The effective removal of oxytetracycline hydrochloride (OTC) from the water environment is of great importance. Adsorption as a simple, stable, and cost-effective technology is regarded as an ...important method for removing OTC. Herein, a low-cost biochar with a developed mesoporous structure was synthesized via pyrolysis of poplar leaf with potassium bicarbonate (KHCOsub.3) as the activator. KHCOsub.3 can endow biochar with abundant mesopores, but excessive KHCOsub.3 cannot continuously promote the formation of mesoporous structures. In comparison with all of the prepared biochars, PKC-4 (biochar with a poplar leaf to KHCOsub.3 mass ratio of 5:4) shows the highest adsorption performance for OTC as it has the largest surface area and richest mesoporous structure. The pseudo-second-order kinetic model and the Freundlich equilibrium model are more consistent with the experimental data, which implies that the adsorption process is multi-mechanism and multi-layered. In addition, the maximum adsorption capacities of biochar are slightly affected by pH changes, different metal ions, and different water matrices. Moreover, the biochar can be regenerated by pyrolysis, and its adsorption capacity only decreases by approximately 6% after four cycles. The adsorption of biochar for OTC is mainly controlled by pore filling, though electrostatic interactions, hydrogen bonding, and π-π interaction are also involved. This study realizes biomass waste recycling and highlights the potential of poplar leaf-based biochar for the adsorption of antibiotics.
In this work, the MnFesub.2Osub.4/BGA (boron-doped graphene aerogel) composite prepared via the solvothermal method is applied as a photocatalyst to the degradation of tetracycline in the presence of ...peroxymonosulfate. The composite's phase composition, morphology, valence state of elements, defect and pore structure were analyzed by XRD, SEM/TEM, XPS, Raman scattering and Nsub.2 adsorption-desorption isotherms, respectively. Under the radiation of visible light, the experimental parameters, including the ratio of BGA to MnFesub.2Osub.4, the dosages of MnFesub.2Osub.4/BGA and PMS, and the initial pH and tetracycline concentration were optimized in line with the degradation of tetracycline. Under the optimized conditions, the degradation rate of tetracycline reached 92.15% within 60 min, whereas the degradation rate constant on MnFesub.2Osub.4/BGA remained 4.1 × 10sup.−2 minsup.−1, which was 1.93 and 1.56 times of those on BGA and MnFesub.2Osub.4, respectively. The largely enhanced photocatalytic activity of the MnFesub.2Osub.4/BGA composite over MnFesub.2Osub.4 and BGA could be ascribed to the formation of type I heterojunction on the interfaces of BGA and MnFesub.2Osub.4, which leads to the efficient transfer and separation of photogenerated charge carriers. Transient photocurrent response and electrochemical impedance spectroscopy tests offered solid support to this assumption. In line with the active species trapping experiments, SOsub.4 sup.*− and Osub.2 sup.*− radicals are confirmed to play crucial roles in the rapid and efficient degradation of tetracycline, and accordingly, a photodegradation mechanism for the degradation of tetracycline on MnFesub.2Osub.4/BGA is proposed.
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A visible light-driven photoelectrocatalytic system was constructed based on Bi/Bi2O3/TiO2 nanotubes (NTs) to treat wastewater containing oxytetracycline and Cu2+ mixed pollutants. ...The surface morphology, crystal phase, elemental composition, light absorption property and photoelectrochemical activity of the synthesized Bi/Bi2O3/TiO2 NTs were investigated. The composite film, Bi/Bi2O3/TiO2 NTs was used for the photoelectrochemical removal of oxytetracycline, and it had excellent visible light photoelectrocatalytic performance. Under optimal conditions, the composite film was simultaneously used to remove coexisting oxytetracycline-Cu2+. The study results show that the reduction of Cu2+ on cathode was promoted by oxytetracycline while the degradation of oxytetracycline on photoanode was slightly suppressed by Cu2+. Also, possible photoelectrocatalytic degradation pathways for oxytetracycline-Cu2+ were analyzed by HPLC-MS.
Extensive use of oxytetracycline (OTC) and the generation of its corresponding resistance genes have resulted in serious environmental problems. Physical-biological combined remediation is an ...attractive method for OTC degradation because of its high remediation efficiency, stability, and environmental friendliness. In this study, an effective OTC-degrading strain identified as Pseudomonas aeruginosa OTC-T, was isolated from chicken manure. In the degradation experiment, the degradation rates of OTC in the degradation systems with and without the biochar addition were 92.71–100 % and 69.11–99.59 %, respectively. Biochar improved the tolerance of the strain to extreme environments, and the OTC degradation rate increased by 20.25 %, 18.61 %, and 13.13 % under extreme pH, temperature, and substrate concentration conditions, respectively. Additionally, the degradation kinetics showed that biochar increased the reaction rate constant in the degradation system and shortened the degradation period. In the biological toxicity assessment, biochar increased the proportion of live cells by 17.63 % and decreased the proportion of apoptotic cells by 58.87 %. Metabolomics revealed that biochar had a significant effect on the metabolism of the strains and promoted cell growth and reproduction, effectively reducing oxidative stress induced by OTC. This study elucidates how biochar affects OTC biodegradation and provides insights into the future application of biochar-assisted microbial technology in environmental remediation.
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•The isolated strain possessed high degradation efficiency to oxytetracycline.•Biochar increased the biodegradation rate of oxytetracycline by 13.13–20.25 %.•Biochar reduced the biotoxicity of the degradation system.•Biochar increased the antioxidant capacity of the strain.
Understanding the dynamics of veterinary antibiotic and related antibiotic resistance genes (ARGs) during swine manure composting is crucial in assessing the environmental risk of antibiotics, which ...could effectively reduce their impact in natural environments. This study investigated the dissipation of oxytetracycline (OTC), sulfamerazine (SM1) and ciprofloxacin (CIP) as well as the behaviour of their corresponding ARGs during swine manure composting. These antibiotics were added at two concentration levels and two different methods of addition (single/mixture). The results indicated that the removal efficiency of antibiotics by composting were ≥85%, except for the single-SM1 treatment. The tetracycline resistance genes (TRGs) encoding ribosomal protection proteins (RPP) and efflux pump (EFP) and fluoroquinolone resistance genes (FRGs) could be effectively removed after 42 days. On the contrary, the TRGs encoding enzymatic inactivation (EI) and sulfonamide resistance genes (SRGs) were enriched up to 31-fold (sul 2 in single-low-SM1). Statistical analyses indicated that the behaviour of these class antibiotics and ARGs were controlled by microbial activity and significantly influenced by environmental factors (mainly C/N, moisture and pH) throughout the composting process.
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•The addition of antibiotics did not retard the composting process of swine manure.•The removal efficiencies of OTC and CIP were higher than SM1 in swine manure composting.•The TRGs encoding both RPP and EFP and FRGs could be effectively removed in swine manure composting.•Dissipation behaviours of antibiotics and related ARGs were significantly associated with the composting conditions.
•Simultaneous determination of olaquindox, oxytetracycline and chlorotetracycline.•The fully validated method showed high precision and robustness.•This method was applied to three kinds of ...commercial feed samples.•Only one-step extraction process improves detection efficiency.•Ultraviolet detector in series with fluorescence detector can prevent false positive.
Olaquindox, oxytetracycline and chlorotetracycline were widely used in feed as antibiotics and growth promoter to improve feed conversion efficiency and increase the rate of weight gain for animals. However, the use of these antibiotics in feed was gradually prohibited because of concerns about contamination and resistance in animals. A quantitative and confirmatory method for determining the presence of olaquindox, oxytetracycline and chlorotetracycline in feed by high performance liquid chromatography equipped with ultraviolet detector in series with fluorescence detector (HPLC-UVD-FLD) was developed, optimized, and validated in three different matrices (compound, concentrated and premix feed). The analytes extraction was performed with a mixture of acetonitrile and 0.1 mol/L ethylenediamine tetraacetic acid disodium-Mcllvaine buffer (1:4, v/v) by one step sample preparation procedure. The validated method presented a broad linear range and good linearity with weighted least square method. The decision limit of the analytes ranged from 0.61 to 0.77 mg/kg for olaquindox, 0.90 to 1.2 mg/kg for oxytetracycline and 1.3 to 2.0 mg/kg for chlorotetracycline. The average recovery values found in intermediate precision conditions were ranged from 88.0 to 99.7% for olaquindox with RSD lower than 11.1%, from 84.4 to 99.0% for oxytetracycline with RSD lower than 9.6%, from 83.8 to 97.5% for chlorotetracycline with RSD lower than 10.0%. By Youden test and bottom-up method, the method was proved to be sufficiently robust and had a small uncertainty for different concentration levels. The developed method was successfully utilized for commercial feed samples to monitor complex cross contamination and residue conditions. Online synchronous derivation and separation using ultraviolet detector in series with fluorescence detector can effectively prevent false positive of chlorotetracycline in feed caused by vegetable meal. Since olaquindox, oxytetracycline and chlorotetracycline are widely used in feed, the developed method provide an important and analytical tool for the simultaneous identification and quantification of them in feed to monitor its risk of cross contamination and excessive content.
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•More oxygen-containing functional groups exhibited on the surface of PLA MPs after degradation.•Degraded PLA without biofilms had the highest adsorption amount due to enhanced ...hydrogen bonding.•Microbial adhesion increased adsorption capacity of PLA MPs through OTC chemical complexation.•OTC adsorption capacity of PLA MPs first increased and then decreased with the pH of 3.0–9.0.•The presence of FA suppressed the adsorption of OTC on PLA MPs.
Biodegradable plastics have been evaluated as promising alternatives for conventional polymers in various fields. Although microplastics (MPs) have been reported as vectors for pollutants in the environment (e.g. antibiotics), knowledge about the chemicals carrying mechanisms of degradable MPs during the biodegradation process is limited. In this study, we investigated the adsorption behavior of oxytetracycline (OTC) on polylactic acid (PLA) MPs during its biodegradation process. Scanning electron microscopy (SEM) discovered the growth of scattered rod-shaped bacteria on the surface of PLA MPs. Two-dimensional correlation spectroscopy (2D-COS) combined with Fourier transform infrared spectroscopy (FTIR) identified the breakage of ester linkages and the generation of more oxygen-containing functional groups, indicating PLA biodegradation occurred. The presence of a biofilm coating increased the OTC adsorption capacity on MPs by 20.15%, mainly due to OTC complexing with chemical functional groups existing in biofilms (e.g. N–H functional group). More oxygen-containing functional groups were exposed on the surface of PLA MPs after removing biofilms, which further increased the adsorption quantity of OTC by 39.01% through enhanced hydrogen bonding compared with biofilm coating MPs. The adsorption quantity of OTC adsorbed onto MPs first increased and then decreased with the pH ranging from 3.0 to 9.0, which was dominated by electrostatic interaction and hydrophobic interaction. In addition, the adsorption capacity of MPs was suppressed by the presence of fulvic acid (FA) due to that the adsorbed FA blocked further OTC adsorption and OTC showed higher affinity to free FA compared with MPs. These results unravel the OTC adsorption behavior of PLA MPs undergoing microbial adhesion and degradation, which could be useful for understanding the environmental sorption behavior of degradable MPs.
Keywords NiSe; g-C.sub.3N.sub.4; Noble-metal-free cocatalyst; Hydrogen generation; Pollutants degradation Highlights * NiSe was applied as a cost-effective cocatalyst for decorating g-C.sub.3N.sub.4. ...* NiSe/g-C.sub.3N.sub.4 had superior catalytic activities of H.sub.2 production and OTC/MO removal. * The separation efficiency of photogenerated e.sup.-/h.sup.+ pairs was significantly enhanced. * The mechanism was proposed based on electrochemical tests and DFT calculations. Identifying suitable noble-metal-free cocatalyst-modified photocatalysts has received tremendous attention in the nonrenewable field. Herein, non-noble metal NiSe modified g-C.sub.3N.sub.4 was produced through an environmental-friendly hydrothermal method. The NiSe/g-C.sub.3N.sub.4 photocatalyst exhibited superior photocatalytic H.sub.2 production, when the optimum mass content of NiSe was 3 wt%. The best H.sub.2-production activity could be as high as 1250 micromol*g.sup.-1*h.sup.-1, superior than that of bulk g-C.sub.3N.sub.4 by 139 times. Significantly, the 3 wt% NiSe/g-C.sub.3N.sub.4 photocatalyst showed a remarkable photocatalytic activity in oxytetracycline (OTC) and methyl orange (MO) degradation and almost completely degraded within 60 min and 5 min under the visible light irradiation, respectively. Attributed to the intimated contact between NiSe and g-C.sub.3N.sub.4, the NiSe/g-C.sub.3N.sub.4 composite shows an outstanding photocatalytic performance. Additionally, the experimental results further confirmed that the use of highly-dispersed NiSe nanodots enlarged the visible-light absorption range, boosted charge carrier mobility as well as afforded rich active sites. Importantly, DFT computation and photoelectrochemistry measurements also identified that NiSe nanodots cocatalysts accelerated the charge separation and migration, thereby implied that electron transfer pathway from g-C.sub.3N.sub.4 to NiSe. This novel technology provides a new idea for designing and studying efficient noble-metal-free cocatalyst/semiconductor compounds in the degradation of pollutant and photocatalytic H.sub.2 generation. Author Affiliation: (a) School of Material Science and Technology, Jilin Institute of Chemical Technology, Jilin 132022, PR China (b) Jilin Petrochemical Company Organic Synthetic Plants, Jilin 132021, PR China * Corresponding authors. Article History: Received 24 July 2020; Revised 13 October 2020; Accepted 19 October 2020 Byline: Zhe Chen chenzhe0809@foxmail.com (a,*), Yuting Gao (a), Feng Chen (b), Hongfei Shi shihf813@nenu.edu.cn (a,*)
A novel electrochemiluminescence (ECL) aptasensor for the determination of lincomycin (LIN) was developed based on CdS QDs/carboxylated g-C.sub.3N.sub.4 (CdS QDs/C-g-C.sub.3N.sub.4). CdS ...QDs/C-g-C.sub.3N.sub.4 served as the substrate of the aptasensor, and then CdS QDs/C-g-C.sub.3N.sub.4-modified electrode was incubated with aptamer DNA (Apt-DNA). When the non-specific sites of the electrode surface was blocked by 6-mercaptohexanol, the ferrocene-labeled probe (Fer-DNA) was assembled onto the electrode surface through base complementation with Apt-DNA. In the absence of LIN, the ECL signal was quenched effectively by Fer-DNA and a decreased ECL emission (off state) was acquired. On the contrary, LIN was specifically bond with Apt-DNA, and Fer-DNA was detached from the aptasensor surface because of the deformation of Apt-DNA, resulting in an effectively enhanced ECL signal (on state). The constructed ECL aptasensor exhibited a wide detection range for LIN determination (0.05 ng mL.sup.-1-100 mug mL.sup.-1) with a low detection limit (0.02 ng mL.sup.-1). Importantly, the proposed ECL aptasensor showed outstanding accuracy and specificity for LIN determination, and also provided a potential strategy for other antibiotic determinations. Graphical
Oxytetracycline (OTC) is a commonly used tetracycline antibiotic in veterinary and human medicine. To establish a quantitative model for predicting OTC plasma and tissue exposure, a ...permeability-limited multiroute physiologically based pharmacokinetic model was developed in dogs. The model was calibrated with plasma pharmacokinetic data in beagle dogs following single intravenous (5mg/kg), oral (100mg/kg), and intramuscular (20mg/kg) administrations. The model predicted other available dog data well, including drug concentrations in the liver, kidney, and muscle after repeated exposure, and data in the mixed-breed dog. The model was extrapolated to humans and the human model adequately simulated measured plasma OTC concentrations after intravenous (7.14mg/kg) and oral exposures (6.67mg/kg). The dog model was applied to predict 24-h OTC area-under-the-curve after three therapeutic treatments. Results were 27.75, 51.76, and 64.17 μg/mL*h in the plasma, and 120.93, 225.64, and 279.67 μg/mL*h in the kidney for oral (100mg/kg), intravenous (10mg/kg), and intramuscular (20mg/kg) administrations, respectively. This model can be used to predict plasma and tissue concentrations to aid in designing optimal therapeutic regimens with OTC in veterinary, and potentially, human medicine; and as a foundation for scaling to other tetracycline antibiotics and to other animal species.
