ADSORPTION-DESORPTION KINETICS OF POTASSIUM AS INFLUENCED BY TEMPERATURE AND BACKGROUND ANIONS

Adsorption-desorption kinetics of potassium as influenced by temperatu re and background anion was investigated on soil samples of a typical alluvial profile (Tulewal loamy sand, Udic Ustochrepts) using continuo us stirred flow reaction technique. Cumulative K adsorption decreased with increase in temperature from 298 K to 313 K and the decrease was more conspicuous in lower depths, where total adsorption of K was high er due to higher clay content and micaceous and vermiculitic clay mine rals. Chloride as background anion helped in relatively higher K adsor ption as compared to ClO4- ions. Apparent rates of K-exchange as calcu lated from first-order equation increased with increase in temperature and with change from Cl- to ClO4- as background anion. Although appar ent desorption rate coefficient, (kd') was 2-3-fold lower than apparen t adsorption rate coefficient, (ka'), but effect of increased temperat ure was more glaring in desorption of K; while adsorption rate increas ed by 25 to 36.5% with increase in temperature, corresponding increase in desorption rate was from 38.5 to 69.0%. (C) 1998 Elsevier Science B.V.