锰型离子交换剂的合成及对K^+的离子交换动力学研究

Synthesis of Manganese-type Ion Exchanger and Its Exchange Kinetics with K^+

用高锰酸钾和硫酸锰合成出隐钾锰型水合二氧化锰(CRYMO)前躯体,对前躯体酸改性制得隐钾锰型水合二氧化锰,并对其进行了粉末X射线衍射分析,测定了其对K+的饱和交换容量和25℃时对0.1 mol.L-1K+的离子交换动力学。结果表明,制备CRYMO交换剂的较佳条件为KMnO40.5 mol.L-1,MnSO42.0 mol.L-1,n(KMnO4)∶n(MnSO4)=1∶2,反应温度75℃,酸浸时硝酸浓度5 mol.L-1。其晶体结构为α-MnO2。每克交换剂CRYMO对K+的饱和交换容量达到181.5 mg。用几种不同的吸附模型关联交换剂CRYMO对0.1 mol.L-1K+的离子交换动力学数据,得出适宜的动力学模型Bangham模型,交换剂对K+的离子交换动力学方程是lgQ=-0.892 23+0.627 47lgt(25℃)。

Cryptomelane-type hydrous manganese dioxide（CRYMO） precursor was synthesized using potassium permanganate and manganese sulfate as raw materials. CRY- MO was obtained by acid-modifying of the precursor and characterized by XRD. Its saturated exchange capacity and ion exchange kinetics for 0.1 mol·L^-1 K＋ at 25 ℃ were determined. The obtained optimum conditions for preparing CRYMO were KMnO4 concentration 0.5 mol·L^-1 , MnSO4 concentration 2.0 mol·L^-1, n（KMnO4 ） · n（MnSO4 ） = 1 ： 2,reaction temperature 75 ℃ and concentration of HNO3 for acid-modifying 5 mol · L^-1. The crystal structure of CRYMO was a-MnO2 and its saturated exchange capacity of 1 g CRYMO for K＋ was 181.5 rag. The ion exchange kinetic data of CRYMO for 0.1 mol · L^-1K＋ were related with different adsorption models and the results showed that the optimum kinetic model was Bangham and the kinetic equation was lg Q = -0. 892 234-0. 627 471g t（25℃）.