Biosorption of copper from aqueous solutions by date stones and palm-trees waste

The removal of toxic metals from wastewaters by biosorption, based on the metal-binding capacities of various biological materials, has received much interest. However, the success of this approach depends on economic feasibility, which can be obtained by optimization of the environmental conditions. This paper evaluates, for the first time, the use of low-cost biosorbent (date stones (DS) and palm-tree waste (PTW)) to eliminate Cu(II) from aqueous solutions. The effect of some parameters on copper biosorption has been studied using date stones and palm-tree waste as solid sorbents. Results show that the highest percentage of copper adsorption was obtained for the smallest size of the sorbent particles. The biosorption process was found to occur rapidly, i.e. the maximum sorption capacity was reached within 20 min. The process involved pseudo-second-order kinetics with an activation energy value within the normal range considered for processes, where a physical interaction between the sorbate and the sorbent solid predominated. The thermodynamic parameters of the copper ions uptake onto the solid sorbents indicated that, the process was endothermic and proceeds spontaneously from the date stones. However, the thermodynamic studies of the adsorption of copper on palm-tree waste indicated that the process was exothermic and proceeds spontaneously.