Study On The Fouling Characteristics Of Carbon Material Based Electrode In Capacitive Deionization

Capacitive desalination?CDI?technology is one of the new technologies with energy-saving and environmentally-friendly for desalination.Along with the CDI has been applied widely in the water treatment,the CDI electrode fouling was increasingly prominent.In this study,the dynamic/cyclic composite desalting process was used to reasearching the fouling in graphene nanoribbons electrodes and ion-doped polypyrrole/carbon nanotube?PPy/CNT?composite electrodes.The results will provide some value information for the practical application of CDI technology and the preparation of anti-fouling electrodes.At first,the dynamic desalting process and cycle desalting process were used to researching the organic and inorganic fouling on the graphene nanoribbons electrodes,respectively.The advantages and disadvantages of the two methods were compared.Besides,the dynamic/cyclic composite desalting process was put forward,which was combined the advantages of dynamic desalting process and cycle desalting process.Besides,the dynamic/cyclic composite desalting process was ued to studying the fouling in graphene nanoribbons electrodes and PPy/CNT composite electrodes,respectively.In the experiments,the electrode voltage was 1.4 V and the flow rate of feed solutions was 142 ml/min.The results indicated that,Ca²⁺and Fe³⁺reduced 1.6%and 3.6%of the desalination performance for CDI electrodes,respectively.However,Ca²⁺and Fe³⁺reduced 0.5%,1%of the desalination performance for PPy/CNT composite electrodes,respectively.During the adsorption stage,the pH of solution gradually reduced and during the desorption stage the pH gradually increased.Moreover,the pH range of NaCl solution with the graphene nanoribbons was3.22-10.21,and it with PPy/CNT composite electrodes was 5.35-8.54.This indicated that the variations of solution pH was associated with the fouling degree of the CDI electrodes.In addition,this research also explored the relationship between electrode fouling and zero charge potential of the electrodes.This would provide some valuable informations for the development of anti-fouling electrode.