Developing high-efficient catalysts is crucial for activating peroxymonosulfate (PMS). Fe-N-C catalysts exhibit excellent performance for PMS activation because of the contribution of doped N, Fe-Nx ...and Fe3C sites. In our work, a series of Fe-N-C catalysts with high-performance was obtained by pyrolyzing Fe-Zn-MOFs precursors. During pyrolysis process, the change of chemical bonds and formation of active sites in the precursor were elucidated by characterization analysis and related catalytic experiments. Graphitic N, Fe-Nx and Fe3C were confirmed to activate PMS synergistically for ciprofloxacin (CIP) degradation. Besides, the catalytic performance was proportional to the amount of doped iron and calcination temperature. Moreover, the Fe-N-C-3-800/PMS system not only displayed good recycling performance, but also had high anti-interference ability. Integrated with quenching and electron paramagnetic resonance (EPR) experiments, a non-radical pathway dominated by 1O2 was proposed. Furthermore, PMS could bond to Fe-N-C-3-800 to form intermediate for charge transfer, thus accelerate electron transfer between CIP and PMS to realize degradation of CIP. Six main pathways of CIP degradation were proposed, which include bond fission of N-C on piperazine ring and direct oxidation of CIP. This study provided a new idea for the design of heterogeneous carbon catalysts in advanced oxidation field.
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•Fe-N-C catalysts with 3D porous structure and excellent catalytic performance were synthesized.•The relationship between active sites formation and pyrolysis temperatures was revealed.•Non radical pathway dominated by singlet oxygen played a key role in Fe-N-C/PMS system.•The formation of electron transfer intermediates between catalyst and PMS was proposed.•The degradation pathway and mechanism of CIP has been studied based on LC-MS analysis.
Nanoparticles (NPs) fabrication is a significant approach to enhance the visible light response of photocatalysts, to realize inexpensive and more harmful compound removal, at larger scale. The poor ...electrons and holes separation capability and low light activity of bulk materials can be notably enhanced through developing NPs. From photocatalytic investigation, better performance was received in the tungsten diselenide (WSe2) NPs than that in bare WSe2, exhibiting the action of restrained recombination of charge carriers in the NPs. The photocatalytic Cr(VI) reduction efficiency of WSe2 NPs is 2.7 folds greater than that by bare WSe2. On the other hand, the photocatalytic efficiency follows the order of nano WSe2-3 > nano WSe2-2 > nano WSe2-1 > bare WSe2, nano WSe2-3 is nearly 2.7 folds greater than that of bare WSe2. The results imply the fabrication of WSe2 NPs and it possesses improved visible light utilization. The proposed WSe2 NPs have merged with the three aspects of photocatalytic capability including the visible light activity, the valid separation of photo-response charge carriers and enough surface active sites owing to the nanoscale formed. This research endows conduct on the potential style of NPs for photo-response water environmental remediation.
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•Nano-scale structure of WSe2 helps transport of photoinduced electron-holes.•This WSe2 NPs efficiently removed CIP and Cr(VI) by photocatalysis under visible light irradiation.•This WSe2 NPs could be applied at a wide pH range in photocatalytic reactions.•A dependable photodegradation mechanism for the superior photocatalytic performance was explained.
•Novel S-doped CuBi2O4 was synthesized by a one-step hydrothermal method.•S-doping and Ov modulated the charge density distribution in the Cu-O tetrahedron.•The formation of Ov-Cu-S promoted the ...adsorption and activation of PMS and O2.•S-doped CuBi2O4 catalyst exhibited excellent catalytic activity and stability.•Radical and non-radical pathway synergistically enhance the catalytic performance.
The regulation of the metal–oxygen tetrahedron active center in spinel catalysts is crucial for enhancing the photocatalytic activation of peroxymonosulfate (PMS) to degrade organic pollutants. Herein, S−doped CuBi2O4 (CBOS) catalysts with surface oxygen vacancies (Ov) were prepared via a one-step hydrothermal method. The cycling of Cu(I)/Cu(II) and the trapping of photogenerated electrons by Ov significantly enhance the migration of photogenerated carriers. Density functional theory (DFT) calculations revealed that the synergistic effect of S doping and Ov successfully modulated the charge distribution around the Cu site in Cu−O tetrahedron. Furthermore, the exceptional adsorption and activation abilities of Ov−Cu−S on PMS greatly enhanced the photocatalytic activation of S−doped CuBi2O4, which resulted in the degradation of ciprofloxacin (CIP). The optimal CBOS2 was capable of removing 95.3 % of CIP in 60 min, a 40.7 % increase compared to pure CuBi2O4. Electron paramagnetic resonance (EPR) spectroscopy and quenching tests confirmed the synergistic effect of radical and non-radical mixed pathways (SO4•−, •OH, 1O2) on the removal of CIP. The potential pathways for CIP degradation were further explored using liquid chromatography-mass spectrometry (LC−MS) test results. This study offers a novel perspective for the research and application of spinel-based catalysts in water treatment.
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•α-MnO2 with different morphologies was successfully fabricated and utilized in heterogeneous PMS activation.•The effects of water constituents on CIP degradation were deeply ...investigated and elaborated.•Degradation products and their concentration changes during the oxidation were identified.•The toxicity of CIP could be efficiently eliminated.•EEM images were used to observe the removal of CIP in real water.
Nanoscale α-MnO2 with different morphologies (nanoparticles, nanoflowers and nanorods) were synthesized via a facile hydrothermal method and tested in peroxymonosulfate (PMS) activation for ciprofloxacin (CIP) degradation. The catalytic activity of α-MnO2 mainly relied on the specific surface area and crystallinity, and followed the order of α-MnO2 nanoflowers>α-MnO2 nanorods>α-MnO2 nanoparticles>commercial MnO2. Acidic condition was more beneficial to CIP removal than neutral condition, and the degradation would be greatly accelerated in alkaline circumstance. The introduction of chloride and bicarbonate displayed concentration-dependent dual effect. The presence of natural organic matter (NOM) exerted the detrimental effect on CIP degradation. Eleven oxidation products were identified by UPLC–MS/MS and the changes of their concentrations were monitored, five products showed monotonous uptrend while four intermediates present monotonous downtrend once they were generated. Piperazine ring cleavage, hydroxylation and F/OH substitution were found to be the important oxidation pathways. The acute toxicity of resulted solution gradually decreased with the lapse of time, and higher PMS concentration favored the detoxification. The CIP removal in α-MnO2/PMS process was also efficient under the actual water background, which was testified by the results of fluorescence excitation-emission matrix (EEM).
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•N doped ZIF-67 (N@ZIF-67) was synthesized using hydrothermal method.•N@ZIF-67 exhibited a good charge transfer for peroxymonosulfate activation.•CIP degradation by ...N@ZIF-67/peroxymonosulfate occurred in different water matrixes.•O2●− was the main active substance involved in the CIP degradation.•N@ZIF-67 was stable and effective in multiple cycles of CIP degradation efficiency.
In this study, N doped ZIF-67 (N@ZIF-67) was prepared via hydrothermal method and applied for heterogeneous catalytic activation of peroxymonosulfate (PMS) in the remediation of pharmaceuticals, exemplified by antibiotic ciprofloxacin (CIP) in aqueous solution. The morphological and physicochemical properties of N@ZIF-67 were characterized and the catalytic activity for degradation of organic contaminants was studied. The N@ZIF-67 significantly enhanced electron transfer between reacting species with excellent catalytic performance in CIP degradation. CIP degradation in the N@ZIF-67/PMS system took place over a broad pH range of 5 to 9. Moreover, the synergistic effect between nitrogen and ZIF-67 structure not only significantly boosted the CIP removal efficiency but also long-term stability of the composite. The dissolution of cobalt ion was below the allowable drinking water standard. The superoxide radical (O2⋅−) was not only involved in the generation of singlet oxygen (1O2) but also played a crucial role in CIP degradation. This proof-of-concept study for the development of N@ZIF-67 paves the new venue for wastewater remediation through PMS activation.
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•Brown algal was hydrothermally carbonized to modify surface physicochemistry.•ZnCl2-activated hydrochar produced mesoporous biochar.•Algal biochar showed superior ciprofloxacin ...removal in different conditions.•Electrostatic interaction, H-bond and π-EDA were major adsorption mechanism.
In this study, biochar derived from brown algal Ascophyllum nodosum was synthesized through hydrothermal carbonization (HTC) coupling with ZnCl2 chemical activation and applied as a sustainable adsorbent for antibiotic removal from water exemplified by ciprofloxacin (CIP). Various surface analysis techniques such as Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and zeta potential were used to clarify the surface properties of prepared biochars. The adsorption performance of biochars was investigated using batch adsorption experiments with a variety of parameters (initial pH, ionic types, temperature and water matrixes). The application of prepared biochar in CIP removal showed a good result of adsorption capacity (150–400 mg g−1) in different conditions. Overall, algal biochars, as a product recycled from biowaste, demonstrated a novel and promising adsorbent for effective and sustainable method for removal of antibiotics from water.
A coating was prepared on the carbonyl iron powders by plasma electrolytic deposition to improve its corrosion resistance. SiO2 was uniformly coated with the thickness of ~10 nm. The composite ...powders exhibited superior corrosion resistance in both the NaCl and HCl solutions. The formation of the coating was the result of the electro-chemical absorption and reaction in the electrical field. The aqueous plasma had an important role in activating the surface and optimizing the microstructure of the coating. The superior corrosion resistance makes it available to be used in special environments and has greatly expanded its application fields.
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•A novel plasma electrolysis was applied on carbonyl iron powders.•SiO2 was uniformly coated with the thickness of ~10 nm.•No corrosion happened for the coated powders in NaCl solution after 1440 h.•The coated powders were slightly corroded in HCl solution after 48 h.•The plasma arc activated the surface and formed a strong absorption.
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•GQDs@MnOOH could enhance the CIP degradation and inhibit the formation of bromate.•GQDs@MnOOH exhibited excellent electron transport capability for catalytic ...ozonation.•GQDs@MnOOH + O3 system exhibits good efficiency of CIP removal over different water conditions.•Radicals and non-radicals were involved in CIP degradation by catalytic ozonation process.
A catalyst GQDs@MnOOH was successfully synthesized by attaching graphene quantum dots (GQDs) on the surface of MnOOH nanorods to boost catalytic ozonation of antibiotic, exemplified by ciprofloxacin (CIP). The result demonstrated that the GQDs@MnOOH/O3 system had the greatest CIP removal effectiveness, followed by that of MnOOH/O3 and O3 only. The 0.02 mM CIP was degraded with 99.9% efficiency in 30 min in the presence 9.6 mg L-1 of O3 catalyzed by 12.5 mg L-1 of GQDs@MnOOH. The kinetic rate constants were in the order: GQDs@MnOOH/O3 (0.161 min−1) > MnOOH/O3 (0.079 min−1) > O3 (0.055 min−1). The GQDs@MnOOH could enhance CIP degradation and inhibit BrO3- formation in different water sources. Results of scavenger and electron paramagnetic resonance (EPR) experiments demonstrated that oxygen radical (O2•-), singlet oxygen (1O2), and hydroxyl radicals (•OH) were involved in CIP degradation by the GQDs@MnOOH/O3 system. Accordingly, the degradation pathways of CIP and mechanism of catalytic ozonation over GQDs@MnOOH were investigated and proposed. This research is expected to shed light on the connection between carbonaceous material and metal hydroxide in catalytic ozonation.
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