Cadmium removal from aqueous solutions using olive stone activated carbon

Activated Carbon (AC) was made from olive stone (OS), which is the basic material in olive industry wastes, by chemical treatment using phosphoric acid H3PO4 at 80 % concentration, then a heat treatment at 500 degrees C for two hours. Olive stone activated carbon (OSAC) was used as an adsorbent to remove Cadmium from aqueous solutions. The morphological and functional groups of the OSAC were determined by SEM, XRD, and FTIR analysis. The optimal conditions for the removal process were studied, and the results showed that the conditions required to reach the highest removal capacity are as follows: contact time of 180 min, particle size of ds <= 100 mu m, solution pH of 6-7 and OSAC concentration of 0.1 g per 25 mL. The results showed that the adsorption in this study follows the Freundlich model with the correlation coefficient (R2 = 0.9943) with maximum removal efficiency (91.6 %), which indicates that the adsorption is competitive and the effective sites are not equal in adsorption capacity.