A comparative study of copper and zinc ion adsorption on to activated and non-activated date-pits

Date-pits (an agricultural by-product available commercially) were utilized, with and without activation, as an adsorbent for the removal of Zn2+ and Cu2+ ions from aqueous solutions. Activated carbons were prepared from date-pits by carbon dioxide activation at 700degreesC. The effects of contact time, pH, temperature and the adsorbent concentration on the removal of Zn2+ and Cu2+ ions were studied. The Freundlich isotherm model described the equilibrium adsorption data. Non-activated date-pits exhibited higher Zn2+ and Cu2+ ion uptake than activated date-pits. The uptake of Cu2+ ions by both activated and non-activated date-pits was higher than the uptake of Zn2+ ions. The uptake of both metal ions increased on increasing the pH value of the system from 3.5 to 5.0 as well as on decreasing the temperature from 50degreesC to 25degreesC. Adsorption capacities for the non-activated date-pits towards Cu2+ and Zn2+ ions as high as 0.15 mmol/g and 0.09 mmol/g, respectively, were observed. This study demonstrated that date-pits without any physical or chemical pretreatment could be used as an effective adsorbent for the treatment of waters containing heavy metal ions such as Zn2+ and Cu2+.