Removal of metal ions from aqueous solution on low cost natural polysaccharides - Sorption mechanism approach

The fixation of Cu2+, Ni2+ and Pb2+ on sugar beer pulp, a low-cost material , has been studied. After a simple treatment of the sorbent, the results ha ve shown that the mode of fixation depends on the metal. The key part of th e mode of fixation is attributed to ion exchange, while a non-negligible pa rt of adsorption could sometimes occur. As far as lead ions are concerned, 25% of their fixation capacities are due to adsorption mechanism at pH 4. T he overall uptake is at a maximum at pH 6 and gives up to 60 mg g(-1) for P b2+, 30 mg g(-1) for Cu2+ and 12 mg g(-1) for Ni2+, which seems to be remov ed exclusively by ion exchange. These capacities increase with the pH. Diff usion models have been tested on samples of different particle size, and th ey have suggested a transfer to the intraparticular sites. (C) 2000 Elsevie r Science B.V. All rights reserved.