Ciprofloxacin Degradation Efficiency Research Articles

Effect of metal doping (Me = Zn, Cu, Co, Mn) on the performance of bismuth ferrite as peroxymonosulfate activator for ciprofloxacin removal

In this study, a facile hydrothermal method was employed to prepare Me-doped Bi2Fe4O9 (Me = Zn, Cu, Co, and Mn) as peroxymonosulfate (PMS) activator for ciprofloxacin (CIP) degradation. The characteristics of the Me-doped bismuth ferrites were investigated using various characterization instruments including SEM, TEM, FTIR and porosimeter indicating that the Me-doped Bi2Fe4O9 with nanosheet-like square orthorhombic structure was successfully obtained. The catalytic activity of various Me-doped Bi2Fe4O9 was compared and the results indicated that the Cu-doped Bi2Fe4O9 at 0.08 wt.% (denoted as BFCuO-0.08) possessed the greatest catalytic activity (kapp = 0.085 min−1) over other Me-doped Bi2Fe4O9 under the same condition. The synergistic interaction between Cu, Fe and oxygen vacancies are the key factors which enhanced the performance of Me-doped Bi2Fe4O9. The effects of catalyst loading, PMS dosage, and pH on CIP degradation were also investigated indicating that the performance increased with increasing catalyst loading, PMS dosage, and pH. Meanwhile, the dominant reactive oxygen species was identified using the chemical scavengers with SO4•ˉ, •OH, and 1O2 playing a major role in CIP degradation. The performance of BFCuO-0.08 deteriorated in real water matrix (tap water, river water and secondary effluent) due to the presence of various water matrix species. Nevertheless, the BFCuO-0.08 catalyst possessed remarkable stability and can be reused for at least four successive cycles with >70% of CIP degradation efficiency indicating that it is a promising catalyst for antibiotics removal.

Enhanced Visible-Light-Responsive Photocatalytic Degradation of Ciprofloxacin by the CuxO/Metal-Organic Framework Hybrid Nanocomposite.

Ciprofloxacin (CIP) is a commonly used antibiotic, however, once in the environment, it is highly toxic with a poor biodegradability. Given these attributes, an effective strategy for the removal of CIP is urgently needed for the protection of water resources. Herein, a novel copper metal-organic framework (CuxO/MOF) multifunctional material has been produced, in this work, by the calcination of Cu-MOF urea at 300 °C, in the presence of a 5% H2 atmosphere. The morphological, structural, and thermal properties of the prepared CuxO/MOF were determined through various techniques, and its photocatalytic behavior was investigated for the degradation of CIP under visible-light irradiation. The prepared CuxO/MOF bifunctional material is presented as a graphitic carbon-layered structure with a particle size of 9.2 ± 2.1 nm. The existence of CuO-Cu2O-C, which was found on the CuxO/MOF surface, enhanced the adsorption efficiency and increased the photosensitivity of CuxO/MOF, towards the degradation of CIP in aqueous solutions. The tailored CuxO/MOF, not only shows an excellent CIP degradation efficiency of up to 92% with a constant kinetic rate (kobs) of 0.048 min−1 under visible light, but it can also retain the stable photodegradation efficiency of >85%, for at least six cycles. In addition, CuxO/MOF has an excellent adsorption capacity at pH 6.0 of the maximum Langmuir adsorption capacity of 34.5 mg g−1 for CIP. The results obtained in this study demonstrate that CuxO/MOF is a reliable integrated material and serves as an adsorbent and photocatalyst, which can open a new pathway for the preparation of visible-light-responsive photocatalysts, for the removal of antibiotics and other emerging pollutants.

Intensification of non-thermal plasma for aqueous Ciprofloxacin degradation: Optimization study, mechanisms, and combined plasma with photocatalysis

As it is well known that wastewater treatment is becoming a global concern, the search for advanced intensive oxidation processes with minimal waste generation for wastewater treatment remains a major challenge. In the present work, the photodegradation of Ciprofloxacin (CIP) was studied using the Dielectric-Barrier-Discharge (DBD) process. The effect of some operating parameters such as CIP initial concentration (from 1 to 6 mg/L), air flow rate (from 0 to 240 L/h) and frequency (from 350 to 600 Hz) on DBD performance in term of CIP degradation efficiency (%D) has been investigated. Here, as a major result, the CIP degradation efficiency and the mineralization yield (%M) reached >99 % and >49 %, respectively, during 60 min, under the obtained optimum experimental conditions (an initial concentration of 1 mg/L, an air flow rate of 100 L/h, a voltage of 18 kV, and a frequency of 350 Hz). It can be concluded that the DBD process exhibits an eco-friendly and great potential for aqueous CIP degradation. Moreover, the mechanisms involved in the degradation process by DBD were explained. The scavengers study revealed that °OH, HO2°and O2−° radicals were the basic reactive oxygen species (ROS) in CIP degradation process. Results show that in addition to ROS, the reactive nitrogen species (RNS) also play a key role in the CIP removal process. In order to get closer to the real conditions, DBD experiments were also carried out in other water matrices, tap water (TW) and synthetic pharmaceutical water (SW). Significant inhibition of CIP degradation (%D) and mineralization (%M) was observed in TW (%D = 76, %M = 33) and SW (%D = 60, %M = 10) with reference to the CIP degradation and mineralization in ultra-pure water (UPW) (%D ≥99, %M = 54), after 90 min irradiation. It showed that the presence of organic and inorganic molecules in TW and SW lowered the CIP degradation efficiency. Thus, the combined plasma-photocatalysis system, using luminous textile as photocatalyst, was performed for the CIP degradation in SW, in order to get closer to the real conditions, leading to >99 of %D and 64 of %M. Moreover, the use of combined DBD plasma-photocatalysis process significantly enhanced the CIP degradation performance if compared to each process considered separately. Overall, the combination of DBD and photocatalysis may be a promising technology for economical, efficient and environmentally friendly removal of pollutants in wastewater.

Magnetic recyclable g-C3N4/Fe3O4@MIL-100(Fe) ternary catalyst for photo-Fenton degradation of ciprofloxacin

The slow Fe(III)/Fe(II) cycle rate seriously limits the photo-Fenton degradation efficiency. In this work, a novel g-C3N4/Fe3O4@MIL-100(Fe) ternary heterojunction catalyst was prepared via a facile in-situ route under a mild reaction condition, and was further used as a photo-Fenton catalyst for efficient degradation of ciprofloxacin via the synergistic effect. Compared with g-C3N4 and Fe3O4@MIL-100(Fe), the composite g-C3N4/Fe3O4@MIL-100(Fe) exhibited excellent photo-Fenton catalytic activity for high concentration ciprofloxacin (up to 200 mg L−1); approximately 94.7% of CIP was degraded within 120 min light irradiation. It is concluded that g-C3N4 can produce photo-generated electron transfer and further accelerate Fe(III)/Fe(II) cycle, leading to an improvement in the degradation efficiency of ciprofloxacin. In addition, the catalyst presents excellent reusability, whereas the removal efficiency of CIP attained 70.0% after three cycles. This study provided a means to enhance the photo-Fenton activity of Fe-MOFs-based catalysts.

Insights into the radical and nonradical oxidation degradation of ciprofloxacin in peroxodisulfate activation by ultraviolet light

Ultraviolet light (UV light) was broadly utilized as persulfate activation source in advanced oxidation process to degrade contaminants in water due to its simple operation and environmental protection. In this paper, the degradation of ciprofloxacin (CIP) was investigated with peroxodisulfate (PDS) as oxidant and UV light as PDS activation source (UV/PDS system). The influence of initial pH, PDS dosage, UV light power, different CIP concentrations and coexisting substances (inorganic anions and natural organic matter) on CIP degradation process were investigated. Under the specific reaction conditions ([pH]0 = 7, [PDS] = 15 mM, UV light power = 3 W, [CIP] = 10 mg L−1), the CIP degradation efficiency reached 94.00 % within 40 min. The quenching experiments demonstrated that 1O2, O2−∙, ∙OH and SO4−∙ were the main active species, especially O2−∙ was the most dominant active species. In addition, CIP degradation in other water qualities (tap water and landscape river water) was explored, metronidazole (MNZ) and tetracycline (TC) were applied as representative pollutants for effective degradation. The above results indicated that the UV/PDS system would be possible to effectively degrade other types of refractory pollutants and less affected by water quality.

Mechanochemical treatment for degradation of ciprofloxacin (CIP) in solutions.

Ciprofloxacin (CIP) is a kind of widely used fluoroquinolone antibiotic, and the widespread presence of CIP in aquatic environment has become a serious issue. Mechanochemical treatment (MCT), as an effective approach to degrade persistent organic pollutants, has many advantages of low cost, simplicity, and being environmentally innocuous. However, little attention has been paid to employing MCT to treat effluents containing CIP. In this study, MCT was introduced to degrade CIP in aquatic solutions. A series of CIP degradation experiments were conducted by a planetary ball mill, and the influences of main parameters on CIP degradation efficiency were investigated. Furthermore, an optimum combination was selected through orthogonal experiments, and CIP degradation efficiency could reach as high as 99% in certain conditions. Besides, the biotoxicity of CIP solution was also studied. MCT exhibits satisfying performance for degrading CIP in solutions, which makes MCT a promising approach to CIP elimination and also encourages further applications in treating effluents containing other organic pollutants.

Sonophotocatalytic degradation of ciprofloxacin by Bi2MoO6/FeVO4 heterojunction: Insights into performance, mechanism and pathway

In this study, Bi2MoO6/FeVO4 core–shell heterojunction was adopted as sonophotocatalyst to investigate its sonophotocatalytic degradation of ciprofloxacin (CIP) under ultrasonic and visible light. The properties of Bi2MoO6/FeVO4 sonophotocatalyst were analyzed by XRD, FTIR, SEM, TEM, BET, DRS, XPS, PL and EIS. The effects of different operating parameters on the sonophotocatalytic degradation performance of CIP were investigated. Under the optimal operating conditions, a CIP degradation efficiency of 98.2 % and a mineralization rate of 68.9 % could be achieved after 60 min of reaction. Kinetic studies showed that the degradation process obeyed a pseudo-first-order reaction with a rate constant of ksonophotocatalytic > kphotocatalytic > ksonocatalytic. Before and after the addition of H2O2, the sonophotocatalytic degradation of CIP reached high synergy values of 2.02 and 2.50, respectively. The synergistic effect of degradation can be attributed to the generation of OH, O2− and h+ in the system. Contribution rate calculation displayed that OH and h+ were the most significant reactive oxygen species. In addition, twenty degradation products were identified by HPLC-MS analysis, and the toxicity of the degradation products was further analyzed by ECOSAR. Ultimately, three potential degradation pathways for CIP were proposed.

Z-scheme heterojunction composed of Fe doped g-C3N4 and MoS2 for efficient ciprofloxacin removal in a photo-assisted peroxymonosulfate system

Herein, a series of Z-type heterojunctions FexCN@MoS2-Y were synthesized by a combination of calcination and hydrothermal methods for the removal of ciprofloxacin (CIP) by peroxymonosulfate (PMS) activation under visible light. It was optimized that Fe3CN@MoS2-4 exhibited excellent photocatalytic performance, with the degradation rate of CIP 84 % within 140 min. Besides, its rate constants were 23.74, 3.59, and 3.98 times higher than those of pure g-C3N4, Fe3CN, and MoS2, respectively. Furthermore, the Fe3CN@MoS2-4/PMS/vis system could efficiently degrade other antibiotics (enrofloxacin (ENRO), metronidazole (MNZ) and tetracycline (TC)). The quenching experiments and electron paramagnetic resonance (EPR) characterization showed that reactive substances such as 1O2, h+ and Ovs played a dominant role in this system. We deeply explore the possible mechanisms and CIP degradation pathways for the enhanced CIP degradation efficiency in the Fe3CN@MoS2-4/PMS/vis system. Among them, the exposed Mo (IV) and Fe (II) sites on the catalyst surface accelerated the electron transfer, while the S2- therein promoted the cycling between ions, thus increasing the reaction rate. Finally, Fe3CN@MoS2-4 maintained appreciable performance even after 5 cycles. This study may provide a new approach for the development of metal-doped g-C3N4-based complexes.

Sonocatalytic degradation of ciprofloxacin and organic pollutant by 1T/2H phase MoS2 in Polyvinylidene fluoride nanocomposite membrane

The development of recyclable catalysts with effective properties and stable reusability is great importance for the removal of different types of pollutants in wastewater. Herein, we have synthesized Polyvinylidene fluoride (PVDF) polymer and mixed-phase 1T/2H MoS2 for immobilizing the sonocatalyst material. Techniques such as FESEM, XRD, FTIR, XPS, and UV–vis spectra have been used for analyzing the structural, and morphological properties. The formation of a 1T/2H mixed phase in MoS2 has been revealed by XRD and XPS analysis. Consequently, the sonocatalytic performance of the nanocomposite membrane was investigated through ciprofloxacin (CIP) and organic pollutants (Rhodamine B (RhB)). As a result, MoS2/PVDF (PM4) nanocomposite membrane exhibited a superior sonocatalytic activity with 94.37% and 84.37% of RhB and CIP degradation efficiency with pseudo-first-order kinetic constant (k) of 0.0187 min−1, and 0.0044 min−1. The sonocatalytic property of the nanocomposite membrane is related to 1T/2H mixed-phase and PVDF. Additionally, the metallic based 1T phase MoS2 helps to promote electrons and holes and reduce the recombination rate. Moreover, it promotes the generation of more hydroxy radicals (.OH), and superoxide radicals (∙O2−) play a significant role in sonocatalytic degradation of RhB pollutants. Thus, the improved sonocatalytic degradation of 1T/2H MoS2/PVDF composite membrane exhibited its application in real-time wastewater treatment.

Degradation of ciprofloxacin in aqueous solution using ozone microbubbles: spectroscopic, kinetics, and antibacterial analysis

Ciprofloxacin (CIP) has been listed in the last version of the surface water due to its ability to kill human cells by inhibiting the activity of DNA topoisomerase IV. Thus, CIP, along with other antibiotic pollution has become a serious threat to the environment and public health. Ozonation has been used as an advanced technique that is applied in wastewater treatment to remove CIP, but the primary limitation of this method is the low solubility of ozone in water. This study is the first report of CIP removal in a scale-up of its aqueous solution using a self-developed aerator pump-enhanced ozonation (APO) system, which only employs a propeller and a zigzag arrangement of meshes. This aerator pump decreased the size of ozone bubbles by 90% and increased the effective ozone solubility to 0.47 ppm. The mechanism of degradation of CIP is attributed to an oxidation reaction of the antibiotic with reactive oxygen species, such as hydroxyl, oxygen, and hydroperoxyl radicals, generated on the surface of the ozone microbubbles. It was found that the rate and efficiency of degradation of CIP using the APO system were 3.64 × 10−3/min and 83.5%, respectively, which is higher compared with those of conventional flow ozonation (FO) systems (1.47 × 10−3/min and 60.9%). The higher degradation efficiency of CIP by the APO system was also revealed by its higher electrical energy efficiency (0.146 g/kWh), compared to that of the FO system (0.106 g/kWh). The degradation of CIP was also monitored by the resulting antibacterial activity against Escherichia coli and Staphylococcus aureus.

Photo-Fenton Degradation of Ciprofloxacin by Novel Graphene Quantum Dots/α-FeOOH Nanocomposites for the Production of Safe Drinking Water from Surface Water

In the current work, novel graphene quantum dots (GQDs)-doped goethite (α-FeOOH) nanocomposites (GQDs/α-FeOOH) were prepared by following a feasible hydrolysis method and applied for ciprofloxacin (CIP) removal. Results showed that the CIP degradation efficiency was significant (93.73%, 0.0566 min−1) in the GQDs/α-FeOOH + H2O2 + Vis system using much lower amounts of H2O2 (0.50 mM), which is 3.9 times the α-FeOOH + H2O2 + Vis system. It was found that •OH, O2•−, and 1O2 were mainly responsible for CIP degradation in the GQDs/α-FeOOH photo-Fenton system. GQDs/α-FeOOH demonstrated broad-spectrum UV–vis-IR responsiveness in the degradation of ciprofloxacin as a function of the doping of GQDs. Additionally, GQDs/α-FeOOH showed outstanding durability (recyclability up to 3 cycles with a lower iron leaking amount, 0.020 mg L−1), a broad range of application pH, and a pretty acceptable catalytic efficacy in a variety of surface water matrices. Overall, GQDs/α-FeOOH have been shown to be an effective photocatalyst for the remediation of emerging contaminants via the workable exploitation of solar energy.

Hydrogel 3D network derived and in-situ magnetized Fe@C for activation of peroxymonosulfate to degrade ciprofloxacin

Hydrogels possess 3D network with abundant reactive groups, and can bind with active metal ions within their confined 3D structure for fabricating functional materials. In this study, a chitosan grafted polyacrylic acid (CTS-g-PAA) hydrogel was prepared for loading Fe2+, which was then converted into magnetic Fe@C via subsequent pyrolysis process. In Fe@C activated peroxymonosulfate (PMS) (Fe@C/PMS) system, the degradation behaviors of ciprofloxacin (CIP) were systematically investigated, including influencing parameters, reactive oxygen species (ROSs), degradation mechanism and potential eco-toxicity of degradation intermediates. The results showed that CTS-g-PAA supported, in-situ derived magnetic Fe@C had not only stable catalytic ability at pH 3.0–9.0, but also high degradation efficiency in the presence of inorganic Cl− and HCO3− (5–20 mM) as well as organic humid acid (10 and 20 mg/L). Under the optimized conditions, the degradation efficiency of CIP could reach to 96.84 % within 1 h. In Fe@C/PMS system, the main ROSs involved free radicals SO4•−, •OH, O2•− and non-free radical 1O2. Through free radical quantitative experiments, the concentration of SO4•− and •OH at 60 min was determined respectively to be 11.84 µM and 0.14 µM, proving the dominant role of SO4•−. By HPLC-MS analysis, the degradation products were proposed via four degradation pathways, including hydroxylation, defluorination and decarboxylation, as well as the ring opening of quinolone and piperazine. Finally, the potential eco-toxicity of CIP and its degradation intermediates was evaluated by using ECOSAR method based on quantitative structure–activity relationships analysis.

Synergistic enhancement of piezocatalysis and electrochemical oxidation for the degradation of ciprofloxacin by PbO2 intercalation material

In this study, the TiO2 nanotube array intercalated PbO2 (Ti/TiO2-NTA/PbO2-La) material was applied in the piezo-electro-catalytic removal of ciprofloxacin (CIP). The degradation rate of CIP reached up to 91.4% after the mechanical ultrasonic vibration of the Ti/TiO2-NTA/PbO2-La material for 20 min with applied current density of 0.04 mA cm−2. The degradation rate constant (kCIP) of CIP by piezo-electro-catalysis was 8.6 and 17.2 times that of the electrochemical oxidation and piezocatalysis. The degradation of CIP exhibited a rapid nearly-linear increase with increasing applied ultrasonic power (<13.6 W) at a current density of 0.04 mA cm−2 or the current density (<0.11 mA cm−2) at an ultrasonic power of 15.0 W. The enhancement mechanism of the synergistic process was due to that the dynamic piezoelectric field and the applied bias facilitate the carriers transport and accelerate the electric charges carrier separation, hence favouring the generation of homogeneous reactive species. Based on quenching experiments and electron spin resonance (ESR) results, holes (h+) and hydroxyl radical (OH) were found to be the predominant reactive species in CIP removal in the piezo-electro-catalytic process. h+ may be involved in the rate-limiting degradation steps. With the identification of the intermediate byproducts and the theoretical calculations of the frontier electron densities, three possible degradation pathways were proposed in the cleavage of the piperazine and quinolone rings, and substitution of –COOH by –OH group. The findings of this study suggest that the synergistic process of piezocatalysis and electrochemical oxidation is an effective way to promote degradation efficiency of CIP at a ultralow current density and ultrasonic power.

Efficient photocatalytic degradation of emerging ciprofloxacin under visible light irradiation using BiOBr/carbon quantum dot/saponite composite

The use of visible-driven photocatalysts has fascinated attention as a capable and sustainable approach for wastewater remediation. In this work, BiOBr/carbon quantum dot (CQDs)/saponite composites (CQDs/Clay@BiOBr) were fabricated via hydrothermally using two different CQDs/Clay precursors (in-situ synthesis (IS) and physical mixing (PM)). The obtained products were characterized, and the photocatalytic performances of the prepared samples were evaluated in the photocatalytic decomposition of emerging ciprofloxacin (CIP) pharmaceutical waste. The highest CIP mineralization performance was achieved when a combination of BiOBr and CQDs/Clay (IS) with the appropriate proportion because the strong adhesion between CQDs and clay generate a great heterojunction in the composite. The stronger interaction of CQDs and better distribution of CQDs on the surface of clay in the CQDs/Clay (IS) enhanced the interaction of BiOBr and CQDs, and avoided the re-agglomeration of excess of CQDs on surface of BiOBr which reduce the active surface to receive the light and react with CIP. The ultrafast degradation rate of the optimized CQDs/Clay@BiOBr composite was better compared to others. The significant improvement in the CIP degradation efficiency of the CQDs/Clay@BiOBr composite was attributed to the excellent separation and transportation of photogenerated electrons and holes, as confirmed by photoluminescence, photocurrent density, and electrochemical impedance spectroscopy results. Moreover, the photocatalytic degradation mechanism of CIP in the CQDs/Clay@BiOBr composite was proposed based on the electronic states of each material in the composite and on a scavenger test. Thus, the proposed CQDs/Clay@BiOBr composite can be employed as a potential visible-light-driven photocatalyst for the decomposition of organic contaminants in wastewater.

Three-dimensional electro-Fenton degradation of ciprofloxacin catalyzed by CuO doped red mud particle electrodes: Influencing factors, possible degradation pathways and energy consumption

In this work, CuO doped red mud (CuO/URM) as particle electrode was applied in three-dimensional electro-Fenton (3D/EF) system for ciprofloxacin (CIP) degradation. The operating conditions of CuO/URM dosage, initial pH, applied voltage and aeration intensity were investigated in detail. The optimum degradation efficiency of CIP about 80.66% were achieved after 80 min treatment with CuO/URM dosage of 4 g/3 L, initial pH of 7, applied voltage of 10 V and aeration intensity of 5 L/min. Moreover, the effect of inorganic anions on the degradation of CIP was investigated, and it was found that Cl- promoted the degradation of CIP, while the NO3-, HCO3-, and H2PO4- had an inhibitory effect on CIP degradation. Based on the analysis of UV-Visible spectrophotometer (UV–vis) and liquid chromatograph-mass spectrometer (LC-MS), the degradation intermediates and degradation pathway of CIP in the 3D/EF system catalyzed by CuO/URM particle electrodes were proposed. Compared with the two-dimensional electrochemical (2D/E) system, 3D/EF system had more excellent removal capability of CIP and higher power energy utilization efficiency. The CuO/URM electrodes before and after use were characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR). It was proved that CuO/URM exhibited excellent stability. All results demonstrated that the 3D/EF system catalyzed by CuO/URM particle electrodes is a reliable technology for the disposal of CIP wastewater.

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.