Adsorption of cadmium, copper, nickel, zinc and lead from aqueous solution onto Astragalus gossypinus

This paper describes a study of the adsorption conditions of cadmium, copper, nickel, zinc and lead ions onto Astragalus gossypinus (AG). Various variables affecting the adsorption capacitysuch as pH of the solution, adsorption time, initial metal ion concentration, and temperature were investigated. The metal ions were removed by AG up to 92% from an initialconcentration of 30 mg/L at pH 6.0. Kinetic data fitted very well to a pseudo-second-order rateexpression and less well to a pseudo-first-order equation. The equilibrium parameters for adsorption isotherms of the metal ions on the AG was obtained using the Langmuir, Freundlichand Temkin models, and the Langmuir model was found to be in better correlation with theexperimental data. Thermodynamic parameters such as enthalpy change, free energy change, and entropy change were calculated; the adsorption process was spontaneous and endothermic.The results showed that AG developed in this study could be an economical and effective adsorbent for application in removal of heavy metal ions from water and wastewater

کلیدواژه ها:

Isotherm ، Cadmium ، Copper ، Lead ، nickel ، Adsorption