Preparation Of Cupric Hexacyanoferrate Based Composite Electrodes And Their Electrochemical Performance For Cesium Recovery

Rare alkali metal cesium is a critical worldwide strategic resource.Our country is abundant in liquid cesium resources stored in the Qinghai salt lakes and Tibet geothermal water.Therefore,the study on efficient recovery of cesium from liquid cesium resources has important academic significance and significant social and economic significance.The Cs recovery using the electrically-switched ion exchange technology has various advantages,including simple equipment,green,and high efficiency.At the same time,it is scarcely reported for cesium recovery from liquid cesium resources like geothermal water by electrochemical method.In this thesis,high-performance cupric hexacyanoferrate-based composite electrodes were synthesized and used for the electrochemical recovery of Cs⁺in geothermal water.The main results are summarized as follows:（1）Highly dispersed nanoscale cupric hexacyanoferrate@porous carbon（Cu HCF@PC）was synthesized firstly,and the Cu HCF@PC electrode was prepared using Cu HCF@PC as active material,Nafion as a binder and carbon cloth as a collector.The effects of reduction potential,initial concentration,time,competitive ions,and eluant concentration were investigated by cyclic voltammetry and chronoamperometry.Under the optimum electrochemical adsorption conditions,the Cu HCF@PC electrode could reach adsorption equilibrium within 10 min and the maximum adsorption capacity was 270 mg/g.The electrochemical adsorption experiments in complex geothermal water showed that the Cu HCF@PC had high selectivity for Cs⁺,and the distribution coefficient was 7471 m L/g Moreover,the desorption experiments that were carried out at 1 V oxidation potential with Cs NO₃ as eluent indicated the adsorption performance of Cu HCF@PC electrode was not significantly reduced after fourtimes adsorption-desorption cycles,and the recovery of Cs⁺could reach 75%.（2）The cupric hexacyanoferrate@nanocellulose membrane electrode（Cu HCF@CNF）was prepared by vacuum filtration using nanocellulose rich in carboxyl groups as raw materials.Under the optimum electrochemical adsorption conditions,the Cu HCF@CNF electrode can reach adsorption equilibrium within 15 min and the maximum adsorption capacity can reach 220 mg/g.However,Cu HCF@CNF still had high selectivity for Cs⁺,and the distribution coefficient was 4690 m L/g.After fivetimes adsorption-desorption cycles in the geothermal water,the concentration of Cs⁺in the eluent can be enriched to 1.5 times of the original solution.This inexpensive,green,stable and easily prepared Cu HCF@CNF membrane material is expected to achieve Cs⁺recovery in complex geothermal water.