Equilibrium study of binaries and ternary ion exchange systems envolving copper, cadmium and calcium ions by alginate biopolymer / Estudo do equilibrio dos sistemas binarios e ternario de troca ionica dos ions cobre, cadmio e calcio pelo biopolimero alginato

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

In this work, it was studied the ion exchange process involving copper, cadmium and calcium ions. The heavy metals, copper and cadmium, were evaluated due to its high toxicity, its presence in industrial effluent and difficulty in its removal when in low concentrations, however, above permitted levels by law. Alginate was used as ionic exchanger. In the presence of high affinity ions, such as calcium, it has the ability to gelate and form rigid particles which are suitable for ion exchange operations. These particles were obtained from different methods, such as dripping, atomization and emulsification, however, each method resulted in particles with different physical properties. Emulsification method resulted in particles of suitable diameter and size for the ion exchange process in porous bed. Among the considered methods, it showed to be the one with higher ion exchange capacity, under the same operating conditions, for batch system experiments. Therefore, ion exchange equilibrium experiments for binary systems, involving Cu-Ca, Cd-Ca and Cu-Cd ions, and ternary system Cu-Cd-Ca, were conducted in porous bed, using particles obtained by emulsification, at a flow rate of 3 mL/min and pH 4.5. These operational parameters were defined by previous studies. Binary systems experimental data were evaluated using monocomponent adsorption isotherms, which showed good behavior, however, binary adsorption isotherms models showed higher accuracy. Binary systems treatment using Ideal LAM and LAM, were satisfactory for the experimental data behavior, however, there was a considerable variation in Keq values. Activity coefficients involving ions attached to the solid phase were close to 1, which means that the alginate-metal system is close to ideality. The ternary system showed unsatisfactory results for its treatment using binary adsorption isotherms and LAM predictive model, where just ternary adsorption isotherms, Langmuir 4 parameters, Langmuir 6 parameters and Langmuir-Freundlich models showed satisfactory results

ASSUNTO(S)

ion exchange modelos matematicos alginatos metais pesados heavy metals troca ionica mathematical modeling alginates

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