Initial Ciprofloxacin Concentration Research Articles

Z-scheme heterojunction WO3/BiOBr supported-single Fe atom for ciprofloxacin degradation via visible-light photocatalysis

Single-atom catalysts have drawn tremendous attention on account of their high activity, selectivity and stability. Z-scheme heterojunctions can effectively improve the utilization of optical energy due to the enhanced separation of photogenerated electrons and holes. In this work, several catalysts associated with single-atom Fe (FeSA) loaded on Z-scheme heterojunction WO3/BiOBr were prepared; their structure, morphology and photoelectric properties were analyzed; their photocatalytic degradation performance of Ciprofloxacin (CIP) was investigated; and the effects of initial pH, initial CIP concentration, catalyst dosage, light intensity, inorganic anions and humic acid on CIP removal rate were examined. Relevant results showed that the percentage of CIP removal by FeSA/WO3/BiOBr could reach 98.5% (120 min); the optimal conditions were pH= 9, [CIP]0 = 10 mg/L, [FeSA]0 = 0.8 g/L and Ilight= 500 W (100% degradation rate within 30 min);·O2- and h+ were the key active species. Results of the cyclic experiments suggested good stability of the catalyst. Furthermore, the mechanism of CIP photocatalytic degradation was proposed to be a synergistic mechanism of Z-scheme heterojunction migration and valence cycling between single-atom Fe2+ and Fe3+. Finally, the products and pathways of CIP degradation were analyzed.

Photocatalytic removal of ciprofloxacin antibiotic from aqueous medium by applying AgI/Ag2 O nanocomposite: Activity test, reaction kinetics, and catalyst reusability

Background: This study examined the removal of ciprofloxacin (CIP), which is a very widely used antibiotic, from an aqueous medium by applying AgI/Ag2 O photocatalyst under visible light radiation. Methods: AgI/Ag2 O was synthesized conveniently by applying a two-stage precipitation method. The synthesized compound was characterized by X-ray powder diffraction (XRD), FE- field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray (EDX), and UV-Vis spectrophotometry. Different parameters including initial pH of the solution, initial CIP concentration, reaction kinetics, and catalyst reusability were investigated. Results: Concurrent use of AgI and Ag2 O caused improved photocatalytic properties in the presence of UV light. The pH and initial concentration of CIP affected the process efficiency; 95% efficiency was achieved within 100 min at pH 9. Furthermore, the process efficiency was still maintained over 90% after four consecutive cycles. Conclusion: The photocatalytic degradation process using AgI/Ag2 O nanocomposite under visible light radiation is a suitable method for removing CIP from aqueous media due to its high efficiency and stability.

Preparation of green sodium alginate adsorption membrane and its high adsorption performance for fluoroquinolones antibiotics

Fluoroquinolones (FQs) were widely used in human and veterinary medicine, however, the presence of FQs at lower concentration in the environment could threaten to human health and agricultural production. In this research, the adsorption membranes were prepared based on sodium alginate (SA) crosslinking with multivalent metal ions. The SA-Al/Ca membranes and SA-Ca membrane were prepared by crosslinking with AlCl3/CaCl2 solutions and CaCl2 solutions, respectively. Comparing with SA-Ca membrane, the presence of Al3+ in crosslinking agent could produce a large number of adsorption sites on the surface of SA-Al/Ca membrane and remarkably improve the adsorption performance of SA-Al/Ca membrane. Effects of preparation conditions such as crosslinking ways, CaCl2 percentage in compound crosslinker, and crosslinking time on the adsorption performance of prepared SA-Al/Ca membrane were demonstrated. Moreover, the effects of the initial concentration of ciprofloxacin (CIP) and Levofloxacin (S-OFX), adsorption time, solution pH, ionic strength and adsorption temperature on the performance of SA-Al/Ca membrane were studied. The thermodynamics of the adsorption of CIP and S-OFX were well fitted with the Tempkin adsorption isotherm model (R2 = 0.9455) and D-R adsorption isotherm model (R2 = 0.9822), respectively. The maximum adsorption capacity of S-OFX and CIP using SA-Al/Ca membrane was 836.31 mg·g−1 and 858.94 mg·g−1. The results showed that SA-Al/Ca membranes with good adsorption capacity, low cost and high stability.

Optimizing Fenton-like process, homogeneous at neutral pH for ciprofloxacin degradation: Comparing RSM-CCD and ANN-GA.

Antibiotics are considered among the most non-biodegradable environmental contaminants due to their genetic resistance. Considering the importance of antibiotics removal, this study was aimed at multi-objective modeling and optimization of the Fenton-like process, homogeneous at initial circumneutral pH. Two main issues, including maximizing Ciprofloxacin (CIP) removal and minimizing sludge to iron ratio (SIR), were modeled by comparing central composite design (CCD) based on Response Surface Methodology (RSM) and hybrid Artificial Neural Network-Genetic Algorithm (ANN-GA). Results of simultaneous optimization using ethylene diamine tetraacetic acid (EDTA) revealed that at pH≅7, optimal conditions for initial CIP concentration, Fe2+ concentration, [H2O2]/[Fe2+] molar ratio, initial EDTA concentration, and reaction time were 14.9mg/L, 9.2mM, 3.2, 0.6mM, and 25min, respectively. Under these optimal conditions, CIP removal and SIR were predicted at 85.2% and 2.24 (gr/M). In the next step, multilayer perceptron (MLP) and radial basis function (RBF) artificial neural networks (ANN) were developed to model CIP and SIR. It was concluded that ANN, especially multilayer perceptron (MLP-ANN) has a decent performance in predicting response values. Additionally, multi-objective optimization of the process was performed using Genetic Algorithm (GA) and Non-dominated Sorting Genetic Algorithm-II (NSGA-II) to maximize CIP removal efficiencies while minimizing SIR. NSGA-II optimization algorithm showed a reliable performance in the interaction between conflicting goals and yielded a better result than the GA algorithm. Finally, TOPSIS method with equal weights of the criteria was applied to choose the best alternative on the Pareto optimal solutions of the NSGA-II. Comparing the optimal values obtained by the multi-objective response surface optimization models (RSM-CCD) with the NSGA-II algorithm showed that the optimal variables in both models were close and, according to the absolute relative error criterion, possessed almost the same performance in the prediction of variables.

Ciprofloxacin removal from aqueous solutions by granular ferric hydroxide: Modeling and optimization

BackgroundGranular ferric hydroxide is a good commercial adsorbent used to remove various impurities in aqueous systems. Ciprofloxacin is known as an emerging pollutant in aquatic environment. Materials and methodsTo understand the adsorption process of ciprofloxacin by GFH, this study evaluates the performance of GFH using response surface methodology. The effects of pH, initial ciprofloxacin concentration, adsorbent dose and contact time on the adsorption rates of ciprofloxacin were investigated. ResultsThe results of optimization of the variables derived in the initial pH = 7.5, ciprofloxacin concentration, were 6.05 mg. L-1, adsorbent dosage = 1.39 g. L-1 and contact time = 27.5 min, maximum removal efficiency of 42.31% and desirable 0.987. According to RSM, this study follows the quadratic model (R2 = 0.969). ConclusionConsidering the aspects of good quality, economic efficiency and feasibility, adsorption with GFH is recommended as a successful pretreatment for the removal of ciprofloxacin from various aqueous solutions.

Statistical optimization of process conditions for pyrvinium pamoate elimination using UV/zeolite‐based nanostructures/H 2 O 2

Statistical optimization of process conditions for pyrvinium pamoate elimination using UV/zeolite‐based nanostructures/H ₂ O ₂

Experimental Data and Modeling the Adsorption-Desorption and Mobility Behavior of Ciprofloxacin in Sandy Silt Soil

The improved understanding of the behavior of antibiotics in soil is of great importance due to their environmental hazard and frequent detection. In this work, the adsorption-desorption and mobility behaviors of ciprofloxacin in sandy silt soil, affecting the fate of ciprofloxacin in the environment, were studied by a series of batch tests and column tests. In batch tests, the effects of contact time, initial ciprofloxacin concentration, sandy silt soil dosage, solution pH, and ionic strength on ciprofloxacin adsorption and desorption in sandy silt soil were considered. Adsorption results were satisfactorily modeled, with good fittings to the pseudo-second-order model (R2 > 0.999) and Langmuir model (R2 > 0.991), with the value for Langmuir’s maximum adsorption capacity (qm) 5.50 mg g−1. Ciprofloxacin adsorption decreased sharply by increasing the pH from 7.0 to 10.0 and the ionic strength from 0.01 to 0.2 mol L−1 CaCl2. Comparatively, ciprofloxacin was more readily desorbed from sandy silt soil at alkaline and high ionic strength conditions. Breakthrough curves of ciprofloxacin obtained from the column experiments were described by the two-site model, Thomas model, and Yan mode. Of these models, the two-site model was the most suitable to describe the mobility of ciprofloxacin. The retardation factor (R) obtained in the two-site model was 345, suggesting strong adsorption affinity with ciprofloxacin on the sandy silt soil surface. The results from the Thomas model suggested the extremely small external and internal diffusion resistances. The Yan model was not suitable. Cation exchange interaction, electrostatic interaction, mechanical resistance, entrapment between porous media, and gravity sedimentation were proposed to be the important adsorption mechanisms.

High Photocatalytic Activity of g-C3N4/La-N-TiO2 Composite with Nanoscale Heterojunctions for Degradation of Ciprofloxacin.

Ciprofloxacin (CIP) in natural waters has been taken as a serious pollutant because of its hazardous biological and ecotoxicological effects. Here, a 3D nanocomposite photocatalyst g-C3N4/La-N-TiO2 (CN/La-N-TiO2) was successfully synthesized by a simple and reproducible in-situ synthetic method. The obtained composite was characterized by XRD, SEM, BET, TEM, mapping, IR, and UV-vis spectra. The photocatalytic degradation of ciprofloxacin was investigated by using CN/La-N-TiO2 nanocomposite. The main influential factors such as pH of the solution, initial CIP concentration, catalyst dosage, and coexisting ions were investigated in detail. The fastest degradation of CIP occurred at a pH of about 6.5, and CIP (5 mg/L starting concentration) was completely degraded in about 60 min after exposure to the simulated solar light. The removal rates were rarely affected by Na+ (10 mg·L−1), Ca2+ (10 mg·L−1), Mg2+ (10 mg·L−1), and urea (5 mg·L−1), but decreased in the presence of NO3− (10 mg·L−1). The findings indicate that CN/La-N-TiO2 nanocomposite is a green and promising photocatalyst for large-scale applications and would be a candidate for the removal of the emerging antibiotics present in the water environment.

Photocatalytic degradation of ciprofloxacin by a novel visible light activated Ag2O-AgI/TiO2 nanocomposite: Activity, kinetic, mineralization and continuous-flow stability test

ABSTRACT This study examined effective elimination of Ciprofloxacin (CIP) from an aqueous flow using Ag2O-AgI/TiO2 nanocomposite stabilised on glass under visible light radiation. The synthesised catalyst was characterised using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray (EDX), and Ultraviolet–visible spectroscopy (UV-VIS) methods. Some important parameters including initial pH, CIP concentration, and reaction kinetics were investigated. Stability of the catalyst under continuous operating conditions was measured in an aqueous solution and real wastewater medium. Modification of TiO2 with AgI and Ag2O resulted in its improved photocatalytic properties in the presence of visible light. CIP concentration and pH of the solution affected the process efficiency. Specifically, 92.8% of CIP with initial concentration of 10 mg/L and pH 9.5 was removed using Ag2O-AgI/TiO2 nanocomposite within 120 min, and the resulting effluent degradability increased. Minor leakage of silver and titanium as well as maintained photocatalytic activity of the synthesised catalyst within six days of continuous CIP treatment showed high stability of the catalyst. The photocatalytic degradation process using Ag2O-AgI/TiO2 nanocomposite under visible light radiation can be a suitable method for removing resistant organic compounds due to high efficiency and high stability during the CIP removal process.

Insight into the degradation of ciprofloxacin by medium-pressure UV-activated monochloramine process

The degradation efficiency and mechanisms of ciprofloxacin (CIP), a typical antibiotic, by a medium-pressure ultraviolet/chloramine (MPUV/NH2Cl) treatment were investigated. The results showed that CIP degradation by MPUV/NH2Cl was significantly higher than that by NH2Cl oxidation and MPUV photolysis, and that this degradation processes were consistent with pseudo-first-order kinetics. The initial CIP concentration (7.5–30.2 μM) and the presence of HCO3− (0.5–10 mM) significantly inhibited CIP degradation with kobs,CIP 0.0090–0.0069 and 0.0078–0.0048 cm2/mJ. In contrast, NO3− (50–500 μM) and Br− (0.5–10 mM) significantly promoted the degradation with kobs,CIP 0.0078–0.0102 and 0.0078–0.0124 cm2/mJ. The effect of Cl− (0.5–10 mM) and natural organic matter (1–5 mg/L) were negligible. The NH2Cl dosage (30–60 μM) presented a dual effect, in which its increase within the optimal concentration range (30–40 μM) accelerated CIP degradation due to the formation of reactive radicals, whereas an excessive increase (40–60 μM) quenched the free radicals, ultimately quenching the free radicals and inhibiting the degradation. The optimum pH for CIP degradation under MPUV/NH2Cl treatment was 7.0. The contribution of reactive halogen species (i.e., reactive chlorine species and reactive nitrogen species) to CIP degradation was substantially greater than that of hydroxyl radicals under acidic or neutral conditions. We identified the degradation products of CIP and proposed degradation pathways, which included defluorination and cracking of the piperazine ring, with the latter being dominant. Compared to haloacetic acid (HAA) and nitrogenous disinfection byproducts (N-DBPs), MPUV/NH2Cl significantly reduced trihalomethane (THM) production and theoretical cytotoxicity by 80.1% and 78.4% respectively, compared to the background experiment in natural water at a UV dose of 300 mJ/cm2.

Sonochemical degradation of ciprofloxacin by hydrogen peroxide and persulfate activated by ultrasound and ferrous ions

This paper evaluates the use of various oxidation methods such as ultrasonic/persulfate (US/PS), ultrasonic/hydrogen peroxide (US/H2O2), US/H2O2/Fe2+, US/PS/Fe2+, and the US/PS/H2O2/Fe2+ process and compares their potential in removal of ciprofloxacin (CIP). The results showed that US/PS/H2O2/Fe2+, was the most efficient among the studied processes. In US/PS/H2O2/Fe2+, 100% removal of CIP was achieved at pH 3 and 50 min of treatment when the initial concentration of CIP, H2O2, PS and Fe2+ were 25 mg/L, 4 mM, 6 mM and 1 mM, respectively. The results showed that with increasing ultrasonic power and increasing concentrations of H2O2, PS, and Fe2+, the removal percentage increases. Toxicity of CIP solution was scrutinized by Daphnia magna, and the US/PS/H2O2/Fe2+ process was able to provide toxicity elimination of 100% for the solution. Also, the equilibrium data for all processes followed first-order kinetics with a regression coefficient above 0.9, and the reaction rate constant for the US/PS/H2O2/Fe2+ process was higher than other systems. At 60 min of sonochemical time, the energy consumptions by US/PS, US/H2O2, US/H2O2/Fe2+, US/PS/Fe2+, and US/PS/H2O2/Fe2+ were 105.5, 87.5, 64.7, 41.4 and 16.2 kWh/m3, respectively, suggesting the last one as the most economical. Additionally, for the processes combined with the iron, biochemical oxygen demand/chemical oxygen demand (BOD5/COD) in the CIP solution was above 0.4, which indicated the conversion of non-biodegradable wastewater to biodegradable form. The total organic carbon (TOC) test was performed, and the mineralization percentage by the US/PS/H2O2/Fe2+ process was 82%. Studies conducted for evaluating the effect of scavengers also showed that both sulfate (SO4•−) and hydroxyl (•OH) radicals play an important role in the studied process.

Colloidal biochar for enhanced adsorption of antibiotic ciprofloxacin in aqueous and synthetic hydrolyzed human urine matrices

Objectives of the present research were to examine the capacity of disc-milled high lignin biochar colloids (CBC) for the removal of ciprofloxacin (CPX) from aqueous solution and synthetic hydrolyzed human urine. In this study, adsorption of CPX was tested against the initial pH (3–10), ionic strength (0.001–0.1 M NaNO3), resident time (up to 8 h), initial CPX concentration (5–100 mg/L) and temperature (25, 35, and 45 °C). The surface morphology was examined using Brunauer-Emmett-Teller (BET) specific surface area. The CBC was observed to be < 300 nm whereas the BET surface area was 284 m2/g. Best CPX adsorption demonstrated at pH 5–6 and however, indicated ionic strength dependency. Experimental kinetics data in aqueous media were well-fitted to the pseudo-second-order (r2 of 0.98), while the Hill and Langmuir isotherm models best described the isotherm data (r2 of 0.95 and 0.94, respectively) confirming chemisorption followed by physisorption interactions. The thermodynamics results indicate that CPX adsorption onto CBC is spontaneous (–ΔG), endothermic (+ΔH) and has increased randomness (+ΔS) in the aqueous system. The kinetic experimental data in synthetic urine matrix was fitted with Elovich (r2 = 0.99) and fractional power (r2 = 0.96) models whereas Hills (r2 = 0.99) and Langmuir (r2 = 0.97) models were the most fitted with isotherm data suggesting the adsorption of CPX on the CBC by chemisorption mechanisms. In conclusion, CBC demonstrated effective removal of CPX indicating its potential to be used in wastewater treatment.

Optimization by Box–Behnken Design and Synthesis of Magnetite Nanoparticles for Removal of the Antibiotic from an Aqueous Phase

Some environmental problems caused by the intrusion of active drug ingredients, especially antibiotics, into water resources pose a serious threat. Ciprofloxacin (CIP) is an antibiotic from the group of fluoroquinolones that is used extensively in the treatment of bacterial infections. The presence of drug residues in the environment, especially in water resources, is an essential issue due to their stability and nondegradability. This study is aimed at investigating the efficiency of magnetite (Fe3O4) nanoparticles and the effect of independent variables, including initial concentrations of CIP (35-80 mg/L), adsorbent doses (20–60 mg), and pH values (4–10) at reaction time (80 min) for the removal efficiency of CIP antibiotics based on the Box-Behnken design (BBD) method. The analysis of variance (ANOVA) results indicated that a quadratic model was convenient for modeling CIP removal. The first step, the coprecipitation method, was appropriate for the preparation of Fe3O4 nanoparticles and developed as highly efficient adsorbents. Synthesized nanoparticles were later characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier transform infrared spectra (FT-IR). The results of XRD have shown that angles for the peaks at [Formula: see text], which corresponded to the crystal planes 220, 311, 400, 422, 511, 440, and 535, respectively, were consistent with standard peaks of magnetite and a cubic face structure. The obtained results indicated that the CIP removal efficiency was 74.44% under optimum operation parameters: initial concentration of CIP 44.15 (mg/L), adsorbent dosage of 59.6 (mg), [Formula: see text], and contact time of 80 min. In fact, a cooperative agreement between model prediction and experimental data using BBD with significant [Formula: see text] values of 0.95 was observed. Based on the results, magnetite nanoparticles have an excellent ability to remove antibiotics from an aqueous phase.

Enhanced Ciprofloxacin Removal from Aqueous Solution Using a Chemically Modified Biochar Derived from Bamboo Sawdust: Adsorption Process Optimization with Response Surface Methodology

Contamination of water by ciprofloxacin has become a significant concern due to its adverse health effects and growing evidence of antimicrobial-resistant gene evolution. To this end, a chemically modified bamboo biochar was prepared from bamboo sawdust to effectively remove ciprofloxacin (CIP) from an aqueous solution. Under similar adsorption conditions, the modified bamboo biochar (MBC) has an excellent CIP removal efficiency (96%) compared to unmodified bamboo biochar (UBC) efficiency (45%). Thus, MBC was used in batch adsorption experiments, and the process was optimized with the central composite design (CCD) framework of response surface methodology (RSM). Sorption process parameters such as initial CIP concentration, pH, adsorbent dose, and contact time were studied and found to have a significant effect on CIP removal. The optimal CIP removal (96%) was obtained at MBC dose (0.5 g L-1), CIP initial concentration (20 mg L-1), pH (7.5), and contact time (46 min). The adsorption kinetic data were well described by the pseudo-second-order model ([Formula: see text]), and both Langmuir ([Formula: see text]) and Freundlich ([Formula: see text]) models gave the best fit in CIP adsorption isotherm analysis. The maximum monolayer adsorption capacity of the MBC was 78.43 mg g-1 based on the Langmuir isotherm model. These results suggest that CIP adsorption was mainly controlled by chemisorption. Moreover, the CIP adsorption process was endothermic and spontaneous. Overall, MBC is a low-cost, efficient, and recyclable adsorbent for eliminating emerging contaminants such as ciprofloxacin from an aqueous solution.

Carbon dioxide activated biochar-clay mineral composite efficiently removes ciprofloxacin from contaminated water - Reveals an incubation study

Ciprofloxacin, a second-generation synthetic fluoroquinolone derivative widely used in human and veterinary medicines, has the potential to pose a serious risk to aquatic organisms and humans. The current research investigated the removal of ciprofloxacin using biochar treated with clay mineral and subsequently activated with carbon dioxide (CO2) produced at two different pyrolysis temperatures (350 and 650 °C). Batch adsorption experiments were carried out to assess the removal efficiency of ciprofloxacin by as-synthesized materials. The effects of various factors, such as pH, contact time, adsorbent dose, initial ciprofloxacin concentration, and temperature were studied during the removal process. The physicochemical characterization results verified the successful loading of clay minerals on biochar. Non-linear adsorption models were employed to understand the nature of adsorption processes however, the Pseudo-second-order kinetic and Freudlich and Redlich Peterson isotherm models best fitted with the adsorption data. These findings indicated that the adsorption did not follow an ideal monolayer adsorption suggesting hybrid chemical adsorption process that was spontaneous and endothermic. The maximum adsorption (50.32 mg g−1) of ciprofloxacin was achieved by CO2 activated biochar-clay mineral composite prepared at 350 °C, and was almost two times higher than the pristine biochar at neutral pH and 40 °C. The possible proposed mechanisms involved for the removal of ciprofloxacin were electrostatic attraction, cation exchange, pore-filling effect, and π-π interactions. Our findings demonstrate that application of CO2 activated biochar-clay mineral composite is a promising technique for efficient removal of ciprofloxacin from aqueous solution.

Optimization, Kinetics, Thermodynamic and Arrhenius Model of the Removal of Ciprofloxacin by Internal Electrolysis with Fe-Cu and Fe-C Materials

The ciprofloxacin (CIP) removal ability of a Fe-Cu electrolytic material was examined with respect to pH (2–9), time (15–150 min), shaking speed (100–250 rpm), material mass (0.2–3 g/L), temperature (298, 308, 323) and initial CIP concentration (30–200 mg/L). The Fe-Cu electrolytic materials were fabricated by the chemical plating method, and Fe-C materials were mechanically mixed from iron powder and graphite. The results show that at a pH value of 3, shaking time 120 min, shaking speed 250 rpm, a mass of Fe-Cu, Fe-C material of 2 g/L and initial CIP concentration of 203.79 mg/L, the CIP removal efficiency of Fe-Cu material reached 90.25% and that of Fe-C material was 85.12%. The removal of CIP on Fe-Cu and Fe-C materials follows pseudo-first-order kinetics. The activation energy of CIP removal of Fe-Cu material is 14.93 KJ/mol and of Fe-C material is 16.87 KJ/mol. The positive ΔH proves that CIP removal is endothermic. A negative entropy of 0.239 kJ/mol and 0.235 kJ/mol (which is near zero and is also relatively positive) indicated the rapid removal of the CIP molecules into the removed products.

Investigation of Isotherm, Kinetics and Thermodynamics of Ciprofloxacin Adsorption by Molecularly Imprinted Polymer from Aqueous Solutions

Background: Improper use of antibiotics and their discharge into the environment have serious and dangerous consequences. About 30-30% of antibiotics are not metabolized in the body and enter the environment through urine and feces, so the main source of antibiotics in the environment is wastewater treatment plant effluent. The aim of this study was to investigate the removal efficiency of ciprofloxacin (CIP) from aqueous media by molecularly imprinted polymer (MIP). Methods: This study is an experimental-laboratory study performed in a reactor with a discontinuous system. In this study, the effect of parameters such as solution pH, adsorbent dose, initial concentration of CIP, reaction contact time and reaction temperature on the reduction rate the antibiotics amoxicillin and CIP were administered. Results: Results showed that removal efficiency for both antibiotics was increased with increasing contact time and adsorbent mass and initial antibiotics concentration while decreased with increasing solution pH and the best pH to remove was neutral pH. Equilibrium data were analyzed by Freundlich and Langmuir isotherm models and the results showed that the data from Langmuir isotherm had a higher correlation coefficient. In addition, the reaction rate was performed with pseudo-first-order and pseudo-second-order models, and the data were consistent with pseudo second order kinetic kinetics. According to result of thermodynamic study, entropy changes (ΔSO), enthalpy changes (ΔHO) and Gibbs free energy (ΔGO) were negative that represent the adsorption process is spontaneous and exothermic. Conclusion: The results of this study showed that the process of adsorption of MIP is a very effective process for removing the CIP from aqueous solutions.

Optimization for the conditions to prepare sewage sludge derived adsorbent and ciprofloxacin adsorption.

In the present study, sewage sludge (SS) was used to synthesize activated carbon (AC) which was further utilized as adsorbent for the removal of ciprofloxacin (CPX) from synthetic wastewater. The adsorbent was prepared by chemical activation method using ZnCl2 as activating agent. Design of experiments (DOE) approach was explored to determine the optimum operating conditions for the synthesis of AC and CPX removal from the wastewater. The optimum conditions for AC synthesis (i.e., carbonization temperature = ~500°C, activation time = 30 min, and impregnation ratio = 2.26) were decided based on results for three response parameters, that is, adsorbent yield, methylene blue removal, and iodine number. The synthesized adsorbent showed ~93% CPX removal (initial CPX concentration = 100 mg/L) at the following optimum conditions: adsorbent dose =1.31 g/L, pH =7 and reaction time =12 h. Langmuir isotherm model was best fit to the equilibrium adsorption data (maximum adsorption capacity of SS derived AC = 102 mg/g) whereas pseudo-second order model showed the best fit to adsorption kinetic data (adsorption capacity = 77.5 mg/g). An effort was also made to reduce fresh water requirement for adsorbent synthesis by recycling the wastewater produced during chemical activation of SS. PRACTITIONER POINTS: Experiment design approach was used for optimization of adsorbent preparation conditions and CPX removal conditions by waste derived adsorbent. Sewage sludge derived adsorbent had BET surface area of 564 m2 /g which is comparable to commercial activated carbon. 93% CPX adsorption with the sewage sludge derived adsorbent at optimum conditions. Langmuir model better suited the CPX adsorption data. Wastewater recycling and ZnO recovery from wastewater produced during adsorbent synthesis were performed.

Fabrication and characterization of carbon quantum dots decorated hollow porous graphitic carbon nitride through polyaniline for photocatalysis

Metal-free photocatalysts are widely used to decontaminate aqueous solutions by eliminating toxic and non-biodegradable compounds. It is desirable to develop a photocatalyst with high charge separation and migration efficiency. The addition of carbon quantum dots (CQDs) to graphitic carbon nitride with polyaniline (PANI) can improve its light absorption abilities and reduce the recombination of holes and electrons. In this study, a novel CQDs decorated on PANI with hollow porous graphitic carbon nitride (CN) was fabricated via an in situ polymerization followed by an ultra-sonication. The optimal CQDs–loaded CN-PANI nanocomposite exhibited the high visible light absorption with a high specific surface area. Furthermore, better photocatalytic degradation of ciprofloxacin (CIP) was achieved under the visible light. The improved photocatalytic activity of CN-PANI-CQDs (5.0%) can be attributed to its higher charge separation, and destruction of recombination rate through the heterojunction of excited electrons among CN, PANI, and CQDs. This effect was further confirmed by high photocurrent intensity, low photoluminescence emission, and electrical resistance. In addition, different parameters including catalyst weight, initial CIP concentration, and interfering effect of anions during CIP removal were investigated. The main active species in the degradation of CIP were identified to h+, •OH, and •O2− through the scavenger test. The high reusability and stability of the photocatalyst composite were also verified. The degradation intermediates and reaction pathways were identified. Furthermore, the effectiveness of the photocatalyst was evaluated using different toxic pollutants including imidacloprid, tetracycline, phenol, and rhodamine B under similar conditions. The CQDs–decorated CN-PANI was proved as a promising material for efficient photodegradation of toxic pollutants in water.

Degradation of pharmaceutical antibiotic (ciprofloxacin) by photocatalysis process using sol-gel based titanium dioxide nanoparticles

Abstract This study is an attempt to the removal of Ciprofloxacin (CIP) antibiotic from simulated wastewater using a photocatalytic process. The photocatalytic process was carried out in a photocatalytic reactor in the presence of TiO2 nanoparticles. TiO2 nanoparticles were successfully prepared in a laboratory scale using sol-gel method with titanium-isopropoxide (TTIP) as titanium precursor. Prepared material was found very effective to the removal of CIP antibiotic. The maximum removal efficiency of 87.95% of ciprofloxacin from aqueous solution was achieved at the pH 5, catalyst doze of 40 mg L−1 with initial concentration of ciprofloxacin 5 mg L−1, and the reaction time of 100 min additionally; material characterization of TiO2 was presented in detail in terms of XRD, SEM, UV, and FTIR. It has been found that at the optimum condition the total operating cost indicated for the removal of ciprofloxacin from aqueous solution is 786.56 (INR/kg of CIP removal). This technique demonstrated that photocatalytic reaction in presence of TiO2 nanoparticles is well applicable to treat pharmaceutical wastewater.