Abstract:Investigation of interactions and energy relationships between cations (Na+、K+、NH4+、Ca2+、Zn2+, and Cd2+) and clay fraction of red soil with the aid of Wien effect in dilute suspensions Results show that the mean Gibbs binding energies of the clay fraction of red soil with cations are 4.50, 7.35, 7.15, 9.12, 9.84, and 9.63 kJ mol-1 for Na+, K+, NH4+, Ca2+, Zn2+, and Cd2+, respectively, in the experimental condition. Electric conductivity increased very fast with field strength in the suspension containing Ca2+, at a similar rate in the suspension containing K+, Zn2+ or Cd2+, but very slowly in the suspensions containing Na+ or NH4+. In terms of releasing rate, the cations in the red soil suspension are in the order of Ca2+ > K+ > Zn2+ = Cd2+ > Na+ = NH4+. The mean Gibbs free adsorption energies, ΔGad, of the cations remained basically the same when the field strength was in the range of 15 to 80 kV cm-1 , but when the field strength reached over 100 kV cm-1 ΔGad of the divalent cations were more obviously higher than of the monovalent cations, following an order of NH4+ ≤Na+ < K+ < Cd2+ < Zn2+ < Ca2+. However, when the field strength got high up to 150 kV cm-1, ΔGad of the cations were 0.64, 0.80, 0.57, 1.66, 1.43, and 1.27 kJ mol-1 for Na+, K+, NH4+, Ca2+, Zn2+, and Cd2+, respectively, which shows that the mean Gibbs free adsorption energy of the divalent cations were about 2.5-3 times as much as that of the monovalent cations. The cations in the red soil suspensions at a low field strength ranging from 10 to 30 kV cm-1 showed a decreasing order of Na+ >> K+ = NH4+ > Ca2+ > Zn2+ = Cd2+ in mean dissociation degree. The increasing rate of mean dissociation degree, which is the increment of dissociation degree induced by the increment of 1 kV cm-1 in field strength, is the highest with Na+ being 0.000427 cm kV-1, the second with Ca2+ being 0.000221 cm kV-1, and the lowest with other cations in the range of 0.00012~0.00014 cm kV-1.