KINETIC OF SODIUM ADSORPTION REACTION IN SOME CALCIORTHID SOILS OF NORTHERN IRAQ

Abstract

A kinetic approach was applied for sodium adsorption reactions using miscible displacement technique. Chloride salt concentration (50, 100, 500) mmolcl-1 of calcium, magnesium and sodium were allowed to pass quietly through glass columns (30cm in length and 10cm diameter) containing five calcareous soil samples collected from Nineveh Province classified as Calciorthid . Each level of concentration consists of five different solutions with different Na/Ca+Mg ratios comparison five SAR values (1.05, 2.38, 7.08, 12.77 and 28.48mmol.l ­½ for the 50mmol-1 TEC, 1.49, 5.07, 10.0, 18.10 and 40. 3648mmol.l ­½ for the second salt solution and 3.33, 11.34, 22.36, 40.41 and 90.0048mmol.l ­½ for the 500mmolcl-1 TEC). Solutions passed through the columns were collected after 30 up to 300 minutes. Sodium adsorption reactions were described with the following kinetic equations: Zero order, first order, diffusion equation, Elovich and power function equations. The results indicated the applicability of these equations for describing sodium absorption of calcareous soils and were classified accordingly to: First order > diffusion > power function > zero order > Elovich Coefficient rates of adsorption reaction according to first order kinetic equation ranged between (2-7)10-4, (3-13)10-4 and (3-24)10-4 min-1 for the salt concentration 50.100 and 500mmolcl-1 respectively. The coefficient rates were significantly correlated with the added salt level (R2 = 0.9**).