Treatment of Alhagi Residues with Tartaric Acid for the Removal of Zn(II) Ions from Aqueous Solution

Abstract

Alhagi cellulose tartrate (ACT) with a high carboxyl group content was prepared by treatment of Alhagi residues (AR) with tartaric acid (TA) at high temperature. Factors influencing the reaction were investigated, viz. tartaric acid concentration, dehydration temperature, particle size and dehydration time. The prepared Alhagi cellulose tartrate samples were characterized using FT-IR spectroscopy and by estimation of the carboxyl group content. The esterified samples were utilized for the adsorptive removal of Zn(II) ions from aqueous solution with all the factors influencing the process being studied. These factors were the pH value of the adsorbate solution, the adsorbent concentration, agitation time and temperature. The Langmuir and Freundlich models were applied to the data obtained from the adsorption studies. It was demonstrated that the Alhagi cellulose tartrate samples could be used effectively for the adsorption of Zn(II) ions from aqueous solutions. The thermodynamics constants of the adsorption process, viz. ΔH0, ΔS0 and ΔG0, were evaluated. The results showed that the adsorption of Zn(II) ions onto ACT was exothermic and spontaneous. The adsorption data followed second-order kinetics, with the equilibrium data being only satisfactorily described by the Langmuir isotherm.