Zahra Mirkazehi; Mohammad Reza Rezaei; Mohammad Sayadi
Abstract
Landfill leachate is the fluid percolating through the landfill and is one of the most important environmental challenges that lead to the contamination of water and soil resources. In this study, magnetic graphene oxide nanoparticles with WO3 (GO-Fe3O4/WO3) were synthesized through the hydrothermal ...
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Landfill leachate is the fluid percolating through the landfill and is one of the most important environmental challenges that lead to the contamination of water and soil resources. In this study, magnetic graphene oxide nanoparticles with WO3 (GO-Fe3O4/WO3) were synthesized through the hydrothermal method to eliminate chemical oxygen demand (COD) from leachate. The obtained products were characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetric analysis (TGA), and Vibrating sample magnetometer (VSM) analysis. The influence of various operating parameters, such as initial solution pH, adsorbent dosage, contact time, and temperature, on COD removal was studied. Additionally, kinetic, isotherm, and thermodynamic studies were conducted to evaluate the adsorption capacity of the adsorbent. The results revealed that the maximum adsorption capacity of GO-Fe3O4/WO3 was 2500 mg/g adsorbent at pH 4, a contact time of 90 minutes, an adsorbent dosage of 25 mg g-1, and a temperature below 298 K, respectively. According to the adsorption kinetic fitting results, the experimental adsorption data were well described by the pseudo-second order kinetic with an R2 value of 0.97, and the Freundlich isotherm equation with an R2 value of 0.99. The thermodynamic results indicated that the adsorption was spontaneous and exothermic for COD adsorption. In general, the adsorption process of the synthesized GO-Fe3O4/WO3 nanocomposite revealed that it is highly effective for landfill leachate treatment and has great practical value in leachate treatment.
Janan Parhizkar; Mohammad Hossein Habibi
Abstract
Photocatalytic treatment of wastewater from azo dyes with semiconductors promises efficient method to refine water. Cobalt ferrite is synthesized and utilized for dye removal as a semiconducting composite. To compare photocatalytic performance of its individual oxides, cobalt oxide and iron oxide were ...
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Photocatalytic treatment of wastewater from azo dyes with semiconductors promises efficient method to refine water. Cobalt ferrite is synthesized and utilized for dye removal as a semiconducting composite. To compare photocatalytic performance of its individual oxides, cobalt oxide and iron oxide were synthesized by the same route and applied to water treatment. In this work, cobalt ferrite, cobalt oxide and iron oxide nanoparticles were synthesized as photocatalysts by employing wet chemical method with chloride precursors respectively (CoCl2.6H2O & FeCl3.6H2O, CoCl2.6H2O, FeCl3. 6H2O). The synthesized photocatalysts were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and field emission scanning electron microscopy (FESEM). The obtained photocatalysts were coated on glass by Dr Blade method. The degradation of Acid Black 1 (AB1) and Reactive Red 4 (RR4) by cobalt ferrite, cobalt oxide and iron oxide was carried out under UV light irradiation to investigate their photocatalytic activities. FeO nanoparticles were found as the best photocatalyst to achieve maximum degradation of Azo dyes. The high degradation performance of FeO can be attributed to photo-Fenton phenomena-like furthermore photocatalytic process. The Degradation rate of AB1 by photocatalysts decreases in the order of FeO > Co3O4> CoFe2O4. The photocatalytic degradation kinetics of AB1 using photocatalyst nanoparticles was found to be the first order kinetic rate. For RR4, CoFe2O4 followed first order, FeO and Co3O4 followed second order kinetic rate. Presence of iron oxide in cobalt ferrite improved the photocatalytic performance.
Marjan Tanzifi; Marzieh Kolbadi nezhad; Kianoush Karimipour
Abstract
The present work seeks to investigate the ability of polypyrrole/titanium dioxide nanocomposite to adsorb cadmium ions from aqueous solution. The impact of various experimental conditions, including solution pH, adsorbent dosage, adsorption time and initial concentration on the uptake of cadmium were ...
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The present work seeks to investigate the ability of polypyrrole/titanium dioxide nanocomposite to adsorb cadmium ions from aqueous solution. The impact of various experimental conditions, including solution pH, adsorbent dosage, adsorption time and initial concentration on the uptake of cadmium were studied. The adsorption kinetic was studied with the first-order, second-order, pseudo-first-order, pseudo-second-order and Morris–Weber models. The results revealed that adsorption process is controlled by pseudo-second-order model which illustrated that the adsorption process of cadmium is chemisorption-controlled. The adsorption capacity obtained from this model is 20.49 mg/g which close to the experimental value. The study yielded the result that when the initial concentration of the solution changed from 20 mg/l to 120 mg/l, the adsorption capacity increased from 0.99 to 24.52 mg/g. Further, Langmuir, Freundlich and Temkin isotherm models were applied to investigate the adsorption isotherm. Based on the results of the adsorption isotherm, Freundlich isotherm proved to be the best fit with the experimental data. Also, the morphology, chemical structure and thermal stability of adsorbent were studied by using SEM, EDX, FTIR, and TGA.
Taher Yousefi; Meisam Torab-Mostaedi; Amir Charkhi; Abolfazl Aghaei
Abstract
An uptake of Cd(II) from aqueous solutions by ion exchange on Iranian natural zeolitic (TOSKA) has been studied. Experiments were carried out using batch method as a function of the initial concentration of metal ions, contact time, and temperature. The adsorbent is characterized using XRF, FTIR, TEM, ...
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An uptake of Cd(II) from aqueous solutions by ion exchange on Iranian natural zeolitic (TOSKA) has been studied. Experiments were carried out using batch method as a function of the initial concentration of metal ions, contact time, and temperature. The adsorbent is characterized using XRF, FTIR, TEM, and XRD. The TEM images showed that the zeolite particle sizes are reduced into the size range of less than 90 nm by means of ball milling. The characterization of sample indicates that the natural zeolite used in this study was classified into clinoptilolite. Equilibrium modelling data were fitted to linear Langmuir and Freundlich models. Thermodynamics parameters such as change in free energy (ΔG◦), enthalpy (ΔH◦) and entropy (ΔS◦) were also calculated. The negative values obtained for ΔG◦ indicated that the sorption of Cd(II) on natural zeolite was spontaneous at all studied concentrations. These results show that natural zeolites hold great potential to remove Cd(II) from industrial wastewater.
Marjan Tanzifi; Mohsen Mansouri; Maryam Heidarzadeh; Kobra Gheibi
Abstract
In the present study, adsorptive properties of Polyaniline (PAn) were investigated for Amido Black 10B dye in aqueous solution. Different variables, including adsorption time, adsorbent dosage, solution pH and initial dye concentration were changed, and their effects on dye adsorption onto PAn nano-adsorbent ...
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In the present study, adsorptive properties of Polyaniline (PAn) were investigated for Amido Black 10B dye in aqueous solution. Different variables, including adsorption time, adsorbent dosage, solution pH and initial dye concentration were changed, and their effects on dye adsorption onto PAn nano-adsorbent were investigated. The study yielded the result that an increase in pH decreases the adsorption efficiency of nano-adsorbent. Also, Dye adsorption capacity increased with increase in the initial dye concentration. Optimum adsorption time and nano-adsorbent dosage were obtained 30 min and 0.1 gr, respectively. Kinetic studies illustrated that the Amido Black 10B dye adsorption process onto PAn nano-adsorbent followed the pseudo-second-order model, which indicates that the adsorption process is chemisorption-controlled. Also, adsorption equilibrium data were fitted to Freundlich isotherm. The maximum dye adsorption capacity, predicted by the Langmuir isotherm, was 142.85 mg/g. Moreover, Dubinin-Radushkevich isotherm showed that the adsorption of dye onto PAn nano-adsorbent is a chemisorption process.