The effect of complex-forming agent (EDTA) on the exchange of manganese ions on calcium-montmorillonite - I. Reaction scheme and calcium-montmorillonite Na(2)EDTA system

摘要

The possible reactions in the calcium-montmorillonite-Mn(ClO4)(3)-Na2EDT system are shown. In addition, the effect of EDTA on the distribution of calcium ions between the surface of montmorillonite and solutions with different pH values and EDTA concentrations is studied. The results are interpreted by the principles of Schubert's method for the simultaneous ion exchange and complex-formation reactions. The significant role of pH is observed. An expression is deduced which is suitable for the calculation of the ratio between "free" calcium ions and total calcium concentration of the solution if we know pH, the total concentration of the complex-forming agent, its pH-dependent a parameter and the stability constants of its complexes. (C) 1998 Elsevier Science B.V. [References: 34]