Sorption of uranyl ions by a modified chitosan: Kinetic and equilibrium studies

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Abstract
The uranium sorption of an ascorbic chitosan derivative polymer (N.D.T.C. N‐[2‐(1,2‐dihydroxyethyl) tetra‐hydrofuryl] chitosan) was shown to be three to four times greater than chitosan under the same conditions, reaching 600 mgU.g−1 polymer (i.e. 2.5 mmolU.g−1 polymer). The effect of variation of the classic parameters was studied: pH, metal concentration and particle size. pH and metal concentration, which induced a change in metal solution chemistry, were found to be the controlling parameters, mainly affecting intraparticle diffusion; the diffusion rate is strongly affected by ionic size of solute, as opposed to a limited effect on external mass transfer. pH plays an important part in equilibrium studies, and sorption isotherms are mainly a function of pH. The Freundlich model shows a better correlation coefficient than the Langmuir model when fitted to experimental results; the uptake mechanism involves a monolayer sorption with molecular interactions between molecules sorbed on surface.