Removal of Nickel ions from aqueous solution using peppermint stem powder

Abstract

   In this work, peppermint stems (PMS) which were  collected from Baghdad area, is a wild plant, samples were dried and ground to particle size of about  200-500µm, and washed repeatedly with plenty of deionized water to remove all soluble materials. The PMS samples thus prepared  were  used for removal of Ni (II) ions from aqueous solution. Adsorption of Ni(II) ions onto PMS was found to be pH dependent and maximum removal of Ni(II) ions were obtained at pH 7. The adsorption kinetic data of Ni (II) onto PMS was best fitted with the Pseudo-second-order kinetic model. The equilibrium data were also fitted well with the Langmuir and Freundlich isotherm models. From R_L values, it was concluded that the adsorption of Ni(II) onto PMS was favored. The activation energy E_a of the adsorption process was determined and found to be 7.7 KJ mol^-1 for the adsorption of Ni(II) onto PMS reflecting the physisorption process