Tetracycline Removal Efficiency Research Articles

Promoting the performance of electrooxidation-PMS system for degradation of tetracycline by introduction of MnFe2O4/CNT as a third-electrode

In this work, MnFe2O4/CNT was introduced into electrochemical oxidation (EC)-peroxymonosulfate (PMS) system to be served as a third electrode. In which, 20 wt% MnFe2O4/CNT due to its excellent physical characterization was proven to promote the catalytic degradation performance of tetracycline (TC). The optimal conditions for EC-20 wt% MnFe2O4/CNT-PMS on TC removal efficiency was investigated by dosage of catalyst, dosage of oxidant, current density and initial pH of TC. When 20 wt% MnFe2O4/CNT was injected at 0.1 g·L−1, PMS was injected at 6 m M, current density was 10 mA·cm−2, initial pH was 5.9, and reaction time was 120 min, TC removal rate reached 87.7%. The effect of humic acid (HA) on TC degradation was investigated by simulating real water bodies. The results showed that EC-20 wt% MnFe2O4/CNT-PMS system was less affected by water background. Judging by capturing free radicals’ experiments, it proved that this novel system facilitates to make much more •OH and SO4−• as active species in degradation of TC. The degradation mechanism of TC in the EC-20 wt% MnFe2O4/CNT-PMS system was estimated by XPS analysis of catalysts before and after the reaction. This research provides a new perspective for electrochemical oxidation by introducing nanomaterials as microelectrodes.

Tetracycline Adsorption from Aqueous Media by Magnetically Separable Fe3O4@Methylcellulose/APTMS: Isotherm, Kinetic and Thermodynamic Studies

This study aimed to synthesize Fe3O4@Methylcellulose/3-Aminopropyltrimethoxysilane (Fe3O4@MC/APTMS) as a new magnetic nano-biocomposite by a facile, fast, and new microwave-assisted method and to be utilized as an adsorbent for tetracycline (TC) removal from aqueous solutions. Fe3O4@MC/APTMS was characterized by Fourier transform-infrared (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive spectroscopy (EDS), Mapping, X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and vibrating sample magnetometer (VSM). The point of zero charge (pHzpc) value of the nano-biocomposite was estimated to be 6.8 by the solid addition method. Optimum conditions were obtained in TC concentration: 10 mg L−1, adsorbent dosage: 80 mg L−1, contact time: 90 min, and solution pH 6 with the maximum TC removal of 90% and 65.41% in synthetic and actual samples, respectively. The kinetic and isotherm equations pointed to a pseudo-second order kinetic and Langmuir isotherm optimum fitting models. Based on the values of entropy changes (ΔS) (50.04 J/mol k), the enthalpy changes (ΔH) (9.26 kJ/mol), and the negative Gibbs free energy changes (ΔG), the adsorption process was endothermic, random, and spontaneous. The synthesized adsorbent exhibited outstanding properties, including proper removal efficiency of TC, excellent reusability, and simple separation from aqueous media by a magnet. Consequently, it is highly desirable that Fe3O4@MC/APTMS magnetic nano-biocomposite could be used as a promising adsorbent for TC adsorption from aqueous solutions.

Evaluation of tetracycline removal by adsorption method using magnetic iron oxide nanoparticles (Fe3O4) and clinoptilolite from aqueous solutions

In the present study, Fe3O4/Clinoptilolite nanocomposite was synthesized in the laboratory as a magnetic nanosorbent; mentioned nanocomposite and Clinoptilolite were employed as adsorbent for adsorption of tetracycline (TC) from aqueous solution. Structure and properties of Fe3O4/Clinoptilolite nanocomposite and Clinoptilolite adsorbents were detected by vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscope (SEM), X-ray diffraction (XRD) analyses. The maximum adsorption capacity (qmax) for Clinoptilolite adsorbent was 20.17 mg/g, while it was 180.9 mg/g for Fe3O4/Clinoptilolite nanocomposite. Under optimal conditions, the removal efficiency of tetracycline by Fe3O4/Clinoptilolite nanocomposite was 98.6%, and the highest removal efficiency was obtained at pH values of 7 and 8, which could be due to physical adsorption mechanisms such as van der Waals forces and hydrogen bonds between TC polar molecules and functional groups on Fe3O4/Clinoptilolite nanocomposite. The results of nanocomposite reuse study showed that Fe3O4/Clinoptilolite adsorbent can be reused without significant reduction in efficiency, which economically and environmentally justifies the use of Fe3O4/Clinoptilolite nanocomposite to remove various contaminants.

CuFe2O4 modified expanded graphite synthesized by urea-assisted hydrothermal method for tetracycline treatment through persulfate activation: Characterization, mechanism and degradation intermediates

• Expanded graphite (EG) was applied as the support of CuFe 2 O 4 . • Composite catalyst (EG-CuFe 2 O 4 -U) was synthesized by the urea-assisted hydrothermal method. • EG-CuFe 2 O 4 -U possessed outstanding catalytic performance to PDS activation for TC degradation. • Both SO 4 ·− , ·OH and 1 O 2 were generated in the EG-CuFe 2 O 4 -U/PDS system. • The intermediates of TC were detected and analyzed. Owing to the stable crystal structure and wide range of pH applications, CuFe 2 O 4 particles have been intensively concerned in the field of advanced oxidation, but their serious agglomeration and slow catalytic efficiency are still the stumbling blocks. The composite catalyst (EG-CuFe 2 O 4 -U) prepared by urea-assisted hydrothermal method with expanded graphite (EG) as the substrate immobilized CuFe 2 O 4 not only exposed more active sites but also exhibited a higher electron transfer rate. Additionally, EG-CuFe 2 O 4 -U showed excellent performance in degrading tetracycline (TC) in model wastewater by activated peroxydisulfate (PDS). The synthesis mechanism of EG-CuFe 2 O 4 -U and the principle of urea in the formation of reduction environment were discussed in detail by the experimental results of key preparation parameters and characterization. Meanwhile, several critical influencing factors were examined including PDS concentration, catalyst dosage, initial pH of the solution, and the change of pH in different systems. Furthermore, the removal efficiency and mineralization efficiency of TC (50 ppm) exceed 91% and 34.6%, on the conditions of 0.4 gL −1 EG-CuFe 2 O 4 -U, 6 mM PDS, initial solution pH of 4, and room temperature. What’s more, the internal reaction mechanism of free radicals and non-free radicals in the EG-CuFe 2 O 4 -U/PDS system was further elaborated via scavenging tests, electron paramagnetic resonance (EPR). Finally, based on twenty-one principal intermediates of TC, four possible degradation pathways were proposed. In general, the catalyst with a rich pore structure and high catalytic activity has great potential in the effective activation of PDS and is prospective to be further applied in the field of antibiotic wastewater degradation.

Band gap narrowing ternary phosphorus-doped g-C3N4/Fe0@expanded graphite carbon layer hybrid composite for effective degradation of tetracycline via multiply synergistic mechanisms

The wide band gap of g-C3N4 and severe aggregation of Fe0 adequately limit their applications. To address these two critical issues, novel ternary phosphorus-doped g-C3N4/Fe0 @expanded graphite carbon layer (P-CN/Fe0 @EGC) photocatalyst with extremely narrow band gap and significantly enhanced catalytic activity was in-situ synthesized. P-CN/Fe0 @EGC hybrid composite exhibited excellent photodegradation performance of tetracycline (TC) removal, which is 5.18 and 1.92 times higher than that of pristine g-C3N4 and Fe0, respectively. Enhancement in photocatalytic activity is evaluated via photoluminescence (PL), UV–vis DRS, XRD and electron spin resonance (ESR). A reasonable catalytic mechanism of P-CN/Fe0 @EGC is proposed. The multiply synergistic mechanisms of phosphorus-doped g-C3N4 (P-CN), Fe0 and expanded graphite carbon layer (EGC), as well as the strong reducibility of Fe0 were accounted for the expanded visible light absorption range. The even dispersion of Fe0 on porous and worm-like structured P-CN/EGC effectively and successfully avoided the decline in photocatalytic activity caused by aggregation of Fe0 nanoparticles. Compared with g-C3N4, the band gap of phosphorus-doped g-C3N4 was narrowed from 2.79 to 2.60 eV. It is worth noting that Fe0 plays an important role in accelerating electron transfer speed and efficiency between P-CN and EGC. The·O2− and h+ were the dominant active substances for TC degradation. Moreover, P-CN/Fe0 @EGC catalyst could be used repeatedly for at least 7 cycles with high TC removal efficiency. This study may pave a new way on designing high efficient ternary hybrid photocatalyst for antibiotic degradation.

Efficient degradation of tetracycline in aqueous solution using a coupled S-scheme ZnO/g-C3N4/zeolite P supported catalyst with water falling film plasma reactor

To overcome the plasma system drawbacks, the hybrid system is used for the removal of pharmaceutical pollutants from effluents. In this study, the tetracycline (TC) removal from water was investigated using hybrid water falling film plasma-catalyst system. The ternary compounds nanocomposites containing zinc oxide (ZnO), nitride carbon graphite (g-C3N4), and zeolite with different ratios were synthesized at two stages using hydrothermal treatment method. Thereafter, the prepared nanocomposites were loaded on constructed plasma reactor equipped with the water falling film facility. The results of the characterization process confirmed that all synthesized nanocomposites had a suitable specific surface area, crystallinity, and the heterojunction formation ZnO with g-C3N4. The formation probability of S-scheme heterojunction structure of ZnO/g-C3N4 was discussed because of Fermi level’s difference between ZnO and g-C3N4. Under the suitable operational condition, 95.5% TC removal efficiency as well as 4.43 synergistic effects were obtained using the hybrid system. The TC removal for hybrid system was ascribed as 30% more than sole plasma system. Afterward, the stability tests confirmed the ideal reusability of the prepared nanocomposite. The scavenger addition satisfied that the roles of both •OH and hole were critical. A mechanism was proposed for the TC degradation in this fabricated system.

Co-doped Fe-MIL-100 as an adsorbent for tetracycline removal from aqueous solution.

In the study, Fe-MIL-100 was modified by adding Co2+ in the synthesis process; Co/Fe-MIL-100 was successfully synthesized and used to adsorb tetracycline. The addition of Co2+ increased the thermal stability of Fe-MIL-100 without changing the crystal structure. It was found that Co/Fe-MIL-100 exhibited satisfactory performance in tetracycline removal, the tetracycline removal efficiency reached almost 100% in the initial concentration range of 10-40mg/L, and it still reached 82.38% under the condition of 60mg/L tetracycline. Besides, the factors of tetracycline concentration, pH and inorganic anion on removal efficiency were explored. The coexistence of inorganic anion decreased the adsorption capacity of tetracycline due to the competitive adsorption. CO32- had a more obvious inhibition effect on the adsorption efficiency of tetracycline than Cl-. The fitting correlation coefficient of Langmuir model was higher and the kinetics better fitted by pseudo-second-order, respectively. As a result of its high removal efficiency and excellent recycling performance, it has great potential in application fields such as removing tetracycline from wastewater.

0D/3D NiCo2O4/defected UiO-66 catalysts for enhanced degradation of tetracycline in peroxymonosulfate/simulated sunlight systems: Degradation mechanisms and pathways

Developing synergistic systems and taking environmental risks into account are two necessary aspects of being considered to remove persistent organic pollutants efficiently. Thus, a combined catalytic system uniting the Fenton-like process and simulated solar-light photocatalysis has been constructed. Moreover, a series of NiCo2O4/HP-UiO-66 catalysts (yNiCo-DUx) were also fabricated to improve tetracycline (TC) removal efficiency. The NiCo2O4 nanoparticles (NPs) and hierarchically porous metal-organic frameworks (HP-MOFs) were synthesised using one-step calcination. The Z-scheme structure of the catalysts was confirmed by ESR, XPS, DRS, time-resolved PL (TR-PL) spectra and the quenching experiments. The NiCo2O4 nanoparticles could be embedded and fixed into the defects of the MOF structure, and the leaching of toxic metals was also significantly suppressed. In the optimal reaction condition with 15NiCo-DU50, sunlight, and peroxymonosulfate (PMS), the total removal efficiency of TC could reach 98.5% within 8 min of irradiation, and the highest % RSE could reach 11.2%. Moreover, the corresponding reaction rate was 28.7, 3.6 and 1.3–10.2 times higher than photocatalysis, Fenton-like processes and other catalysts. Furthermore, the possible degradation mechanism, generation of reactive species and PMS excitation pathways were also investigated in depth. The present study sheds light on the fabrication of HP-MOFs based catalysts and the combination of various methods to eliminate organic pollutants.

A High Flux Electrochemical Filtration System Based on Electrospun Carbon Nanofiber Membrane for Efficient Tetracycline Degradation

In this work, an electrochemical filter using an electrospun carbon nanofiber membrane (ECNFM) anode fabricated by electrospinning, stabilization and carbonization was developed for the removal of antibiotic tetracycline (TC). ECNFM with 2.5 wt% terephthalic acid (PTA) carbonized at 1000 °C (ECNFM-2.5%-1000) exhibited higher tensile stress (0.75 MPa) and porosity (92.8%), more graphitic structures and lower electron transfer resistance (23.52 Ω). Under the optimal condition of applied voltage 2.0 V, pH 6.1, 0.1 mol L−1 Na2SO4, initial TC concentration 10 ppm and membrane flux 425 LMH, the TC removal efficiency of the electrochemical filter of ECNFM-2.5%-1000 reached 99.8%, and no obvious performance loss was observed after 8 h of continuous operation. The pseudo-first-order reaction rate constant in flow-through mode was 2.28 min−1, which was 10.53 times higher than that in batch mode. Meanwhile, the energy demand for 90% TC removal was only 0.017 kWh m−3. TC could be converted to intermediates with lower developmental toxicity and mutagenicity via the loss of functional groups (-CONH2, -CH3, -OH, -N(CH3)2) and ring opening reaction, which was mainly achieved by direct anodic oxidation. This study highlights the potential of ECNFM-based electrochemical filtration for efficient and economical drinking water purification.

Effect of ZnFe-LDHs modified oyster shell on the removal of tetracyclines antibiotics and variation of tet genes in vertical flow constructed wetlands

The emission of residual antibiotics has already caused environmental hazards. The removal performance of typical tetracyclines antibiotics (oxytetracycline and tetracycline) and the effect of 4 corresponding antibiotic resistance genes (ARGs) were investigated in vertical flow constructed wetlands (VFCWs) with ZnFe-layered double hydroxides (ZnFe-LDHs) modified substrates. The characterizations tests exhibited ZnFe-LDHs were successfully coated to the oyster shell, and increased the specific surface area and atomic species of the modified oyster shell. Adsorption experiments showed that the highest saturated adsorption capacity of oxytetracycline and tetracycline in ZnFe-LDHs respectively reached 1171.51 and 2035.25 mg/kg, which was higher than those of the gravel and oyster shell (264.37 and 353.74 mg/kg, respectively). The CWs experiment indicated that the average removal rates of oxytetracycline and tetracycline in modified oyster shell and artificial sphere systems were respectively 87.27%, 86.55% and 71.94%, 74.09%, which was significantly superior to the gravel (45.57% and 39.3%) and oyster shell systems (59.79% and 54.86%). Moreover, the microbial ASVs/OTUs numbers and the total relative abundance of four resistance genes in the modified systems (0.315 and 0.228) were lower than those in natural systems (0.237 and 0.427). These results suggested that ZnFe-LDHs coating significantly affected microbial activity and reduced the accumulation of ARGs. Correlation analysis between ARGs and conventional pollutants exhibited that nutrient might affect the spread of ARGs in CWs. In summary, ZnFe-LDHs modified substrates could significantly improve the removal efficiency of tetracycline and oxytetracycline, and affected the N biodegradation, while ARGs might still accumulate in the systems due to the presence of nutrients.

Ag-TiO2/biofilm/nitrate interface enhanced visible light-assisted biodegradation of tetracycline: The key role of nitrate as the electron accepter

Due to the pivotal role of Ag-TiO2/biofilm/nitrate interface, enhanced visible light-assisted biodegradation of tetracycline (TC) in anoxic system was realized through both batch experiment and long-term operation in this study. The results of the batch experiment elucidated that 50 mg L−1 TC could be completely removed within 10 h in Ag-TiO2/biofilm/nitrate system. The continuous flow experiment was operated for 75 d to evaluate the performance and stability of Ag-TiO2/biofilm/nitrate system. TC removal efficiency in Ag-TiO2/biofilm/nitrate system was as high as 92.4 ± 1.6% at influent TC concentration of 50 mg L−1 TC and hydraulic retention time (HRT) of 10 h, which would be attributed to the promoted separation of photoholes and photoelectrons at the presence of nitrate as electron acceptor. Facilitated electron transfer between semiconductor and biofilm was beneficial for enhancing TC biodegradation, thus lowering toxicity of intermediate products and promoting microbial activity. Moreover, the species related to TC biodegradation (Rhodopseudomonas, Phreatobacter and Stenotrophomonas), denitrification (Thauera) and electron transfer (Delftia) were enriched at Ag-TiO2/biofilm/nitrate interface. Besides, a possible mechanism involved in enhanced TC degradation and nitrogen removal at Ag-TiO2/biofilm/nitrate interface was proposed. This study provided a novel and promising strategy to enhance recalcitrant TC removal from industrial wastewater.

Enhanced electro-oxidation performance of FeCoLDH to organic pollutants using hydrophilic structure

Iron-cobalt layered double hydroxides (FeCoLDH) showed superior oxygen evolution reaction (OER) performance, but the sluggish water adsorption and dissociation dynamics restrict its capacity to degrade organic pollutants by electro-oxidation. Herein, enhanced electro-oxidation performance of FeCoLDH with hydrophilic structure was designed and exhibited efficient removal efficiency of tetracycline. Theoretical calculation and characterization results consistently elucidated that the electronic structure of FeCoLDH is optimized by doping phosphorus and depositing copper nanodots (NDs). In addition, the obtained Cu NDs/P-FeCoLDH shows higher degradation ability of tetracycline in all-pH conditions than pristine FeCoLDH. That’s because it owns smaller barrier with 0.6 eV to generate hydroxyl radicals (•OH) than pristine FeCoLDH. Furthermore, it can effectively degrade organic pollutants in seawater, river water and pharmaceutical wastewater samples. This work provides novel and rational electrode materials for electro-oxidation system with practical application potential, which could offer new insights into the fundamental understanding of electrochemistry.

δ-FeOOH coupled BiOBr0.5I0.5 for efficient photocatalysis-Fenton synergistic degradation of organic pollutants

The development of effective catalysts is crucial for refractory antibiotics pollutants removal. A visible light-driven δ-FeOOH/BiOBrxI1−x photocatalyst for the tetracycline (TC) degradation was fabricated and a photocatalysis-Fenton synergy system was formed in the presence of H2O2. δ-FeOOH/BiOBrxI1−x indicated better photo-Fenton catalytic activity and good cycle stability under visible light irradiation. Especially, δ-FeOOH/BiOBr0.5I0.5 exhibited the highest photo-Fenton catalytic activity and the removal efficiency of TC was 93% within 1 h, which was 1.63 times of the degradation efficiency of photocatalysis alone. This could be attributed to the synergistic effects of δ-FeOOH and BiOBr0.5I0.5, which promoted the separation of the photoinduced charge carriers and thus improved the photo-Fenton performance. Meanwhile, the presence of H2O2 enabled the conversion between Fe2+ and Fe3+. In addition, the •O2−and •OH active radicals were confirmed to greatly accelerate the degradation of TC and the possible mechanism was revealed. This study might provide a promising candidate for the development of effective catalyst in the treatment of antibiotic wastewaters.

The removal performance and mechanisms of tetracycline over Mn-rich limonite

Naturally occurring Mn-rich limonite mainly composed of goethite and manganese oxides was used to remove tetracycline (TC) from the aqueous solution. The effects of dosage, initial solution pH, temperature, and coexisting anions on TC removal were investigated. Results showed that 95% of TC (30.0mg·L-1) was removed in a wide pH range of 3.0-9.0 by limonite with high specific surface area (145.0 m2·g-1) and mesoporous structure. The presence of Cl-, NO3-, and SO42- in the studied concentration range did not influence TC removal efficiency significantly, while PO43- inhibited the adsorption of TC over limonite due to the competition with TC for active sites. Integrated with the FT-IR analysis, electrostatic interaction and complexation were proved to be the adsorption mechanisms of TC by limonite. The quenching experiments and ESR analysis revealed that singlet oxygen (1O2) also was involved in TC degradation. In addition, limonite displayed an efficient recycling performance and stability after four cycles. This study revealed that the Mn-rich limonite was a promising adsorbent for TC removal from aqueous solutions and promoted the application of natural mineral material in the environmental field.

Catalytic degradation of tetracycline using peroxymonosulfate activated by cobalt and iron co-loaded pomelo peel biochar nanocomposite: Characterization, performance and reaction mechanism

Tetracycline (TC) is a refractory pollutant that widely exists in water environments. Therefore, effective TC treatment methods must be developed. In this work, a cobalt and iron coloaded pomelo peel biochar composite (Co-Fe@PPBC) was successfully synthesized and used to activate peroxymonosulfate (PMS) for TC removal. The crystal structure, surface morphology, pore structure, and elemental valence of the synthesized Co-Fe@PPBC catalyst were investigated by BET, SEM, XRD, FTIR, XPS, TGA, Raman, and VSM. The effects of Co-Fe@PPBC dosage, PMS concentration, initial pH, initial TC concentration, and coexisting anions on TC removal were studied. In comparison with the oxidation (13.6%) by PMS alone and adsorption (9.6%) by Co-Fe@PPBC alone, the removal efficiency of TC was increased to 86.2% in the Co-Fe@PPBC/PMS system, indicating that Co-Fe@PPBC can successfully activate PMS. Remarkably, the results of scavenging examination and EPR analysis demonstrated the synergistic effect of free radical and non-free radical pathways in TC degradation. The cycling test showed that Co-Fe@PPBC has favourable stability and recyclability during repeated activation processes of PMS. Finally, three possible TC degradation methods were presented through the analysis of eight intermediates. Overall, Co-Fe@PPBC could be an economic and high-efficiency catalyst for PMS activation to remove organic pollutants in wastewater.

Efficient degradation of tetracycline by persulfate activation with Fe, Co and O co−doped g−C3N4: Performance, mechanism and toxicity

In this work, the porously thin layered Fe, Co and O co − doped g − C3N4 (FCOCN) was synthesized as persulfate (PS) activator for tetracycline (TC) degradation. The characterization demonstrated that Fe, Co and O doping could boost the specific surface area and modulate the electronic structure of g − C3N4. With addition of PS, the FCOCN2 exhibited the maximum TC removal efficiency of 90.1 % after 120 min reaction, and the kinetic constant was 2.67 times that of pure g–C3N4. Meanwhile, the removal ratio of total organic carbon and reaction stoichiometric efficiency of PS could reach to 68.6% and 5.2%, respectively. When the addition of catalyst and PS were 0.6 g/L and 10.5 mM, respectively, the lower pH and TC concentration, as well as higher temperature were conducive to degradation reaction with activation energy at 23.88 kJ.mol−1. As indicated by work function, a lower internal electronic excitation energy barrier enhanced electron transfer, so the active species of •O2−, 1O2, SO4•−, SO5•− and •OH could be favorably generated on over metal (II/III) redox shuttles, electron − rich O/N and electron–deficient C active sites. The quantitative structure − toxicity relationship prediction of intermediates and the acute toxicity experiment showed that the toxicity of water treated for 60 min to V. fischeri, E. coli and B. subtilis was significantly reduced. Moreover, after five consecutive degradation cycles, the removal efficiency of TC still remained at 72.7%. Besides, even in matrices of tap water, river water, municipal wastewater and medical wastewater, the elimination proportion of TC by FCOCN2/PS were 90.0%, 88.6%, 74.0% and 81.5%, respectively. Hence, the FCOCN2/PS system may be a promising alternative for highly effective treatment of antibiotic contained wastewater and environmental protection.

Acetate stimulates tetracycline biodegradation pathways in bioelectrochemical system

Tetracycline (TC) is a widely used pharmaceutical and personal care product (PPCP), and considering its biotoxicity in aquatic systems, the metabolism and stimulation of TC in wastewater purification processes are still deserving of concern. This study reveals the stimulation of TC biodegradation by acetate in bioelectrochemical systems (BESs). Attributed to the abundance of exoelectrogens Geobacter (mainly G. sulfurreducens) and putative TC-degraded bacteria (PTDB) in the electroactive biofilm samples, 94% of 100 mg/L TC decomposed within 48 h. Limited acetate (0.1 g/L, AC-0.1) as a cosubstrate enhanced the removal efficiency of TC by 44% when compared to abundant acetate (1 g/L, AC-1) and controls. This resulted from the enhancement of PTDB and the stability of the Geobacter population under limited acetate stimulation. With the differentiation of the microbial community, ubiquinone and other terpenoid-quinone biosynthesis and histidine metabolism were significantly upregulated in AC-0.1 but downregulated in AC-1, another factor that enhanced the removal efficiency of TCs. Here, we concluded that limited acetate could partially relieve the selective pressure of TC and improve the biodegradation of TC, and the catabolism pathways, as well as the main metabolites, were stimulated by acetate and its concentration.

Simultaneous adsorption of tetracycline, ammonium and phosphate from wastewater by iron and nitrogen modified biochar: Kinetics, isotherm, thermodynamic and mechanism

The simultaneous removal of various pollutants in wastewater is increasingly deserved attention. In this study, an efficient adsorbent Fe/N@BC was synthesized by Fe–N co-modification. The adsorbability of Fe/N@BC was evaluated using a mixture with tetracycline (TC), NH4+-N and PO43–P. In comparison to BC, N@BC and Fe@BC, Fe/N@BC exhibited an excellent performance for simultaneously absorbing TC, NH4+-N and PO43–P. The pseudo-first-order was used to describe the adsorption process of NH4+-N and PO43–P, while the pseudo-second-order could be well fitted to TC adsorption data. The adsorption isotherms of TC, NH4+-N and PO43–P were more in line with Sips model (Adj.R2 > 0.97). The maximum adsorption capacities of Fe/N@BC towards TC, NH4+-N and PO43–P were 238.94, 111.87 and 165.02 mg g−1, respectively, which were 1.31–1.91 times than that of BC, N@BC and Fe@BC. The simultaneous adsorption mechanism mainly involved pore filling, electrostatic interaction, ion exchange, surface complexation, surface precipitation, H bond and π–π interaction. Furthermore, after six cycles, the removal efficiencies of TC, NH4+-N and PO43–P were 75.3, 66.1 and 64.5% by Fe/N@BC, highlighting its promising potential to adsorb multi-pollutants from aqueous solution.

Performance and mechanism of tea waste biochar in enhancing the removal of tetracycline by peroxodisulfate.

In this work, tea waste biochar was prepared and used to activate peroxodisulfate (PDS) for the removal of tetracycline (TC) efficiently. And SEM, XRD, Raman, and FTIR were used to characterize the biochar. The effects of reaction conditions including initial pH, biochar dosage, and PDS concentration on the removal of TC were explored, and the result showed that compared with the biochar prepared at 400 °C and 500 °C, the biochar pyrolyzed at 600 °C (TBC600) had the highest TC removal performance due to its higher sp2 hybrid carbon content, richer defective structure, and stronger electron deliverability. Under the optimal dosage of PDS (4 mM) and TBC600 (0.8 g L-1), the removal efficiency of TC (10 mg L-1) reached 81.65%. After four cycles of TBC600, the removal rate could still reach 75.51%, indicating that TBC600 has excellent stability. In addition, quenching experiments and electron paramagnetic resonance (EPR) verified that the active oxygen including SO4·-, ·OH, O2·-, and singlet oxygen (1O2) was involved, among which 1O2 and OH were the main active substance in the TC removal. Therefore, this work provided a green and efficient persulfate activator and a method for recycling tea waste.

Change of Tetracycline Speciation and its Impacts on Tetracycline Removal Efficiency in Vermicomposting with Epigeic and Endogeic Earthworms

Change of Tetracycline Speciation and its Impacts on Tetracycline Removal Efficiency in Vermicomposting with Epigeic and Endogeic Earthworms