Study On Dynamic Adsorption Characteristics And Mechanism Of CDI Porous Electrode Based On Pore Scale

Capacitance deionization(CDI)is a new technology which can rapidly remove charged ions from salt solution.The technology is to make the salt solution flow through a channel composed of a pair of charged electrodes to realize the adsorption and separation of ions in the solution under the action of electric field.Compared with distillation,reverse osmosis and other traditional desalination technologies,CDI has attracted more and more attention due to its low operating cost,environment friendly and high desalination efficiency.In order to research the desalting mechanism of capacitive deionization technology,the flow between electrodes CDI(FBE CDI)unit experimental device was designed and assembled,and the CDI desalination performance experiment was carried out under different operating parameters by using the device.On this basis,the CDI desalination mechanism analysis was carried out.In addition,the lattice Boltzmann method was used to simulate and analyze the dynamic mass transfer and adsorption process of ions in the CDI porous electrode at the pore scale.The main research contents are as follows:(1)Experimental researchingA small-scale FBE CDI cell was designed and assembled,and a complete CDI desalination system was built to study the capacity deionization performance.Scanning electron microscope(SEM)was used to analyze the surface morphology of the activated carbon electrode;cyclic voltammetry(CV)was used to analyze the electrochemical performance of CDI porous electrode;the influence of working voltage,inlet concentration flow rate and other parameters on the desalting effect of CDI was studied to provide basis for the selection of operating parameters in the desalting process of CDI;isothermal adsorption model and adsorption kinetic model were used to analyze The adsorption process of ions in solution by CDI porous electrode was analyzed,and the desalting mechanism of CDI was studied.(2)LBM simulation researchingFor the porous electrode negative electrode of FBE CDI unit,a two-dimensional digital skeleton model of CDI porous electrode was constructed using a simplified structure.The Navier-Stokes equation,the concentration diffusion equation and the Langmuir adsorption model were coupled to solve the solution.The dynamic mass transfer and adsorption processes of salt solution in CDI porous electrode were simulated,and the influences of inlet velocity,porosity and particle size on the adsorption performance of CDI porous electrode were investigated.