Journal of Applied Chemical Science International

Selenium is recognized as toxic in excess (> 0.01 mg.L^-1). It is removed from wastewater principally through either biological or chemical/physical processes. This article will describe the removal of the selenium from the water by adsorption onto raw and modified geomaterial. (Zn-clay-rich material) which it has not yet been tested in the selenium adsorption. These materials are characterized before and after use in adsorption by various techniques, in particular XRD, ICP, FTIR, SEM coupled with EDX. The selenium adsorption efficiency was studied varying time, pH, initial solution concentration and temperature. Se(IV) adsorption was found fast reaching equilibrium within ~2 h with better performance for the sorbent. Se(IV) adsorption appears to be enhanced by low pH. Kinetic data for Se(IV) was found to follow pseudo-second order model and the Langmuir model better describe the adsorption process. A maximum amount of selenium adsorbed was registered at 8.47 mg.g^-1 for the modified material and 5.26 mg.g^-1 for the raw material. The effect of temperature on adsorption and the thermodynamic study showed that ∆G° and ∆H° exhibit positive values which shows that the Se(IV) adsorption on the different materials used is a non spontaneous and endothermic process. The desorption/regeneration process was studied by using different acids, and it appear to be the best desorption agents to regenerate selenium. The use of aqua regia gave a rate of adsorbed selenium regeneration close to 89.11%. On other hand these results indicate the significance of the modification of the material to develop a new support for the removal of the selenium.