Cobalt (II) removal from aqueous solutions by adsorption on modified peat moss [articol]

Abstract

The adsorption behaviour of cobalt (II) from aqueous solutions on un-treated and treated peat moss was investigated. The treatments suppose the mixing of peat moss with 0.2 mol/L aqueous solution of HNO3 and NaOH, respectively. The influence of initial solution pH, peat moss dose, initial cobalt (II) concentration and contact time, was studied in batch experiments. The optimum results were obtained at pH = 6.0 (acetate buffer), an adsorbent dose of 5 g/L and an initial concentration of 240 mg Co(II)/L. The experimental results have show that in case of peat moss treated with NaOH, the adsorption capacity increase with 15 % and the contact time necessary for to attain the equilibrium decrease until 15 min. In case of peat moss treated with HNO3, the adsorption capacity slowly decrease and the contact time required for to attain the equilibrium has almost the same value as un-treated peat. The adsorption process of cobalt (II) on un-treated and treated peat moss was tested with Langmuir isotherm model and the isotherm constants were deduced from this.