Abstract: Cryptomelane-type hydrous manganese dioxide (CRYMO) was prepared by using manganese sulfate and potassium permanganate as raw materials. Potassium ion-sieve（CRYMO-H）with a crystal structure of α-MnO2 was obtained by acid-modification of CRYMO. CRYMO-H showed a high saturated ion-exchange capacity for K+ as measured as 4.6429mmol (181.54mg) K+/g ion-sieve in 0.1mol/L K+ solution. The exchange isothermal curves of H+-K+ on CRYMO-H were measured at 15℃，25℃，35℃，45℃ respectively. The activity coefficients were calculated by using Pitzer electrolyte solution theory，other thermodynamic constant such as equilibrium constant ， ， and during the exchange process were obtained. The equilibrium constant reduced with increasing temperature，the selectivity of CRYMO for K+ was higher than the original ion (H+)，the exchange process was exothermic and spontaneous( <0).

摘要： 以硫酸锰和高锰酸钾为原料合成隐钾锰型水合二氧化锰（CRYMO），酸改型后得晶体结构为α-MnO2的钾离子筛（CRYMO-H）。CRYMO-H对K+的饱和交换容量达到4.6429 mmol (181.54 mg) K+/g离子筛，对钾离子有较高的表观交换容量。测定了15、25、35、45℃下CRYMO-H对H+-K+体系的离子交换等温线，采用Pitzer电解质溶液理论计算出该离子交换体系的活度系数，得到H+-K+交换的平衡常数 、 、 和 等热力学函数。结果表明： 随温度的升高而降低、CRYMO-H对K+的选择性大于原来可交换阳离子H+的选择性、吸附钾的过程是自发过程（ <0），该离子交换反应是放热反应。