Fabrication of reactive flat-sheet ceramic membranes for oxidative degradation of ofloxacin by peroxymonosulfate
Graphical abstract
Introduction
Antibiotics have been overused both in humans and livestock to inactivate or eliminate pathogens since their discovery in 1928 [1]. Most antibiotics cannot be completely metabolized, and their residues are released into the environment. The presence of these antibiotic residues in water systems is an environmental problem, as they may induce adverse effects on human health by triggering the development of antibiotic-resistance in pathogens [2]. Therefore, effective management and treatment processes should be provided and adopted to remove antibiotic residues from all water and wastewater matrices [3].
Conventional biological treatment is not sufficient to degrade antibiotic residues, as the biological toxicity of antibiotics means such treatment would also generate domesticated resistant strains [4]. Adsorption processes can absorb antibiotics from aquatic environments, but the disposal of used adsorbents is a great challenge and may cause secondary pollution. Electrochemical methods are often adopted to produce strong oxidizing agents in situ for the degradation of antibiotics [5], but these require expensive facilities and large amounts of energy, thus limiting their practical application. Heterogeneous sulfate radical-based advanced oxidation processes (SR-AOPs) have recently attracted great attention for their potential in decomposing antibiotics, due to the high redox potential (2.5–3.1 V) and long life-time (30–40 μs) of sulfate radicals [6]. Nevertheless, it is hard to separate dispersed catalysts in this process from effluents.
Compared with the above methods, membrane filtration is a promising strategy for removing small molecules from wastewater. However, membranes are typically made from polymer composites with low mechanical strength, high thermal sensitivity, low chemical resistance and an invariable tendency to foul membranes. These drawbacks have limited the widespread utilization of organic membranes in wastewater treatment. Furthermore, nanofiltration (NF) organic membranes with relatively low flux are commonly utilized for antibiotics separation [7,8], which will limit the treatment capacity of antibiotic wastewater.
Currently, ceramic membranes are used in water treatment due to their high mechanical strength, high flux, chemical and thermal stability, great hydrophilicity, low energy requirement and long operating life. Despite the production cost of ceramic membranes is higher than that of organic membranes, the lower operation and maintenance cost, and longer lifespan of ceramic membranes render them cost-effective in wastewater treatment [9]. However, the large pore size of common microfiltration (MF) and ultrafiltration (UF) ceramic membranes means that they cannot effectively reject antibiotics [10]. To address this limitation, functionalized ceramic membranes with catalytic layers for PMS activation were developed [11,12], and these can realize the catalytic degradation of antibiotics. In brief, the high-flux ceramic membrane provides a stable platform to immobilize catalysts and separate them from effluent, and the catalysts react with oxidants to generate reactive radicals and subsequently destroy the antibiotics in the effluent. Under forced filtration, these catalytic ceramic membranes can enhance the contact between reactants, reducing the mass transfer resistance and thereby achieving a higher catalytic efficiency than heterogeneous catalysis using catalyst particles [13].
PMS could be activated by UV, heat, base and transition metals [14]. Among them, the activation of PMS by transition metals is easy to manipulate and requires no extra energy, so transition metals have been widely adopted as activator for PMS. Previous literature has reported that among all of the transition metals evaluated, Co2+ exhibited the highest reactivity for PMS activation [15]. But the aqueous toxicity of dissolved cobalt limits its application in wastewater treatment. The spinel structure with the general formula of AIIBIII2O4 was investigated in our previous studies to immobilize metal ions [16,17], where divalent metal A occupies tetrahedral sites and trivalent metal B is in the octahedral environment. This structure possesses great stability with low leaching behavior [17], which could be considered for Co(II) immobilization. Therefore, the cobalt ferrite spinel (CoFe2O4) was selected to act as a stable catalyst for PMS activation. The two types of Co-O bond length in CoFe2O4 are 1.86 Å and 2.02 Å, shorter than those in CoO (2.17 Å), CoTiO3 (2.17 Å and 2.05 Å) and Co(OH)2 (2.10 Å) [18,19]. The shorter bond length of Co-O in CoFe2O4 means stronger Co-O bond energy, which could help immobilize Co(II) in spinel and may result in better water stability with reduced leaching concentration of cobalt than other cobalt compounds.
Existing functionalized ceramic membranes are typically synthesized by a modified sol-gel method accompanied by a dip-coating process. This requires a long operation time and combustion to form the coated catalytic layer, resulting in high energy consumption. Therefore, a facile and low-energy strategy should be developed to manufacture novel catalytic ceramic membranes.
To that end, we have fabricated a cobalt ferrite (CoFe2O4)- decorated flat-sheet ceramic membrane via a one-step hydrothermal method, and used the resulting functionalized membrane in a catalytic degradation process to eliminate ofloxacin (OFX) via activation of PMS. The degradation of OFX under different conditions was investigated to confirm the optimal conditions for this catalytic degradation. The stability and reusability of the membrane were also studied to evaluate its practicability and environmental friendliness. The mechanism of catalytic degradation was further probed by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations.
Section snippets
Chemicals and reagents
Cobalt(II) nitrate hexahydrate (Co(NO3)2·6H2O) and iron (III) nitrate nonahydrate (Fe(NO3)3·9H2O) were purchased from Alfa Aesar. The HiQ-7223 alumina powder was obtained from Alcoa Corp. and identified as boehmite (AlOOH). Ethylene glycol (99%), potassium peroxymonosulfate (2KHSO5·KHSO4·K2SO4, 4.7% active oxygen), tert-butyl alcohol (TBA) and ofloxacin (98%) were purchased from J&K Scientific. Sulfuric acid (H2SO4, 95%), sodium acetate (NaAc), sodium hydroxide (NaOH), sodium sulfate (Na2SO4),
Characterization of CFCM
Pure water flux was tested using deionized water under 100 kPa TMP, and the change of flux was depicted as in Fig. S1a. Results showed that the pure water flux of the Al2O3 substrate and the CFCM was maintained at 82.30 and 55.50 L m−2 h−1 (LMH) after 730 operation seconds, respectively (Fig. S1b). The decrease of flux for CFCM can be attributed to the coated CoFe2O4 catalytic layer, which shrank the pore size of membrane and reduced the flow rate of the liquids. This property can increase the
Conclusion
In summary, a functionalized flat-sheet ceramic membrane (CFCM) was fabricated by a one-step hydrothermal method and used in catalytic degradation to decompose the small molecule OFX. Unlike traditional energy-consuming nanofiltration (NF) and reverse osmosis (RO) processes, the energy-efficient catalytic degradation using CFCM obtained clean effluent at higher flux. The pure water flux could be maintained at 55.5 LMH with average catalyst loading amounts of 0.0428 g per piece of CFCM. The
CRediT authorship contribution statement
Yiang Fan: Writing - original draft, Conceptualization, Methodology, Software, Formal analysis, Investigation, Visualization. Ying Zhou: Investigation, Formal analysis. Yong Feng: Resources, Methodology. Pei Wang: Resources, Investigation. Xiaoyan Li: Resources, Project administration. Kaimin Shih: Writing - review & editing, Supervision, Conceptualization, Resources.
Declaration of competing interest
☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
The authors gratefully acknowledge the funding for this study provided by the Research Grants Council of Hong Kong (Projects 17257616, 17203418 and T21-711/16R). The computations were performed using research computing facilities offered by Information Technology Services, the University of Hong Kong. We thank Miss Vicky Fung for her technical assistance and Mr. Frankie Chan from the Electron Microscope Unit for his help with the SEM and EDS analysis.
References (88)
- et al.
Retentions of bisphenol A and norfloxacin by three different ultrafiltration membranes in regard to drinking water treatment
Chem. Eng. J.
(2016) - et al.
Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: current development, challenges and prospects
Appl. Catal., B
(2016) - et al.
Superhydrophilic and antibacterial zwitterionic polyamide nanofiltration membranes for antibiotics separation
J. Membr. Sci.
(2016) - et al.
High-flux zwitterionic nanofiltration membrane constructed by in-situ introduction method for monovalent salt/antibiotics separation
J. Membr. Sci.
(2020) - et al.
Ceramic nanocomposite membranes and membrane fouling: a review
Water Res.
(2020) - et al.
Amino-functionalized MOFs combining ceramic membrane ultrafiltration for Pb (II) removal
Chem. Eng. J.
(2016) - et al.
Urea-assisted one-step synthesis of cobalt ferrite impregnated ceramic membrane for sulfamethoxazole degradation via peroxymonosulfate activation
Chem. Eng. J.
(2018) - et al.
Peroxymonosulfate-based cleaning technology for metal oxide-coated ceramic ultrafiltration membrane polluted by Alcian Blue 8GX dye: radical and non-radical oxidation cleaning mechanism
J. Membr. Sci.
(2019) - et al.
Free-standing hierarchical α-MnO2@CuO membrane for catalytic filtration degradation of organic pollutants
Chemosphere
(2018) - et al.
Oxidation of bromophenols by carbon nanotube activated peroxymonosulfate (PMS) and formation of brominated products: comparison to peroxydisulfate (PDS)
Chem. Eng. J.
(2018)
Characterisation of polymeric UF membranes by liquid–liquid displacement porosimetry
J. Membr. Sci.
Studies on the preparation of mesoporous titania membrane by the reversed micelle method
J. Membr. Sci.
Pore-functionalized ceramic membrane with isotropically impregnated cobalt oxide for sulfamethoxazole degradation and membrane fouling elimination: synergistic effect between catalytic oxidation and membrane separation
Appl. Catal., B
Ternary nickel iron phosphide supported on nickel foam as a high-efficiency electrocatalyst for overall water splitting
Int. J. Hydrogen Energy
Efficient degradation of phenol using Sn4+ doped FeOCl as photo-Fenton catalyst
Mater. Lett.
Electronic structure studies of the spinel CoFe2O4 by X-ray photoelectron spectroscopy
Appl. Surf. Sci.
Development of hydrophilic microporous PES ultrafiltration membrane containing CuO nanoparticles with improved antifouling and separation performance
Mater. Chem. Phys.
High removal efficiency of antibiotic resistance genes in swine wastewater via nanofiltration and reverse osmosis processes
J. Environ. Manag.
Modelling of the retention of uncharged molecules with nanofiltration
Water Res.
Radical induced degradation of acetaminophen with Fe3O4 magnetic nanoparticles as heterogeneous activator of peroxymonosulfate
J. Hazard Mater.
Degradation of clofibric acid in aqueous solution by an EC/Fe3+/PMS process
Chem. Eng. J.
Photocatalytic degradation of fluoroquinolone antibiotics using ordered mesoporous g-C3N4 under simulated sunlight irradiation: kinetics, mechanism, and antibacterial activity elimination
Appl. Catal., B
Electrophoretic behavior and pKa determination of quinolones with a piperazinyl substituent by capillary zone electrophoresis
J. Chromatogr. A
Cobalt exchanged zeolites for heterogeneous catalytic oxidation of phenol in the presence of peroxymonosulphate
Appl. Catal., B
Sulfate radical-based ferrous–peroxymonosulfate oxidative system for PCBs degradation in aqueous and sediment systems
Appl. Catal., B
Sulfite activation by a low-leaching silica-supported copper catalyst for oxidation of As(III) in water at circumneutral pH
Chem. Eng. J.
Degradation efficiencies of azo dye Acid Orange 7 by the interaction of heat, UV and anions with common oxidants: persulfate, peroxymonosulfate and hydrogen peroxide
J. Hazard Mater.
Oxidative removal of NO from flue gas using ultrasound, Mn2+/Fe2+ and heat coactivation of Oxone in an ultrasonic bubble reactor
Chem. Eng. J.
Gingerbread ingredient-derived carbons-assembled CNT foam for the efficient peroxymonosulfate-mediated degradation of emerging pharmaceutical contaminants
Appl. Catal., B
Enhanced degradation of iopamidol by peroxymonosulfate catalyzed by two pipe corrosion products (CuO and δ-MnO2)
Water Res.
Capacitive deionization of chloride ions by activated carbon using a three-dimensional electrode reactor
Separ. Purif. Technol.
Macroscopic and spectral exploration on the removal performance of pristine and phytic acid-decorated titanate nanotubes towards Eu(III)
J. Mol. Liq.
Application of three surface complexation models on U(VI) adsorption onto graphene oxide
Chem. Eng. J.
Nanoscaled magnetic CuFe2O4 as an activator of peroxymonosulfate for the degradation of antibiotics norfloxacin
Separ. Purif. Technol.
Surface controlled generation of reactive radicals from persulfate by carbocatalysis on nanodiamonds
Appl. Catal., B
Electro-oxidation of Ofloxacin antibiotic by dimensionally stable Ti/RuO2 anode: evaluation and mechanistic approach
Chemosphere
Reductive and oxidative degradation of iopamidol, iodinated X-ray contrast media, by Fe(III)-oxalate under UV and visible light treatment
Water Res.
Application of UV-C LED activated PMS for the degradation of anatoxin-a
Chem. Eng. J.
Peroxymonosulfate activation by iron(III)-tetraamidomacrocyclic ligand for degradation of organic pollutants via high-valent iron-oxo complex
Water Res.
Al2O3 support triggering highly efficient photoreduction of CO2 with H2O on noble-metal-free CdS/Ni9S8/Al2O3
Appl. Catal., B
Deposition of Al2O3 by resistive evaporation and thermal oxidation of Al to be applied as a transparent FET insulating layer
Ceram. Int.
Contribution of alcohol radicals to contaminant degradation in quenching studies of persulfate activation process
Water Res.
Highly-efficient degradation of amiloride by sulfate radicals-based photocatalytic processes: reactive kinetics, degradation products and mechanism
Chem. Eng. J.
Heterogeneous activation of peroxymonosulfate using Mn-Fe layered double hydroxide: performance and mechanism for organic pollutant degradation
Sci. Total Environ.
Cited by (63)
CoFe<inf>2</inf>O<inf>4</inf>-titanium hollow fiber membrane filtration coupling peroxymonosulfate activation for water purification: Preparation, performance and mechanism
2024, Separation and Purification Technology