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Fluoride (F–) is one of the common water pollutants, which causes severe diseases if be present over 1.5 mg/L suggested by WHO for drinking water. There is essential to find a simple and cost-effective method for excess F– removal from contaminated water. In this study, municipal solid waste compost ash (MSWCA) was used to remove F– from aqueous solution. The effect of operational variables such as adsorbent calcination temperature (550–900°C), adsorbent dose (0.25–1.5 g/L), pH (2–12), occurrence of competing anions (HCO3−, CO32−, Cl−, NO3− and SO42−), adsorption temperature (20–50°C) and mixing time (15–120 min) were investigated. F–adsorption was highest when compost ash calcinated at 550°C. F– removal increased from 42.6 to 87.7% by increasing adsorbent dose from 0.25 to 1.5 g/L. The removal also increased 4.4% when the temperature of solutions increased from 20 to 50°C, an indicative of endothermic process. Furthermore, adsorption increased by increasing pH from 4 to 10 and then decreased with pH up to 12. F− removal reduced about 10% in the presence of SO42−. Based on pseudo- second-order kinetic model, it was found that the process was controlled by chemisorption. The equilibrium data were well fitted with Langmuir model, which implied the F−ions doesn't interact and adsorbed in monolayer onto MSWA. The Langmuir maximum adsorption capacity was 30.56 mg F/g MSWCA. Due to excellent adsorptive properties, MSWCA presents as a promising material for F− adsorption from wastewaters or landfill leachates. [ABSTRACT FROM AUTHOR]

Dyes are one of the most important environmental pollutants that have a significant impact on the environment, especially water resources. Dyes are toxic compounds that have severe effects on the environment. Methylene blue dye (MBD) causes problems like nausea, profuse sweating, vomiting, mental confusion, and methemoglobinemia. In this study, ZIF-8 with leaf-shaped morphology was used for MBD adsorption. All experiments were performed in batch conditions. The Leaf-shaped ZIF-8 is obtained at the molar ratio of 2-methylimidazole/Zn = 8. The prepared leaf-shaped ZIF-8 was white powder. The as-synthesis adsorbent is in the form of the leaves of a tree. The thickness of Leaf-shaped ZIF-8 is about 6–98 nm. Alkaline conditions were much more favourable than acidic to MBD adsorption. By increasing the dosage of Leaf-shaped ZIF-8, MBD adsorption increased until reaching an equilibrium dose at 0.5 g/L. the kinetic model of pseudo-first-order and the isotherm model of Langmuir have the highest coefficient of determination (R-square). Based on the Langmuir model, the maximum capacity of MBD adsorption on the Leaf-shaped ZIF-8 was 205 mg/g. In this study, the RL was less than one which indicates MBD adsorption is favourable. Also, based on the Freundlich model, 1/n was 0.26, favourable adsorption condition was favourable. [ABSTRACT FROM AUTHOR]

Recently, the presence of endocrine disrupting compounds in the environment has emerged as a global and ubiquitous problem. In this study, a novel synthesis of magnetically carbon nanotube modified with biological polymeric was successfully prepared. The effect of different parameters on the Bisphenol A (BPA) adsorption was studied. A prediction model for BPA adsorption was extended based on the Central Composite Design. Also, the prepared biopolymeric nanotubes were characterized by FT-IR, XRD, TEM, FE-SEM. The surface morphology of nanocomposite was observed, increased carbon nano tube size, and the levels after surface deposition were completely covered by chitosan proteins. The results of our experiments showed that optimum adsorption conditions was achieved at t = 76 min, BPA concentration 6.5 mg/L, adsorbent dosage 1 g/L and pH = 6.2.The data obtained in this study followed the Langmuir isotherm model and the pseudo-second order model. The maximum monolayer adsorption capacity of nanocomposite for BPA was 46.2 mg/g at 20 °C. This study showed that the adsorption of BPA onto nanocomposite was spontaneous and thermodynamically desirable. • In this study, a novel synthesis of magnetically carbon nanotube modified with biological polymeric was prepared. • The purpose of coating the magnetic nanocomposite with silicon oxide is to prepare it for final coating with chitosan. • A prediction model for BPA adsorption was extended based on th CCD. • The Langmuir isotherm and pseudo-second-order model, represent best the kinetics and equilibrium adsorption data. • The maximum monolayer adsorption capacity of nanocomposite for BPA was 46.2 mg/g. [ABSTRACT FROM AUTHOR]

Granular ferric hydroxide was used in the present study to evaluate the efficiency of phosphate removal from aqueous solutions using central composite design and optimization by response surface methodology (RSM). The interaction of important parameters including pH, contact time, adsorbent dose and initial concentration of phosphate was used on the phosphate removal process and optimization of the removal process. The design of this research was based on central composite, which is one of the methods of RSM. The number of standard samples in this study was 35. The results of optimization of the variables derived by solver command in the initial phosphate concentration were 1.78 mg L-1, pH = 5.81, contact time = 82 min, and adsorbent dosage = 4.03 g, maximum removal efficiency of 92.14%. Experimental results of phosphate removal with three repetitions indicated that maximum removal efficiency of phosphate in optimal conditions was 91.6%. Also, the experimental adsorption data indicated that the data follow the pseudo-second-order kinetic model (R² = 0.979) and Freundlich isotherm model (R² = 0.997). Based on the Langmuir model, the maximum phosphate adsorption (Qmax) was 6.541 mg g-1. In general, it can be concluded that granular ferric hydroxide with a good quality and low operating cost has high efficiency in removal of phosphate from various aqueous solutions. [ABSTRACT FROM AUTHOR]

In this study, an electromembrane extraction (EME) method combined with a simple HPLC-UV analysis was developed and validated for the determination of valproic acid in human plasma samples. The major parameters influencing EME procedure, namely the solvent composition, voltage, pH of acceptor and donor solutions, salt effect, and time of extraction, were evaluated and optimized. The drug was extracted from the donor aqueous sample solution (pH 5) to the acceptor aqueous solution (pH 13). The donor and acceptor phases were separated by a hollow fiber dipped in 1-octanol as a supported liquid membrane. A voltage of 60 V during 25 min was applied as the driving force. The drug concentration enrichment factor obtained was >125, which enhanced the sensitivity of the method. The limit of detection and the limit of quantitation were 0.2 and 0.5 µg/mL, respectively. The proposed method was successfully applied to a human plasma sample, with a relative recovery of 75%. The method was linear over the range 0.5-10 µg/mL for valproic acid (R² > 0.9996) with a repeatability (%RSD) between 0.9 and 3.3% (n = 3). Valproic acid is an anticonvulsant drug with poor UV absorption, and EME can improve the sensitivity of HPLC-UV for the determination of valproic acid in plasma samples. [ABSTRACT FROM AUTHOR]

A novel magnetic polymer-ZnO composite was prepared by incorporating Fe3O4 and ZnO nanoparticles in the structure of an adsorbent polymer. Precipitation polymerization was used for synthesizing the adsorbent polymer and its efficiency for extracting doxycycline from aqueous solution was optimized according to several parameters including time, pH and amount of polymer. Results showed the highest extraction efficiency at neutral pH of the doxycycline solution in 20 min, and the capacity of the polymer was about 20 mg/g. The magnetic property of a material is important for fast and facile separation of composite particles after each use. Magnetic polymer-ZnO composite was synthesized by adding Fe3O4 and ZnO nano-particles to the polymerization mixture in order to take advantage of both sorption and photocatalytic degradation mechanisms. The obtained composite was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy equipped with wavelength dispersive X-ray spectroscopy and used for enhanced photocatalytic degradation of doxycycline in aqueous solution. Results showed 76.5% degradation of doxycycline in 6 hours which was significantly higher than the degradation observed by an equivalent amount of ZnO nano-particles. Photocatalytic degradation of doxycycline fitted the pseudo first order kinetic model with a rate constant of 4 x 10-3 µg mL-1 min-1. [ABSTRACT FROM AUTHOR]

Zinc oxide nano-particles were synthesized, characterized and used for photocatalytic degradation of doxycycline using UV-C and visible light. Effects of several operational factors including initial pH of antibiotic solution, initial antibiotic concentration and ZnO nano-particles loading amount were investigated. Comparing photocatalytic degradation and mineralization of doxycycline under UV-C and visible light showed successful application of the method under both light sources. However, reaction rate was higher under UV-C irradiation, which degraded doxycycline almost completely in 5 hours, and 68% mineralization was achieved. Synthesized ZnO nano-particles were successfully applied for photocatalytic degradation of doxycycline in a pharmaceutical wastewater sample. The process was fitted to the pseudo first order kinetic model with rate constants in the range of 6-22 (10-3) mg L-1 min-1 with respect to initial concentration of doxycycline under UV-C irradiation. The Langmuir-Hinshelwood model was also employed for describing the photocatalytic reaction with surface reaction kinetic constant kc and equilibrium adsorption constant KLH values calculated as 0.12 mg L-1 min-1 and 2.2 L mg-1, respectively. Degradation of doxycycline was followed by UVvisible spectroscopy and a validated stability indicating high-performance liquid chromatography method that was developed using stressed samples of doxycycline and could selectively determine doxycycline in the presence of its degradation products. Mass spectrometry was used for determining final degradation products. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) nanoparticles were synthesized, characterized, and used for photocatalytic removal of amoxicilline and sulfamethoxazole from contaminated water. Microwave-assisted gel combustion synthesis method was optimized for type and amount of complexing agent and calcination temperature, in order to obtain the best photocatalytic activity. Characterization of ZnO nanoparticles according to their scanning electron microscopy and transmission electron microscopy images and X-ray diffraction pattern showed homogenous spherical nanoparticles with an average crystalline size of 25.82 nm. Effects of several operational factors such as pH of antibiotic solution, initial concentration of antibiotic, ZnO nanoparticles loading amount, and presence of NaCl salt or buffered solution were investigated. Results showed complete removal of antibiotic compounds in six hours using ZnO nanoparticles/UV-C irradiation. Mineralization of organic content were 62.8 and 20.8% for amoxicilline and sulfamethoxazole, respectively. Photocatalytic removal of both antibiotics followed the Langmuir–Hinshelwood model in the range of concentration of 5–20 mg L−1. ZnO nanoparticles were used for three subsequent runs without significant decrease in their photocatalytic activity. [ABSTRACT FROM PUBLISHER]

A new nanoparticle Cd(II) ion-imprinted polymer (IIP) has been prepared via precipitation polymerization using 2-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-Azobisisobutyronitrile (the initiator), diphenylcarbazide (the ligand), and cadmium nitrate (the template ion). The prepared IIP was characterized by FT-IR spectroscopy, scanning electron microscopy, and transmission electron microscopy. The optimal pH value for the quantitative sorption was 6.0 and maximum sorbent capacity was 16.52 mg/g. Under the optimized conditions, the method had a linear analytical range from 1 to 50 μg/L. The detection limit, relative standard deviation, and recovery of the method were evaluated as 0.14 μg/L, 2.6% and 96–98%, respectively. The prepared IIP revealed good selectivity over a wide variety of other cations. The developed method was successfully applied for the selective extraction and determination of trace amount of cadmium ions in synthetic and real water samples and some medicinal plants by inductively coupled plasma optical emission spectrometry. [ABSTRACT FROM AUTHOR]

A new ion-imprinted polymer (IIP) was synthesized by bulk polymerization from 2-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (EGDMA; the cross-linker), 2, 2′- azobisisobutyronitrile (the initiator), diphenylcarbazone (the ligand), and nickel nitrate (the template ion) in acetonitrile solution. The prepared IIP was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, and studied for the preconcentration and determination of trace nickel ion from aqueous solutions using inductive couple plasma optical emission spectroscopy. The optimal pH value for the quantitative preconcentration was 6.0 and maximum sorbent capacity was 3.26 mg g−1. Under the optimized conditions, the method had a linear analytical range from 0.5 to 50 μg L−1. The detection limit, relative standard deviation, and recovery of the method were evaluated as 0.38 μg L−1, 3.6% and 95–98%, respectively. The developed method was successfully applied to the selective extraction and determination of trace nickel in synthetic and real water samples and some medicinal plants with satisfactory results. [ABSTRACT FROM PUBLISHER]

Multi-walled carbon nanotubes (MWCNT) were used to separate amoxicillin from aqueous media. The parameters affecting amoxicillin adsorption such as pH, temperature, time, interferences of similar molecules, and the amount of adsorbent used were studied. Amoxicillin adsorption using MWCNT was compared to that using Fullerene C60 and activated carbon (AC). The adsorption efficiency of 0.1 and 0.2 g of MWCNT using in a continuous mode were 86.5% and 87.9%, respectively. Evaluation of the adsorbent capacity showed that each gram of MWCNT can absorb 22.9 mg amoxicillin. The effect of pH was studied over the range 2–8 and revealed that adsorption of the amoxicillin at the initial pH of 4.6 was more effective than any other pH. The adsorption of amoxicillin on MWCNT was much greater than Fullerene C60 and AC. Adsorption data showed that they were best fitted to the Langmuir isotherm. [ABSTRACT FROM PUBLISHER]

This inquiry focuses on acquiring empirical models to predict ciprofloxacin removal using magnetization of functionalized multi-walled carbon nanotubes (FMWCNTs-Fe 3 O 4) from an aqueous solution. The response surface methodology (RSM) and support vector regression (SVR) as data mining techniques were adopted to develop models. Critical parameter effects comprising pH (3−10), adsorbent dose (0.2–1 g/L), contact time (5–60 min) and ciprofloxacin concentrations (30–100 mg/L) were analysed. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isothermal models were utilized to fit the empirical data. FMWCNTs-Fe 3 O 4 prepared by chemical co-precipitation method was loaded by Fe 3 O 4 nanoparticles (using sonication) to synthesize functionalized multi-walled carbon nanotubes to remove ciprofloxacin (CIP). FMWCNTs-Fe 3 O 4 were characterized by fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) methods. The Langmuir model was utilized to precisely describe the maximum adsorption capacity(q max) of 107.66 mg/g with R2 = 0.998. In this study, the pseudo-second-order model exactly described the adsorption process(R2 = 0.99). The results illustrated that the LSSVM (least squares support vector machine) model efficiently predicted the CIP removal percentage with very high accuracy in the training phase (R2 = 0.975) and the test phase (R2 =0.970). Moreover, the highest removal percentages in optimized step were achieved for RSM (pH 5.4, dose 0.78 g/L, time of 24.5 min, and CIP concentrations of 59 mg/L) and GA (genetic algorithm) (pH 4.4, dose 0.74 g/L, time of 42 min, and CIP concentrations of 38 mg/L) techniques by 88% and 99.1%, respectively. The FMCNTs-Fe 3 O 4 efficiency has decreased by 12% even after five used cycles relative to the optimal conditions (regeneration). Therefore, FMWCNTs-Fe 3 O 4 adsorption was considered to be an effective technique for CIP removal in the aqueous environment. [Display omitted] • RSM and LSSVM modeling to efficiency in adsorption of CIP from aqueous solutions using FMWCNTs-Fe 3 O 4. • The CIP removal percentage were accurately predicted by LSSWM model. • The Langmuir model was utilized to precisely describe the q max of 107.66 mg/g with R2 = 0.998. • The removal percentages in the optimized step were achieved for RSM and GA techniques by 88% and 99.1%. • RSM and GA techniques' highest removal percentage in the optimized step 88% and 99.1% were obtained. [ABSTRACT FROM AUTHOR]

In the present study, metal organic frameworks (MOFs) and aminated graphitic carbonaceous structure (ACS-RGO) through chemical synthesis prepared by a simple precipitation method and used for diazinon removal. Several techniques such as XRD , FESEM and FTIR were applied for identification of MOF-5 and ACS-RGO. Also, response surface methodology (RSM) was employed in this work to look at the effectiveness of diazinon adsorption. To forecast pesticide removal, we applied artificial neural network (ANN) and Box-Behnken Design (BBD) models. For the ANN model, a sensitivity analysis was also performed. The effect of independent variables like solution pH, various concentrations of diazinon, MOFs and ACS-RGO adsorbent dose and contact time were assessed to find out the optimum conditions. Based on the model prediction, the optimal condition for adsorption ACS-RGO and MOF-5 were determined to be pH 6.6 and 6.6, adsorbent dose of 0.59 and 0.906 g/L, and mixing time of 52.15 and 36.96 min respectively. These conditions resulted in 96.69% and 80.62% diazinon removal using ACS-RGO and MOF-5, respectively. Isotherm studies proved the adsorption of ACS-RGO and MOF-5 following the Langmuir isotherm model for diazinon removal. Diazinon removal followed by the pseudo-second and Pseudo-first order kinetics model provides a better fit for analyzing the kinetic data associated with pesticide adsorption for ACS-RGO and MOF-5, respectively. Based on the obtained results, the predicted values for the efficiency of diazinon removal with the ANN and BBD were similar (R2=0.98). Therefore, two models were able to predict diazinon removal by ACS-RGO and MOF-5. [Display omitted] • MOF-5 and ACS-RGO were synthesized and applied for diazinon removal. • A comparison was made between the ANN and BBD models for diazinon removal prediction. • At optimal conditions, the diazinon removal for ACS-RGO and MOF-5 were 96.69% and 80.62%, respectively. [ABSTRACT FROM AUTHOR]