Tetracycline Removal Efficiency Research Articles

Molten salt induced strong interaction between Co3O4 and montmorillonite for the promoted peroxymonosulfate activation toward tetracycline degradation

Cobalt-based materials exhibit great premises for activating peroxymonosulfate (PMS) toward water remediation. Generally, active Co species are anchored on the surface of supports to improve the utilization efficiency, yet the stability of the catalyst is difficult to resolve due to the weak interaction between the active species and the support. Herein, a molten salt method is employed to reinforce the interfacial interaction between Co3O4 and montmorillonite (Mt) support. The use of molten Na3PO4 can mitigate the dehydroxylation process of Mt, and thus the electronic structure of Co3O4 NPs can be regulated by the surface hydroxyl species more efficiently. Consequently, the prepared Co3O4/Mt displays an enhanced CoII/CoIII ratio, and the degradation of tetracycline (TC) could reach 99% in 7 min by the PMS-based advanced oxidation process. Meanwhile, the TC removal efficiency can still reach 96% after 8 cycles, and the Co ion leaching is over 10 times lower as compared with the catalyst prepared not using the molten salt. This study highlights the significance of the molten salt method for enhancing the strong interfacial interaction, which is crucial to regulating the nature of supported catalysts, and provide satisfactory Co-based catalyst for PMS activation toward TC degradation.

Photo-Fenton-like degradation of tetracycline through peroxymonosulfate activation over 2D BiOBr/FeOOH nanosheets and membrane application

The selection of photosensitizer substrates with high photocatalytic efficiency is crucial for leveraging the advantages of metal-based materials in photo-Fenton-like process. Herein, we report a novel 2D layered BiOBr/FeOOH nanosheets equipped with a built-in electric field (BIEF) to activate peroxymonosulfate (PMS) for the degradation of tetracycline (TC). The photocatalytic efficiency of BiOBr is enhanced by fine-tuning the Br source quantity. Both experimental and theoretical analyses confirm that BIEF at the BiOBr/FeOOH heterointerface expedites the movement of photogenerated electrons, significantly boosting both photocatalytic and photo-Fenton-like activities. The BiOBr/FeOOH + PMS + Vis system exhibits a high TC removal rate of 96 % with only 0.24 mM of PMS and nearly 100 % of PMS utilization. Moreover, affixing BiOBr/FeOOH nanosheets onto a PVDF microfiltration membrane, we establish a continuous flow reactor system for antibiotic wastewater treatment. This system demonstrates a remarkable TC removal efficiency consistently above 97.5 % for 6 h of continuous injection, underscoring its practicality and potential for real-world applications.

Construction of functionalized In-based metal organic framework/BiOCl1−xIx Z-scheme heterojunction for efficient photocatalytic degradation of tetracycline: Performance and mechanism

The environmental implications of antibiotics have drawn widespread attention. Numerous monomer-based bismuth oxide halide catalysts have been extensively studied to remove tetracycline (TC) from aquatic environments. Integrating bismuth oxide halide composites with In-based metal organic framework (NH2-MIL-68(In)) might potentially serve as a novel strategy. By meticulously adjusting Cl and I within the composite bismuth halide oxide (B-x), a suite of purpose built heterojunctions (NMB-x) were synthesized, which were engineered to facilitate the efficient photodegradation of TC in simulated and actual aquatic environments. The incorporation of Z-scheme heterojunctions yielded a significant enhancement in photocatalytic responsiveness and charge carrier separation. Notably, NMB-0.3 demonstrated remarkable TC removal efficiency of 88.52 ± 3.05%, which is 3.74 times of B-0.3 within 90 min. The apparent quantum yield was also increased from 8.97% (B-0.3) to 19.68% (NMB-0.3). The removal of TC from natural water bodies was also assessed. Moreover, the photocatalyst concentration, assessed using response surface method, was found to show influential factors on TC removal. In addition, density functional theory (DFT) simulations were employed to identify vulnerable sites within TC. Intermediates and pathways in the photodegradation of TC have also been inferred. Furthermore, a comprehensive environmental toxicity assessment of representative intermediates demonstrated that these intermediates exhibited significantly reduced environmental toxicity compared to TC. This study provides a new approach to the design strategy of efficient and environmentally friendly MOF-based photocatalysts.

Anatase TiO2/Defective UiO-66 porous octahedral S-scheme heterojunctions toward optimized photocatalytic performance

Photocatalysis is an alternative for antibiotics removal from wastewater for the sustainable development of human society. However, applying photocatalysts for antibiotics (e.g., tetracycline) degradation under practical conditions is highly restricted by the low reaction efficiency due to the prompt charge recombination. Constructing porous heterojunctions is an efficient way to regulate the electron transfer path and accelerate charge migration efficiency. Herein, TiO2/defective UiO-66 porous octahedral S-scheme heterojunctions are successfully fabricated through an in-situ growth strategy. The strong interaction and charge migration behavior between TiO2 and defective UiO-66 have been studied using X-ray photoelectron spectroscopy and electron paramagnetic resonance measurements. The photocatalytic removal efficiency of tetracycline is notably improved by forming TiO2/defective UiO-66 porous heterojunctions. The promoted photocatalytic performance can be ascribed to the strong interaction between TiO2 and defective UiO-66, and the accelerated charge separation and transfer efficiency due to the formation of S-scheme heterojunctions, thus generating abundant reactive oxygen species, including O2− and OH. The optimized 38-TiO2/UiO-66-300 can eliminate 97.9 % of tetracycline in 60 min with a reaction constant rate of 0.0425 min−1, which is approximately 4 and 10 times that of pristine TiO2 and UiO-66-300, respectively. This work provides an alternate strategy for preparing highly active heterojunction photocatalysts for environmental applications.

Critical review on the tetracycline degradation using photo-Fenton assisted g-C3N4-based photocatalysts: Modification strategies, reaction parameters, and degradation pathway

Over the years, the enormous use of tetracycline (TC) in pharmaceutical industries caused unwanted heap in the environment that led to the deterioration of human and ecological conditions. Therefore, the synergistic functioning of photo-Fenton and photocatalysis has been introduced which enables the regeneration of more •OH, •O2- species thereby enhancing the TC degradation performance of photocatalysts. Graphitic carbon nitride (g-C3N4) photocatalyst recently, gained massive consideration due to the suitable energy band gap, efficient preparation method, and physicochemical properties. However, due to some drawbacks, various modification strategies (doping, Z-Scheme, S-Scheme) have been adopted to perk up the degradation activity of bare g-C3N4. In the current review, we have provided insights into various modification strategies employed for g-C3N4 and reaction parameters for the effective remediation of tetracycline using photo-Fenton-assisted photocatalysis. The review further highlighted the potential of the integrated effect of g-C3N4-based photo-Fenton-assisted photocatalytic processes for achieving higher tetracycline removal efficiency followed by current challenges and future perspectives.

Novel CQDs/BiOI Microspheres with Gradient Oxygen Vacancies for Efficient Photocatalytic Performance Boosting by the Synergism of Reactive Oxygen and Iodine Species

AbstractThe synergy of reactive oxidative species (ROSs: ⋅OH, ⋅O2− and 1O2) and reactive iodine species (RISs: ⋅I and ⋅I2−) is conclusive to driving organic pollutant degradation in various aquatic environments. Over the past years, rational design of Vis‐NIR responsive photocatalyst with enhanced photocatalytic performance has attracted drawing attention. Herein, CQDs/BiOI composites with up‐conversion photoluminescence (UCPL) properties and oxygen vacancies was constructed for tetracycline (TC) and oxytetracycline (OTC) degradation. The apparent kinetic constant of the 4‐CQDs/BiOI is 2.13 and 2.38 times on pure BiOI. The excellent photodegradation efficiency can be attributed to the enhanced light absorption originated from the up‐conversion property and improved charge separation efficiency. Furthermore, the iodine free radicals (⋅I) and superoxide free radicals (⋅O2−) played a crucial role in the photodegradation procedure. I− from BiOI could be partially oxidized to form ⋅I. At the same time, the electron capture traps formed by Oxygen vacancies can promote the production of ⋅O2−. Remarkably, the removal efficiency of TC and OTC was still maintained at 80 % by 4‐CQDs/BiOI under different water quality conditions due to the synergy of ⋅O2− with ⋅I. This work sheds light on a new treatment for the synergistic degradation of pollutants in complex water by RISs and ROSs.

Enhancing Tetracycline Removal Efficiency through Ozone Micro–Nano Bubbles: Environmental Implication and Degradation Pathway

Enhancing Tetracycline Removal Efficiency through Ozone Micro–Nano Bubbles: Environmental Implication and Degradation Pathway

Insight into the key factors for the tetracycline removal in biochar-mediated oxidative system

This study prepared pomelo peel biochar (PBC) under different pyrolysis temperatures (T) (300–800 °C) and investigated the removal efficiency of tetracycline (TC) under the oxidative systems established by PBC and oxidants (hydrogen peroxide (H2O2), peroxymonosulfate (PMS), and peroxydisulfate (PDS)). The correlation between the properties of PBC and the removal efficiencies of TC was studied by Pearson analysis to clarify the critical properties of biochar in catalytic processes. The inorganic carbon (IC), ash, pH, basic functional groups (BFG), specific surface area (SSA), microporous surface area (Smicro), pore volume (PV), and graphitization degree (ID/IG) of PBC were positively correlated with the increase of T (p < 0.05). Notably, the SSA and PV of PBC increased from 4.294 m2/g and 0.002 cm3/g to 496.864 m2/g and 0.261 cm3/g as the pyrolysis temperature increased from 300 to 800 °C. In contrast, the yield, organic carbon (OC), and acidic functional groups (AFG) of PBC displayed negatively correlated with the increase of T (p < 0.05). Rad, RPBC/H2O2, RPBC/PMS, and RPBC/PDS represented the removal efficiencies of TC by PBC adsorption, PBC/H2O2, PBC/PMS, and PBC/PDS system. RPBC/H2O2, RPBC/PMS, and RPBC/PDS showed a highly positive correlation to the Rad (r = 0.965, 0.952, 0.946, p < 0.01). Rad, RPBC/H2O2, RPBC/PMS, and RPBC/PDS were positively correlated with K, Mg, ash, pH, BFG, and ID/IG (p < 0.01). There was no statistically significant correlation between persistent free radicals (PFRs) and the removal efficiencies of TC. Furthermore, SSA and PV showed positive relationships with the removal efficiencies of TC in the PBC/PMS and PBC/PDS systems, but no significant correlation with the removal efficiencies of TC in the PBC/H2O2 systems. Moreover, the catalytic behaviors and mechanisms were studied in the PBC-800 based oxidative systems. The quenching experiments and EPR spectra indicated that singlet oxygen (1O2) was the main active species. Except for 1O2, superoxide radical (O2•−) also contributed to TC removal in the oxidative systems. From the changes in used PBC-800, the disordered sp2 hybrid carbon, sp3 C–C, and pyridinic-N were the main active sites in activation.

Key role of carbon as an efficient electron bridge in CuO@C@Fe2O3 for enhancing H2O2 activation during photo-assisted Fenton-like reaction

The Fe3+/Fe2+ cycle has been identified as the rate-limiting step in the Fenton system, and many efforts have been made to promote the Fe3+ reduction via external electrons provided by various electron donors. However, how to design an efficient electron transport pathway and then inhibit the invalid electron shuttle has been largely underestimated. In this study, two kinds of heterogeneous Fenton catalysts of CuO@Fe2O3 and CuO@C@Fe2O3 were prepared. The key role of carbon in transporting electrons as an electron bridge and its enhancement mechanism in photo-assisted Fenton-like performances were explored in detail. Compared with CuO@Fe2O3, the removal efficiency of tetracycline (TC) and the corresponding pseudo-first order reaction rate constants over CuO@C@Fe2O3 increased significantly from 88.6% and 0.1054min-1 to 99.7% and 0.2058min-1, respectively. Based on a series of probe experiments, visible light irradiation can promote the reduction of Cu2+ to Cu+, then the carbon in CuO@C@Fe2O3 can effectively transfer electrons from Cu+ to Fe3+, enhancing the Fe3+/Fe2+ cycle and the following Fenton-like efficiency. Since more ·OH while less ∙O2- was produced over CuO@C@Fe2O3, which further supports the fact that the enhanced Fe3+/Fe2+ cycle was due to the transfer electron from Cu+ to Fe3+ instead of the Haber-Wiss mechanism. Hence, this study provides new insight for effectively improving the transfer efficiency and effective utilization of electrons in Fenton systems.

An efficient photo-Fenton In2O3@FeIn2S4 composite catalyst for tetracycline degradation

Photo-Fenton technology has been widely used as an efficient and environmentally friendly method for pollutant degradation. Herein, novel In2O3@FeIn2S4 microflowers are prepared by a two-step hydrothermal method and used as the photo-Fenton catalyst for tetracycline (TC) degradation. Under illumination (λ > 420 nm), the In2O3@FeIn2S4-0.5 (molar mass ratio of FeIn2S4 to In2O3 is 0.5) shows a higher removal efficiency of TC (98.3 %) in 75 min, than pure In2O3 (60.8 %) and FeIn2S4 (65.8 %). The degradation rate constant of In2O3@FeIn2S4-0.5 for TC is about 5.1 and 3.2 times compared to that of In2O3 and FeIn2S4. In addition, the TC removal efficiency only dropped by 6.7 % after 5 cycles, indicating the superior stability of In2O3@FeIn2S4-0.5. Superoxide radical (∙O-2), hydroxide radical (∙OH), and singlet oxygen (1O2) play a crucial role in TC degradation process, while photogenerated holes (h+) only play a minor role. The improved performance of In2O3@FeIn2S4 photo-Fenton catalyst could be described as the following: the porous In2O3 microflower supporter extends the reactive interface of FeIn2S4; FeIn2S4 effectively enhances optical absorption ability in the visible range; 2D-2D tight interface formed between In2O3 and FeIn2S4 helps to accelerate the charge transfer; the formation of S-scheme heterostructures improves the parting ability of the photoproduced carriers.

Green synthesis of manganese ferrite magnetic nanoparticle and its modification with metallic-organic frameworks for the tetracycline adsorption from aqueous solutions: A mathematical study of kinetics, isotherms, and thermodynamics

In the current investigation, MnFe2O4/ZIF-8 nanocomposite was generated as a magnetic nanoadsorber using the extract of Dracocephalum plant and characterized by XRD, FTIR, VSM, BET, FESEM, EDS-mapping, TEM, XPS, TPD-NH3, and TGA analyses. Also, to determine its efficiency in the adsorption process of tetracycline, the effect of pH (3-9), nanocomposite dose (0.025-2 g/L), initial pollutant concentration (5-100 mg/L), contact time (5-200 min), and temperature (5-50 °C) were studied. The results of the morphological properties of the magnetic nanocomposite confirmed the spherical shape of this nanoadsorber with an average size of 54±31 nm. BET analysis showed that modification of MnFe2O4 material with ZIF-8 as a new nanoadsorber leads to excellent modification of SBET (143.8 m2/g) and VTotal (0.44 cm3/g). The highest removal efficiency of tetracycline in optimal conditions (pH=7, contact time=120 min, nanocomposite dose=1.5 g/L, and temperature=20 °C for a tetracycline concentration of 20 mg/L) was 90.11%. As the temperature increased, the removal efficiency increased from 40.46% to 95.06% during 120 min, which indicates that the adsorption reaction is endothermic. In addition, the data obtained from the isotherms of Langmuir (R2=0.958), Freundlich (R2=0.534), and Temkin (R2=0.747) showed that the tetracycline adsorption is monolayer and on the homogeneous surface of the synthesized magnetic nanoadsorber. The elimination process of tetracycline by nanoadsorber followed the pseudo-second order model (R2=0.998). Investigating the effect of interfering ions also confirmed the decrease in the adsorption efficiency. Also, the investigation of the reusability of the synthesized magnetic nanoadsorber in tetracycline adsorption indicates that after eight cycles, the efficiency decreases by %16.51. According to the results, the magnetic nanocomposite synthesized in this work can be a suitable and economical adsorber for the removal of tetracycline from aqueous environments.

Efficient visible light-based photocatalytic performance for tetracycline degradation by novel dual z-type ZnO nanorods /Bi2MoO6 /ZIF-67 heterostructure: Mechanism and water matrix investigation

BackgroundContamination of water with antibiotics poses environmental challenges. Photocatalytic semiconductor heterostructure technologies prove effective in water purification, particularly in eliminating pharmaceutical pollutants. Achieving high-quality heterostructures remains a considerable challenge. MethodsZnO/Bi2MoO6/ZIF-67 photocatalyst was synthesized using the ambient temperature method and characterized through XRD, FTIR, SEM, EDX, TEM, UV–vis DRS, TGA, PL, and BET analyses.Significant findings: The novel ZnO/Bi2MoO6/ZIF-67 photocatalyst's efficacy in degrading tetracycline under visible light was evaluated. The optimal composite molar ratio of ZnO: Bi2MoO6: ZIF-67 was found to be 1.53:1:0.4, exhibiting superior photocatalytic performance compared to ZnO, Bi2MoO6, and ZIF-67. With ZnO/Bi2MoO6/ZIF-67, the highest removal efficiency of tetracycline reached 90.3 % under ideal conditions (catalyst dose = 0.4 g/L, pH = 6.5, illumination time = 90 min, initial tetracycline concentration = 40 mg/L). The photocatalytic degradation of tetracycline follows first-order kinetics. The trapping experiments showed that OH• and •O2– species played a beneficial role in enhancing the photodegradation process.

Promoting oxygen vacancies utility for tetracycline degradation via peroxymonosulfate activation by reduced Mg-doped Co3O4: Kinetics and key role of electron transfer pathway

Developing cobalt-based catalysts with a high abundance of oxygen vacancies (Vo) and exceptional Vo utility efficiency for the prompt removal of stubborn contaminants through peroxymonosulfate (PMS) activation poses a significant challenge. Herein, we reported the synthesis of the reduced Mg-doped Co3O4 nanosheets, i.e. Mg-doped Co3O4-r, via Mg doping and followed by NaBH4 reduction, aiming to degrade tetracycline (TC). Various characterization results illustrated that NaBH4 reduction imparted higher Vo utility efficiency to Mg-doped Co3O4-r, along with an ample presence of reduced Co2+ species and an increased surface area, thereby substantially elevating PMS activation capability. Notably, Mg-doped Co3O4-r achieved more than 97.9% degradation of 20 mg/L TC within 10 min, showing an over 8-fold increase in reaction rate relative to the Mg-doped Co3O4 (kobs: 0.3285 min-1 vs 0.0399 min-1). The high removal efficiency of TC was sustained across a broad pH range of 3 to 11, even in the presence of common anions and humic acid. Radical quenching trials, EPR outcomes, and electrochemical analysis indicated that neither radicals nor 1O2 were the primary active species. Instead, electron transfer pathway played dominant role in TC degradation. The Mg-doped Co3O4-r displayed excellent recyclability and versatility. Even after the fifth cycle, it maintained an impressive 83.0% removal of TC. Furthermore, it exhibited rapid degradation capabilities for various pollutants, including levofloxacin, pefloxacin, ciprofloxacin, malachite green, and rhodamine B. The TC degradation pathway was proposed based on LC-MS determination of its degradation intermediates. This study showcases an innovative strategy for the rational design of an efficient cobalt-based activator, leveraging electron transfer pathways through PMS activation to degrade antibiotics effectively.

Degradation of tetracycline based on activated persulfate by microbial-induced calcium carbonate precipitation as templates modified sludge biochar

The template method is capable of enhancing the catalytic sites by controlling the size and properties of the material. However, the integration of the template and biological methods requires further development. In this study, an environmentally friendly modified sludge biochar (TBC) was successfully synthesized by modifying sludge with biosynthetic calcium precipitation as a template. TBC effectively activated peroxydisulfate (PDS), achieving a tetracycline (TC) removal efficiency of 95.07 %. Active species identification and electrochemical analyses confirmed that the main mechanism for TBC to activate PDS in degrading TC involved the non − radical pathway, including singlet oxygen (1O2) production and direct electron transfer. The CO functional group was the main active group to produce 1O2. Additionally, the adsorption of TBC also played a role in TC removal. Experimental results indicated that TBC exhibits significant stability and reusability. This study offers novel insights into utilizing the template method for PDS activation to degrade TC and presents a viable approach for the rational disposal of sludge.

Efficient decontamination of tetracycline via fenton-like process mediated by chitosan-based Fe-MOFs under wide pH range

Fe-MOF is one of the highly-promising Fenton-like catalysts. However, the shape of powder and low Fe(II)/Fe(III) cycle efficiencies restrict its applications. In this research, MIL-101(Fe) was incorporated into a chitosan (CS) matrix to obtain easy-recyclable MIL-101(Fe)@CS beads as Fenton-like catalysts for tetracycline (TC) degradation. The CS partially wrapped the octahedral MIL-101(Fe) particles for protection and dispersion. The MIL-101(Fe)@CS/H2O2 system demonstrated better TC removal efficiency (∼90.00 % within 140 min), with a pseudo-first-order kinetic constant 3.5 times higher than that of the MIL-101(Fe)/H2O2 system. In addition, the reaction system exhibited a wider pH application range (5.12 – 12.96), higher H2O2 utilization rate (70 %), better interference resistance of the common anions in water, excellent reusability (94.10 % degradation efficiency retained over five cycles), and lower risk of secondary pollution with Fe ions (1.47 mg/L). Furthermore, theoretical evaluations and antibacterial tests revealed that the MIL-101(Fe)@CS/H2O2 system effectively reduced the potential risk of TC in the ecosystem. A mechanistic study showed that hydroxyl radicals (•OH) were the main reactive species involved in the reaction and that the presence of CS accelerated the Fe(II)/Fe(III) cycle. This study offers an immobilization strategy to optimize the catalytic performance of Fe-MOFs and improve their practical application, providing theoretical and technical support for refractory organic degradation in wastewater by Fenton-like processes.

Visible-light-driven 2D π-conjugated polyimide/ZnO efficiently removes tetracycline

Heterojunction organic-inorganic composites are promising for wastewater treatment due to their excellent physical and chemical properties. ZnO was immobilized on the PI surface using the hydrothermal technique to prepare PI/ZnO n-n heterojunctions with outstanding visible photocatalytic properties. The photocatalytic performance of different ratios of PI/ZnO composites was significantly improved in comparison to pure PI and ZnO, among which 40% PI/ZnO showed the most outstanding results. The 40% PI/ZnO can adsorption remove around 40% of tetracycline (TC) in 20 min in entirely shaded conditions and can attain up to 90% of the TC removal efficiency in 40 min under visible light exposure. The formation of a PI/ZnO heterojunction enhances the efficiency of charge separation and reduces the recombination of photogenerated electron-hole pairs, resulting in improved photocatalytic performance. Meanwhile, the 40% PI/ZnO composites showed a substantial increase in specific surface area (205.22 m2/g) compared to pure PI and ZnO, which was 103 and 25 times that of PI and ZnO, respectively. The increase in surface area provided a larger number of adsorption sites, thereby increasing the contact area between the pollutants and the photocatalysts, which led to a significant improvement of the PI/ZnO composites in the adsorption and photocatalytic properties. In this study, the heterojunction was formed by the composite of conjugated polymer and metal oxide, so that the composites could remove the organic matter more efficiently by adsorption and then photocatalysis, which will provide some ideas for the development of more efficient conjugated polymer materials.

Decontamination of tetracycline from aqueous solution using activated carbon/Fe3O4/ZIF-8 nanocomposite adsorbent

The increase in the amount of antibiotics in water sources, especially after the spread of COVID-19, has caused serious environmental problems. Therefore, finding a suitable adsorbent for these pollutants is a new and serious challenge for researchers. In this study, magnetic activated carbon (AC/Fe3O4) was selected as a novel support to zeolitic imidazolate framework (ZIF-8)to create magnetic separation properties besides promoting its tetracycline (TC) removal efficiency. The successful formation of AC/Fe3O4/ZIF-8 nanocomposite was proved by FTIR, XRD, and SEM-EDX analysis. The surface area of AC/Fe3O4/ZIF-8 nanocomposite was computed at 996.38 m2/g using BET analysis. The maximum removal efficiency was obtained in the optimum condition of adsorption parameters, e.g., pH = 7, dose 1 g/L, initial concentration 20 mg/L, contact time 30 min, and temperature 25 °C. The maximum adsorption capacity (qmax) of AC, AC-H3PO4, AC/Fe3O4, ZIF-8, and AC/Fe3O4/ZIF-8 using Langmuir isotherm was obtained at 25.28, 30.03, 45.45, 51.2, and 57.47 mg/g, respectively revealing the effectiveness of AC/Fe3O4 in improving elimination performance of ZIF-8. Thermodynamically, the removal process of TC using AC/Fe3O4/ZIF-8 nanocomposite happened spontaneously and exothermally due to negative values of ΔG° (-6.94 kJ/mol) and ΔH° (-36.44 kJ/mol). The removal performance of AC/Fe3O4/ZIF-8 nanocomposite after four ad(de)sorption cycles is nearly constant (about 86 %) showing their stability in acidic and water media. Hydrogen bonding, electrostatic interaction, and π-π interactions are main mechanisms in TC removal by AC/Fe3O4/ZIF-8 nanocomposite. The results demonstrate that prepared adsorbents, mainly AC/Fe3O4/ZIF-8 nanocomposite, can be applied as recyclable and efficient adsorbents for TC elimination.

3D-printed Al2O3 framework supported carbon-bridged tri-s-triazine of g-C3N4 for photocatalytic tetracycline oxidation

Powder-like g-C3N4 has been widely used as a photocatalyst but exhibits several drawbacks, including unrecyclable, high charge recombination, and limited light absorption. In this study, carbon-bridged g-C3N4 was successfully prepared and coated on a 3D-printed Al2O3 substrate for the photocatalytic oxidation of tetracycline. Oxamide (OD), malonamide (MD), and succinamide (SD) were used as carbon-containing linkers to react with precursors (melamine and urea) and produce carbon-bridged g-C3N4. Carbon substitution at the bridged N atoms of g-C3N4 improved light absorption, reduced charge recombination, and resulted in high photocatalytic tetracycline removal efficiency. Computational calculations were also employed, and Bader charge analysis supported the charge redistribution and charge transfer of the carbon-bridged g-C3N4 samples. Our results indicated that the degradation of tetracycline followed step-by-step oxidation, deamination, and mineralization to form CO2 and H2O. The 3D-printed Al2O3-supported carbon-bridged g-C3N4 exhibited a high removal rate of 85–90 % and stability for photocatalytic reactions and can be reused for at least 10 cycles. This study demonstrates that the 3D-printed Al2O3-supported carbon-bridged g-C3N4 catalyst is an efficient and effective catalyst support system for photocatalytic reactions.

Electro-induced carbon black particle electrodes for sustainable tetracycline degradation

For the purpose of degrading tetracycline (TC), a three-dimensional electro-oxidation (3D EO) system using particle electrodes of carbon black (CB) and polytetrafluoroethylene (PTFE) was developed. The CB-PTFE particles fabricated at a CB/PTFE mass ratio of 3:2 and calcination time of 60 min exhibited the high performance for TC removal, as well as low energy consumption and high mechanical strength. TC removal efficiency reached 95% within 15 minutes, driven by a pseudo-first-order reaction with a rate constant of 0.20 min−1. The process incurred an energy consumption of 20.31 kWh/m3. The surface characterizations indicated that the CB-PTFE particles possessed excellent catalytic properties for H2O2 production. Despite the substantial influence of voltage and particle dosage on performance, the system demonstrated consistently high efficiency in TC removal regardless of solution pH within the range of 3–11. Quenching experiments and probe experiments using benzoate suggested that the surface-bound hydroxyl radicals (•OH (ads)) dominated (64.7%) the oxidation of TC in the 3D CB-PTFE EO system. The •OH (ads) was produced by the reduction of H2O2 on the particle surface. Products examination by LC-MS-MS confirmed a degradation pathway of TC by •OH attacking. These findings indicate that the CB-PTFE EO system has unique advantages and potentials in treating antibiotics due to its high oxidizing capacity, a wide range of applicable pH, no chemical adding, and self-cleaning.

Construction of Bi2WO6/g-C3N4 Z-Scheme Heterojunction and Its Enhanced Photocatalytic Degradation of Tetracycline with Persulfate under Solar Light.

Z-scheme heterojunction Bi2WO6/g-C3N4 was obtained by a novel hydrothermal process; its photocatalysis-persulfate (PDS) activation for tetracycline (TC) removal was explored under solar light (SL). The structure and photoelectrochemistry behavior of fabricated samples were well characterized by FT-IR, XRD, XPS, SEM-EDS, UV-vis DRS, Mott-Schottky, PL, photocurrent response, EIS and BET. The critical experimental factors in TC decomposition were investigated, including the Bi2WO6 doping ratio, catalyst dosage, TC concentration, PDS dose, pH, co-existing ion and humic acid (HA). The optimum test conditions were as follows: 0.4 g/L Bi2WO6/g-C3N4 (BC-3), 20 mg/L TC, 20 mg/L PDS and pH = 6.49, and the maximum removal efficiency of TC was 98.0% in 60 min. The decomposition rate in BC-3/SL/PDS system (0.0446 min-1) was 3.05 times higher than that of the g-C3N4/SL/PDS system (0.0146 min-1), which might be caused by the high-efficiency electron transfer inside the Z-scheme Bi2WO6/g-C3N4 heterojunction. Furthermore, the photogenerated hole (h+), superoxide (O2•-), sulfate radical (SO4•-) and singlet oxygen (1O2) were confirmed as the key oxidation factors in the BC-3/SL/PDS system for TC degradation by a free radical quenching experiment. Particularly, BC-3 possessed a wide application potential in actual antibiotic wastewater treatment for its superior catalytic performance that emerged in the experiment of co-existing components.