Tetracycline Research Articles

Donor polarization engineering of conjugated microporous polymers to boost exciton dissociation for photocatalytic degradation of tetracycline

The misuse and inevitable release of antibiotics can cause significant harm to both human health and the environment, and the use of polymeric semiconductors for photodegradation of antibiotics in aqueous environments is one of the most effective strategies to alleviate the current dilemma. Nevertheless, the inherently high exciton binding energy (Eb) and low photogenerated carrier transfer efficiency for most photocatalysts results in unsatisfactory photodegradation performance. Hence, this work proposes a donor polarization strategy to regulate the exciton dissociation of conjugated microporous polymers (CMPs) by minimizing their Eb. Results exhibited that the introduction of the strong donor unit 3,4-ethylenedioxythiophene (EDOT) not only reduces the Eb and effectively promotes exciton dissociation, but also broadens the visible light absorption of CMP. Among them, EdtTz-CMP with the lowest Eb (99 meV) delivered an efficiency of 94.6% in photocatalytic degradation of tetracycline (TC) with in 90 min, significantly higher than those of its analogues. This work provides a viable approach to design CMPs by tuning the intrinsic dipole of the donor for efficient environmental purification.

Ferroelectric polarization synergism boosting CdS/PbTiO3 S-scheme heterostructures for efficiently bifunctional environmental applications

It is of great significance and challenges to construct physical field-enhanced photocatalysts for energy and environmental applications. Herein, an artificial-photosynthesized CdS/PbTiO3 S-scheme heterostructures with the enhancement of polarization electric field have been developed to promote the bifunctionally catalytic efficiencies for Cr(VI) photoreduction degradation of heavy metal pollution and Tetracycline (TC) photooxidation degradation of antibiotic. In our work, CdS nanoparticles are selectively grown on the positive polarization planes of PbTiO3 microplates to form the same direction for both the ferroelectric polarization field of PbTiO3 and the built-in electric field of S-scheme heterojunction. In this case, the stable heterostructures of PTO(00−1)/CdS(010) are obtained, and the greatly improved photocatalytic performances of redox degradation are achieved. The charge transfer mechanism and the synergetic effect between the spontaneous ferroelectric polarization and S-scheme heterojunction have been revealed by DFT calculations and experimental verifications. This interesting finding provides new insight into the design of efficient artificial-photosynthesized photocatalytic systems and we hope our work could serve as a valuable reference for our colleagues.

Underestimation of tetracycline antibiotic residues in chicken meat: The role of protein binding

Interesting variations in the analyte content were observed in chicken samples contaminated with tetracycline antibiotics (TCs) following pretreatment with various enzymatic hydrolysis before quantification by conventional analytical methods. Compared with untreated samples, the detectable contents of three TCs in protease-treated samples were 1.51 to 2.05 times higher, whereas lipase treatment did not significantly influence the contents. The marked changes following protease treatment confirmed the presence of protein-associated antibiotics. Infrared spectroscopy analysis indicated that the formation of protein-bound antibiotics resulted from non-covalent interactions between TCs and proteins. Further dissociation experiments determined that the intermolecular forces involved hydrogen bonding, hydrophobic interactions, and electrostatic attraction. Molecular docking substantiated these forces and detailed the binding mechanism at the molecular level. Moreover, the masking effect of protein binding on the determination of TCs was also evidenced in an additional 30 positive chicken samples, suggesting that the actual residue levels of TCs in protein-rich foodstuff are underestimated.

Oxygen vacancy defect engineering in MoO2/Mo-doped BiOCl Ohmic junctions for enhanced photocatalytic antibiotic elimination

Vacancy defect engineering is an effective strategy for improving photocatalytic activity, but controlling surface vacancies precisely remains a challenge. In this study, MoO2/Mo doped BiOCl (Mo-BiOCl) composites enriched with oxygen vacancies (OVs) were prepared by a facile defect engineering strategy with MoO2 hollow spheres as a precursor and molybdenum sources, where the slowly released Mo4+ ions in the reaction system resulted in the tailored formation of Mo-BiOCl. The optimized MoO2/Mo-BiOCl composite (BOM-3) demonstrated significantly improved photocatalytic degradation efficiency for Tetracycline hydrochloride (TC) under visible light, with an apparent rate constant (k) 4.7 and 120 times higher than that of BiOCl and MoO2, respectively. The enhanced photocatalytic activity of BOM-3 can be attributed to the presence of abundant OVs, which extend the light response range by creating intermediate defect level from OVs. Additionally, the formation of ohmic heterojunction between Mo-BiOCl and MoO2 with close interface contacts facilitates rapid separation of interfacial charge carries and efficient migration of photogenerated electrons from Mo-BiOCl to MoO2. The possible degradation pathway of TC using BOM-3 is proposed, and toxicity evaluation indicates that most intermediates have lower toxicity than TC. This work presents a straightforward approach for improving photocatalytic antibiotic degradation through the construction of a novel Ohmic-junction with tuned surface OVs.

A donor-acceptor π-stacked multifunctional Eu-MOF based on a novel viologen-like photosensitive ligand: Degradation of tetracycline, photochromism, and photoluminescence

The photosensitive building blocks of photochromic MOFs are mostly 4,4′-bipyridine. However, the linear structure and kind of 4,4′-bipyridine derivatives limit the development of its properties and applications. Therefore, a “Y"-shaped 2,4,6-tri (4-pyridyl)-1,3,5-triazine derivative ([H3p-Batpt]Cl3, TPT) with high conjugation, bare nitrogen and oxygen sites that was selected as a novel photosensitive ligand to replace the traditional 4,4′-bipyridine ligand for photochromic MOFs. Then, [H3p-Batpt]Cl3 was combined with EuIII and terephthalic acid (H2TPA) to construct a multifunctional Eu-MOF [Eu2 (p-Batpt) (TPA)3(H2O)]n (1). 1 possess degradation of tetracycline (TC), photochromic and photoluminescence properties. The colored 1 (1P) after irradiation with UV–vis light (300 W, Xe-lamp) is difficult to fade due to donor-acceptor (D-A) π-π and radical-π interactions. In addition, 1 is used in photocatalysis because it is an excellent N-type semiconductor. The TC degradation rate of 1 can reach 67.42 % under visible light and be recycled six times. Interestingly, the TC degradation rate of 1P was 6.78 % higher than that of 1. Electrochemical tests show that 1P has higher charge separation efficiency and a smaller band gap. The free radicals capture and ESR experiments of 1 revealed that holes (h+) played a leading role in the photocatalytic degradation of TC. This research expands the application of photochromic MOFs and provides a reference for removing organic pollutants.

Solar-driven remediation of antibiotics in synthetic and real reverse osmosis brine: Addressing lattice oxygen demand and electron transfer for improved purification

This study investigated the significance of integrated advanced oxidation process with reverse osmosis (RO) to ensure the purification and elimination of micropollutants, primarily pharmaceuticals prior to the discharge of brine to the environment. To envisage this, TiO2 based solar driven photocatalysis was employed, highlighting the crucial role of oxygen vacancy formation in the lattice of TiO2 for enhancing the purification of antibiotic contaminants from RO brine. The study elucidated how variations in oxygen environments such as oxygen rich yellow TiO2 (Y-TiO2) and oxygen vacancy black TiO2 (B-TiO2) influence photodegradation reaction kinetics taking ofloxacin (OFX) and tetracycline (TC) as model pollutants. The B-TiO2 exhibited 8.5 times higher photodegradation for OFX compared to Y-TiO2, proving significance in tuning of oxygen environment in lattice. The photodegradation efficiency plot showcases B-TiO2′s efficacy, demonstrating 99.8 % and 99.4 % for OFX and TC, respectively. Additionally, the study investigated the photocatalytic degradation mechanism, identifying predominant charge carriers and reactive species involved, while also assessing the durability of photodegradation processes. The impact of pH on the photocatalytic performance of B-TiO2 in degrading antibiotics explored, spanning pH levels from 2.5 to 10.5. An exploration on band alignment formation in B-TiO2 explains the effectiveness of it over Y-TiO2. Lastly, efficacy of B-TiO2 in degrading antibiotics in real RO brine with high level of salinity (60,200 ppm TDS) is demonstrated, which resulted with photodegradation efficiency of 31.25 % for OFX and 67.8 % for TC, proving applicability of integrated system as a sustainable purification approach. Moreover, the blockage of chloride ions quenching demonstrated improvements in photodegradation emphasizing the influence of chloride ions in high saline conditions.

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.

Peroxymonosulfate-assisted photocatalysis system enhanced magnetic Fe3O4@P-C3N4 treatment of tetracycline wastewater: Multi-pathways mediated electrons migration to generate reactive species

Photocatalytic wastewater purification is essential for environmental remediation, but rapid carrier recombination and limited oxidative capacity hinder progress. This study proposes an innovative strategy by integrating homogeneous and heterogeneous electron acceptors into a g-C3N4−based photocatalytic system, significantly enhancing the multipath utilization of photogenerated electrons. A novel Fe3O4@P-C3N4 was developed to activate an advanced peroxymonosulfate−assisted photocatalysis (PAP) system, achieving complete degradation and significant mineralization of tetracycline (TC) in real water environments, outperforming others reported in the last five years. Phytic acid, as a key precursor, modifies the hollow tubular morphology and introduces phosphorus (P) heteroatoms as electronic trapping centers, enhancing the visible light response and carrier separation, thereby promoting the Fe2+/Fe3+ cycle and the formation of reactive species. Density functional theory (DFT) calculations pinpointed TC’s vulnerable sites and synergically identified reactive species, revealing almost non-toxic degradation processes. Moreover, the recyclable magnetic Fe3O4@P-C3N4/PAP system demonstrates practical application potential and leaching stability in cyclic and continuous testing. This study offers unique insights into the strategic design of photocatalysts and catalytic environments, potentially advancing practical wastewater remediation.

Investigation into the Synergistic Effect of the Zinc Peroxide/Peroxymonosulfate Double-Oxidation System for the Efficient Degradation of Tetracycline.

The increasingly severe antibiotic pollution has become one of the most critical issues. In this study, a zinc peroxide/peroxymonosulfate (ZnO2/PMS) double-oxidation system was developed for tetracycline (TC) degradation. A small amount of ZnO2 (10 mg) and PMS (30 mg) could effectively degrade 82.8% of TC (100 mL, 50 mg/L), and the degradation process could be well described by the pseudo-second-order kinetic model. Meanwhile, the ZnO2/PMS double-oxidation system showed high adaptability in terms of reaction temperature (2-40 °C), initial pH value (4-12), common inorganic anions (Cl-, NO3-, SO42- and HCO3-), natural water source and organic pollutant type. The quenching experiment and electron paramagnetic resonance (EPR) characterization results confirmed that the main reactive oxygen species (ROS) was singlet oxygen (1O2). Moreover, three possible pathways of TC degradation were deduced according to the analyses of intermediates. On the basis of comparative characterization and experiment results, a synergistic activation mechanism was further proposed for the ZnO2/PMS double-oxidation system, accounting for the superior degradation performance. The released OH- and H2O2 from ZnO2 could activate PMS to produce major 1O2 and minor superoxide radicals (•O2-), respectively.

Synthesis of multifunctional rGO/g-C3N4/FeTiO3 ternary nanocomposites for photocatalyst, antibacterial, and ecotoxicity assessment of zebrafish embryo model

The wastewater from the dye and pharmaceutical industries antibiotics has caused serious environmental and health problems for humans and other species. For the development of superior photocatalysts, effective separation of photogenerated electron-hole pairs is essential in addition to optimizing solar absorption throughout a wide wavelength range. In order to produce bare, rGO/g-C3N4, rGO/FeTiO3, and rGO/g-C3N4/FeTiO3 (GCNFeT NCs) nanocomposites, this study describes the fabrication of perovskite-type titanate (FeTiO3) and its incorporation onto graphitic carbon nitride (g-C3N4) and reduced graphene oxide (rGO) using a hydrothermal synthesis technique. The generated nanocomposites structural, morphological, and optical properties were evaluated. After being exposed to solar light for 90 min, the resultant GCNFeT NCs efficiently broke down 80 % of Tetracycline (TC) and 90 % of Malachite Green (MG) dye. The photocatalytic efficacy is significantly improved by these results when compared to the pure and binary composites. Substantial catalytic efficiency to GCNFeT NCs was shown by the degradation rate constant (k) for MG and TC elimination by GCNFeT NCs, which was almost 20 times greater than that of pure and binary composites. Additionally, the antibacterial activity of GCNFeT nanocomposites was studied, and the results showed that it was significantly more efficient against Gram-negative bacteria than Gram-positive bacteria, including Escherichia coli and Staphylococcus aureus. Furthermore, the freshwater zebrafish embryo development proved effective in assessing the non-toxicity of GCNFeT NCs. Our research findings indicate that high doses, GCNFeT NCs induce less toxicity in zebrafish embryo (6.25–100 µg/L). These results demonstrated the enhanced mechanism of GCNFeT NCs, indicating their great potential for use in antibacterial and water remediation applications.

BioTemplated Fe3+-Doped g-C3N4 Heterojunction Micromotors for the Degradation of Tetracycline through the Photo-Fenton Reaction

The excessive discharge of antibiotics into aquatic systems is a major issue in many countries worldwide and poses a threat to human health and the sustainable development of society. Hence, developing efficient treatment methods and purification technologies to degrade antibiotics is essential. Herein, we present the synthesis of low-cost, self-propelled tubular Fe3+-incorporated graphitic carbon nitride (g-C3N4-Fe@KF) micromotors using kapok fibers (KFs) as templates and their application as photo-catalysts for the photo-Fenton degradation of tetracycline (TC) under visible-light irradiation. The g-C3N4-Fe@KF micromotors moved rapidly when being propelled by oxygen bubbles generated in a hydrogen peroxide (H2O2) solution as a result of a photo-assisted Fenton reaction. The motion behavior of the g-C3N4-Fe@KF micromotors was dependent on the concentration of H2O2 and the length of the micromotors. The propulsion mechanism was discussed in detail. The micromotors efficiently degraded antibiotics via the photo-Fenton process. Photo-Fenton degradation efficiency was attributed to the synergistic effects of the doped Fe3+ and g-C3N4 under visible-light irradiation and self-propulsion of the micromotors. In addition, the micromotors possessed good reusability, thereby efficiently realizing multiple cycles of degradation. The current work offers an avenue for the design of micromotors, using inexpensive approaches, for various potential environmental applications.

Solar-driven chloride activation via 3D oxygen-vacancy-rich TiO2 network photoanode for ultrafast and durable purification of saline wastewater

Photoelectrochemical chloride activation (PEC-Cl) is a promising and reagent-free strategy to treat saline organic wastewater by activation of chloride (Cl–) using sunlight. However, the low efficiency and Cl– corrosion of photoelectrode, and the limited mass transfer of pollutant hinder its application. Herein we successfully solve these challenges by developing porous oxygen-vacancy-rich TiO2 nanoneedle arrays (TiO2 NNs-r400) photoanode. Under illumination, the photoinduced holes in TiO2 NNs-r400 oxidize Cl– to reactive species (e.g., HOCl, Cl•, Cl2•− and ClO•), resulting in the degradation rate of tetracycline hydrochloride (HTC, 0.861 min−1) by TiO2 NNs-r400/PEC-Cl system is 2–3 orders of magnitude higher than the state-of-the-art. Experiments and computational analysis indicate that oxygen vacancies (Ovs) on TiO2 NNs-r400 promote the photocarriers separation efficiency and more importantly, facilitate Cl– adsorption with intermediary strength and reduce the energy barriers of Cl– oxidation. Furthermore, we design a continuous flow-through PEC reactor for TiO2 NNs-r400/PEC-Cl technology. The process exhibits 100% HTC degradation (TOC = 60.23%) for over 2000 h flow-through operation, which maintains high activity in the treatment marine aquaculture wastewater with nearly zero energy consumption by directly utilize natural sunlight. In the final effluent, the toxicity of almost all degradation intermediates is decreased, and the formation of total organic chlorine is low (17.2 µg L–1). This work provides insights into Cl– activation on Ov-rich photoanode and strategy for practical application of solar energy in efficient, sustainable and eco-friendly wastewater decontamination.

Revolutionizing Tetracycline Hydrochloride Remediation: 3D Motile Light-Driven MOFs Based Micromotors in Harsh Saline Environments.

Traditional light-driven metal-organic-frameworks (MOFs)-based micromotors (MOFtors) are typically constrained to two-dimensional (2D) motion under ultraviolet or near-infrared light and often demonstrate instability and susceptibility to ions in high-saline environments. This limitation is particularly relevant to employing micromotors in water purification, as real wastewater is frequently coupled with high salinity. In response to these challenges, ultrastable MOFtors capable of three-dimensional (3D) motion under a broad spectrum of light through thermophoresis and electrophoresis are successfully synthesized. The MOFtors integrated photocatalytic porphyrin MOFs (PCN-224) with a photothermal component made of polypyrrole (PPy) by three distinct methodologies, resulting in micromotors with different motion behavior and catalytic performance. Impressively, the optimized MOFtors display exceptional maximum velocity of 1305±327µms-1 under blue light and 2357±453µms-1 under UV light. In harsh saline environments, these MOFtors are not only maintain high motility but also exhibit superior tetracycline hydrochloride (TCH) removal efficiency of 3578±510mgg-1, coupling with sulfate radical-based advanced oxidation processes and peroxymonosulfate. This research underscores the significant potential of highly efficient MOFtors with robust photocatalytic activity in effectively removing TCH in challenging saline conditions, representing a substantial advancement in applying MOFtors within real-world water treatment technologies.

Catalytic ozonation performance and mechanisms of Cu-Co/γ-Al2O3 to achieve antibiotics and ammonia simultaneously removal in aquaculture wastewater

Antibiotics and ammonia are generally co-existed in aquaculture tailwater; moreover, ammonia would also be produced from during ozonation, and should be simultaneously removed before discharge or reuse. In this study, catalyst Cu-Co/γ-Al2O3 was screened from a variety of metal oxides and applied in catalytic ozonation of three kinds of antibiotics and NH+4-N. Factors that affected their removal, including catalyst dosages, O3 concentration, initial pH as well as co-existing ions, were investigated. Moreover, the mechanisms were probed by exploring free radicals’ role as well as intermediates identification; and the characteristics of catalysts before and after use were evaluated using SEM, EDS, XRD, XPS, and BET. Results demonstrated that Cu-Co/γ-Al2O3 could significantly stimulate the degradation of the selected antibiotics and NH+4-N during ozonation. The degradation efficiencies of ciprofloxacin (CIP), tetracycline (TC), sulfamethoxazole (SMX) and NH+4-N can reach up to 95.0 %, 100.0 %, 96.2 %, and 75.7 %, respectively. Plenty of oxygen vacancy (Ovs) and sufficient alkaline sites on the surface of catalyst facilitated the adsorption of pollutants. Furthermore, the transformation of metal ions Cu+/Cu2+ and Co2+/Co3+ enhanced the electron transfer capacity and favored the formation of reactive oxygen species (ROS) during catalytic ozonation reaction, and their roles in catalytic ozonation has also been verified. The radical quenching experiments demonstrated that ·OH was the main contributor for enhancing pollutants removal. The results of Gaussian calculation coincided with those intermediates detected by UPLC-Q-TOF-MS, the pollutants’ removal mechanisms by catalytic ozonation were proposed basing on them. The overall toxicities were compared for ozone only/catalytic ozonation by zebrafish embryo experiment. The results of this study would provide new a feasible way for treating antibiotics and NH+4-N simultaneously in aquaculture wastewater.

Rational Engineering of Nanostructured NiS/GO/PVA for Efficient Photocatalytic Degradation of Organic Pollutants

A novel nanocomposite film synthesized from an inexpensive and easily accessible polymer such as poly (vinyl alcohol) (PVA), which is coated with nickel sulfide (NiS) and graphene oxide (GO), was obtained from used drinking-water bottles. The produced coated film was examined as a potential photocatalyst film for wastewater treatment promotion in a batch system for the removal of methylene blue (MB) and tetracycline (TC) antibiotics. The experimental results show that the presence of GO significantly increases the photocatalytic efficiency of NiS, and the MB and TC degradation results proved that the incorporation of GO with NiS led to a more than one-and-a-half-fold increase in the removal percentage in comparison with the NiS/PVA-coated film. After 30 min of illumination using GO/NiS/PVA-coated film, the removal efficiency reached 86% for MB and 64% for TC. The photodegradation kinetic rate followed the pseudo-first-order rate. Furthermore, the response surface methodology (RSM) model was utilized to study and optimize several operating parameters. The ideal circumstances to achieve 91% elimination of MB are 12 mg L−1 MB initial concentration, two lamps, and an illumination time of 15 min; however, to achieve 85% TC removal, 11 mg L−1 TC initial concentration, two lamps, and a 45 min illumination time should be used. The fabricated nanocomposite photocatalyst film seems to have promise for use in water purification systems.

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

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

Efficient synthesis of multifunctional α-Fe2O3 QDs/TS-1 as an artificial nanozyme for simultaneous colorimetric detection and photodegradation of tetracyclines

In this study, a multifunctional catalyst was developed innovatively by loading α-Fe2O3 quantum dots (QDs) onto Titanium Silicalite-1 (TS-1), creating an artificial nanozyme capable of simultaneously detecting, adsorbing, and photodegrading tetracyclines (TCs) in water. The catalyst demonstrated a limit of detection (LOD) as low as 19.7 μg/L for oxytetracycline (OTC), 23.1 μg/L for doxycycline (DOX), and 35.9 μg/L for tetracycline (TC). The peroxidase-mimic activity of the nanozyme, which was enhanced by TCs and caused a visible color change in 3,3′,5,5′-tetramethylbenzidine (TMB), was thoroughly investigated using DFT calculations. Additionally, the artificial nanozyme exhibited exceptional adsorption capabilities and photocatalytic activity under solar light irradiation, achieving a total removal rate of about 70 %. The underlying mechanism was also studied. This research provided valuable insights for the scalable production of multifunctional catalysts, thereby advancing the practical application of “integration of diagnosis and treatment” strategies for managing and controlling TCs in the environment.

Designing Polychromatic Er3+/Yb3+-Codoped Bi2WO6 Upconverting Nanoparticles with Enhanced Visible-Light-Triggered Photocatalytic Properties toward Tetracycline Degradation.

To address the unsatisfactory photodegradation capacities of photocatalysts, Er3+/Yb3+-codoped Bi2WO6 (Bi2WO6:Er3+/xYb3+) nanoparticles (NPs) with polychromatic upconversion (UC) emission and boosted visible-light-triggered photocatalytic abilities were designed. First-principles density functional theory was employed to study the impact of Er3+ and Yb3+ codoping on the electronic structure of Bi2WO6. Upon 980 nm excitation, the resultant NPs emitted polychromatic UC emissions caused by energy back transfer from Er3+ to Yb3+. Moreover, the involved UC emission mechanism was clarified through examining the pump power related to UC emission spectra. By investigating the visible-light-induced tetracycline (TC) decomposition, the photocatalytic activities of developed NPs were explored, where Bi2WO6:Er3+/0.07Yb3+ NP can degrade 81.76% of TC within 30 min, with a k value of 0.0552 min-1. Both the theoretical calculation and trapping results reveal that the •O2-, h+, and •OH were formed during the pollutant removal process. Additionally, the toxic TC can be photodegraded to nontoxic products via the synthesized photocatalysts, leading to wastewater purification. These achievements manifest that Bi2WO6:Er3+/xYb3+ NPs are promising visible-light-triggered photocatalysts to degrade pollutants, and our findings also propose a facile approach to regulate the photocatalytic activities of photocatalysts via utilizing doping and UC emission strategies.

A novel iron oxide (Fe3O4)-laden titanium carbide (Ti3C2) MXene stacks for the efficient removal of tetracycline from aqueous solution

Fe3O4 has the advantages of unique magnetic stability and low biological toxicity, which can improve pollutants separation efficiency. MXenes are two-dimensional materials and easy surface functionalization that can provide suitable carriers for Fe3O4. In this work, we synthesized magnetic MXene composites by a one-pot method that relies on doping Fe3O4 particles onto Ti3C2 MXene nanosheets by heat treatment. The Fe3O4/Ti3C2 MXene was analyzed by SEM, XRD, FTIR and XPS techniques, which showed that the material has good tetracycline (TC) removal properties and magnetic separation ability. The results showed that the adsorption capacity of it was 46.42 mg g−1, and the removal efficiency of 0.06 g adsorbent for 50 mL of 30 mg L−1 TC could reach 92.1% in a wide pH range of 4–10, when the adsorption temperature was 25 °C, and the adsorption time was 3 h. The adsorption data were consistent with Langmuir and the proposed second-order kinetic model, and the thermodynamic experiments confirmed that the adsorption of TC was a monolayer physicochemical adsorption coexisting heat-trapping process (ΔH = 15.72 kJ mol−1). In addition, the adsorption of TC by Fe3O4/Ti3C2 MXene was attributed to the synergistic effect of electrostatic attraction, hydrogen bonding and π-π packing. In conclusion, the saturation magnetization of Fe3O4/Ti3C2 MXene is 27.3 emu/g and it can not only be separated from water using its strong magnetic properties to avoid secondary contamination, but also can be used as a promising material to effectively remove antibiotics from aqueous media.

Z-scheme Ag2O/ZnO heterostructure on carbon fibers for efficient photocatalysis of tetracycline

Antibiotics can be transferred from water bodies to soil environment through irrigation, and then enriched in agricultural products, causing larger scale pollution. Due to the ability of antibiotics to inhibit microbial activity, the use of traditional microbial methods is not suitable for treating wastewater containing antibiotics. In nowadays, photocatalytic technology has been widely studied to deeply mineralize low concentration water-soluble pollutants like antibiotics. However, the photocatalytic technology still faces two challenges, namely the difficulty of recovering and reusing powdered catalysts, and the insufficient activity of catalysts. In this work, we designed a Z-scheme Ag2O/ZnO heterostructure in situ grown on large scaled carbon fiber (named CF/ZnO/Ag2O) to enhance the efficiency of photocatalysis of tetracycline (TC) in water. The large-area carbon fiber cloth facilitates the recovery and industrial application of the catalyst, while the Z-scheme heterojunction structure significantly enhances the charge separation efficiency and catalytic performance. The results show that the interface formed by the close contact between ZnO and Ag2O provides an effective channel for charge transfer between them. Compared with existing catalysts, the prepared Z-scheme Ag2O/ZnO photocatalyst not only has higher activity, but also could solve the problem of easy loss and difficult recycling of powdered catalysts in water. Importantly, the efficiency for photocatalysis of tetracycline (TC) over CF/ZnO/Ag2O is about 94.50%, and after sixth cycles, the degradation rate is still 81.32%. The catalyst grows in situ on the surface of carbon fibers and is not easily detached. The degradation pathways of TC, toxicity analysis of intermediates and mechanism of the photocatalysis over CF/ZnO/Ag2O were explored. These characteristics make this catalyst have higher practical application potential and value, especially in improving the biodegradability of antibiotic wastewater and achieving deep purification of wastewater to improve effluent quality.