Abstract:The K+ adsorption kinetics of Fluvo-aquic soil and Cinnamon soil under different K+ concentration were studied. The results showed: (1) adsorption rate decreased with the increase in adsorption, and the relationship between them could be described with significant linear regressive equations, indicating the adsorption were fit for the first order equations; (2) the apparent adsorption rate constant ka and the product of ka multiplied by the apparent equilibrium adsorption q∞ were significantly Sinearly correlated to K+ concentration C: (3) the relationship between q∞ and C conformed to Langmuir and Freundlich isothermal adsorption equations. Based on those results the K+ adsorption kinetics was deduced, leading to four kinetics parameters n、k1、k2、qmax independent of C. With n、k1、k2、qmax the apparent parameters and free energy change △G of adsorption could be worked out, and under certain conditions n、k1、k2、qmax could also be used to judge isothermal adsorption and reckon its parameters.