G. Ramezani; S. E. Moradi; M. Emadi
Abstract
Graphene oxide based nano-composites have attracted huge attention for wastewater treatment specially removal of heavy metals. This paper reports adsorption of onto modified magnetic graphene oxide with chitosan and cysteine (GO/ /Chi/Cys). To study the adsorbent morphology, Field Emission Scanning ...
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Graphene oxide based nano-composites have attracted huge attention for wastewater treatment specially removal of heavy metals. This paper reports adsorption of onto modified magnetic graphene oxide with chitosan and cysteine (GO/ /Chi/Cys). To study the adsorbent morphology, Field Emission Scanning Electron Microscope (FE-SEM) and Fourier Transform Infrared Spectrometer (FTIR) were used in different stages of surface modification. In order to reveal the nature of sorption process, linear forms of different adsorption isotherms such as Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich were studied. Experimental data were fitted well by Langmuir model with a maximum monolayer coverage capacity ( ) of 86.21 . Prediction of from Langmuir model was in good agreement with maximum empirical adsorption capacity ( =85.4 ). Various types of kinetic models such as pseudo-first-order, pseudo-second-order, Elovich, and intra particle diffusion were investigated to determine characteristic parameters in the adsorption process. The kinetic studies showed that pseudo-second-order model represents the adsorption process better than others due to its high correlation coefficient ( =0.9996). Therefore, the adsorption process is chemisorption.
F. J. Ogbozige; M. A. Toko
Abstract
Growth in population has caused a corresponding increase in agricultural production which consequently led to an increase in agricultural wastes or byproducts. This is sometimes difficult to manage and may pose a menace to the society if not properly disposed. Hence, this research investigated the efficacy ...
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Growth in population has caused a corresponding increase in agricultural production which consequently led to an increase in agricultural wastes or byproducts. This is sometimes difficult to manage and may pose a menace to the society if not properly disposed. Hence, this research investigated the efficacy of utilizing agricultural byproduct (melon husk) in removing Pb2+ and Cd2+ from wastewaters so as to prevent their deleterious impact on ecosystem and public health. This was achieved by treating tannery effluents with melon husks modified with H3PO4, NaOH and CH4N2O. Results showed that, the Freundlich and Langmuir adsorption capacities on the modified melon husks ranged from 0.1403 – 1.551 mg/g and 0.1499 – 0.6013 mg/g, respectively. Also, the R2 values for Pseudo 1st and 2nd order rate constants ranged from 0.0272 – 0.2391 and 0.9112 – 0.9958, respectively. Hence, it was concluded that the modified melon husks followed Freundlich isotherm model as well as Pseudo-2nd order kinetics and could be effectively used to remove Pb2+ and Cd2+ from wastewater.
M. Massoud; M. Erhayem; F. Al-Tohami
Abstract
In the present study, batch adsorption experiments of hazardous cadmium ions, Cd(II), onto low-cost Dodonaeae Viscose Legs (DVLs) surface were conducted with respect to contact time, solution pH, adsorbent dosage, initial Cd concentration and temperature. Sorption isotherm, kinetic and thermodynamic ...
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In the present study, batch adsorption experiments of hazardous cadmium ions, Cd(II), onto low-cost Dodonaeae Viscose Legs (DVLs) surface were conducted with respect to contact time, solution pH, adsorbent dosage, initial Cd concentration and temperature. Sorption isotherm, kinetic and thermodynamic models were used to describe the equilibrium stage and their constants were determined. The DVLs were used without chemical or physical activation processes. The results showed that the optimum adsorption capacity of DVLs for Cd(II) ions was found to be 25.29 mg/g at solution pH 5.26, 50 min and 303K. DVL adsorption data was fitted well with Langmuir isotherm. The mean free energy was found to be 1.82E-02 using Dubinin-Radushkevich (DRK) isotherm, which indicates that the adsorption of Cd(II) ions onto DVL surface is physical adsorption. The activation energy (Ea) was 3.06 kJ/mol, which confirms that Cd(II)-DVL adsorption process is physical sorption. Pseudo-first-order, pseudo-second-order, Elovich, intra-particle and extra-particle diffusion models were used to describe the adsorption kinetics. The results show strong correspondence to a pseudo-second-order kinetics. Thermodynamic parameters suggested that the adsorption of Cd(II) ions onto DVL surface is an exothermic process.
D. Basrur; J. Ishwara Bhat
Abstract
In this study the preparation of activated carbon from agricultural product were reported. The fenugreek seeds were activated by chemical and microwave activation methods. The characterization of carbon materials were carried out using different techniques like Fourier Transform Infrared Spectroscopy ...
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In this study the preparation of activated carbon from agricultural product were reported. The fenugreek seeds were activated by chemical and microwave activation methods. The characterization of carbon materials were carried out using different techniques like Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermo Gravimetric Analysis (TGA), X-Ray Diffraction (XRD). Adsorption experiment was carried out for the adsorption of two different basic dyes, Methylene Blue (MB) and Crystal Violet (CV) under varying conditions such as concentration of dye, mixing time and adsorption temperature. The data acquired from concentration variation were found to fit well with Langmuir and also Freundlich isotherms. Kinetic studies revealed the fact that the system follows second order. Thermodynamic parameters like ΔH≠, ΔS≠ and ΔG≠ were calculated from the study on adsorption at different temperature. The adsorbent preparation via microwave technology is a desired methods which is resulted in conservation of energy for an efficient production of activated carbon.
L. E. Yahaya; A. K. Akinlabi
Abstract
The adsorption of lead (II) ions onto EDTA- modified cocoa pod husk (CPH) in an equilibrium system was investigated. Kinetics, mechanism and thermodynamic parameters were estimated. Adsorption capacity was rapid and time dependent as appreciable level of Pb (II) uptake was achieved at an optimum contact ...
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The adsorption of lead (II) ions onto EDTA- modified cocoa pod husk (CPH) in an equilibrium system was investigated. Kinetics, mechanism and thermodynamic parameters were estimated. Adsorption capacity was rapid and time dependent as appreciable level of Pb (II) uptake was achieved at an optimum contact time of 50 minutes. Three kinetic models were used to fit the kinetic data; Pseudo- first order, Pseudo-second order and intraparticle diffusion. Adsorption of the metal ions follows the Pseudo-second order and intraparticle kinetics as these provide a better fit to the experimental data with high R2 values ranging from 0.9776 – 1. Thermodynamic parameters such as change in Gibbs free energy ( ∆Go ) change in enthalpy (∆Ho), and entropy change (∆So ) were calculated. The ∆Go (-5.499kJmol-1), ∆Ho (60.36 kJmol-1) and ∆So (212.44 Jmol-1K-1) of the adsorption process of metal ions onto the modified adsorbent was found to be feasible, endothermic, spontaneous and physiosorption in nature. These results indicate that modified CPH is a promising sorbent for the removal of Pb (II) in industrial effluent and wastewaters containing same.
