Removal of metal ions from aqueous solution by adsorption on the natural adsorbent CACMM2

The adsorption of Cd+2, Cr+3, Cu+2, Fe+3, Ni+2, Pb+2 and Zn+2 from aqueous solution was used to study the sorption properties of the adsorbent CACMM2 extracted from a cactus. Quantitation of the cation concentrations was performed by HPLC with diode array detection using on-column complex formation with 8-hydroxyquinoline. Removal degree from 100 mg Mn+ l(-1) solutions followed the series: Cu > Cd > Fe > Ni > Cr > Zn. Henry and Freundlich constants were determined since adsorption did not reach saturation plateaux in the studied concentration interval. Sorption of chromium by CACMM2 was stronger than the sorption onto lignin, calcium oxalate and cellulose up to 1000 mg Cr3+ l(-1). Copper and iron were desorbed to a greater extent, while lead adsorption was practically irreversible. CACMM2 was able to remove more than 83% of chromate in a freshly prepared and exhausted chromate commercial solution. (C) 2001 Elsevier Science B.V. All rights reserved.