可变电荷表面对磷的吸附与解吸动力学

研究了可变电荷表面为主的土壤对磷的吸附与解吸动力学。结果麦明,磷吸附和解吸动力学均可用修正的Elovich方程、双常数速率方程和分段拟合的抛物线扩散公式来表征。吸附和解吸过程均可分为快、慢两个反应阶段。磷吸附过程是一个扩散控制的不可逆过程.

KINETICS OF ADSORPTION AND DESORPTION OF PHOSPHATE ON VARIABLE CHARGED SURFACE

The kinetics of adsorption and desorption of phosphate oa variable-charged surface was studied and the results showed that the kinetics could be described by amended Elovich equation and two-constant rate equation. The adsorption process of phosphate is not a complete reversible phy-siochemical reaction, the reversibility might be determined by (1/m)d/(1/ m)2, For all absorbents, the adsorption rate constants, Ka, were shown in following order: G>A(Fe)>V>L>A(A1)-Si>KL. and the desorption rate , constant: A(Fe)>V>G>A(A1)-si>L>KL. The ratio of Kd/Ka could be used as an index of desorption degree of phosphate adsorbed previously. The phosphate adsorption and desorption processes can be divided into two stages, i.e., the fast reaction, which took place on the outer surface of the samples through diffusion and generally finished in 8 hours, and the slow reaction, which occured in the inner surface of the samples through diffusion and continued for over 10 days.