Abstract: The thermodynamic properties of merlinoite in the process of ion exchange were simulated by Density Functional Theory（DFT）.It can be found that the process of K+-Na+ and K+-NH4+ ion exchange for Na-merlinoite and NH4-merlinoite respectively was an exothermic reaction，however，the process of Na+-NH4+ ion exchange for NH4-merlinoite was an endother- mic reaction.Meanwhile，merlinoite was prepared by hydrothermal method and characterized by X-ray diffraction（XRD），Fourier transform infrared spectrum analyzer（FT-IR） as well as scanning electron microscopy（SEM）.The sample was modi- fied successively with NH4Cl and NaCl heated solution.Then，adsorption kinetics of separating potassium from simulated sea- water with the sample modified were investigated.Results indicated that the modified merlinoite had the same framework structure as the synthetic merlinoite；the adsorption ratio of potassium from simulated seawater for NH4-merlinoite was more rapid than that for Na-merlinoite；in addition，the adsorption kinetics of the merlinoite was best described by pseudo-second-order kinetic equation and the ion exchange process was controlled by liquid film diffusion.

Key words: merlinoite, ion exchange, thermodynamic simulation, kinetics