M. Erhayem; R. Gaith; O. E. Otman; M. U. Frage
Abstract
Palm kernel (PK) was activated by chemical activation (HNO3 at 230oC) to remove Ni(II) ions from aqueous solutions. Physicochemical properties of PK were reported. FT-IR analysis revealed changes in wave numbers and absorbance indicating Ni(II) adsorption onto activated carbon-PK surface. Energy dispersive ...
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Palm kernel (PK) was activated by chemical activation (HNO3 at 230oC) to remove Ni(II) ions from aqueous solutions. Physicochemical properties of PK were reported. FT-IR analysis revealed changes in wave numbers and absorbance indicating Ni(II) adsorption onto activated carbon-PK surface. Energy dispersive X-ray fluorescence technique was used to determine the content of metals in activated carbon-PK and showed the metals found in activated carbon-PK were in recommended human usages. The maximum removal of Ni(II) ions was to be 49.7% at pH 4.6 and the equilibrium reached at 80 min. The removal efficiency of Ni(II) ions increased as the dosage of activated-PK increases and the optimum amount of activated carbon-PK dose was found to be 70 mg. The optimum pH was 4.6. The isotherm, kinetics and thermodynamics were studied. The Ni(II)- activated carbon-PK adsorption was found to follow the Freundlich isotherm based on correlation coefficient (R2) values and to be physical adsorption from the mean free energy found by Dubinin-Radushkevich, which confirmed by isothermal microcalorimetry data and the heat of sorption process using Temkin Isotherm model to be 1.58 kJ/mol. The adsorption kinetic data were described well by a second order, with the kinetic constant rates in the range of 1.82-83.5 g/g.min and was not controlled by intra-particle diffusion model. The thermodynamic studies showed that the Ni(II)-ACPK adsorption process is exothermic due to the negative values of ∆H (-30.9 J/mol) and is physical nature process due to the negative values of ∆S (-14.9 J/mol). The magnitude of Ea is 15.04 kJ/mol, which is proven the physical adsorption in nature.
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.