Separation And Purification Of Vanadium Using Capacitive Deionization With Resin/active Carbon Composite Electrode

Roasting-leaching is usually a kind of vanadium shale extraction technology.The characteristic of this technology are high leaching rate,high energy efficiency and low pollution.However,by means of strong acid leaching which has low selectivity,the vanadium acid leaching solution have many kinds of impurity ions,and the concentration of impurity ions of the vanadium leaching solution is quite high,which would influence vanadium precipitation technology to produce unqualified vanadium product.In this study,capacitive deionization technology(CDI)is used to recover and refine vanadium.The physical and chemical properties of composite electrodes were studied.The appropriate recovery and purification technology was determined.The adsorption performances of composite electrodes and active carbon(AC)electrodes are also compared.The adsorption process theory of composite electrodes was built.And then,the cycling stability of composites electrodes was researched.The main conclusions are as follow:1.During the experiments of recovery and purification V(V),the appropriate conditions is follow: pH=2.5,voltage = 1.0 V.Under the appropriate conditions,the V(V)adsorption capacity of D201/AC composite electrodes is 127 mg/g,which is about 69% higher than AC electrodes.During the experiments of recovery and purification V(IV),D860 resin was selected to preparing composite electrodes due to high adsorption capacity and outstanding properties of three kinds of composite electrodes(D860,D001,D840).The appropriate conditions is follow: pH=2.0,voltage = 1.0 V.Under the appropriate conditions,the V(IV)adsorption capacity of D860/AC composite electrodes is 37 mg/g,which is about 142% higher than AC electrodes.2.By means of analyzing SEM-EDS image?FTIR results and desorption solution ions concentration,the adsorption process theory of ion exchange/AC composite electrodes was speculated as follow: Firstly,ions would move to surface of electrodes under the effect of electric field,and be adsorbed by double electrode layer under the effect of electrostatic force.Secondly,ions would pass through the pore of electrodes,and be fasten by resin by means of ion exchange reaction.What's more,by means of substep desorption technology,vanadium can be refined again.3.By cycling adsorption-desorption experiments,the recovery and purification of vanadium can be effectively realized by using composite electrodes.Moreover,according the results of cycling experiments,both kinds of composites electrodes had stable adsorption capacity,which indicated composites electrodes have high cycling usage stability.According to ions concentration of desorption solutions,both composite electrodes have more efficient recovery and purification for V than resins.