Adsorption of Copper and Zinc from Aqueous Solutions by Bentonite

Abstract

Bentonite has been used as an adsorbent for the removal of Cu²⁺

and Zn²⁺ ions from aqueous solutions via adsorption. The effect of the

adsorbent amount, pH of suspension, solution concentration and temperature

and the contact time on adsorption was investigated. The amount

of Cu²⁺ and Zn²⁺ ions adsorbed increased with increasing adsorbent

amount, pH and temperature and with decreasing concentration. The

adsorption parameters were obtained using Reciprocal Langmuir,

Langmuir, Linear Freundlich, Freundlich and Langmuir-Freundlich

isotherm models by use of non linear regression analysis. The adsorption

isotherm studies indicated that adsorption was consistent with the Reciprocal

Langmuir isotherm model. Results of the thermodynamic studies

indicated that the adsorption of both ions on bentonite was spontaneous

and favourable and an endothermic nature of adsorption. A pseudosecond

order equation described the adsorption process for either Cu²⁺

or Zn²⁺. The results of this study demonstrated that the bentonite is a

potential adsorbent for the removal of Cu²⁺ and Zn²⁺ ions from aqueous

solutions.