Ciprofloxacin Degradation Efficiency Research Articles

Insight into peroxymonosulfate assisted photocatalysis over Fe2O3 modified TiO2/diatomite composite for highly efficient removal of ciprofloxacin

The ternary Fe2O3/TiO2/diatomite (Fe2O3/TDE) composite was synthesized through a chemical precipitation-calcination method to boost the ciprofloxacin (CIP) degradation performance under persulfate catalysis and visible-light photocatalysis (PMS+Vis) synergistic system. It is indicated that Fe2O3 and TiO2 uniformly dispersed on the surface of diatomite, leading to the increase of active sites. Moreover, the lower recombination of electron-hole pairs promoted the photocatalytic performance and PMS activation. Therefore, the obtained Fe2O3/TDE composite (Fe2O3/TDE-5) exhibited superior degradation efficiency of CIP with the removal rate of approximately 88% under PMS+Vis system, and the degradation rate constant was 3.58 and 8.06 times higher than Vis and PMS single system, respectively. Besides, the introduction of diatomite not only enhanced the activation of PMS by superficial hydroxyl groups, but also enhanced the migration of photogenerated carriers. In addition, the radical pathway (h+, O2−, SO4− and OH) and non-radical pathway (1O2) work together for the removal of CIP. This work provides a deep insight for coupling application of photocatalysis and PMS activation for water environmental remediation.

In-situ fabrication from MOFs derived MnxCo3-x@C modified graphite felt cathode for efficient electro-Fenton degradation of ciprofloxacin

Since high degradation efficiency and environmental friendliness, the Electro-Fenton technology has been widely applied to remove antibiotics in wastewater. In-situ loading of electrochemically active metals on graphite felt (GF) is considered as a promising strategy for improving its electrocatalytic activity and reusability. Here, a series of Mn/Co MOFs derivatives modified graphite felt cathodes (MnxCo3-x@C-GF) were fabricated without any binder, which was used for the treatment of ciprofloxacin (CIP). The morphology, pore structure and electrochemical activity of MnxCo3-x@C-GF changed by adjusting the ratio of Mn/Co in the MOF-74 precursor. Owning to the optimized Mn/Co ratio, Mn2Co1@C-GF exhibited the most excellent catalytic ability with hierarchical porous structure and faster electron transfer. The results showed that the CIP degradation efficiency could reach 99.8% in 60 min. Mn2+/3+/4+ and Co3+/2+ enhanced the generation of active radicals (·OH) by Fenton-like reaction and further improved degradation performance. In addition, the cathode had maintained good stability during four cycles. This work provides an alternative strategy for fabricating efficient self-supporting cathode materials in the future.

Efficient degradation of organic pollutants by S-NaTaO3/biochar under visible light and the photocatalytic performance of a permonosulfate-based dual-effect catalytic system

Removing large concentrations of organic pollutants from water efficiently and quickly under visible light is essential to developing photocatalytic technology and improving solar energy efficiency. This study used a simple hydrothermal method to prepare a non-metallic, S-doped NaTaO3 (S-NTO) photocatalyst, which was then loaded onto biochar (BC) to form a S-NTO/BC composite photocatalyst. After uniform loading onto BC, the S-NTO particles transformed from cubic to spherical. The photogenerated electron-hole pair recombination probability of the composite photocatalyst was significantly lower than those of the NTO particles. The light absorption range of the catalyst was effectively widened from 310 nm UV region to visible region. In addition, a dual-effect catalytic system was constructed by introducing peroxymonosulfate (PMS) into the environment of the pollution to be degraded. The Rhodamine B, Methyl Orange, Acid Orange 7, tetracycline, and ciprofloxacin degradation efficiency at 40 mg/L reached 99.6%, 99.2%, 84.5%, 67.1%, and 70.7%, respectively, after irradiation by a 40 W lamps for 90 min. The high-efficiency visible-light catalytic activity of the dual-effect catalytic system was attributed to doping with non-metallic sulfur and loading of catalysts onto BC. The development of this dual-effect catalytic system provides new ideas for quickly and efficiently solving the problem of high-concentration organic pollution in aqueous environments, rationally and fully utilizing solar energy, and expanding the application of photocatalytic technology to practice.

Efficient photocatalytic degradation of ciprofloxacin using novel dual Z-scheme gCN/CuFe2O4/MoS2 mediated peroxymonosulphate activation

Modulation in the constituent composition of heterojunction composite materials can efficiently separate photogenerated charge carriers and promote significant improvement towards visible light aided photocatalytic degradation of recalcitrant pollutants. Herein, a novel ternary heterojunction composite g-CN/CuFe2O4/MoS2 (CNCuMo) has been fabricated by improvising g-C3N4 as a fuel and the supporting matrix. The stable dual Z-scheme heterojunction manifested superior visible light driven catalytic activity through efficient electron/hole (e-/h+) separation and generation of reactive species through peroxymonosulphate (PMS) activation. Various surface bound redox cycles play prominent roles in transport of photogenerated charge carriers, activation of adsorbed PMS species and generation of reactive radicals. Benefiting from their synergistic effects, visible light aided photocatalytic degradation of refractory antibiotic Ciprofloxacin (CIP) was studied. 98% CIP was degraded (with 74.8% mineralization) using 0.1 g/l of ternary composite with 10 wt% MoS2 (CNCuMo(10)) and 0.5 g/l of PMS, within 60 min of visible light irradiation. Scavenging experiments confirmed the simultaneous activity of both radical and non-radical species towards degradation. The system also exhibited satisfactory CIP degradation efficiency in various surface water matrixes. LCMS/MS analysis of the identified intermediates interpreted the probable degradation pathways of CIP molecules. Magnetic retrievability, recyclability for five cycles, good structural stability and low metal ion leaching tendency of the synthesized photocatalyst elucidate its potential application for degradation of emerging pollutants for water decontamination.

Activation of peroxymonosulfate by iron oxychloride with hydroxylamine for ciprofloxacin degradation and bacterial disinfection

Iron oxychloride (FeOCl) is a known effective iron-based catalyst and has been used in advanced oxidation processes (AOPs). This study intends to achieve more facile free radicals generation from peroxymonosulfate (PMS) activation by exploring the Fe(III)/Fe(II) cycle of FeOCl in the presence of hydroxylamine (HA). With 0.2 g/L FeOCl, 1.5 mM PMS, and 1 mM HA, the PMS/FeOCl/HA system could effectively achieve 98.88% of the oxidative degradation of 5 mg/L ciprofloxacin (CIP) in 15 min and quickly inactivate 99.99% of E. coli (108 CFU/mL) in 5 min at near-neutral pH. HA played an important role in promoting the Fe(III)/Fe(II) cycle, thereby greatly improving the oxidation activity of the system. The reactive oxygen species (ROS) such as HO, SO4− and O2− were identified as the dominated free radicals produced in the system. The intermediate products of CIP detected by liquid chromatograph-mass spectrometer (LC-MS) and three possible degradation pathways of CIP were proposed. The presence of common anions in the PMS/FeOCl/HA system, including HCO3−, Cl−, SO42−, and NO3−, enhanced the degradation efficiency of CIP to varying degrees at the concentrations of 10 mM. Moreover, FeOCl maintained a high degradation capability for CIP after several recycles. This work offers a new promising means of catalyzing the PMS-based AOPs in the degradation of refractory organics.

Cu2O/Fe3O4/MIL-101(Fe) nanocomposite as a highly efficient and recyclable visible-light-driven catalyst for degradation of ciprofloxacin

Nowadays, the widespread production and use of antibiotics have increased their presence in wastewater systems, posing a potential threat to the environment and human health. The development of advanced materials for treating antibiotics in wastewater has always received special attention. This study aimed to synthesize a novel Cu2O/Fe3O4/MIL-101(Fe) nanocomposite and use it to degrade ciprofloxacin (CIP) antibiotics in an aqueous solution under visible light irradiation. The optical, structural, and morphological attributes of the developed nanocomposite were analyzed by XRD, FTIR, FE-SEM, TGA, DRS, BET, VSM, and UV–Vis techniques. Optimum circumstances for CIP photocatalytic degradation were acquired in 0.5 g L−1 of catalyst dosage, pH of 7, and CIP concentration of 20 mg L−1. The degradation efficiency was achieved 99.2% after 105 min of irradiation in optimum circumstances. The chemical trapping experiments confirmed that hydroxyl and superoxide radicals significantly contributed to the CIP degradation process. The results of this study indicated that Cu2O/Fe3O4/MIL-101(Fe) nanocomposite was a highly stable photocatalyst that could effectively remove antibiotics from aqueous solutions. The CIP degradation efficiency only decreased by 6% after five cycles, indicating the excellent recyclability of Cu2O/Fe3O4/MIL-101(Fe) nanocomposites.

Complete Degradation and Detoxification of Ciprofloxacin by a Micro-/Nanostructured Biogenic Mn Oxide Composite from a Highly Active Mn2+-Oxidizing Pseudomonas Strain.

Ciprofloxacin (CIP), as a representative broad-spectrum antibiotic, poses a major threat to human health and the ecological environment as a result of its abuse and emissions. In this study, a highly active Mn2+-oxidizing bacterium, Pseudomonas sp. CCTCC M2014168, was induced to form micro-/nanostructured biogenic Mn oxide (BMO) aggregates through continuous culturing with 1 mmoL−1 Mn2+. Following the characterization of Mn4+ oxides and the micro-/nanostructures by scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction assays, the BMO composites were subjected to CIP degradation and detoxification in laboratory trials. High-performance liquid chromatograph (HPLC) analysis identified that the BMO composites were capable of completely degrading CIP, and HPLC with a mass spectrometer (LC/MS) assays identified three intermediates in the degradation pathway. The reaction temperature, pH and initial ciprofloxacin concentration substantially affected the degradation efficiency of CIP to a certain extent, and the metal ions Mg2+, Cu2+, Ni2+ and Co2+ exerted significant inhibitory effects on CIP degradation. A toxicity test of the degradation products showed that CIP was completely detoxified by degradation. Moreover, the prepared BMO composite exhibited a high capacity for repeated degradation and good performance in continuous degradation cycles, as well as a high capacity to degrade CIP in real natural water.

Facile synthesis of cobalt-iron layered double hydroxides nanosheets for direct activation of peroxymonosulfate (PMS) during degradation of fluoroquinolones antibiotics

How to efficiently and fast remove the serious perniciousness of the residual antibiotics in water environment is crucial for protecting ecosystem. Herein, we reported the Fenton-like system based on layered double hydroxides (LDHs) nanosheets for direct peroxymonosulfate (PMS) activation efficient for fast removing the typical five fluoroquinolones antibiotics ciprofloxacin (CIP), norfloxacin (NOR), levofloxacin (LEV), enrofloxacin (ENR) and ofloxacin (OFL). A series of CoFe-LDHs nanosheets was one-step fabricated by integrating coprecipitation and in-situ exfoliation method. The as-obtained CoFe-LDHs nanosheets catalysts exhibit thin nanosheets (~3 nm) with high redox properties, abundant oxygen vacancies, appreciable adsorption capacity, remarkable catalytic performance and favorable stability. The variable valent state, cheap, easy-to-obtain and low-toxic Co and Fe elements were used to construct stable LDHs for efficient activation of PMS to degrade quinolone antibiotics. Among them, Co1Fe1-LDHs nanosheets exhibited the best CIP degradation efficiency of 86.9% within 12 min, which is superior to most of previous candidates. The impacts of different reaction parameters, catalyst stability, main reactive oxygen species, the main CIP degradation mechanism and rational degradation pathways were systematically studied. This work offers a feasible strategy to tune the performance of LDHs-based materials in Fenton-like system degradation of antibiotics.

Construction of hierarchical CuBi2O4/Bi/BiOBr ternary heterojunction with Z-scheme mechanism for enhanced broad-spectrum photocatalytic activity

A novel Z-scheme CuBi2O4/Bi/BiOBr ternary heterostructured photocatalyst was developed by a simple hydrothermal method. The structural, morphologic, optical and electronic properties were systematacially characterized. The metal Bi was confirmed by the XRD, XPS and SEM, which served as bridge between CuBi2O4 and BiOBr, promoting the charge transfer. The optimized CuBi2O4/Bi/BiOBr heterostructure possessed superior photocatalytic degradation efficiency (81%) towards ciprofloxacin (CIP), which was 2.38- and 1.25-fold higher than that of pure CuBi2O4 and BIOB, respectively. The origin of the improved photocatalytic performance of CuBi2O4/Bi/BiOBr heterostructure was attributed to the enhanced light absorption combined with Z-scheme heterostructure. Additionally, the degradation efficiencies of CuBi2O4/Bi/BiOBr heterostructure towards Methylene blue (MB), Lanasol Red 5B (LR5B), Rhodamine B (RhB), Bisphenol A (BPA) and phenol were 73%, 99%, 99%, 45% and 48%, respectively. However, the simultaneous photocatalytic degradation exhibited the competitive actions between CIP and other organic pollution for radical, resulting in poor degradation performance for CIP. The experimental factor towards degradation efficiency of CIP was investigated. The momentous contribution of superoxide radicals (•O2−) and hydroxyl radical (•OH) were confirmed by the trapping experiment and electron paramagnetic resonance (EPR), which help us deduce Z-scheme charge transfer mechanism, improving the photocatalytic activity.

Synthesis of graphene-based CdS@CuS core-shell nanorods by cation-exchange for efficient degradation of ciprofloxacin

Reduced graphene oxide (RGO) supported [email protected] core-shell nanorods ([email protected]/RGO) were prepared by a simple, solvothermal method involving cation-exchange for efficient degradation of the fluoroquinolone antibiotic, ciprofloxacin (CIP). [email protected]/RGO delivers superior photocatalytic degradation of CIP in simulated sunlight. Ascribed to the unique nanostructure, the CIP degradation efficiency of [email protected]/RGO reaches 91.5%, which is higher than that of CdS (67.1%) alone. Compared with previously reported catalysts, [email protected]/RGO exhibits higher degradation efficiency in less time and lower dosage. Furthermore, its degradation efficiency remains at around 81.5% after five usage cycles, which represents excellent cycling stability. Free radical scavenging experiments show that superoxide radicals and holes play important roles in the degradation. The [email protected]/RGO utilizes the synergistic effects of CdS, CuS and RGO to effectively retard the photo corrosion of CdS upon visible light exposure, reduce the band-gap energy, suppress the recombination of photo-generated electron-hole pairs and promote the adsorption of catalyst toward CIP, thereby, enhancing the catalytic performance of the composite.

Enhanced activated persulfate oxidation of ciprofloxacin using a low-grade titanium ore under sunlight: influence of the irradiation source on its transformation products.

In this work, the activated persulfate oxidation of ciprofloxacin (CIP) using a low-grade titanium ore under sunlight or simulated sunlight were conducted to analyze the CIP degradation efficiency and to identify the transformation products (TPs) generated during oxidation under both types of irradiation sources by using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). All advance oxidation process experiments were performed in a 2700-mL raceway reactor at a pH value of ~ 6.5 and an initial CIP concentration of 1mg/L, during 90min of reaction time. The control experiments carried out under simulated sunlight achieved a 97.7 ± 0.6% degradation efficiency, using 385W/m2 of irradiation with an average temperature increase of 11.7 ± 0.6°C. While, the experiments under sunlight reached a 91.2 ± 1.3% degradation efficiency, under an average irradiation value of 19.2 ± 0.3W/m2 in October-November 2019 at hours between 11:00 am and 3:00 pm with an average temperature increase of 1.4 ± 0.8°C. Mass spectrometry results indicated that 14 of the 108 possible TPs reported in the literature were detected. The calculated exact mass, measured accurate mass, and its characteristic diagnostic fragment ions were listed, and two new TPs were tentative identified. The TP generation analysis showed that some specific compounds were detected in different time intervals with kinetic variations depending on the irradiation used. Consequently, two CIP degradation pathways were proposed, since the type of irradiation determines the CIP degradation mechanism. Graphical abstract.

Photo-electro-Fenton-like process for rapid ciprofloxacin removal: The indispensable role of polyvalent manganese in Fe-free system

The residual ciprofloxacin (CIP) in water seriously menaces the ecological safety and public health. Here, a Fe-free photo-electro-Fenton-like (PEF) system was designed for efficient degradation of CIP in water. A Z-scheme MnOx/g-C3N4 (MCN) nanocomposite with low-cost, large specific surface area and abundant active sites was successfully synthesized as a photoelectric catalyst. The XPS analysis indicated the presence of Mn2+, Mn3+ and Mn4+ in the MCN (1:6) composite, and the conversion among polyvalent manganese made the decomposition of H2O2 more efficient. Therefore, the manganese ions replaced the Fe element in traditional Fenton system. With the MCN (1:6), the PEF system could also produce O2−, OH and h+ under the visible light irradiation. The synergetic excitation of multiple active species promoted the rapid decomposition of CIP. Besides, the polyvalent property of manganese oxide resulted in the presence of oxygen vacancies which could improve the electrocatalytic reactivity of the catalyst. Finally, the degradation efficiency of CIP was 96.23% in 120 min and the mineralization efficiency was 80.02% in 240 min.

Efficient photocatalytic degradation of ciprofloxacin under UVA-LED, using S,N-doped MgO nanoparticles: Synthesis, parametrization and mechanistic interpretation

In this study, the degradation efficiency of ciprofloxacin (CIP) in aqueous solution was evaluated in the photocatalytic process using S,N-doped MgO (S,N-MgO) as an innovative photocatalyst. The photocatalytic activity of S,N-MgO was estimated under UVA-light emitting diodes (UVA-LED) irradiation at 365 nm. Based on differential reflectance spectroscopy (DRS) results, N and S atoms as a dopant modify the MgO lattice structure due to the bandgap energy reduction to 1.5 eV and change the valence band edge compared to pure MgO. The synthesized catalyst was confirmed by the transmission electron microscopy (TEM) analysis to be nano-sized (20–30 nm). The effect of operational factors including initial pH, catalyst concentration, water anions, and reaction time were studied on the S,N-MgO/LED photocatalytic process in the degradation and mineralization of ciprofloxacin (CIP). Furthermore, the intermediate products and reaction mechanisms were studied. The results showed the highest degradation efficiency, about 99%, could be obtained at pH 9, 0.1 g/L catalyst, and 50 mg/L CIP within 30 min. The reaction mechanism evaluation indicated that OH and holes (h+) played the main role in the enhanced photocatalytic activity of S,N-MgO nanoparticles for CIP oxidation. The reusability of the catalyst was tested four times without a considerable reduction in the activity. Therefore, S,N-MgO is an active and reusable catalyst than can be efficiently activated with UVA-LEDs to degrade and mineralize the pharmaceutical compounds.

Bi2Ti2O7/TiO2/RGO composite for the simulated sunlight-driven photocatalytic degradation of ciprofloxacin

Titanium dioxide (TiO2) modified bismuth titanate (Bi2Ti2O7) heterojunction was supported on reduced graphene oxide (RGO) to obtain Bi2Ti2O7/TiO2/RGO composite by simple solvothermal method. Neither toxic reductant nor toxic solvent was used. The structural characterization shows that spherical Bi2Ti2O7/TiO2 nanoparticles are loaded on silk-like transparent RGO. By contrast with each individual component, the prepared Bi2Ti2O7/TiO2/RGO composite shows significantly enhanced photocatalytic performance on the degradation of ciprofloxacin (CIP) under simulated sunlight. The degradation efficiency of CIP using Bi2Ti2O7/TiO2/RGO composite as the catalyst reaches 95% in 180 min and maintains at 88% after 5 photocatalytic reaction cycles. The enhancement of photocatalytic performance of Bi2Ti2O7/TiO2/RGO5 composite is due to the synergistic effect among Bi2Ti2O7, TiO2 and RGO. Moreover, compared with other recently reported bismuth-based catalysts, Bi2Ti2O7/TiO2/RGO exhibits higher photocatalytic activity, or shows comparable activity but with less dosage used. Free radical scavenger experiments were also carried out to explore the photocatalytic degradation mechanism.

Effects of co-loading of polyethylene microplastics and ciprofloxacin on the antibiotic degradation efficiency and microbial community structure in soil

Microplastics (MPs) have become a global environmental concern while soil plastic pollution has been largely overlooked. In view of the severe antibiotic contamination in arable soils owing to land application of sewage sludge and animal manure, the invasion of MPs along with antibiotics may pose an unpredictable threat to soil microbial communities and ecological health. In this work, polyethylene MPs and ciprofloxacin (CIP) were applied to a soil microcosm to investigate the CIP degradation behavior and their combined effects on soil microbial communities. Compared with that of the individual amendment of CIP, the co-amendment of CIP and MPs reduced the CIP degradation efficiency during the 35 d cultivation period. In addition, the high-throughput sequencing results illustrated that the combined loading of MPs and CIP in soil significantly decreased the microbial diversity compared with that of individual contamination. As for the community structure, the microbial compositions at the phylum level were consistent among all treatments, and the most dominant phyla were Proteobacteria, Actinobacteria, and Chloroflexi. At the genus level, only one genus, namely Arthrobacter, was remarkably changed in the CIP-amended soil compared with that in the blank control, but four genera were significantly altered in the MPs-CIP co-amended soil. Serratia and Achromobacter were abundant in the combined polluted soil, which might have been involved in accelerated depletion of soil total nitrogen based on redundancy analysis. These findings may contribute to the understanding of bacterial responses to the combined pollution of MPs and antibiotics in soil ecosystems.

Sunlight-activated 3D-mesoporous-flowerlike Cl–Br bismuth oxides nanosheet solid solution: In situ EG-thermal-sonication synthesis with excellent photodecomposition of ciprofloxacin

In this research, a group of BiOX (Cl:Br) nanosheet solid solution with various Cl/Br molar ratios have been fabricated using a facile one-pot in-situ thermal-sonication method. The crystal phases structure, elemental composition, morphology, specific surface area and optical features of as-synthesized photocatalyst were explored by XRD, EDX, FESEM, HRTEM, AFM, BET-BJH, and DRS techniques. The photocatalytic activity of nanophotocatalysts was investigated by photodegradation of ciprofloxacin as a model pharmaceutical pollutant under simulated solar light illumination. The scavenging effect was studied by using tTriethanolamine and 2-propanol to evaluate the roles of holes and hydroxyl radicals as main active species. All the samples showed higher photocatalytic activity compared to pristine BiOCl and BiOBr. Among the solid solutions, BiOX (Cl:Br = 1:3)-U sample exhibited excellent photocatalytic performance by 100% degradation efficiency of ciprofloxacin within 120 min. The outstanding photocatalytic activity of BiOX (Cl:Br = 1:3)-U might be ascribed to the large specific surface area, suitable morphology and band gap, effective separation of the photo-generated electron-hole pairs and the existence of the meso-size pores in structure. Moreover, results demonstrated that the presence of ultrasound irradiations and generated microjets during the synthesis step could appreciably improve the photocatalytic performance. After 4 cycles, there was no significant change in photocatalytic activity that confirms the high stability of BiOX (Cl:Br = 1:3)-U mesoporous nanophotocatalyst. Besides, the influence of operating parameters on the degradation efficiency and the possible photocatalytic mechanism was examined.

Plasma-catalytic degradation of ciprofloxacin in aqueous solution over different MnO2 nanocrystals in a dielectric barrier discharge system

The α-MnO2, β-MnO2 and γ-MnO2 samples were prepared by the hydrothermal method and were used for the degradation of ciprofloxacin (CIP) wastewater in a combined DBD-catalytic process. The physical and chemical properties of the samples were systematically studied by several analytical techniques including BET, XRD, SEM, HRTEM, XPS, and H2-TPR. The combination of DBD with α-MnO2 showed the highest CIP degradation efficiency, and the efficiency could reach 93.1% after 50 min, which was 10.8% and 18.1% higher, respectively, than those of β-MnO2 and γ-MnO2 catalysts in the plasma-catalytic system. According to the model of response surface methodology, the contribution of key experimental parameters on the CIP degradation decreased in the order: peak voltage > air flow rate > initial concentration > initial pH. The optimum operating parameters were peak voltage 17 kV, air flow rate 2.5 L min−1, an initial concentration 5 mg L−1 and an initial pH 6.9. The quenching experiments of active species showed that OH and O2− were critical to the CIP degradation. The generated O3 might be adsorbed by the α-MnO2 catalyst and resulted in more OH generation. The intermediate products of CIP degradation in DBD+α-MnO2 system were analyzed by LC-MS, and three possible degradation pathways were proposed. This research provides an insight into the use of the crystallographic structures in discharge plasma system for antibiotics in water.

Degradation of ciprofloxacin by CuFe2O4/GO activated PMS process in aqueous solution: performance, mechanism and degradation pathway

ABSTRACT Catalytic degradation of ciprofloxacin (CIP) was studied by using copper ferrite (CuFe2O4) nanoparticles coated on graphene oxide (CuFe2O4/GO) as a heterogeneous activator of peroxymonosulfate (PMS). CIP degradation efficiency by CuFe2O4/GO/PMS system was evaluated by affecting factors such as, pH of aqueous media, reaction time, different concentrations of PMS, various CIP and catalyst concentrations, trapping agents and water matrix inorganic components. Kinetic models of the catalytic oxidation process were also investigated. Also, based on quenching tests, a pathway of PMS activation and reactive species production in both solid and liquid phases was proposed. Results showed that under the optimum conditions (pH = 7, 2 mM PMS and 0.2 g/L catalyst), 98% of CIP (30 mg/L) and 45% of total organic carbon (TOC) were removed within 60 min. Pseudo-first-order kinetic model was the best fit with the experimental data of degradation process. The inhibiting effects of water inorganic species on CIP degradation were as follows: HCO3 − >NO3 − > Cl− > SO4 2-. CuFe2O4/GO remains active even after five cycles of reuse for CIP degradation and leaching of Fe and Cu metals in the solution was negligible. Transformation products of CIP by CuFe2O4/GO/PMS were analysed by GC-MS. Transformation products of CIP by CuFe2O4/GO/PMS were identified using GC-MS, and degradation pathways have been proposed. Investigating the free radicals showed that SO4 •- radicals play an important role in the catalytic oxidative degradation process. CuFe2O4/GO in coupling with PMS can be utilised as an effective method to degrade/mineralise of antibiotics, due to the powerful catalytic activity, the generation of various free radicals, magnetically recyclable and the high stability and reusability potential.

Catalytic degradation of ciprofloxacin by magnetic CuS/Fe2O3/Mn2O3 nanocomposite activated peroxymonosulfate: Influence factors, degradation pathways and reaction mechanism

In the study, CuS/Fe2O3/Mn2O3 magnetic nanocomposite was successfully synthesized and the properties were investigated via a series of characterization. Subsequently, the magnetic nanocomposite was applied to activate peroxymonosulfate (PMS) for ciprofloxacin (CIP) degradation. The results showed that the CuS/Fe2O3/Mn2O3 magnetic nanocomposite possessed higher catalytic performance for ciprofloxacin degradation than bare CuS and Fe2O3/Mn2O3 composite. The degradation process of CIP was suitable for the pseudo-first-order kinetic model and the highest rate was reached 0.10083 min−1. And under the optimized conditions (catalyst = 0.6 g·L−1, PMS = 0.6 g·L−1, pH = 5.84, C0 = 0.2 g·L−1 and t = 120 min), the efficiency of 88% and 48.6% were corresponding to degradation and mineralization of ciprofloxacin, respectively. In addition, the key factors of degradation process such as catalyst dosage, PMS concentration, initial pH value and common anions were investigated. And the results indicated that the degradation efficiency of ciprofloxacin was reduced, which affected by the common anions in order of Cl− > SO42− > NO3− > HCO3− > Humic acid. Besides, several intermediates of ciprofloxacin were detected and the plausible degradation pathways were proposed. In addition, the underlying reaction mechanism was proposed. Meanwhile, the results of free radical quenching experiment and electron paramagnetic resonance (EPR) spectra indicated that both OH and SO4− radicals were existed in the reaction system and the OH radicals had a conquer role in the degradation progress. Moreover, the stability and reusability of CuS/Fe2O3/Mn2O3 magnetic nanocomposite were evaluated, which the degradation efficiency still reached 72% after five times used. Ultimately, the as-constructed CuS/Fe2O3/Mn2O3 magnetic nanocomposite might be a candidate to the removal of refractory pollutants in environmental remediation.

Highly efficient activation of peroxymonosulfate by cobalt sulfide hollow nanospheres for fast ciprofloxacin degradation

We reported a facile preparation of CoS2, Co3S4, and Co9S8 hollow nanospheres (HNSs) and their use as peroxymonosulfate (PMS) activators for ciprofloxacin (CIP) degradation. The CIP degradation efficiency follows the order of CoS2 > Co3S4 > Co9S8. The Co2+ is proved to be active site for PMS activation and reactive oxygen species generation. The effect of operating parameters on performance of CoS2 HNSs/PMS system was explored. CoS2 HNSs exhibited highly catalytic activity in a wide pH range of 3 – 10. Complete removal of 10 mg/L CIP was achieved by CoS2 HNSs in 3 min at initial pH of 8.0 with 62.6% CIP mineralization. Three other organic pollutants (rhodamine B, methylene blue and tetracycline) were also degraded to evaluate the universality of the CoS2 HNSs/PMS system. The catalytic performance dropped in the presence of chloride, phosphate, nitrate ions and humic acid. Above 97% CIP removal was achieved even in the sixth run. The degradation pathway of CIP was proposed based on HPLC–MS/MS analysis of CIP intermediates, and two new intermediates, namely, C15H18O4N3F (m/z 323) and C29H31O4N6F (m/z 546), were identified for the first time. Both OH and SO4− were generated and the latter played a key role in CIP degradation.