Binding of divalent metal cations by sugar-beet pulp
1997; Elsevier BV; Volume: 34; Issue: 1-2 Linguagem: Inglês
10.1016/s0144-8617(97)00055-6
ISSN1879-1344
AutoresV.M. Dronnet, Catherine M.G.C. Renard, Monique Axelos, Jean‐François Thibault,
Tópico(s)Electrostatics and Colloid Interactions
ResumoThe binding of divalent metal cations (Ca2+, Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+) by sugar-beet pulp was studied. In the presence of 0.1 m NaNO3 the level of metal cation uptake was found to reach its maximum value very rapidly with the speed increasing both with the sugar-beet pulp concentration and with increasing initial pH of the suspension. Using a pH-metric method and by comparing binding isotherms drawn by measuring the free cation concentration after equilibration, a clear scale of decreasing selectivity was found as follows: Cu2+~Pb2+⪢Cd2+~Zn2+ > Ni2+ > Ca2+. Binding followed the Langmuir-type isotherm except for Ca2+. Adsorption may contribute to the binding phenomenon in addition to ion exchange, which may include electrostatic interactions and even chelation in the case of the more strongly bound cations. Sugar-beet pulp, which is cheap and highly selective, therefore seems to be a promising substrate to entrap heavy metals in aqueous solutions.
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