Prospective and comparative Novel technique for evaluation the affinity of alginate for binding the alkaline-earth metal ions during formation the coordination biopolymer hydrogel complexes

Abstract

A prospective novel technique has been developed for evaluation the capacity of alginate as a natural polymer absorbent for binding Ca (II), Sr (II) and Ba(II) as alkaline earth metal ions for formation of coordination biopolymer hydrogel complexes. This method was based on avoiding the non-chelated metal-ions which may present free into the interstitial spaces of the spongy network of the alginate matrix. Neglecting of non-chelated metal ions in the various techniques will lead to miscalculation in the definite concentration of the binding metal ions. Hence, some uncertainty and dissimilarity were observed in the reported data with respect to the alginate capacity for binding the metal ions. Therefore, a novel technique for more precise determination was achieved by synthesis of coordination metal alginate gels of granule nature which are free from such non-chelated metal ions. Here, the true binding metal ions were eluted by addition of dilute HClO₄ and the concentration of the metal ions into the effluent was determined, conductometrically. The experimental results indicated that the capacity of alginate was decreased in the order Ba²⁺ > Sr²⁺ > Ca²⁺ ions in good accord with their thermal stability. The factors affected the affinity of alginate for binding the metal ions were interpreted and discussed.

Keywords: Alginate; Alkaline earth metal ion; Capacity.