Adsorption potential of bentonite and attapulgite clays applied for the desalination of sea water

Abstract

A possible new process for the partial desalination of seawater is to use bentonite clay or attapulgite as an adsorbent. The ion exchange property of these clays, which is a result of the characteristic t-o-t layer structure, enables the use of these materials as adsorbents. This technique has the opportunity to be used as a pre-treatment as current commercial seawater desalination processes are very expensive. The clay was characterized using XRD, XRF and SEM analyses. To ensure maximum adsorption of all possible elements onto the clay, burnt dolomite (CaO.MgO) was added to the solution to raise the pH. It was found that adsorption of Ca, Mg, K and Na onto bentonite clay and attapulgite follow pseudo-second order kinetics and the Langmuir isotherm model. With the increase in the pH higher adsorption capacities were obtained. FTIR analyses show that the OH - functional group is responsible for the metal adsorption