Norfloxacin Research Articles

Activation of peroxydisulfate via Fe@sulfur-doped carbon-supported nanocomposite for degradation of norfloxacin: Efficiency and mechanism

In this study, Fe, S co-doped carbon-based catalysts (Fe@SCNs) for activation of peroxymonosulfate (PMS) were prepared by calcination of κ-carrageenan (κ-c) hydrogel cross-linked by Fe3+. The catalysts prepared at a κ-c concentration of 3 wt%, a Fe3+ concentration of 0.3 M and a calcination temperature of 900 °C showed the best performance for activation of PMS, allowing complete degradation of norfloxacin (NOR) within 40 min at a degradation rate of 0.2878 min−1. Different active species (1O2, OH, SO4−, O2− and FeⅣ) collaborated for the degradation of NOR, in which 1O2 dominated the reaction. The doping of S elements in carbonaceous materials could enhance the activation capacity of PMS for the reason that S-doping facilitated the electron transfer capability of the catalysts and the introduction of thiophene sulfur (CSC) generated more active sites, while S22− also enhanced the conversion of Fe3+ to Fe2+, resulting in the continuous formation of more ROS. The Fe@SCN/PMS system not only had a broad range of pH (3.0–11.0) applicability, but also was little affected by inorganic ions (NO3−, Cl−, HCO3− and H2PO4−) or organic compounds (humic acid) in water. This research provides an innovative approach for the preparation of metal and heteroatom co-doped carbon-based catalysts for sulfate radical-based advanced oxidation process.

New insights into the slow-drying modified hydrophilic graphite felt gas-diffusion cathode using acetylene black/PTFE for efficient electro-Fenton removal of norfloxacin

In the electro-Fenton system, designing a low-cost and efficient 2e− oxygen-reducing cathode materials is critical for pollutants of degradation. In this work, we proposed a hydrophilic graphite felt gas diffusion cathode modified by acetylene black/PTFE under slow-drying mechanism to degrade norfloxacin (NOR). The results showed that the graphite felt gas diffusion cathode in slow drying mode had better curing effect due to weak capillarity and formed more 3-phase interfaces compared with the traditional quick-drying way, which was conducive to locally confined O2 storage and transfer. The slow-drying method had more H2O2 yield and efficient NOR removal rate. It was found that 30 mg/L NOR achieved 92.2 % degradation and almost 71.3 % of NOR was completely mineralized within 120 min under optimal reaction conditions. Interestingly, the H2O2 yield was only decreased by 5.2 % after 10 cycles, and the NOR removal rate decreased 3.8 % after pickling, which exerted an excellent reusability. The radicals quenching experiments revealed that ·OH and ·O2− were the main active species in NOR degradation process. Besides, it was found that PTFE coating was not beneficial for the activation of H2O2 by graphite structure. Finally, possible NOR degradation pathways were proposed by Ultra performance liquid chromatography-mass spectrometry (LC-MS).

Potential degradation of norfloxacin using UV-C/Fe2+/peroxides-based oxidative pathways

• Different peroxides-based oxidative pathways were compared towards NOR degradation. • The peroxide HSO 5 − performed best in the degradation of NOR under UV-C and Fe 2+ . • The peroxides yield ● OH and SO 4 ●− under activation by UV-C and Fe 2+ activation. • The ● OH and SO 4 ●− scavengers inhibited degradation of NOR. • Degradation products and ecotoxicities of NOR as well as its DPS were estimated. The removal of norfloxacin (NOR), a widely used pharmaceutical and emerging water pollutant, was studied using UV-C and Fe 2+ catalyzed peroxides-based oxidative processes (e.g., UV-C/Fe 2+ /H 2 O 2 , UV-C/Fe 2+ /S 2 O 8 2− and UV-C/Fe 2+ /HSO 5 − ) and compared with UV-C and UV-C/Fe 2+ . The UV-C and UV-C/Fe 2+ degraded NOR to 38 and 55%. However, use of peroxides, i.e., H 2 O 2 , S 2 O 8 2− , HSO 5 − with UV-C and UV-C/Fe 2+ promoted NOR %degradation to 75, 83, and 90% using [peroxides] 0 = 50 mg/L, [Fe 2+ ] 0 = 1 mg/L, and [NOR] 0 = 10 mg/L, respectively. The significant impact of peroxides on NOR degradation was due to their decomposition into ● OH and SO 4 ●− which showed high activity towards NOR degradation. The ● OH and SO 4 ●− formation from peroxides decomposition and their contribution in NOR degradation was verified by different scavenger studies. Among the UV-C/Fe 2+ /peroxides processes, UV-C/Fe 2+ /HSO 5 − showed better performance. The changing concentrations of peroxides, Fe 2+ , and NOR affected degradation of NOR. The use of different pH and inorganic anions also influenced NOR degradation. The degradation pathways of NOR were established and analyzed acute as well as chronic toxicities of NOR and its DPs.

Facile synthesis of direct Z-scheme UiO-66-NH2/PhC2Cu heterojunction with ultrahigh redox potential for enhanced photocatalytic Cr(VI) reduction and NOR degradation.

Z-scheme heterojunction-based photocatalysts typically have robust removal efficiencies for water contaminants. Herein, we employed p-type PhC2Cu and n-type UiO-66-NH2 to develop a direct Z-scheme UiO-66-NH2/PhC2Cu photocatalyst with an ultrahigh redox potential for Cr(VI) photoreduction and norfloxacin (NOR) photodegradation. Moreover, UV-vis diffuse reflectance, photoelectrochemical measurements, photoluminescence (PL) spectra and electron spin resonance (ESR) technique revealed that the UiO-66-NH2/PhC2Cu composite boosted light capturing capacities to promote photocatalytic efficiencies. Strikingly, the optimized UiO-66-NH2/PhC2Cu50 wt% rapidly reduced Cr(VI) (96.2%, 15min) and degraded NOR (97.9%, 60min) under low-power blue LED light. In addition, the UiO-66-NH2/PhC2Cu photocatalyst also exhibited favorable mineralization capacity (78.4%, 120min). Benefitting from the enhanced interfacial electron transfer and ultrahigh redox potential of the Z-scheme heterojunction, the UiO-66-NH2/PhC2Cu photocatalyst greatly enhanced the separation efficacies of photogenerated carriers. This resulting abundance of active species (e.g., e-, h+, O2•-, and •OH) were generated to photo-reduce Cr(VI) and photo-oxidize NOR. Base on the identified intermediates, four degradation pathways of NOR were proposed. Finally, the Z-scheme mechanism were systematically confirmed through X-ray photoelectron spectroscopy (XPS), ESR, cyclic voltammetry (CV) tests, and photodeposition techniques.

Facile preparation of coprecipitates between iron oxides and dissolved organic matter for efficient Fenton-like degradation of norfloxacin.

As two important components of dissolved organic matter (DOM), dissolved black carbon (DBC) and humic acid (HA) possess different chemical and structural properties, which might influence their activities like metal complexation and mediating electron transfer. In this study, a series of coprecipitates of iron oxides (FeOx) and DOM (HA or DBC) having different C/Fe molar ratios (0.2-3.0) was prepared under ambient conditions, which exhibited excellent catalytic efficiencies upon Fenton-like degradation of norfloxacin (NOR). Pseudo-first-order rate constant of NOR oxidation catalyzed by DBC-FeOx (C/Fe=3.0, 1.13h-1) was 30.5, 4.3-14.2, and 1.3-15.7 folds higher than those mediated by FeOx alone, HA-FeOx and DBC-FeOx coprecipitates having C/Fe molar ratios of 0.2 and 1.6, respectively. Due to the higher concentrations of surface-bound Fe(III)/Fe(II) in the DBC-FeOx mediated systems, improved Fe(III)/Fe(II) cycling rates, •OH accumulation and NOR degradation were observed as compared with those of counterpart systems mediated by HA-FeOx. Besides functioning in Fe-C complexation to accelerate FeOOH cleavage, carbonyl/carboxyl groups of the coprecipitates also serve as electron shuttles, both of which improved Fe(III)/Fe(II) cycling and •OH production. Our findings emphasized the influence of DOM source and compositions on Fe(III)/Fe(II) cycling and provided a facile approach of preparing Fe-C catalyst for contaminants elimination.

Optimization Preparation and Evaluation of Chitosan Grafted Norfloxacin as a Hemostatic Sponge.

Considering the great harm to the human body caused by severe and massive bleeding, in this study, chitosan-grafted norfloxacin (CTS-NF) composites were prepared with chitosan (CTS) and norfloxacin (NF) as raw materials by a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide-mediated coupling method to solve the limitations of slow hemostatic and poor anti-infective effects of current dressings on the market. The effects of the mass ratio of CTS to NF (MCTS/MNF), reaction temperature T and reaction time t on the grafting rate (η%) of the products were investigated through single factor tests. The preparation process was optimized with the η% as an evaluation index by means of the Box-Behnken test design and response surface analysis. The antimicrobial activity was evaluated by inhibition zone assay, and the hemostatic activity of the prepared composites was evaluated in vitro and in vivo. The results suggested that the optimum preparation conditions were the mass ratio of CTS to NF (MCTS/MNF) 5:3, reaction temperature 65 °C, and reaction time 4 h. Under this condition, the η% of CTS-NF was 45.5%. The CTS-NF composites displayed significant antimicrobial activities. Moreover, in vitro hemostasis results revealed that the CTS-NF composite had a lower blood clotting index and absorbed red blood cells to promote aggregation. In vivo ear and live hemostasis, the CTS-NF groups showed short hemostatic time (49.75 ± 3.32 s and 50.00 ± 7.21 s) and more blood loss (0.07 ± 0.010 g and 0.075 ± 0.013 g). The results showed that CTS-NF reduced the bleeding time and volume, exhibiting a significant coagulation effect. Therefore, the CTS-NF sponge is expected to be a new, effective hemostatic and antibacterial material in the future.

Tandem detection of aluminum ion and norfloxacin by Au-doped copper nanoclusters based on AIE and coordination reaction

Herein, we proposed a method for dual detection of Al3+ and norfloxacin (NOR) by Au-doped N-acetyl-L-cysteine capped copper nanoclusters (NAC-Cu@AuNCs) following a tandem process. The non-luminescent NAC-Cu@AuNCs was fabricated via a bottom-up reduction method. Under neutral solutions, Al3+ was detected sensitively and selectively based on AIE mechanism. The sensing achieved satisfactory results, displaying a broad linear range from 0.1 µM to 90 µM and a low LOD of 0.15 µM, which is significantly lower than the World Health Organization criterion (7.41 µM). Subsequently, ratiometric sensing of NOR was further successfully realized by Al3+/NAC-Cu@AuNCs via coordination reaction between NOR and Al3+. A good linear relationship was obtained in the range of 0.02–16 µM, with LOD as low as 38.3 nM. This work shows great potential in constructing MNCs as sensors for multifunctional detection by combinatorial principles.

Construction of a Molecularly Imprinted Sensor Modified with Tea Branch Biochar and Its Rapid Detection of Norfloxacin Residues in Animal-Derived Foods.

Norfloxacin (NOR) is a common antibiotic used in humans and animals, and its high levels can cause intolerance or poisoning. Therefore, NOR levels in animal-derived foods must be monitored due to potential side effects and illegal use phenomena. This research centered on the development of an environmentally friendly electrochemical sensor for NOR detection. Potassium carbonate activated tea branch biochar (K-TBC) as an efficient use of waste was coated on the surface of glassy carbon electrode (GCE), and a molecular-imprinted polymer (MIP) layer was subsequently electropolymerized onto the modified electrode. NOR was used as template molecule and o-phenylenediamine (o-PD) and o-aminophenol (o-AP) were used as bifunctional monomers. The electrochemical sensor was built and its electrochemical behavior on NOR was investigated. The sensor demonstrated an excellent linear current response to NOR concentrations in the ranges of 0.1-0.5 nM and 0.5-100 nM under ideal experimental circumstances, with a detection limit of 0.028 nM (S/N = 3). With recoveries ranging from 85.90% to 101.71%, the designed sensor was effectively used to detect NOR in actual samples of milk, honey, and pork. Besides, the fabricated sensor had low price, short detection time, good selectivity and stability, which can provide a theoretical and practical basis for the actual monitoring of NOR residues.

Fe-heteropolyoxometalate nanodots modified dominant {001} facet Bi4TaO8Cl nanosheets with oxygen vacancies for enhanced photocatalytic-Fenton degradation of fluoroquinolone antibiotics

Surface defect engineering is an appealing and effective strategy to enhance photocatalytic-Fenton degradation performance. Herein, the oxygen vacancies (OVs) enriched Fe-heteropolyoxometalate (Fe-PW12O40)/Bi4TaO8Cl (FPWBT) heterojunction was elaborately designed for the degradation of fluoroquinolone antibiotics. Benefiting from the existence of OVs and the Fe3+/Fe2+ redox couple, the optimized FPWBT-4 heterojunction manifested the highest photocatalytic-Fenton degradation efficiency of ofloxacin (OFL), norfloxacin (NOR), and ciprofloxacin (CIP) up to 98.87%, 98.18%, and 97.26% only under 5 W white LED irradiation, respectively. Based on the liquid chromatography-tandem mass spectrometry analysis and the density functional theory (DFT) calculations, the probable photocatalytic-Fenton degradation pathways of the OFL, NOR, and CIP antibiotics were unraveled. Additionally, the ecotoxicity of identified intermediates from OFL, NOR, and CIP degradation was investigated in detail. This work demonstrates the merits of the FPWBT heterojunction in enhancing photocatalytic-Fenton performance and provides new insight into the fabrication of stable and efficient photocatalytic-Fenton catalysts for environmental applications.

Degradation of antibiotic contaminants from water by gas–liquid underwater discharge plasma

Antibiotic contamination adversely affects human health and ecological balance. In this study, gas–liquid underwater discharge plasma was employed to simultaneously degrade three antibiotics, sulfadiazine (SDZ), tetracycline (TC), and norfloxacin (NOR), to address the growing problem of antibiotic contaminants in water. The effects of various parameters on the antibiotic degradation efficiency were evaluated, including the discharge gas type and flow rate, the initial concentration and pH of the solution, and the discharge voltage. Under the optimum parameter configuration, the average removal rate of the three antibiotics was 54.0% and the energy yield was 8.9 g (kW·h)−1 after 5 min treatment; the removal efficiency was 96.5% and the corresponding energy yield was 4.0 g (kW·h)−1 after 20 min treatment. Reactive substance capture and determination experiments indicated that ·OH and O3 played a vital role in the decomposition of SDZ and NOR, but the role of reactive substances in TC degradation was relatively less significant.

Ecological Risks of Antibiotics in Urban Wetlands on the Qinghai-Tibet Plateau, China.

Although the ecological risks of antibiotics have been extensively researched globally, fewer studies have been conducted in sensitive and fragile plateau wetland ecosystems. To evaluate the ecological risk of antibiotics in plateau urban wetlands, 18 water samples, 10 plant samples, and 8 sediment samples were collected in March 2022 in the Xining urban wetlands on the Qinghai-Tibet Plateau. The liquid chromatography-electrospray ionization tandem mass spectrometry method was utilized to measure the concentrations of 15 antibiotics in three categories in three types of environmental media. Risk quotients were adopted to assess the ecological risk of antibiotics, and the principal component analysis-multiple linear regression model was used to analyze the source of antibiotics. The results showed that (1) the maximum concentrations of antibiotics in water samples, plants, and sediments reached 1220.86 ng/L, 78.30 ng/g, and 5.64 ng/g, respectively; (2) Tylosin (TYL), norfloxacin (NFX), ofloxacin (OFX), and ciprofloxacin (CFX) in water were at medium and high-risk levels, and OFX had the highest risk value, of 108.04; and (3) the results of source apportionment indicate that 58.94% of the antibiotics came from the Huangshui river and wastewater treatment plant (WWTP) near the wetlands. The current study may provide a reference for the risks and management of antibiotics in plateau urban wetlands.

Construction of Fe/N/C nano-clusters anchored on porous diatomite for efficient removal of norfloxacin via the adsorption-PMS activation

In this study, natural porous diatomite was utilized as a conciliatory carrier for the fabrication of Fe/N/C nano-clusters with assistance of binary molten salt of NaCl-ZnCl2 under different annealing temperature and used to removal of norfloxacin (NFA). The sample Fe/Dm900 (prepared at 900 °C) exhibited a high surface area and great catalytic performance for antibiotics in the presence of PMS. Over 97% NFA can be decomposed within 5 min and the final degradation rate reached 98%. Meaningfully, high-efficiency Fe/Dm900-PMS system was nearly impervious to pH values and inorganic cations in aqueous solution and could be a likely candidate for degradation of multiple contaminants in pharmaceutical outlet water. Furthermore, the other impacting variables such as catalyst dosage, PMS dosage, NFA concentration and initial pH were moreover explored towards debasement, and conceivable degradation pathways of NFA were presented through LC-MS. This work builds up a compelling procedure to synthesize super-dispersed Fe clusters, which may be amplified to other transition metal-based catalyst via molten salt.

Promoted electron transfer in Fe2+/Fe3+ co-doped BiVO4/Ag3PO4 S-scheme heterojunction for efficient photo-Fenton oxidation of antibiotics

A Fe2+/Fe3+ co-doped BiVO4/Ag3PO4 S-scheme heterojunction catalyst was synthesized by a simple hydrothermal method and applied to achieve efficient photo-Fenton for antibiotics degradation (99.70 %). The co-doping of Fe3+/Fe2+ highlighted red shift of optical absorption edge (535–800 nm) and adjustable band structure of BiVO4/Ag3PO4. The collaborative system of photocatalytic and Fenton could maintain high catalytic activity and stability in the treat of simulated actual water and high efficiency within wide pH conditions (3–7). The degradation experiments were employed to show removal efficiency on tetracyclines and quinolones antibiotics including tetracycline (TC), ciprofloxacin (CIP), doxycycline (DO), levofloxacin (LEV), norfloxacin (NOR), and enrofloxacin (ENR). Mechanism exploration elaborated that the m-FBVO/APO composites with dominant Fe2+ preserved both high oxidation potential (<−0.33 eV vs NHE) and reduction potential (>2.45 eV vs NHE) through the constructed BiVO4/Ag3PO4 S-scheme heterojunction. Efficient e−/h+ pairs separation was further achieved through Fe3+/Fe2+ pairs cycling. And degradation pathway of TC was mainly investigated to verify its mineralization. This work provides a new sight towards catalytic mechanisms in heterogeneous photo-Fenton degradation systems.

Unveiling interactions of norfloxacin with microplastic in surface water by 2D FTIR correlation spectroscopy and X-ray photoelectron spectroscopy analyses

Microplastics (MPs) has shown adsorption of hydrophilic organic matters (HOMs) in aqueous environments. However, it is still difficult to predict the adsorption behaviors of HOMs by different MPs, especially in authentic water systems. In this study, the adsorption behaviors and mechanisms of norfloxacin (NOR) onto polyamide (PA) MPs were investigated in both simulated and real surface water. The results showed that the adsorption equilibrium of NOR by PA in simulated surface water could be achieved within 15 h, while the adsorption rate of NOR in real surface was slowed down, with the equilibrium time of 25 h. Pseudo-second-order model could well describe the adsorption kinetics data. The experimental maximum adsorption capacity of NOR on PA in real surface water (e. g. 132.54 ug/g) was dramatically reduced by 37.5 % compared with that in simulated surface water (e. g. 212.25 ug/g), and the adsorption isotherm would obey Freundlich model. Besides, the leaching of NOR from the surface of PA could occur obviously at acidic environment. Furthermore, the salinity and natural organic matter exhibited significantly adverse effects on the NOR adsorption. Finally, the results of 2D Fourier transform infrared correlation spectroscopy and X-ray photoelectron spectroscopy indicated that the electrostatic, H-bond and van der Waals interactions were involved in the adsorption. More importantly, the sequential functional groups in the adsorption process followed the orders: 1638 (CO) > 1542 amide II (-NH-CO) > 717 (CH2) > 1445 (CO) > 973 amide IV (CONH). This study could provide an insight into the interactions between PA and NOR in different water environments.

High efficiently degradation of organic pollutants via low-speed water flow activation of Cu2O@MoS2/PVDF modified pipeline with piezocatalysis performance

Using water flow energy in the environment for water treatment is a feasible solution to alleviate energy shortages and environmental pollution. This work prepared a Cu2O@MoS2/PVDF modified pipeline with superior piezoelectric properties for norfloxacin (NOR) degradation. The piezoelectric coefficient d33 of Cu2O@MoS2/PVDF increased by 27.7 % compared with PVDF. The piezoelectric current response test demonstrated that Cu2O@MoS2/PVDF had a higher current response than PVDF. FTIR showed that the presence of Cu2O@MoS2 significantly increased the piezoelectric β-phase content of PVDF. The Cu2O@MoS2/PVDF pipeline exhibited the best degradation efficiency of 99.3 % within 40 min when the flow rate reached 1.389 L min−1. O2– and OH have been shown to play an important role in NOR degradation and the possible degradation mechanism and pathways of NOR were proposed. This work provides a promising method for the efficient and green treatment of organic pollutants in water by using water flow energy and has practical application significance.

Study of degradation of norfloxacin antibiotic and their intermediates by natural solar photolysis.

In this work, the photolysis of the antibiotic norfloxacin (NOR) and the formation of its photodegradation products were studied using UV and solar radiation. Their extraction was also assessed in Milli-Q water and secondary effluents from a wastewater treatment plant. The photolysis of NOR was chromatographically monitored. The structure of each degradation product is related to the reaction of NOR with reactive oxygen species (ROS), as confirmed using radical quenchers and mass spectrometry. Additionally, the feasibility of extracting NOR and its degradation products was assessed using a commercial solid phase extraction system. Photolysis results showed the formation of five degradation products, generated under exposure to both types of radiation. The decays in NOR concentrations for the solar and UV treatments were adjusted to pseudo first-order kinetics with apparent constant values of ksolar = 1.19 × 10-3s-1 and kUV = 3.84 × 10-5s-1. Furthermore, the superoxide radical was the main participant species in the formation of the degradation products P3, P4, and P5. Species P1 and P2 do not need this radical for their formation. The presence of NOR in water opens the possibility of its photolysis by solar radiation. This work contributes to the understanding of the mechanisms that mediate its photodegradation, in addition to studying potential options for its determination and its photodegradation products in the sample treatment.

Colorimetric Chemosensor Based on Fe3O4 Magnetic Molecularly Imprinted Nanoparticles for Highly Selective and Sensitive Detection of Norfloxacin in Milk.

Long-term use of norfloxacin (NOR) will cause NOR residues in foods and harm human bodies. The determination of NOR residues is important for guaranteeing food safety. In this study, a simple, selective, and label-free colorimetric chemosensor for in situ NOR detection was developed based on Fe3O4 magnetic molecularly imprinted nanoparticles (Fe3O4 MMIP NPs). The Fe3O4 MMIP NPs showed good peroxidase-like catalytic activity to 3,3',5,5'-tetramethylbenzidine (TMB) and selective adsorption ability to NOR. The colorimetric chemosensor was constructed based on the Fe3O4 MMIP NPs-H2O2-TMB reaction system. The absorbance differences were proportional to the concentrations of NOR in the range of 10-300 ng/mL with a limit of detection at 9 ng/mL. The colorimetric chemosensor was successfully applied to detect NOR residue in milk. The recovery range was 78.2-95.81%, with a relative standard deviation of 2.1-9.88%. Together, the proposed colorimetric chemosensor provides a reliable strategy for the detection of NOR residues in foods.

Enhanced H2O2 formation and norfloxacin removal by electro-Fenton process using a surface-reconstructed graphite felt cathode: New insight into synergistic mechanism of defective active sites

The efficient catalytic activity and strong durability possibility of carbon-based three-dimensional fiber materials remains an important challenge in Electro-Fenton advanced oxidation technology. Graphite felt (GF) is a promising electrode material for 2-electron oxygen reduction reaction but with higher catalytic inertia. Anodizing modification of GF has been proved to enhance it electro-catalytic property, but the disadvantages of excessive or insufficient oxidation of GF need further improved. Herein, the surface reconstituted graphite felt by anodizing and HNO3 ultrasonic integrated treatment was used as cathode to degrade norfloxacin (NOR) and the substantial role of different modification processes was essentially investigated. Compared with the single modification process, the synergistic interaction between these two methods can generate more defective active sites (DASs) on GF surface and greatly improved 2-electron ORR activity. The H2O2 can be further co-activated by Fe2+ and DASs into •OH(ads and free) and •O2− to efficiently degrade NOR. The treated GF with 20 min anodizing and 1 h HNO3 ultrasound had the highest electrocatalytic activity in a wide electric potential (−0.4 V to −0.8 V) and pH range (3–9) in system and the efficient removal rate of NOR was basically maintained after 5 cycles. Under optimal reaction conditions, 50 mg L−1 NOR achieved 93% degradation and almost 63% of NOR was completely mineralized within 120 min. The possible NOR degradation pathways and ecotoxicity of intermediates were analyzed by LC-MS and T.E.S.T. theoretical calculation. This paper provided the underlying insights into designing a high-efficiency carbon-based cathode materials for commercial antibiotic wastewater treatment.

Fe3O4-supported N-doped carbon channels in wood carbon form etching and carbonization: Boosting performance for persulfate activating

Fe-based carbon catalysts prove their great potential in activating persulfate for antibiotic wastewater treatment. Considering their limitation in reduced catalytic performance and large-scale application of powder catalysts, porous support catalysts provide an alternative solution. Herein, via Lewis acid (FeCl3) etching and carbonization, monolithic Fe3O4-supported N-doped wood-carbon catalysts were constructed. FeCl3 etching achieved the uniform dispersion of Fe into porous wood channels, but also enlarged the pore sizes with more structural defects. The hierarchical wood-carbon channels anchored with accessibly active Fe3O4 and induced graphitic N after carbonization allowed rapid electron transfer for peroxydisulfate (PDS) activation to eliminate norfloxacin (NOF). As anticipated, the prepared catalyst Fe-1–600 could make 99 % NOF degraded and 63 % TOC removed within 60 min in PDS system, and the corresponding first-order kinetic constant (0.0541 min−1) was 30 times that of C-600 (0.0018 min−1). Mechanism investigation revealed the role of Fe2+/Fe3+ conversion and the participation of generated SO4•-, •OH and O2•- in NOF oxidization. Further evaluations demonstrated the excellent catalytic activity of Fe-1–600/PDS system in wide pH ranges (2–10), as well as satisfactory antijamming capability towards various anions. This work proposed a facial way to fabricate monolithic Fe-based catalysts for persulfate excitation in antibiotic removal.

Fabrication of CoFe2O4/Mn3O4 decorated ultrathin graphitic carbon nitride nanosheets membrane for persistent organic pollutants removal: Synergistic performance and mechanisms

Integration of sulfate radicals-based advanced oxidation processes (SR-AOPs) with separation membranes has enthralled considerable attentions because it can remove persistent toxic micropollutants in a low-energy and cost-effective manner. However, fabrication of such an integrated membrane simultaneously with excellent self-cleaning property, catalytic capability and long-term durability remains a challenge. Herein, for the first time, CoFe2O4 (CFO) and Mn3O4 (MO) nanoparticles were anchored on ultrathin graphitic carbon nitride (UCN) nanosheets via a solvothermal method to prepare heterogeneous Fenton-like catalysts (MO/CFOUCN). Systematic characterizations demonstrated the successful preparation of powder catalysts with favorable degradation ability. Notably, the optimal composite catalyst possessed satisfactory degradation (94.5 %) and kinetic rate (0.1367 min−1) for norfloxacin (NOR) within 30 min. Thereafter, an integrated MO/CFO/UCN@P membrane was fabricated by vacuum-assisted filtration of the catalyst on a supporting membrane surface. It was interestingly found that, benefiting from the synergistic effect of in-situ oxidation and membrane filtration, activating peroxymonosulfate (PMS) endowed the membrane with high removal rates (over 91.8 % for tetracycline, bisphenol A, humic acid (HA)) and high permeation flux (332.7 L·m−2·h−1) driven solely by gravity. Significantly, the membrane achieved a flux recovery rate of 91.9 % with the assistance of PMS after filtering HA solution. Furthermore, quenching experiments and electron paramagnetic resonance (EPR) tests confirmed that both radical and nonradical pathways contributed to the mineralization of NOR. Based on the detection of intermediates in the degradation process, potential NOR degradation pathways were proposed. Overall, this study provided new ideas about integrating Fenton-like catalysts with membrane technology for removal of persistent organic pollutants.