Metal ions sorption equilibrium on chitosan foamedstructure

摘要

In this study, experiments were carried out to estimate sorptivity of a chitosan foamedstructure and its selectivity towards Cu+2, Zn+2 and Cr+6 ions. In the case of single ions itwas found that in the whole range of concentrations, experimental data were welldescribed by the Langmuir-Freundlich equation which is a relationship between theamount of adsorbed metal per adsorbent mass unit and equilibrium concentration of thesolution. A mathematical description of sorption isotherms of the analyzed ions in thepresence of one or two additional ions in the solution is complicated from the theoreticalpoint of view. In this case the application of a neural MLP network was proposed. Thenetwork consisted of three inputs corresponding to equilibrium concentrations ofparticular components, a hidden layer and an output layer. On the basis of availableexperimental data in the so-called process of network training, the number of hiddenneurons and weights of neurons combinations were given. Calculations with the use ofMLP enabled description of sorption isotherms for one ion, for selected two and forthree ions present at the same time in the solution. The network enabled also an analysisof sorption of the selected ion, taking into account the effect of its concentration on thesorption of other ions. This assessment would not be possible in an experimental wayonly.