Tetracycline Removal Efficiency Research Articles

Reduced graphene oxide/Bi4O5Br2 nanocomposite with synergetic effects on improving adsorption and photocatalytic activity for the degradation of antibiotics

A photocatalyst based on the integration of reduced graphene oxide (rGO) with Bi4O5Br2 nanosheets was facilely prepared and was confirmed by transmission electron microscope, scanning electron microscope, X-ray diffraction and Raman spectroscopy. The integration of rGO can effectively improve the adsorption and the photocatalytic properties of Bi4O5Br2 nanosheets towards the target antibiotics under visible light irradiation. rGO/Bi4O5Br2 nanocomposite containing 1.0 wt% of rGO exhibits the optimal adsorption and photocatalytic activity towards ciprofloxacin (CIP), norfloxacin (NOR) and tetracycline (TC). The removal efficiencies of CIP, NOR and TC are 97.6%, 80.7% and 98.7%, which are higher than that obtained with Bi4O5Br2 nanosheets. The capture experiments and ESR data show that ·O2−, OH· and h+ are the main active species that participated in the photodegradation system. This work provides a simple strategy to integrate rGO with BixOyXz (X = Cl, Br, I) nanosheets to construct effective photocatalysts for the degradation of antibiotics.

Cu/CuFe2O4 integrated graphite felt as a stable bifunctional cathode for high-performance heterogeneous electro-Fenton oxidation

• Cu/CuFe 2 O 4 with different Cu 0 ratios were synthesized by a solvothermal method. • Cu/CuFe 2 O 4 integrated GF was developed for cathode of the heterogeneous EF process. • PTFE improved the oxygen utilization rate and stability of the composite cathode. • Cu 0 as electron-rich centers can accelerate redox cycling of Fe(III)/Fe(II). The development of transition metal oxide-based integrated carbonaceous materials for use as bifunctional electrodes of high stability and activity in the heterogeneous electro-Fenton (EF) process is supposed to have great potential in environmental governance. Herein, Cu/CuFe 2 O 4 (CCFO) with different Cu 0 ratios were synthesized by a facile one-step solvothermal approach. These materials were subsequently used to fabricate modified graphite felt through the polytetrafluoroethylene (PTFE)-bonding technique. Importantly, with its hydrophobicity PTFE effectively inhibited metal leaching from the thus obtained cathodes and improved the oxygen utilization rate. Cathode performance in EF-based tetracycline (TC) degradation was found to increase with Cu 0 ratio. The observed increase in activity was attributed to Cu 0 enhancing the 2-electron oxygen reduction reaction selectivity (i.e., H 2 O 2 production) and endowing the cathode with abundant electron-rich centers that accelerated active Fe(II) regeneration, causing rapid conversion of H 2 O 2 to hydroxyl radical ( OH). The possible TC mineralization pathway was inferred by liquid chromatography–mass spectrometry (LC–MS) analysis, and a catalytic mechanism of the heterogeneous EF process was proposed. The most effective cathode fabricated displayed high stability even at pH 3 (0.84 ± 0.11 mg/L Fe and 1.35 ± 0.17 mg/L Cu leaching) and exhibited nearly 80% TC removal efficiency after five oxidation cycles, demonstrating its potential use in heterogeneous EF technology for efficient and durable wastewater treatment.

Enhanced the visible light photocatalytic decomposition of antibiotic pollutant in wastewater by using Cu doped WO3

Due to the rapid increase in the use of tetracycline (TC), a broad-spectrum antibiotic, the environmental residues of TC in water have aroused critical health issues. This work investigates the effectiveness and capability of Cu ions loaded WO3 (Cu-WO3) for the enhancement of photocatalytic decomposition of TC in wastewater. Different techniques were employed to characterize the catalyst such as XRD, XPS, FESEM, TEM and UV–vis. The optical properties analysis showed that Cu doped WO3 was successfully narrowed the bandgap energy, resulting in improved the removal efficiency of TC. Experimental results illustrate that Cu doping effectively improved the photocatalytic activity of WO3 and 2.5 %. wt. Cu doped exhibited the highest TC degradation efficiency (96.8 %). The photocatalytic decomposition of TC by Cu-WO3 was significantly increased under strongly alkaline conditions (pH 8–10). The reusability of catalysts and the leaching of transition metal ions was also investigated. After the fifth cycle, the photocatalytic degradation of TC by Cu-WO3 only reduced by 18.2 %, indicated that the Cu-WO3 can use as an excellent photocatalyst response for the TC degradation. The radical screening, the intermediates products and the proposed mechanism were discussed in detail. Finally, the Cu-WO3 was applied to remove TC from wastewater and it could efficiently remove 93.7 % TC within 60 min. Based on these findings, Cu-WO3 can use as a good candidate with long-time stability for photodegradation of TC in wastewater.

Zinc (II) modified hydroxyapatites for tetracycline removal: Zn (II) doping or ZnO deposition and their influence in the adsorption

Zn(II) modified hydroxyapatites were prepared through the microwave-assisted co-precipitation/hydrothermal method using zinc acetate and HAp in the presence of casein as the template, followed by calcination at 500 °C in an oxygen atmosphere with the heating rate of 2 °C min−1 for 12 h. The zinc acetate proportion in relation to the mass of pure HAp was varied to obtain theoretical final products with 5%, 10%, and 20% ZnO, which were labeled as HAp/ZnO-1, HAp/ZnO-2, and HAp/ZnO-3, respectively. The synthesized solids were then characterized using X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray dispersive spectroscopy, and nitrogen adsorption/desorption isotherm measurements. The adsorptive properties of the materials for the removal of tetracycline (TC) from aqueous solutions were evaluated using the Langmuir, Freundlich, and Temkin isotherm models. The structural characterizations revealed the formation of Zn-doped HAp/ZnO-type composites. The samples rich in ZnO (HAp/ZnO-3) exhibited good TC removal efficiency with a maximum adsorption of 168.5 mg L−1 within 20 min. The adsorption capacity data of the samples could be well-fitted to the Langmuir model. The ZnO content played an important role in adjusting the adsorptive properties of HAp for applications in wastewater treatment, especially for the removal of drugs from aqueous solutions.

Magnetic ball-milled FeS@biochar as persulfate activator for degradation of tetracycline

In this study, composite of iron sulfide and biochar (FeS@BC) was synthesized successfully via physical ball milling and applied to the oxidative removal of tetracycline (TC) in the presence of persulfate (PS). Characterization results showed that FeS@BC, which has a small particle size, can be synthesized at a preset FeS-BC mass ratio. In addition, the ball-milled FeS@BC showed sufficient ferromagnetism. The effects of pH, dosages of FeS@BC and PS, and co-existing anions on TC degradation were investigated. Our results showed that TC degradation efficiency was enhanced at low pH and high dosages of PS and FeS@BC. Under optimal conditions (pH = 3.6, [FeS@BC] = 0.3 g/L and [PS] = 10 mM), a TC removal efficiency of 87.4% could be achieved after 30 min. Nevertheless, the TC removal rate was slightly inhibited by inorganic anions in the order of CO32− > Cl− > NO3−. Surface-bound Fe(Ⅱ) and S(Ⅱ) acted as electron donors in the activation process and generated SO4− and OH at the surface of FeS@BC. In addition, S(Ⅱ) also participated in Fe(III) reduction. BC not only reduced the agglomeration of FeS, serving as a continuous source of effective Fe, but also acted as an electron shuttle and a suitable carbon-based adsorption material, facilitating fast electron transfer among PS, electron donors, and pollutants. Moreover, non-radical degradation processes might also exist in the FeS@BC/PS/TC system. The FeS@BC could be a promising effective activator for the remediation of other emerging organic contaminants.

Construction of CuO@CuS/PVDF composite membrane and its superiority for degradation of antibiotics by activation of persulfate

Antibiotics were frequently detected in influent of wastewater treatment plants (WTPs), which brought potential crisis to human beings and the environment. In this study, series of CuO@CuS nanocomposites were synthesized by co-precipitation combined with microwave treatment, which was employed to activate persulfate (PS) toward degrading tetracycline (TC). Results indicated that CuO@CuS with a molar ratio of 2:1 displayed the superior PS activation performance with TC removal efficiency. In order to further improve the recycle and utilization of nano-composites, CuO@CuS/PVDF membrane were constructed, leading to a greatly enhancement of TC removal efficiency (87.4%) within 3 h. Subsequently, physicochemical properties of CuO@CuS/PVDF membrane were characterized systematically. The effects of operating parameters, such as PS concentration, the initial pH value and co-existing ion on the CuO@CuS/PVDF-PS system were optimized in detail. The analysis results disclosed that when [PS] = 0.4 g/L, pH = 3, the system exhibited excellent degradation efficiency by elimination of contaminant solution. Furthermore, the enhanced mechanism of CuO@CuS/PVDF-PS system for organic pollutants elimination was proposed and confirmed, which was ascribed to the involvement of hydroxyl radical (·OH), sulfate radical (SO4·−) and singlet oxygen (1O2). Thence, the constructed membrane/PS system exhibited potential application in wastewater treatment.

Trace Ti3+- and N-codoped TiO2 nanotube array anode for significantly enhanced electrocatalytic degradation of tetracycline and metronidazole

A trace Ti3+- and N-codoped TiO2 nanotube array (TiON) anode is fabricated by electrochemical reduction after introducing nitrogen into the TiON. The TiON anode material is characterized by scanning electron microscopy, X-ray diffraction, Raman spectra and X-ray photoelectron spectroscopy. Electrochemical analyses of TiON, including cyclic voltammetry, electrochemical impedance spectroscopy and linear scan voltammetry, are conducted to confirm that the electrochemical performance could be significantly improved by electrochemical reduction and N doping. The achieved TiON anode is applied to the electrocatalytic oxidation of tetracycline (TC) and metronidazole (MNZ). The effect of applied current density, initial solution pH and initial TC/MNZ concentration on the reaction kinetics is systematically evaluated to obtain the optimal conditions. The degradation processes follow an apparent first-order kinetic model in all conditions. After 240 min of reaction time, the TC removal efficiency, chemical oxygen demand (COD) removal rate and total organic carbon (TOC) removal rate are >99%, 92.86% and 74.98%, respectively. The MNZ removal efficiency, COD and TOC removal rate achieved are >99%, 93.03% and 79.30%, respectively, after 240 min of degradation. The excellent removal efficiency of TC and MNZ indicates that this TiON anode is a promising material in the practical application of removing antibiotics from water.

Tailored synthesis of Ag/AgBr nanostructures coupled activated carbon with intimate interface interaction for enhanced photodegradation of tetracycline

Tailored synthesis of Ag/AgBr nanostructures (AABR) with intimate interface interaction for enhanced photocatalytic performance is a challenge for its extensive applications. Herein, tailored Ag/AgBr nanostructures promoted with char-microwave activated carbon (ACK) was synthesized through a modified deposition-precipitation method. The influence of four reaction parameters comprising of a mass of surfactant, temperature, ACK mass and ammonium hydroxide volume for the AABR-ACK composites were optimized using response surface methodology (RSM). Their simultaneous interactions on removal efficiency of tetracycline (TC) antibiotics under visible light were investigated under visible light. The high photocatalytic degradation of TC over AABR-ACK composites was governed by ammonium hydroxide volume and temperature. The SEM, XRD, FTIR, TEM, optical and electrochemical properties of the composites from these influential parameters, evidenced the formation of tailored AABR-ACK nanostructures with intimate interface interaction. The tailored near spheres nanostructures of AABR promoted with ACK boosted the visible light absorption, intimate interface contact, which promotes photo-induced charge pairs separation for the enhanced visible-light photocatalytic activity of AABR-ACK 7 composite TC (87 %). In addition, AABR-ACK 7 composite possessed significant recycle efficiency up to four consecutive cycles. The mineralization efficiency of AABR-ACK 7 on TC achieved 78.5 % and possible degradation pathways of TC were proposed. This work offers good insight into the tailored design of visible-light responsive heterojunction photocatalysts for sustainable environmental remediation.

Excellent photocatalytic degradation of tetracycline over black anatase-TiO2 under visible light

As an emerging semiconductor different from regular white TiO2, black TiO2 has attracted intensive attention on visible light driven photocatalysis for degrading dyes, but rarely for degradation of antibiotics. In this study, black anatase-TiO2 was demonstrated to be an effective catalyst for tetracycline (TC) visible light photodegradation. 66.2% removal efficiency of TC was achieved over black TiO2 under visible light illumination, while white TiO2 and N-doped TiO2 exhibited 43.4% and 59.6% removal efficiencies, respectively. Furthermore, only ⋅O2− radicals played an important role in TC photodegradation over white TiO2, whereas both ⋅O2− and h+ were responsible for the degradation over black TiO2 and N-doped TiO2. Different from white TiO2 for visible light photocatalytic TC degradation that follows photosensitization, the visible light photodegrataion over black TiO2 is due to photoexcitation.

Bifunctional copper modified graphitic carbon nitride catalysts for efficient tetracycline removal: Synergy of adsorption and photocatalytic degradation

In order to efficiently remove tetracycline in wastewater through the synergistic effect of adsorption and photocatalytic degradation, a series of novel composite materials (Cu doped g-C3N4) were synthesized by two-pot hydrothermal method. It was found that the composite materials with optimized ratio (Cu/CN-1) displayed outstanding adsorption and photocatalytic performance as compared with pure g-C3N4 photocatalyst. The removal efficiency of tetracycline (TC, 50 mg/L) reached almost 99% within 30 min by Cu/CN-1 through the synergy of adsorption and photocatalysis under visible-light irradiation, which was the highest removal efficiency ever reported. The adsorption kinetics and isotherms of TC on the Cu/CN-1 were well fitted with the pseudo-second-order kinetic model and Langmuir model, respectively. Moreover, it was confirmed that the main effective reactive groups were O2− and h+ in photocatalytic process. The Cu/CN-1 exhibited high stability and excellent reusability after five cycle experiments. Finally, the mechanism of synergy between Cu and g-C3N4 was proposed: on the one hand, the decoration of Cu particles significantly increased the adsorption sites of Cu/CN-1 to tetracycline, on the other hand, the modification of Cu particles effectively inhibits charge recombination and broadens the visible light absorption range of the photocatalyst.This study provided a promising photocatalyst to be used for TC removal in the actual wastewater.

Fe3O4 accelerates tetracycline degradation during anaerobic digestion: Synergistic role of adsorption and microbial metabolism

Antibiotics contaminants, for example, tetracycline (TC) in the environment have attracted extensive attention around the world, and appropriate treatments for such contaminants are urgently required. In this study, five groups of anaerobic reactors supplemented with different amounts of Fe3O4 were operated periodically to investigate their performance on TC removal. The results showed that Fe3O4 effectively promoted TC removal. Compared with the control reactor, the TC removal efficiency was increased by 7.3% when co-digested with glucose, and increased by 40.4% when mono TC was digested in reactors with 5.0 g/L Fe3O4. Further analysis indicated that the probable mechanism of Fe3O4 promoting TC removal was through TC being adsorbed from the liquid onto Fe3O4, making TC more available for microbes to be biodegraded. Microbial community analysis indicated that the bacteria (Klebsiella, Pseudomonas, and Escherichia) related to TC removal were enriched, which meant more pathways for TC removal were available following the addition of Fe3O4. In addition, in the Fe3O4-supplemented reactors, syntrophic metabolism (between Desulfovibrio and Methanobacterium, Azonexus and Methanobacterium) were possibly established, which played an important role in improving TC removal and CH4 production. The electron transport system data further confirmed these results. The functional gene classification for Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that the dominant functions enhanced by Fe3O4 supplementation was microbial metabolic activities.

AgI nanoparticles decorated Bi3O4Cl microspheres: An efficient Z-scheme heterojunction photocatalyst for the degradation of rhodamine B and tetracycline

A novel Z-scheme AgI/Bi3O4Cl composite was fabricated through solvothermal-calcination method followed by an in-situ deposition process. The AgI/Bi3O4Cl composites exhibited improved photocatalytic activity for degrading rhodamine B (RhB) and tetracycline (TC) in comparison with pristine Bi3O4Cl and AgI under simulated sunlight irradiation. Specifically, BAI-3 composite (mass content of 30% of AgI) showed the highest removal efficiency of RhB and TC. And the degradation rate constants (k) of RhB over BAI-3 was 0.038 min−1, which was 25.3 and 3.8 times than that of pristine Bi3O4Cl (0.0015 min−1) and AgI (0.01 min−1), respectively. The photoelectrochemistry measurements and photoluminescence (PL) spectra manifested that the recombination of photogenerated electrons and holes in AgI/Bi3O4Cl composite was suppressed evidently because of the construction of AgI/Bi3O4Cl heterojunction. Radicals trapping experiments and electron spin resonance (ESR) test showed that ·O2− and h+ were the main reactive species. Combined with the analysis of band structures, a Z-scheme charge transfer mechanism of AgI/Bi3O4Cl composite was confirmed.

Effect of carbon source on pollutant removal and microbial community dynamics in treatment of swine wastewater containing antibiotics by aerobic granular sludge

Aerobic granular sludge sequencing batch reactor (AGSBR) is a promising approach for wastewater treatment. In the paper, the effects of methanol, starch and sucrose as carbon sources on the treatment of swine wastewater (SW) containing antibiotics by aerobic granular sludge (AGS) were studied. The results revealed that the carbon sources could affect the morphology, biomass, and settleability of AGS, and AGS could maintain a better sludge performance when sucrose was used as carbon source. The pollutants (ammonium nitrogen (NH+ 4-N), organic matter and total phosphorus (TP)) in SW also had a good removal effect, and the removal rates reached 81.14%, 96.83% and 97.37% respectively. The removal efficiencies of tetracycline (TC) and oxytetracycline (OTC) from SW were the best when sucrose as co-metabolic matrix by microorganisms. The analysis of miseq pyrosequencing demonstrated that carbon sources with methanol, starch and sucrose improved the diversity of microbial community in AGS, and the dominant bacteria also changed. The dominant groups involved in TC and OTC, removal at different classification levels suggested that the formation of bacterial communities was determined by carbon sources.

3D hydrangea-like Mn3O4@(PSS/PDDA/Pt)n with ultrafine Pt nanoparticles modified anode for electrochemical oxidation of tetracycline

Three-dimensional (3D) hydrangea-like Mn3O4@(PSS/PDDA/Pt)n was prepared via in situ reduction of Pt4+ on sea-urchin-like MnO2 coated with lay-by-layer (LBL) films of polyelectrolytes. Combining of ultrafine Pt nanoparticles, 3D structure and manganese oxide support makes these Mn3O4@(PSS/PDDA/Pt)n particles suitable for anode-oxidation of tetracycline (TC) with both excellent mass activity and durability. The performance and possible mechanism of TC degradation on Mn3O4@(PSS/PDDA/Pt)n anode were investigated. The maximal TC removal efficiency on Mn3O4@(PSS/PDDA/Pt)n anode achieved 98.8% at a TC concentration of 60 mg L−1, pH 7.0 and 8 V in the presence of NaCl. The TC electrochemical oxidation on Mn3O4@(PSS/PDDA/Pt)n anode followed a pseudo-first-order kinetic. Additionally, the efficiency of TC removal on Mn3O4@(PSS/PDDA/Pt)1 anode maintained more than 95% after recycling for 5 times, indicating the considerable durability. We also evaluated the application for degradation of other antibiotics. Thus, our research provides a deep insight into the preparation of efficient anode based on 3D manganese oxides loaded with ultrafine Pt particles for potential application in electrochemical oxidation of TC and other antibiotics in contaminated water.

Functional photoelectrocatalytic membrane fabricated from ZnIn2S4, PVDF and carbon fibre for continuous removal of tetracycline

In this work, a functional photoelectrocatalytic membrane (PEM) electrode was prepared by loading polyvinylidene fluoride (PVDF) layer onto one side of carbon fibre felt (CF) and ZnIn2S4 microparticles onto the other side. The ZnIn2S4/CF/PVDF membrane was characterised by scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy detector (EDS), Fourier transform infrared spectrometer (FT-IR) and BET surface area. The cyclic voltammetry (CV) and the photocurrent response measurements were also tested. The ZnIn2S4/CF/PVDF membrane had good electrical conductivity for photoelectrocatalytic degradation of tetracycline (TC). The optimized degradation condition with applied voltage of -0.3 ​V, pH of 6.5 and electrolyte concentration of 50 ​mmol ​L-1 was determined in operating mode with effluent circulating to reactor, which can realize the TC removal efficiency of 87% and mineralization of 52% under reaction time of 3 ​h. The PEM remained stable during 4 days of continuous influent and effluent experiments. The yield of superoxide radical (·O2-) and hydroxyl radical (·OH) was 4.17×10-5 ​mol ​L-1 and 1.04×10-5 ​mol ​L-1, respectively. The degradation pathways of TC by photocatalysis, electrocatalysis and photoelectrocatalysis were compared and proposed, respectively. The generated intermediates during the continuous influent and effluent process were also identified.

Micropollutants cometabolism of microalgae for wastewater remediation: Effect of carbon sources to cometabolism and degradation products

This study investigated the impacts of selective sole carbon source-induced micropollutants (MPs) cometabolism of Chlorella sp. by: (i) extracellular polymeric substances (EPS), superoxide dismutase and peroxidase enzyme production; (ii) MPs removal efficiency and cometabolism rate; (iii) MPs’ potential degradation products identification; and (iv) degradation pathways and validation using the Eawag database to differentiate the cometabolism of Chlorella sp. with other microbes. Adding the sole carbon sources in the presence of MPs increased EPS and enzyme concentrations from 2 to 100-fold in comparison with only sole carbon sources. This confirmed that MPs cometabolism had occurred. The removal efficiencies of tetracycline, sulfamethoxazole, and bisphenol A ranged from 16-99%, 32–92%, and 58–99%, respectively. By increasing EPS and enzyme activity, the MPs concentrations accumulated in microalgae cells also fell 400-fold. The cometabolism process resulted in several degradation products of MPs. This study drew an insightful understanding of cometabolism for MPs remediation in wastewater. Based on the results, proper carbon sources for microalgae can be selected for practical applications to remediate MPs in wastewater while simultaneously recovering biomass for several industries and gaining revenue.

Mechanistic exploration of the catalytic modification by co-dissolved organic molecules for micropollutant degradation during fenton process

This study aimed to explore the catalytic effect of co-dissolved organic compounds on the tetracycline degradation by Fenton process both in the acidic and neutral environment. The experiments were carried out at [Fe2+]/[H2O2] of 50 μM/50 μM and 50 μM/100 μM. The humic acid, citrate and α-cyclodextrin were selected as the co-dissolved organic compounds. The best removal efficiency of 71% was observed at [Fe2+]/[H2O2] of 50 μM/100 μM without the presence of co-dissolved organic compounds. In the presence of co-dissolved organic compounds, the competition effect occurred and tetracycline removal efficiency was reduced to different extents depending on the H2O2 concentrations and chemical properties of the co-dissolved organic substances. The mechanistic exploration confirmed that the complex-forming interactions among Fe2+, tetracycline and organic co-dissolved molecules kept the catalytic ferrous/ferric redox cycle operating to generate hydroxyl radicals for tetracycline degradation at neutral condition, and this phenomenon was more obvious when the H2O2 concentration was higher. Complex formation also contributed to the overall tetracycline removal in addition to oxidation reactions. By comparing to the mass spectra of citrate, the α-cyclodextrin having a larger molecular structure might react with hydroxyl radicals at a higher probability, resulting in an apparent difference in degradation efficiency despite of the equality of their existing amount in the beginning of the experiment.

Removal of antibiotic tetracycline by metal-organic framework MIL-101(Cr) loaded nano zero-valent iron

Nano zero-valent iron (nZVI) is a highly reactive particle but easily to be aggregated. Porous materials support can improve the stability of nZVI. Materials of Institute Lavoisier Frameworks (MILs), a type of metal-organic frameworks (MOFs), have enormous surface areas, ultrahigh porosity, and good water stability. The combination between MILs and nZVI can provide an intensively “capture & destroy” effect to micro-pollutants in water. In this study, a novel composite, nZVI modified MIL-101(Cr), was prepared, characterized, and applied for tetracycline (TC) adsorption and degradation. The surface morphology and micropore structure of nZVI/MIL-101(Cr) were characterized. The TC adsorption performance of the composite was investigated via various parameters, adsorption kinetics, isotherms, and thermodynamics. Results showed that the TC adsorption followed pseudo-second-order kinetic equation and the maximum adsorption quantity (qm) was 625.0 mg/g. The catalytic property of nZVI/MIL-101(Cr) was also investigated via heterogeneous Fenton-like process, and nZVI/MIL-101(Cr) showed 90% TC removal efficiency in a wide pH range. Moreover, nZVI/MIL-101(Cr) displayed good stability and reusability. The developed composite is a potential adsorbent and heterogeneous catalyst for antibiotics pollution control in water.

Removal of tetracycline by denitrifying Mn(II)-oxidizing bacterium Pseudomonas sp. H117 and biomaterials (BMO and MBMO): Efficiency and mechanisms

Coexistence of multiple pollutants such as antibiotic, nitrate and heavy metal has received increasing attention resently. In this study, the functions of Pseudomonas sp.H117 on the removal of tetracycline(TC), nitrate and Mn(II), and biological materials (BMO(biogenic manganese oxides), MBMO(magnetic BMO)) on the removal of TC were investigated. Strain H117 showed higher TC removal efficiency of 68.86% (0.071 mg·L−1·h−1) within 96 h. Meanwhile, NO3-N and Mn(II) achieved high removal efficiency of 100% (0.211 mg·L−1·h−1) and 64.64% (0.265 mg·L−1·h−1), respectively. Furthermore, trapping experiments testified that Mn(III) intermediate formed during the biological manganese oxidation process, which contribute to the TC degradation. 91.29% and 96.63% of TC removal efficiency within 12 h were achieved by BMO and MBMO. Moreover, XPS, FTIR spectra, kinetics analysis and adsorption isotherms elucidated Mn(III) oxidation, chemical adsorption and ligand exchange reactions contribute to the removal of TC by biomaterials.

Modified MIL-100(Fe) for enhanced photocatalytic degradation of tetracycline under visible-light irradiation

Iron-based metal–organic frameworks (MOFs) with low cost and excellent photocatalytic potential are extremely attractive in the field of energy utilization and environmental remediation. In this study, a novel In2S3/MIL-100(Fe) photocatalyst was successfully synthesized by a facile solvothermal method for the first time. Several technologies (such as X-ray diffraction, scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy) were used to characterize the as-obtained samples and demonstrate the successful combination of MIL-100(Fe) and In2S3. Experimental results showed that 18% of tetracycline (TC) was adsorbed under dark condition and another 70% of TC was degraded under visible-light irradiation when treating 100 mL of TC solution (10 mg/L) with 30 mg of In2S3/MIL-100(Fe) composites. The corresponding TC removal efficiency was almost 1.9 and 1.6 times higher than that of pure MIL-100(Fe) and In2S3, respectively. The mechanism investigations revealed that the heterojunction composite exhibited superior charge transfer than either MIL-100(Fe) or In2S3, and this caused more efficient separation of electron-hole pairs. As a result, more radicals and holes were generated in the composite, leading to better photocatalytic performance. This work highlights the powerful combination of MOFs and semiconductor, which is a promising approach to fabricate heterojunction photocatalyst for wastewater purification.