Improving spectral utilization and carrier separation efficiency is a key point in photocatalysis research. Herein, we prepare hollow g-Csub.3Nsub.4 nanospheres by the template method and synthesize ...a g-Csub.3Nsub.4@Cusub.0.5Insub.0.5S core-shell S-scheme photothermal nanoreactor by a simple chemical deposition method. The unique hollow core-shell structure of g-Csub.3Nsub.4@Cusub.0.5Insub.0.5S is beneficial to expand the spectral absorption range and improving photon utilization. At the same time, the photogenerated carriers can be separated, driven by the internal electric field. In addition, g-Csub.3Nsub.4@Cusub.0.5Insub.0.5S also has a significantly enhanced photothermal effect, which promotes the photocatalytic reaction by increasing the temperature of the reactor. The benefit from the synergistic effect of light and heat, the Hsub.2 evolution rate of g-Csub.3Nsub.4@Cusub.0.5Insub.0.5S is as high as 2325.68 μmol hsup.−1 gsup.−1, and the degradation efficiency of oxytetracycline under visible light is 95.7%. The strategy of combining S-scheme heterojunction with photothermal effects provides a promising insight for the development of an efficient photocatalytic reaction.
Microbial fuel cell (MFC) is regarded as a promising alternative for enhancing the removal of antibiotic pollutants. In this study, oxytetracycline served as an electron donor in the anode chamber of ...MFCs, and after continuous operation for 330 days, the efficiency of removal of 10 mg/L oxytetracycline in MFCs increased to 99.00% in 78 h, whereas removal efficiency of only 58.26% was achieved in microbial controls. Compared to microbial controls, higher ATP concentration and persistent electrical stimulation mainly contributed to bioelectrochemical reactions more rapidly to enhance oxytetracycline removal in MFCs. In addition, the analysis of bacterial communities revealed that Eubacterium spp.—as the main functional bacterial genus responsible for oxytetracycline biodegradation—flourished starting from merely 0.00%–91.69% ± 0.27% (mean ± SD) in MFCs. High-throughput quantitative PCR showed that the normalized copy numbers of total antibiotic resistance genes (ARGs) and mobile genetic elements in MFCs were 1.7364 and 0.0065 copies/cell respectively, which were markedly lower than those in the microbial controls. Furthermore, there was no significant correlation between oxytetracycline concentration in the influent and abundance of ARGs in effluent from MFCs. Nevertheless, Tp614, a transposase gene, was found to be enriched in both MFCs and microbial reactors, suggesting that it may be a common challenge for different biological processes for wastewater treatment. This study therefore showed a lower probability of upregulation and transmission of ARGs in MFCs when compared to a traditional anaerobic microbial treatment.
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•MFC enhanced degradation of 10 mg/L oxytetracycline.•Eubacterium spp. as functional genus biodegrading oxytetracycline flourished greatly.•ARGs in MFCs biofilm could have a lower possibility to horizontal transfer.•Tp614 was enriched in all effluents of biological reactors.
We evaluated the chronic impact of oxytetracycline (OTC) on performance and antibiotic resistance development during the mesophilic anaerobic digestion (AD) of antibiotic-containing biomass. ...Mesophilic AD was conducted in a completely stirred tank reactor by constantly feeding municipal excess sludge spiked with increasing concentrations of OTC (0–1000 mg L−1) under a solid retention time of 20 days over a period of 265 days. Results showed that methane generation of mesophilic AD was inhibited when the OTC concentration in digested sludge was increased to around 18,000 mg kg−1 (OTC dose, 1000 mg L−1), due to the inhibition of fermenting and acidogenic bacteria. Metagenomic sequencing and high-throughput quantitative PCR analysis demonstrated that tetracycline resistance genes were the most dominant type (38.47–43.76%) in the resistome, with tetG, tetX, tetM, tetR, tetQ, tetO, and tetL as the dominant resistant subtypes throughout the whole experimental period. The relative abundance of these tet genes increased from 2.10 × 10−1 before spiking OTC (OTC concentration in digested sludge, 8.97 mg kg−1) to 2.83 × 10−1 (p < 0.05) after spiking OTC at a dose of 40 mg L−1 (OTC concentration in digested sludge, 528.52 mg kg−1). Furthermore, mobile genetic elements, including integrons, transposons, and plasmids, were also enriched with the increase in OTC dose. Based on partial canonical correspondence analysis, the contributions of horizontal (mobile element alteration) and vertical (bacterial community shift) gene transfer to antibiotic resistome variation were 29.35% and 21.51%, respectively. Thus, considering the inhibition of hydrolytic acidification and enrichment of antibiotic resistome, mesophilic AD is not suggested to directly treat the biomass containing OTC concentration higher than 200 mg L−1.
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•Hydrolytic acidification of mesophilic AD was inhibited under high OTC stress.•Resistome in digested sludge was enriched with the increase of OTC dose.•Mobilome in digested sludge was enriched with the increase of OTC dose.•HGT and VGT concurrently governed ARG patterns in digested sludge under OTC stress.
Because of inhibiting hydrolytic acidification and enriching antibiotic resistome, mesophilic AD is not suitable to treat the biomass containing high concentration of OTC.
Antibiotics and antibiotic resistance genes (ARGs) in soil can affect human health via the food chain. Biochar is a soil amendment but its impacts on ARGs and the microbial communities associated ...with soil and vegetables are unclear. Therefore, we established three lettuce pot culture experiments, i.e., O300: 300 mg/kg oxytetracycline (OTC), BO300: 300 mg/kg OTC + 2% biochar, and a control without OTC or biochar. We found that under BO300, the relative abundances of ARGs were reduced by 51.8%, 43.4%, and 44.1% in lettuce leaves, roots, and soil, respectively, compared with O300. intI1 was highly abundant in soil and lettuce, and it co-occurred with some ARGs (tetW, ermF, and sul1). Redundancy analysis and network analysis indicated that the bacterial community succession was the main mechanism that affected the variations in ARGs and intI1. The reduction of Firmicutes due to the biochar treatment of soil and lettuce was the main factor responsible for the removal of tetracycline resistance genes in leaves. Biochar application led to the disappearance of human pathogenic bacteria (HPB), which was significantly correlated with the abundances of ermF and ermX. In summary, biochar is an effective farmland amendment for reducing the abundances of antibiotics, ARGs, and HPB in order to ensure the safety of vegetables and protect human health.
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•Biochar inhibited the accumulation of OTC in soil and lettuce.•ARGs in soil and lettuce tissues were decreased after biochar application.•Bacterial community affected the variations in ARGs and intI1.•Biochar application led to the disappearance of HPB.•Biochar is conducive to protect vegetable safety and human health.
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The presence of residual antibiotics will lead to potential environmental risks. Here cyclodextrins (CDs) were successfully used to modify graphene-based iron nanoparticles (GO@Fe ...NPs) to enhance the absorption of oxytetracycline hydrochloride (OTC). The removal of OTC decreased in the order: γCD-GO@Fe NPs > βCD-GO@Fe NPs > αCD-GO@Fe NPs > GO@Fe NPs, with better performance than that of bare GO and Fe NPs. Characterization techniques were applied to better understand how CDs impact the structure of GO@Fe NPs and improve removal performance. Raman and X-ray diffraction analysis showed that GO acted as a carrier to support Fe NPs within the grafted cyclodextrin, where GO also participated in the removal process. Cyclodextrin modified GO@Fe NPs had relatively small particle sizes (15 nm), with a high surface area (61.7 m2 · g−1). X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy suggested that cyclodextrin acted as both a stabilizing and capping agent during green synthesis, which could protect the reactivity of Fe NPs and simultaneously reduce aggregation. A potential synthesis mechanism of cyclodextrins modified composites was also proposed, and subsequent wastewater testing indicated that γCD-GO@Fe NPs had high potential for practical applications.
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•Relative abundance (RA) of ARGs in compost was similar with four OTC treatment levels.•RAs of tetC, tetX, sul1, sul2, and intI1 increased by 2–43 times after composting.•OTC at ...200mg/kg increased the absolute abundances of 5/8 ARGs and intI.•Changes in ARGs during composting associated with bacterial community succession.•Composting did not remove most ARGs and the compost remained a reservoir of ARGs.
Livestock manure is often subjected to aerobic composting but little is known about the variation in antibiotic resistance genes (ARGs) during the composting process under different concentrations of antibiotics. This study compared the effects of three concentrations of oxytetracycline (OTC; 10, 60, and 200mg/kg) on ARGs and the succession of the bacterial community during composting. Very similar trends were observed in the relative abundances (RAs) of each ARG among the OTC treatments and the control during composting. After composting, the RAs of tetC, tetX, sul1, sul2, and intI1 increased 2–43 times, whereas those of tetQ, tetM, and tetW declined by 44–99%. OTC addition significantly increased the absolute abundances and RAs of tetC and intI1, while 200mg/kg OTC also enhanced those of tetM, tetQ, and drfA7. The bacterial community could be grouped according to the composting time under different treatments. The highest concentration of OTC had a more persistent effect on the bacterial community. In the present study, the succession of the bacterial community appeared to have a greater influence on the variation of ARGs during composting than the presence of antibiotics. Aerobic composting was not effective in reducing most of the ARGs, and thus the compost product should be considered as an important reservoir for ARGs.
The presence of antibiotics in soils may increase the selection pressure on soil bacterial communities and cause tolerance to these pollutants. The temporal evolution of bacterial community tolerance ...to different concentrations of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) was evaluated in two soils. The results showed an increase of soil bacterial community tolerance to TC, CTC and OTC only in samples polluted with the highest antibiotic concentrations tested (2000 mg kg−1). The magnitude of those increases was higher in the soil with the lower organic carbon content (1.6%) than in the soil with an organic carbon content reaching 3.4%. In the soil with low organic carbon content, the time-course evolution showed a maximum increase in the tolerance of bacterial communities to tetracycline antibiotics between 45 and 100 incubation days, while for longer incubation times (360 days) the tolerance decreased. In the soil with high organic carbon content, a similar behavior was found for OTC. However, for CTC and TC, slightly increases and decreases (respectively) were found in the bacterial community tolerance at intermediate incubation times, followed by values close to zero for TC after 360 days of incubation, while for CTC they remained higher than in the control. In conclusion, soil pollution due to tetracyclines may cause bacterial community tolerance to these antibiotics when present at high concentrations. In addition, the risk is higher in soils with low organic matter content, and it decreases with time.
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•Soil pollution with tetracyclines may increase bacterial community tolerance.•Antibiotic concentrations needed to cause those increases are higher than 500 mg/kg.•The increases were higher in soils with low organic carbon content.•The magnitude of the increases in bacterial community tolerance was time dependent.•Bacterial community tolerance to tetracyclines was maximum after 45–100 days.
Background: Oxytetracycline and its derivatives routinely used to treat various ailments have also been shown to inhibit embryonic bone formation, mineralization in pregnant female rats and ...parathyroid hormone induced demineralization of bones. Oxytetracycline has also been routinely used as bone fluorochrome to study bone metabolism. However, despite the above observations, its mechanism of action is not clearly understood. Controversy exists whether or not it acts by influencing collagen biosynthesis. Objective: To study the mechanism by which Oxytetracyclin influences in vitro mineralization and demineralization reactions in the absence and presence of collagen Materials and Methods: Homogeneous and Heterogeneous systems of In vitro mineralization under physiological conditions were used to investigate the effect of oxytetracyline not only on initial mineralization but also the subsequent growth and demineralization of the preformed mineral phase both in the absence and presence of collagen. Results: The studies demonstrated that in the homogeneous reaction system (mineralization in the absence of collagen) oxytetracycline was found to inhibit both the initial mineral phase formation and its subsequent growth without influencing the demineralization. However, when in the heterogeneous system mineralization was studied in the presence of collagen, oxytetracycline was found to inhibit not only the initial mineralization but also the subsequent growth and demineralization of the preformed mineral phase. Conclusions: Oxytetracycline acted like crystal poisons to inhibit the mineralization and demineralization reaction reactions by tightly associating with the mineral phase.
In recent years, polyurethane has drawn great attention because of its many advantages in physical and chemical performance. In this work, firstly, polyurethane was impregnated in a non-woven fabric ...(NWF). Then, polyurethane-impregnated NWF was coagulated utilizing a wet phase inversion. Finally, after alkali treatment, microfiber non-woven fabrics with a porous polyurethane matrix (PNWF) were fabricated and used as substrates. SnInsub.4Ssub.8 (SIS) prepared by a microwave-assisted method was used as a photocatalyst and a novel SIS/PNWF substrate with multiple uses and highly efficient catalytic degradation ability under visible light was successfully fabricated. The surface morphology, chemical and crystal structures, optical performance, and wettability of SIS/PNWF substrates were observed. Subsequently, the photocatalytic performance of SIS/PNWF substrates was investigated by the decomposition of rhodamine B (RhB) under visible light irradiation. Compared with SIS/PNWF-2% (2%, the weight ratio of SIS and PNWF, same below), SIS/PNWF-5% as well as SIS/PNWF-15%, SIS/PNWF-10% substrates exhibited superior photocatalytic efficiency of 97% in 2 h. This may be due to the superior photocatalytic performance of SIS and the inherent hierarchical porous structure of PNWF substrates. Additionally, the hydrophobicity of SIS/PNWF substrates can enable them to float on the solution and further be applied on an open-water surface. Furthermore, tensile strength and recycle experiments demonstrated that SIS/PNWF substrates possessed superior mechanical strength and excellent recycle stability. This work provides a facile and efficient pathway to prepare SIS/PNWF substrates for the degradation of organic pollutants with enhanced catalytic efficiency.
Integrated wastewater treatment processes are needed due to the inefficient removal of emerging pharmaceuticals by single methods. Herein, an adsorbent-photocatalyst integrated material was ...fabricated by coupling calcium alginate with sulfur-doped TiOsub.2/tungsten disulfide (S-TiOsub.2/WSsub.2/alginate beads) for the removal of oxytetracycline (OTC) from aqueous solution by an integrated adsorption-photocatalysis process. The semiconductor S-TiOsub.2/WSsub.2 hybrid photocatalyst was synthesized with a hydrothermal method, while the integrated adsorbent-photocatalyst S-TiOsub.2/WSsub.2/alginate beads were synthesized by blending S-TiOsub.2/WSsub.2 with sodium alginate using calcium chloride as a precipitating agent. The physicochemical characteristics of S-TiOsub.2/WSsub.2/alginate beads were analyzed using X-ray diffraction , scanning electron microscopy, elemental mapping, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The integrated adsorption-photocatalysis process showed enhanced removal from 92.5 to 72%, with a rise in the OTC concentration from 10 to 75 mg/L respectively. The results demonstrated that the adsorption of OTC onto S-TiOsub.2/WSsub.2/alginate beads followed the Elovich kinetic model and Redlich-Peterson isotherm models. The formations of H-bonds, cation bridge bonding, and n-π electron donor-acceptor forces were involved in the adsorption of OCT onto S-TiOsub.2/WSsub.2/alginate beads. In the integrated adsorption-photocatalysis, surface-adsorbed OTC molecules were readily decomposed by the photogenerated active radical species (h⁺, Osub.2 sup.*−, and HOsup.*). The persulfate addition to the OTC solution further increased the photocatalysis efficacy due to the formation of additional oxidizing species (SOsub.4 sup.*⁻, SOsub.4⁻). Moreover, S-TiOsub.2/WSsub.2/alginate beads showed favorable efficiency and sustainability in OTC removal, approaching 78.6% after five cycles. This integrated adsorption-photocatalysis process offered significant insight into improving efficiency and reusability in water treatment.
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