Applications Of Advanced Filter Materials And Their Derivatives In Capacitive Deionization

Capacitive deionization?CDI?technology is an emerging eco-friendly desalination technology with low energy consumption and cost.It has ionic operability as well as unlimited development potential in the field of water treatment.Present researches are mainly focused on electrode materials,device structures and theoretical models of it.Most of the filter materials are porous materials,and some of them have specialized separation function.Combining these filter materials into the capacitive deionization technology can bring more possibilities to both.From the perspectives of device structures and electrode materials,this paper applied specific filter materials and their derivatives to CDI technology,aiming to explore the potential of CDI devices in the rational use of water resources and find out more eco-friendly electrode materials:From the perspective of device structures,the first work added nanofiltration filter materials to a CDI cell to form a new technique?NFCDI?that combined the advantages of CDI and NF for the separation of mono-and divalent ions.This work demonstrated the influence of adding nanofiltration membranes to a CDI cell,when desalinating mono-and divalent salt solutions both theoretically and experimentally.It is revealed that the distinction of the diffusion coefficient between mono-and divalent ions is the key to the effective separation.Combined with the appropriate time of adsorption?1.5 h?,the concentration ratio of NaCl to MgSO₄ can be increased by a factor of 3,from a mixture with equal amount of NaCl and MgSO₄.Moreover,NFCDI shows lower energy consumption?⁰.2 kWh/m³?and higher fractionation capability than NF.This work promoted the application of CDI in the rational use of water resources and the recovery of wastewater components.From the perspective of electrode materials,the second work transferred non-biodegradable cigarette filter materials into three-dimensional porous activated carbon materials via carbonization and activation processes.It was found that samples activated at 700?showed high specific surface area?1485.14 m²/g?,suitable distribution of micropores and mesopores,high specific capacitance?109.65 F/g?,low internal resistance and excellent performance in CDI desalination tests?electrosorption capacity was 12.4 mg/g,and the charge efficiency was 75.8%?.This work turned waste into treasure and reduced the production cost of CDI electrode materials to a certain extent.