosis regulator Bax; B-cell lymphoma 2 – Bcl-2; caspase 3) proteins were evaluated. Data indicate a significant decline (p < 0.0001) of sperm kinetic parameters and higher occurrence (p < 0.0001) of DNA fragmentation in the CRYO group. CTC assay revealed a significant increase of acrosome-reacted spermatozoa in the CRYO group when compared to others. Compositional changes in the sperm membrane were visible as a notable decline of docosahexaenoic acid (p < 0.0001) associated with a significant decrease of membrane cholesterol (p < 0.05) and proteins (p < 0.0001) in the CRYO group while the amount of palmitic, stearic, oleic, and linoleic acid increased (p < 0.0001) significantly. Protein expression of all capacitation-associated proteins (PKC, PLA2, PLCζ, sAC10) was significantly down-regulated (p < 0.001; p < 0.0001) in the CRYO group. Relative quantification of apoptosis-associated proteins revealed increased Bax and decreased Bcl-2 levels in the CRYO group, except for caspase-3, which remained without significant changes.

Enhanced visible light responsive piezoelectric photocatalysis based on Bi2S3 coated BaTiO3 nanorods heterostructures

Although the presence of the built-in electric field will solve the problem of carrier complexation in photocatalytic systems to some extent. However, free carriers will quickly shield the stabilized electric field and lose its effect. Therefore, how to introduce the dynamic piezoelectric field into the photocatalytic system has become an imminent problem. Herein, we developed an overcoated, visible light responsive, piezoelectric-assisted photocatalytic system by depositing Bi2S3 photocatalysts with a narrow-band system onto the surface of highly piezo-responsive BaTiO3 nanorods (BTO NRs). The heterojunction structure, bound by Bi-O chemical bonding, enhances carrier transport efficiency under the influence of the piezoelectric field. In the degradation experiments, the first-order rate constant for the degradation of chlortetracycline hydrochloride (CTC) in the BTO NRs/Bi2S3 system with the optimal complex ratio was 0.0276 min−1, which was 3.1 and 7.8 times higher than that of BTO NRs and Bi2S3, respectively. Additionally, we deduced the degradation pathways of CTC through a combination of Density functional theory (DFT) calculations and Liquid Chromatograph Mass Spectrometer (LC-MS), evaluating the toxicity of the intermediates. This complex system, featuring a highly photo-responsive semiconductor as a photo-acceptor deposited on a piezoelectric semiconductor surface providing a dynamic built-in electric field, enhances carrier separation efficiency under optimal light energy utilization conditions. These findings present novel and effective strategies for addressing two primary challenges in photocatalytic systems: low spectral utilization and significant photogenerated carrier complexation.

Enhanced adsorption-photocatalysis synergy by S-scheme In-MOG/carbon doped ZnO for rapid chlortetracycline removal: Exploring synergistic mechanisms, environmental implications and continuous flow applications

Suitable material design is the bottleneck for synergistic adsorption-photocatalysis reaction system for chlortetracycline (CTC) remediation. Herein, a S-scheme In-MOG/carbon doped ZnO (In-MOG/C-ZnO) was prepared to effectively enhance the adsorption-photocatalysis achieving the CTC removal of 94.01 % in 40 min and displaying excellent immunity to interference. Furthermore, the integrative effect with mutual amplification of adsorption and photocatalysis, the possible CTC degradation pathways, and the potential toxicity evaluation of CTC intermediates were elaborated. Importantly, the shapeable MZ@CBC was synthesized by immobilizing In-MOG/C350-ZnO with chitosan/bacterial cellulose (CBC) as the carrier matrix to effectively improve powder material recyclability, which was further evaluated for the prospect of large-scale application through the continuous removal of contaminants in a CAP reactor. The current study may serve as a reference perspective for engineering design of materials for bifunctional adsorption-photocatalysis system as well as large-scale continuous-flow wastewater remediation.

Insight into photocatalytic chlortetracycline degradation by WO3/AgI S-scheme heterojunction: DFT calculation, degradation pathway and electron transfer mechanism

The construction of S-scheme heterojunction with excellent redox ability holds promising prospects for photocatalytic environment remediation. However, the rationally design of the heterojunction interface to achieve efficient charge transfer still faces challenges. In this study, we fabricated a tight-contacted S-scheme heterojunction by in situ anchoring AgI nanoparticles onto WO3 nanoplates. The significant difference in Fermi energy levels between WO3 and AgI results in the formation of a space charge region around the interface and bending of the energy band, facilitating directional migration and spatial separation of charge carriers. This contributes to enhanced generation of superoxide radicals (•O2−) and holes (h+) active species, leading to a significant increase in chlortetracycline (CTC) degradation rate. The apparent rate constant for CTC removal using the WO3/AgI (WA-2) is approximately 15 times higher than that observed for pure WO3. Furthermore, WA-2 exhibits universal degradation effects on tetracycline (TC) and oxytetracycline (OTC). Molecular dynamics (MD) simulation reveals the synergistic adsorption effect of WO3 and AgI on CTC and reactive oxygen species molecules. Based on Fukui function calculation of CTC molecules and degradation intermediates, liquid chromatography-mass spectrometry (LC-MS) analysis, photocatalytic degradation pathway over WO3/AgI was determined to be sequential demethylation followed by dechlorination and decarbonylation. These findings provide valuable insights into high-performance S-scheme heterojunctions interface design and elucidation of pollutant degradation mechanism.

Efficient removal of chlortetracycline hydrochloride and doxycycline hydrochloride from aqueous solution by ZIF-67

ZIF-67 nanoparticles were synthesized by a simple method at room temperature and used to remove chlortetracycline hydrochloride (CTC) and doxycycline hydrochloride (DOX) from water. ZIF-67 was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), thermogravimetry (TGA) and zeta potential analyzer. The morphology and chemical composition of the synthesized ZIF-67 were characterized. The effects of key parameters such as pH, dosage, temperature, contact time, different initial concentrations and coexisting ions on the adsorption behavior were systematically studied. The results of batch adsorption experiments indicate that the adsorption process conforms to the pseudo-second-order kinetic model and Sips model. At 303K, the removal rates of CTC and DOX at 150 mg/L reached 99.16 % and 97.61 %, and the maximum adsorption capacity of CTC and DOX reached 1411.68 and 1073.28 mg/g, respectively. At the same time, ZIF-67 has excellent stability and reusability. Most importantly, the possible adsorption mechanism is proposed by exploring the changes of SEM, TEM, BET and FT-IR characterization results before and after the reaction, which mainly includes pore filling, electrostatic interaction and π-π interaction. The prepared ZIF-67 has a large specific surface area (1495.967 m2 g−1), achieves a high removal rate within a short time frame, and maintains a high removal rate across a wide pH range. These characteristics make ZIF-67 a potentially promising adsorbent for removing antibiotics from aqueous solutions.

Boosting peroxymonosulfate activation via Fe–Cu bimetallic hollow nanoreactor derived from copper smelting slag for efficient degradation of organics: The dual role of Cu

Valorization of iron-rich metallurgical slags in the construction of Fenton-like catalysts has an appealing potential from the perspective of sustainable development. For the first time, copper smelting slag (CSS) was utilized as the precursor to synthesize hollow sea urchin-like Fe–Cu nanoreactors (Cu1.5Fe1Si) to activate peroxymonosulfate (PMS) for chlortetracycline hydrochloride (CTC) degradation. The hyper-channels and nano-sized cavities were formed in the catalysts owing to the induction and modification of Cu, not only promoting the in-situ growth of silicates and the formation of cavities due to the etching of SiO2 microspheres, but also resulting the generation of nanotubes through the distortion and rotation of the nanosheets. It was found that 100 % CTC degradation rate can be achieved within 10 min for Cu1.5Fe1Si, 75 times higher than that of Cu0Fe1Si (0.0024 up to 0.18 M−1‧min−1). The unique nanoconfined microenvironment structure could enrich reactants in the catalyst cavities, prolong the residence time of molecules, and increase the utilization efficiency of active species. Density functional theory (DFT) calculations show that Cu1.5Fe1Si has strong adsorption energy and excellent electron transport capacity for PMS, and Fe-Fe sites are mainly responsible for the activation of PMS, while Cu assists in accelerating the Fe(II)/Fe(Ⅲ) cycle and promotes the catalytic efficiency. The excellent mineralization rate (83.32 % within 10 min) and efficient treatment of CTC in consecutive trials corroborated the high activity and stability of the Cu1.5Fe1Si. This work provides a new idea for the rational design of solid waste-based eco-friendly functional materials, aiming at consolidating their practical application in advanced wastewater treatment.

Gold nanoparticle decorated bismuth vanadate casting on screen-printed electrode for chlortetracycline detection

Chlortetracycline is one of the tetracyclines with broad-spectrum antibacterial activity (CTC). Humans rarely use CTC, but farm animals consume vast quantities of it, which causes the growth of antibiotic-resistant bacteria and environmental contamination. There is no report on the AuNPs and BiVO4 nanocomposite being dropped cast on SPCE for electrochemical monitoring of the CTC, and the most expensive, time-consuming, and expensively equipped method is conventional chromatography. Here, we report a simple method for preparing gold nanoparticle decorated bismuth vanadate (AuNPs@BiVO4), which was dropped cast on a screen-printed carbon electrode (SPCE). The AuNPs@BiVO4 and AuNPs@BiVO4/SPCE materials were characterized using TEM, SEM-EDX, XPS, DLS, ELS, EIS, and CV, showing a consistent nanocomposite and its electrode. The as-prepared AuNPs@BiVO4/SPCE was used to detect and determine chlortetracycline (CTC) by different pulse potentials in phosphate buffer pH 7.0. The electrode possessed a wide linear range of 0.99–19.06 µM, with obtained LOD = 0.15 µM, LOQ = 0.49 µM, and sensitivity = 0.059 μA μM−1 cm−2. It also exhibited good selectivity, stability, and repeatability, recovering 87.14 %–100 % for detecting CTC in Mili Q and tap water. The findings show that the straightforward approach for making AuNPs@BiVO4 nanocomposite and an AuNPs@BiVO4/SPCE electrode is consistent with electrochemical CTC monitoring. Thus, the proposed electrode could be applied for the detection and determination of CTC in water sources and has the potential to be used for real sample analysis.