Exchange Behaviour of Trace Element Cations viz. Co2+, Ni2+ and Mn2+ in Mixed (heteroionic) Clays in Presence of Different Major Cations

Department of Applied Chemistry, University College of Science, Calcutta 9

Manuscript received 10 February 1972; accepted 10 September 1973

Exchange behaviour of the trace element cations were studied in alkaline to acidic clays where clays had different degrees of saturation in respect to trace cations. The release of Co²⁺, Ni²⁺, and Mn²⁺ ions by H⁺ ion was studied by using varying concentrations of H₂SO₄ and H-resin.

The release of M₁²+ (where M₁²+ is either Co²⁺ or Ni²⁺ or Mn²⁺) was found to increase with increase in the proportion of M₁²+ in clays and is also a function of H+ concentration. The order of release of the metal ions is Mn²⁺ > Ni²⁺\(\geq\) Co²⁺ in case of exchange by H⁺ of H₂SO₄ and is Ni²⁺ \(\approx\) Co²⁺ > Mn²⁺ in case of exchange by H⁺ of H-resin. The effect of complementary cations, viz., Mg²⁺, Ca²⁺ and H⁺, with the exception of Na⁺, was found to be very small and may be stated as H⁺ \(\geq\) Mg²⁺ \(\geq\)Ca²⁺ > Na⁺ and the effect of Na is considered to be probably due to the high pH of the clay.