Ciprofloxacin Removal Research Articles

Optimizing the efficient removal of ciprofloxacin from aqueous solutions by polyethylene terephthalate microplastics using multivariate statistical approach

Emerging pollutants such as ciprofloxacin (CIP) and microplastics (MPs) has been found in environment, as a result of their widespread usage. In this study, the use of different polyethylene terephthalate microplastics (PET MPs) such as pristine (Pr-PET), acid modified (Mod-PET) and thermal-oxidatively aged (Ag-PET) were optimized for their removal efficiencies for CIP (5 to 50 mg/L) from aqueous solution using Response Surface Methodology with Central Composite Design (4 factors − 2 levels) and Machine Learning (ML) algorithm such as Artificial Neural Networks (ANN), Decision Tree (DT), Random Forest (RF), and Support Vector Machine (SVM). Through the use of the desirability function, the optimal conditionswere determined and amaximum removal efficiency of93.95%, 94.36%, and 96.29% for Pr-PET, Mod-PET, and Ag-PET MPs, respectively. The Dumwald-Wagner intraparticle model and the Dual-Exponential Model (DEM) were used to describe the adsorption process. The Dumwald-Wagner modelwas able to describe the adsorption process before equilibrium was reached at 12 hrs. The DEM model divided the adsorption process into two stages, a rapid, initial stage and a slower, secondary stage.These results suggest that the use of PET MPs for removing CIP through adsorption is a viable option and can be implemented in treatment systems.

Mutual enhancement of metal coagulant and peroxymonosulfate for ciprofloxacin removing and the multiple-mode mechanisms

Metal coagulants, which are widely employed in water and wastewater treatments, have been recently found to have catalyzation effect on oxidation, while chemical oxidation, in turn, could possibly impose impacts on coagulation process. In this study, a hybrid coagulation/oxidation process was developed using four metal-based coagulants, i.e., aluminum sulfate (Al2(SO4)3), ferric chloride (FeCl3), titanic sulfate (Ti(SO4)2), zirconium oxychloride (ZrOCl2) and peroxymonosulfate (PMS) as the oxidant, for removing ciprofloxacin (CIP), which is a representative emerging organic contaminant (EOC) with small molecular weight (MW). The results showed PMS (0.2 mM) improved the CIP removals by Al2(SO4)3 and FeCl3 from 13% and 21% respectively to around 92% at the coagulant dose of 0.02 mM, and for Ti(SO4)2 and ZrOCl2, the CIP removal was increased from about 21% to 70∼75%, which was also more efficient than separate PMS oxidation (around 42%). The results of zeta potential, dynamic floc growth and residual coagulants demonstrated PMS led to the destabilization of coagulation suspensions, where lag time for floc formation was largely shortened and also, residual metal coagulants in terms of dissolved and colloids/particles were decreased. PMS alleviated the negative effect of crystallization on colloids and clots aggregation via reducing the quantity and crystallinity of nanocrystal according to the high-resolution transmission electron microscopy (HR-TEM) analysis, which facilitated the flocculation. The results of radicals scavenging experiments verified metal coagulants could activate PMS in turn, where •OH played a dominant role in CIP degradation. While, the four kinds of coagulants behaved significantly different when combined with PMS. Due to the different hydrolysis and polymerization properties, coupling PMS with aluminum/iron salt were more efficient than with titanium/zirconium. Nevertheless, the synthetic effect was suppressed as the coagulant dose increased to 0.1 mM and above, where restabilization occurred. Therefore, coagulation played a major role in coagulant/PMS process, which could provide a promising technology for CIP removals.

Efficient photocatalytic degradation of ciprofloxacin by graphite felt-supported MnS/Polypyrrole composite: Dominant reactive species and reaction mechanisms

The accumulation of antibiotics in aquatic environments poses a serious threat to human health. Photocatalytic degradation is a promising method for removing antibiotics from water, but its practical implementation requires improvements in photocatalyst activity and recovery. Here, a novel graphite felt-supported MnS/Polypyrrole composite (MnS/PPy/GF) was constructed to achieve effective adsorption of antibiotics, stable loading of photocatalyst, and rapid separation of spatial charge. Systematic characterization of composition, structure and photoelectric properties indicated the efficient light absorption, charge separation and migration of the MnS/PPy/GF, which achieved 86.2% removal of antibiotic ciprofloxacin (CFX), higher than that of MnS/GF (73.7%) and PPy/GF (34.8%). The charge transfer-generated 1O2, energy transfer-generated 1O2, and photogenerated h+ were identified as the dominant reactive species, which mainly attacked the piperazine ring in the photodegradation of CFX by MnS/PPy/GF. The •OH was confirmed to participate in the defluorination of CFX via hydroxylation substitution. The MnS/PPy/GF-based photocatalytic process could ultimately achieve the mineralization of CFX. The facile recyclability, robust stability, and excellent adaptability to actual aquatic environments further confirmed MnS/PPy/GF is a promising eco-friendly photocatalyst for antibiotic pollution control.

A novel chitosan-coated Fe–Cu CNS loaded with CMC–Alginate composite for adsorptive removal of ciprofloxacin from water

Indiscriminate usage of antibiotic, Ciprofloxacin (CIPRO) poses a serious environmental threat by accumulating in the water bodies. A novel clay-nanosheet supported with Fe-Cu nanocomposite was developed for CIPRO removal using an eco-friendly approach. This composite was immobilised in a biodegradable chitosan-coated Alginate-CMC matrix to form nanocomposite beads for ease of usage in the column reactors. About 90% CIPRO removal was attained through batch mode under optimal conditions (20 mg/L CIPRO; bead loading 2000 mg/L; bead weight 0.15 g; contact period 300 min; and pH - 6). Effect of various environmental factors such as salts NaCl and CaCl2 (0.05, 0.1, 0.2, 0.5 and 1 M), and micro contaminants humic acid and polyethylene (1, 2, 3, 4 and 5 M) on CIPRO adsorption by NC beads was studied. Pseudo-second order kinetics was observed by the removal process and Langmuir isotherm by the adsorption with a maximum removal capacity of 485.58 mg/g. The effects of various reaction parameters such as the flow rate (1, 2 and 3 mL/min), initial CIPRO concentration (20, 40 and 60 mg/L) and bed height (3, 5 and 7 cm) were studied in the column reactors. The residual toxicity of composite beads interacted CIPRO solution was analysed with environmentally relevant algae such as Chlorella sp. and Scenedesmus obliquus, and the studies confirmed significant reduction in their toxic effects.

Accelerated electron transfer process via MOF-derived FeCo/C for enhanced degradation of antibiotic contaminants towards heterogeneous electro-Fenton system

The Fe(III) to Fe(II) process limits the rate of the electro-Fenton system. In this study, MIL-101(Fe) derived porous carbon skeleton-coated FeCo bimetallic catalyst Fe4/Co@PC-700 was prepared as a heterogeneous electro-Fenton (EF) catalytic process. The experimental results showed its good performance in catalytic removal of antibiotic contaminants, the rate constant of tetracycline (TC) degradation catalyzed by Fe4/Co@PC-700 was 8.93 times higher than that of Fe@PC-700 under the pH conditions of raw water (pH = 5.86), exhibited good removal of TC, oxytetracycline (OTC), hygromycin (CTC), chloramphenicol (CAP) and ciprofloxacin (CIP). It was shown that the introduction of Co promoted more Fe0 production, allowing the material to exhibit faster Fe(III)/Fe(II) cycling rates. 1O2 and high-priced metal oxygen species were identified as the main active species of the system, in addition to the analysis of possible degradation pathways and toxicity of intermediates of TC. Finally, the stability and adaptability of Fe4/Co@PC-700 and EF systems to different water matrices were evaluated, showing that Fe4/Co@PC-700 was easy to recover and could be applied to different water matrices. This study provides a reference for the design and system application of heterogeneous EF catalysts.

Synergistic Removal of Ciprofloxacin and Sulfamethoxazole by Lemna minor and Salvinia molesta in Mixed Culture: Implications for Phytoremediation of Antibiotic-Contaminated Water

Aquatic macrophytes have been used for the removal of antibiotics from contaminated water. Here, we have studied the capacity of Lemna minor and Salvinia molesta to reclaim ciprofloxacin (1.5 µg Cipro L−1) and/or sulfamethoxazole (0.3 µg Sulfa L−1) from artificially contaminated waters when plants were exposed in monoculture (L. minor or S. molesta) or in mixed culture (L. minor + S. molesta). Neither Cipro nor Sulfa alone induced negative effects on plants. As shown by the Abbot modelling, Cipro and Sulfa displayed antagonistic effects on plants. In both species, increased H2O2 concentrations and antioxidant enzyme activities were observed in plants when grown together. Although the antibiotics showed natural degradation, their concentration in water from treatments with plants was significantly lower, indicating the ability of the plants to uptake the compounds. When in co-culture, greater growth rates were observed for both plant species, which resulted in greater Cipro and Sulfa removal in the mixed system when compared with those with plants in monoculture. Both plants showed tolerance to the studied concentrations of antibiotics, with greater antibiotic uptake being reported for S. molesta. Although at the tested concentrations the antibiotics did not induce negative effects on plants, exposure to Cipro changed the relative yield of S. molesta, which may result in effects on community structure. The use of both L. minor and S. molesta in artificial wetlands may increase the phytoremediation capacity of systems.

Integrated adsorption and photocatalytic degradation based removal of ciprofloxacin and sulfamethoxazole antibiotics using Fc@rGO-ZnO nanocomposite in aqueous systems

Ferrocene functionalized rGO-ZnO nanocomposite was synthesized via the facile hydrothermal method. ZnO was reduced over the 3-dimensional rGO framework (3D-Fc@rGO) using Camellia sinensis extract. The Fc@rGO-ZnO nanocomposite was employed for pharmaceutical degradation (sulfamethoxazole (SMX) and ciprofloxacin (CIP)) in an aqueous solution under UV C light. The physicochemical properties of the as-prepared photocatalyst were characterized using FTIR, XRD, FESEM, EDS mapping, HR-TEM, XPS, and DR-UV Vis. The as-synthesized Fc@rGO-ZnO photocatalyst performed remarkably against pristine ZnO, with a fivefold increase in removal efficiency. This superior activity was attributed to its improved light harvesting, charge carrier interface, and enhanced charge separation. Additionally, the photocatalyst obeyed the Lagergen model for pseudo-first-order kinetics. Congruously, the integrated approach of Fc@rGO and ZnO as oxidizing agents was proficient in removing >95% of antibiotics (CIP and SMX) within 180 min. Furthermore, the heterostructure configuration developed between Fc@rGO and ZnO helps in charge migration and generation of abundant •OH and •O2− radicals for photodegradation activities. The toxicity assessment of the treated solutions showed improved cell viability in the algal strains of Scenedesmus and Chlorella sp. Moreover, this novel approach for the synthesis of a photoactive nanocomposite is found to be low-cost and reusable for three cycles. The nanocomposite is environmentally sustainable paving the way for practical applications in the treatment of different classes of antibiotics.

Evaluation of least square support vector machine, generalized regression neural network and response surface methodology in modeling the removal of Levofloxacin and Ciprofloxacin from aqueous solutions using ionic liquid @Graphene oxide@ ionic liquid NC

This study focused on the preparation, characterization of a supported dicationic ionic liquid nanocomposite (IL@GO@IL NC) and employing of it in the adsorption of Levofloxacin (LVX) and Ciprofloxacin (CPF) antibiotic. Also, the nonlinear least square support vector machine (N-LSSVM), generalized regression neural network (GRNN), along with response surface methodology used for modeling the removal of both antibiotics (i.e. LVX and CPF) from aqueous solution. In this work, the experiments designed based on critical parameters such as adsorbent dose, antibiotic concentration, sonication time and temperature. The nonlinear adsorption isotherms and kinetics models as well as thermodynamic used for fitting the experimental data. The statistical results demonstrated that the LSSVM and GRNN model efficiently predicted the antibiotics removal percentage with very high accuracy, respectively. Furthermore, for an optimal adsorption of LVX and CPF by IL@GO@IL NC, the adsorbent dose, antibiotic concentration, temperature and sonication time should be set to 0.23 and 0.35 g, 95.20 and 100.00 mg L-1, 2.10 and 4.60 min, and 45.00 ℃, for LVX and CPF, respectively. Under these optimal conditions, the removal percentages and adsorption capacity of LVX and CPF will be 98.20 and 97.50%, as well as 730 and 630 mg g−1, respectively. Besides, the IL@GO@IL NC efficiency under optimal conditions drops up by 15% after seven cycles for both antibiotics. Therefore, the IL@GO@IL NC may be considered as a promising option in removing fluoroquinolones antibiotics from water.

High-performance functional cellulose foam fabricated with theoretically optimized imidazolium salts for the efficient removal of ciprofloxacin

With the increasing requirements for sustainable development and environmental protection, the design and development of bio-adsorbent based on the widely sourced cellulose have attracted widespread attention. In this study, a polymeric imidazolium satls (PIMS) functionalized cellulose foam (CF@PIMS) was conveniently fabricated. It was then employed to efficiently remove ciprofloxacin (CIP). Three imidazolium salts containing phenyl groups that can lead to multiple interactions with CIP were elaborately designed and then screened through a combination of molecular simulation and removal experiments to acquire the most significant binding ability of CF@PIMS. Besides, the CF@PIMS retained the well-defined 3D network structure as well as high porosity (90.3 %) and total intrusion volume (6.05 mL g−1) as the original cellulose foam (CF). Therefore, the adsorption capacity of CF@PIMS reached an astonishing value of 736.9 mg g−1, nearly 10 times that of the CF. Furthermore, the pH-affected and ionic strength-affected adsorption experiments confirmed that the non-electrostatic interaction took on a critical significance in the adsorption. The reusability experiments showed that the recovery efficiency of CF@PIMS was higher than 75 % after 10 adsorption cycles. Thus, a high-potential method was proposed in terms of the design and preparation of functionalized bio-adsorbent to remove waste matters from samples of the environment.

In-situ growth of C-F@CCS@ZIF8/67–1/1 photocatalysts with internal electric field and interfacial enhancement on cobalt-copper foam surface for simultaneous removal of ciprofloxacin and Cr(VI)

ZIF8/67–1/1 and CuCo2S4 were grown on the surface of cobalt-copper foam by in-situ growth method, and p-n heterostructures were formed by induction of internal electric field. The DFT calculation reveals that the energy levels near the Fermi level are gradually distributed continuously after ZIF8/67–1/1 and CuCo2S4 recombination, which accelerates electron conduction. Furthermore, the electron orbitals in the composite structure are reallocated and the electrical conductivity of the interface is improved. This strong interfacial enhancement promotes the transfer of photoexcited electrons and promotes the photoinduced separation of electron-hole pairs. Thanks to the surface oxygen vacancy and unique structure, C-F@CCS@ZIF8/67–1/1 composites can simultaneously achieve 97.2% ciprofloxacin (CIP) degradation and 96.5% Cr(VI) reduction. This catalyst does not require any recycling process and remains structurally stable during use with only a minimal amount of metal leaching. This work also reveals the mechanism of heterojunction formation between metal-organic frameworks and sulfides, broadening their application potential.

A novel cellulose/lignin/montmorillonite ternary hybrid aerogel for efficiently adsorptive removal of antibiotics from water

A novel fully environmental-friendly organic–inorganic ternary hybrid aerogel (LN/MMT@cellulose), composed of lignin (LN), montmorillonite (MMT), and cellulose, was designed and simply fabricated. LN/MMT@cellulose was employed for the adsorptive removal of typical antibiotic ciprofloxacin (CIP) in water. The combined MMT and LN reinforce the mechanical properties of the cellulose aerogel and notably enhance the selective adsorption capacity toward CIP in the presence of various inorganic and organic matters. LN/MMT@cellulose still presents good adsorption ability toward CIP even at the CIP concentration as low as 0.002 mmol/L in various actual water sources. With the combination of the adsorption kinetics, isotherms, and thermodynamic study as well as the various spectroscopic characterizations before and after adsorption, the mechanisms of LN/MMT@cellulose in CIP adsorption were investigated in detail. Various interactions were involved in CIP adsorption by this composite aerogel under different pH levels, causing the evident pH dependence of its adsorption capacity, specifically, the cation exchange and electrostatic attractions associated with the chelation, π-π electron donor–acceptor interaction, and the ordinary hydrogen bondings were dominant at pH < 6.0, but the complexation and negatively charged assisted hydrogen bondings played the key roles under neutral and alkaline conditions. LN/MMT@cellulose had a slight loss in adsorption ability toward CIP and sustained physicochemical structural stabilities, even after seven adsorption–deadsorption cycles. In addition to CIP, LN/MMT@cellulose could be efficiently used for the adsorptive removal of two other popular antibiotics, namely, tetracycline, and trimethoprim. The said vital characteristics of LN/MMT@cellulose confirmed it is a promising material for the adsorptive removal of antibiotics in practical water treatment.

Tween 80 assisted washing ciprofloxacin-contaminated soil, and recycled it using active chlorines

Active chlorines (ACs) can selectively oxidize contaminants with benzene rings to recycle surfactants, which greatly facilitates the resource cycle. This paper firstly utilized Tween 80 to assist in ex-situ washing the ciprofloxacin (CI) contaminated soil, including the solubilization experiment, shake washing and soil column washing, all of which showed that 2 g/L of Tween 80 (TW 80) was the most effective in removing CI. Then electrochemically treated the collected soil washing effluent (SWE) at 10 V with an electrolyte of 20 mM NaCl + 10 mM Na2SO4; Pre-experiments screened the range of electrode spacing, pH and temperature, based on which an orthogonal design Table L9 (34) was designed. Visual analysis and ANOVA were performed on the ciprofloxacin removal efficiency and Tween 80 retention efficiency during the orthogonal experiments in 9 groups, and the results showed that CI was usually degraded within 30 min, and 50% of TW 80 was still present at the end of the experiment, and there was no significant effect of all three factors. LC-MS demonstrated that CI was mainly degraded synergistically by ·OH and ACs, and ·OH effectively reduced the biotoxicity of the SWE, so the mixed electrolyte may be more suitable for the electrochemical recycling system of ACs. This paper conducted the washing remediation study of CI-contaminated soil for the first time, and applied the theory of selective oxidation by ACs on benzene ring to treat the SWE, which provides a new treatment idea for antibiotic-contaminated soil.

Graphene quantum dots (GQDs) decorated zeolitic imidazole framework-67 (ZIF67) electrode for the in-situ oxidation of ciprofloxacin in water

Ciprofloxacin (CIP) is a biorecalcitrant pharmaceutical compound that is frequently found in wastewater and aquatic environment and has a wide range of detrimental effects on living organisms. In this study, graphene quantum dots doped zeolitic imidazole framework-67 ([email protected]) electrodes were prepared for the direct electrochemical degradation of CIP in NaCl supporting electrolyte. The presence of GQDs improved oxidation peak current at a lower applied potential, which enhanced the direct oxidation capacity and applicability of [email protected] electrode for CIP degradation. Under optimal conditions ([NaCl] = 0.1 M, applied potential of 1.0 V (∼0.5 A m−2), pH = 7, and temperature = 25 °C), the CIP removal and mineralization efficiency was greater than 90 and 70%, respectively, after five consecutive cycles. The [email protected] electrocatalytic system was effective over a broad range of initial pH. Scavenger test and EPR measurement showed that the RCSs, i.e., ClO• and Cl2•− were being generated in the [email protected] electrochemical system and played the main role in CIP oxidation. The intermediates of degradation were studied, and a plausible mechanism was proposed. This research developed an innovative electrocatalytic approach for treating antibiotic-contaminated water.

Removal of ciprofloxacin from aqueous media by Chlorella pyrenoidosa, Scenedesmus obliquus, and isolated Stichococcus bacillaris: A comparative study on toxicity, removal mechanism and biochemical composition

This study investigates the acute toxicity and removal capacity of the native isolated species Stichococcus bacillaris towards Ciprofloxacin (CIP) and compared its efficiency with the most explored algal species Chlorella pyrenoidosa and Scenedesmus obliquus in antibiotic removal. The toxicity assessment revealed that 24 hr EC50 values are in the order of Stichococcus bacillaris (64 mg/L) > Chlorella pyrenoidosa (52 mg/L) > Scenedesmus obliquus (42 mg/L) and 24 hr LC50 values are in the order of Stichococcus bacillaris (313 mg/L) > Chlorella pyrenoidosa (228 mg/L) > Scenedesmus obliquus (197 mg/L). Furthermore, CIP (5 mg/L) was spiked into the algal medium to study their removal potential for 7 days. Stichococcus bacillaris and Scenedesmus obliquus reported higher removal efficiency (40%) compared to Chlorella pyrenoidosa (28%) with biodegradation as the major contributing removal mechanism in all the species with the order of Stichococcus bacillaris (84%) > Scenedesmus obliquus (80%) > Chlorella pyrenoidosa (59%). Biochemical characterization revealed that Scenedesmus obliquus is a suitable candidate for biodiesel production as the lipid production (830 mg/L) is higher in this species and Stichococcus bacillaris is suitable for bioethanol production as the carbohydrates production (609 mg/L) is substantial in this species.

Sunlight-driven photocatalytic degradation of ciprofloxacin and organic dyes by biosynthesized rGO–ZrO2 nanocomposites

Aquatic ecology has been greatly threatened by the discharge of effluents of textile and antibiotic industries into natural waters. Herein, an efficient and easily recycled reduced graphene oxide/zirconium oxide nanocomposite has been synthesized using banana peel extract (abbreviated as rGO-ZrO2 in this work). The X-ray diffraction (XRD), field emission scanning electronic microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET), UV-visible diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy were used to analyze the synthesized material. The as-prepared rGO-ZrO2 nanocomposite was employed as a photocatalyst for the decomposition of rhodamine blue (RhB) and crystal violet (CV) dyes, and ciprofloxacin (CIP) antibiotic by illumination with direct sunlight. The RhB and CV were degraded to maximum extent of around 86 and 90%, respectively, over the rGO-ZrO2 nanocomposite after exposure to direct sunlight for 120min. On the other hand, the degradation of CIP was approximately 93.1% over the rGO-ZrO2 nanocomposite in 240min under same experimental conditions. Further studies were performed regarding the role of parameters like pH, catalyst dose, and scavengers, in order to understand the superiority of rGO-ZrO2 nanocomposite in degrading organic pollutants. Moreover, the intermediate products and plausible CIP degradation mechanisms were examined using liquid chromatography-mass spectrometry (LC-MS). Moreover, the catalyst was easily separated from the solution and demonstrated good stability and reusability. The RhB, CV, and CIP removal efficiency were 80%, 83%, and 88%, respectively, after five cycles.

Photocatalytic Removal of Ciprofloxacin in Water by Novel Sandwich-like CuFe2O4 on rGO/Halloysite Material: Insights into Kinetics and Intermediate Reactive Radicals

In this study, the CuFe2O4 on rGO/halloysite material was made in an uncomplicated manner. The catalyst has a sandwich-like shape with a uniform coating of the active phase on the rGO sheets and halloysite tubes. The catalyst’s large specific surface area (130 m2/g) and small band gap energy (1.9 eV) allow it to adsorb photons and photocatalyze organic contaminants effectively. In approximately 1 h of light, the catalyst showed high performance in achieving almost complete conversion in photodegrading CIP for an initial CIP concentration of 20 ppm. A pseudo-first-order rate law was followed by the process, as revealed by the experimental results. In addition, the pH effect and the contribution of intermediate reactive radicals that emerged during the photochemical process were explored. The results indicated that hydroxyl radicals and holes had a major impact on CIP decomposition, suggesting that the addition of these radicals could enhance CIP degradation efficiency at a larger scale. This study also confirmed the superiority of catalysis and photochemical processes in environmental treatments by the neutral pH values.

Influence of transition metal-based activating agent on the properties and catalytic activity of sewage sludge-derived catalysts. Insights on mechanism, DFT calculation and degradation pathways

Research studies combining the detailed physicochemical properties' analysis, the catalytic activity in different real aqueous matrices, the proposal of degradation mechanisms and the stability of the intermediates/by-products by means of the Density-functional theory (DFT) are scarce. Therefore, this work gives a step forward in the field of circular economy and the removal of emerging pollutants such as the antibiotic ciprofloxacin, covering all the previously aspects mentioned, using four iron and nickel-based catalysts from two different sewage sludge.Experimental results revealed a significant influence of both the source of the sewage sludge and the activating agent used (iron chloride, nickel chloride and a mixture of both) on the physicochemical properties of the materials and, hence, on their catalytic activity. FTIR studies and chemical composition evidenced that the use of this biomass precursor leads to the generation of a wide variety of functional groups and heteroatoms in the synthesized catalyst structure. Moreover, they showed a combination of Type I-IV isotherms with H3-H4 type hysteresis loops, being mainly mesoporous materials and exhibiting a moderate microporosity except when nickel chloride was used solely as activating agent. The carbonaceous materials reached ciprofloxacin adsorption capacities in the range of 40.4–73.9 mg/g. The use of nickel chloride showed the lowest adsorption contribution and catalytic activity. The bimetallic catalyst (synthesized from a mixture of iron and nickel chloride) showed slightly higher catalytic activity than that found for the iron catalyst, but the metal leaching was also considerably higher. Consequently, the use of iron chloride solely as activating agent seems to be the better alternative, achieving a maximum ciprofloxacin removal around 99.7 % and an iron leaching concentration into the reaction medium of 0.48–0.61 mg/L. The main degradation pathways of ciprofloxacin were proposed according to the detection of LC-MS intermediates and DFT calculation, indicating the most likely areas of attack of reactive species on atoms with a high Fukui index (f0).

Characterisation and application of bismuth ferrite - bismuth vanadate p-n heterojunction in the photoelectrocatalytic degradation of ciprofloxacin in water

Towards the photoelectrocatalytic degradation of ciprofloxacin, BFO/BVO heterojunction was constructed to improve the performance of the individual semiconductors. The enhanced performance of the heterojunction photoanode was attributed to increase in visible light harvesting, greater current mobility leading to higher current density, low charge transfer resistance, and low recombination rate of photogenerated electron and hole. The BFO, BVO and BFO/BVO photoanodes prepared were immobilized on fluorine doped tin oxide coated glass and characterised using x-ray diffractometry, scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy (EIS), UV–vis diffusive reflectance spectroscopy, photocurrent measurement, ultra performance liquid chromatography- mass spectrometry (UPLC-MS). The percentage removal of ciprofloxacin using BFO, BVO and BFO/BVO photoanodes were 56%, 49% and 80.3% respectively. The current density of the heterojunction photoanode were markedly improved when compared to the individual performances of the photoanodes. Also, the BFO/BVO heterojunction photoanode showed stability after repeated usages. Data from UPLC-MS studies was used to propose the degradation pathway, products, and mechanism of the degradation process. .

Removal of Ciprofloxacin from Water by a Potassium Carbonate-Activated Sycamore Floc-Based Carbonaceous Adsorbent: Adsorption Behavior and Mechanism.

In this study, a porous carbonaceous adsorbent was prepared from sycamore flocs by pyrolysis method and K2CO3 activation. The effects of preparative conditions of the material on its adsorptive property were explored. The optimal material (SFB2-900) was obtained with a K2CO3/biochar mass ratio of 2:1 at an activation temperature of 900 °C, possessing a huge surface specific area (1651.27 m2/g). The largest adsorption capacity for ciprofloxacin on SFB2-900 was up to 430.25 mg/g. The adsorption behavior was well described by the pseudo-second-order kinetic model and the Langmuir isothermal model. Meanwhile, this process was spontaneous and exothermic. The obtained material showed excellent adsorption performance in the conditions of diverse pH range, ionic strength, and water quality of the solution. The optimum adsorption conditions (pH = 7.01, dosage = 0.6 g/L, and C0 = 52.94 mg/L) determined based on the response surface methodology were in accordance with the practical validation consequences. The good regeneration effect of SFB2-900 manifested that this material had great practical application potential. Combining the experimental results and density functional theory calculation results, the adsorption mechanisms mainly included pore filling, π-π EDA interactions, electrostatic interactions, and H-bonds. The material could be regarded as a novel and high-efficiency adsorbent for antibiotics. Additionally, these findings also provide reference for the reuse of waste biomass in water treatment.

Activation of peroxydisulfate degradation of ciprofloxacin by nitrogen-doped modified graphitized iron-based carbon materials: The transition from free to nonfree radicals

Considering that high concentrations of ciprofloxacin (CIP) are generally ecotoxic and persistent in water bodies, the refractory degradability has not been addressed in depth. In this study, an N-doped modified graphitized iron-based carbon nanomaterial (0.8 N@FeCS) was prepared by hydrothermal synthesis for the rapid degradation of ciprofloxacin by activated peroxydisulfate. More importantly, the N-doped nitrogen configuration in the iron-based carbon material is pyridine nitrogen, pyrrole nitrogen and graphite nitrogen. The nitrogen modification imparts a new twist to the CIP degradation system: a shift from a common free radical reaction to a nonradical process (1O2 and electron transfer pathways). The degradation intermediates were identified by LC-MS analysis and density functional theory (DFT), it is suggested that the possible CIP degradation pathway. In conclusion, the process of catalytic activation results in removal of CIP, and this study provides a new perspective for the removal of antibiotics from aqueous solutions.