Research On The Modification Of Activated Carbon Electrode And The Properties Of Electro-Adsorption Desalination

In the background of electro-adsorption technology has been researchincreasingly and practical application,The activated carbon electrode was prepared bytaking nut shell activated carbon powder as the main raw material,by physicalactivation and simultaneous physical and chemical method,when proportion ofnutshell activated carbon,phenolic resin,methenamine and graphite powder was70：29：0.5：0.5.The properties of the modified electrode， which included porestructure,morphology and electrochemical were investigated by moderinstruments.such as BET specific surface,SEM,X-ray diffraction,TEM andelectrochemical workstation.on the basis of these characterized,the influences ofelectrode gap,initial concentration and work voltage were investigated in theelectro-adsorption study.Under the optimal conditions,The removal of halogen anionand hardness ions were also discussed.Through the trial get the following conclusion:1. Through the modification of activation carbon electrodes, Theelectro-adsorption performance of electrodes has been improvedcomprehensively.And the electrode,which modified by physical and chemicalmethod,is superior than the physical activation electrode. It’s stated as follows:thecumulative pore volume was reached0.120615cc/g,BET specific surface was743.2039m2/g, and have higher mesoporosities,which concentrated in20to150than unmodified ones; In addition.Not only owned good Charge-discharge performance and electric capacity,but also the Polarization resistance ability,thecorrosion potential was-0.070V, higher than the ones by physicalactivation（-0.127V）,reached81.4%.2. The results showed that the electric adsorption balance time of NaCI, NaBr,NaF, NaI, CaCl₂and MgCl₂were180,240,180,300,480,360min,respectively; Theoptimum conditions for the experimental were obtained as follow: the initial voltagewas1V, the electrode gap was5mm and the initial-concentration was1000mg/L.Derived from the kinetic model fitting, the U/K curves of electricity adsorptiondesalination experiments were achieved,the optimum voltage should be less than1.2V from the curves.And the electric could maintained absorption propertiessteady,the desorption rate is always above90%,after repeated cycles of adsorption/desorption.3. Through the data fitting of the electro-adsorption desalination for halogenanion (Cl^-1, Br^-1, F^-1, I^-1),Research on kinetic parameters showed that absorption ofhalogen anion by activated carbon electrics as best described by pseudo second-orderModel from the fitting correlation coefficient R2, which could be reached0.999. ItIndicated that The entire electrical adsorption process is a complex process,whichcontained external film diffusion,surface adsorption and intra-particle diffusion, etc.4. According to the fitting of electro-adsorption process by removed Hardness(Ca²⁺, Mg²⁺),It can be known that the whole absorption would better described bypseudo second-order model, the whole fitting correlation coefficient were above0.9,and reached a highest value of0.978.Without the relevance fitting parameters ofunactivated electrode, the intra-particle diffusion model were better match the experimental results, the correlation coefficient could reached0.983,0.987,higherthan the fitting of pseudo-second-order kinetic model, it indicated that theintra-particle diffusion process wasn’t the sole steps,which controlled the adsorptionrate.both of the surface and intra-particle diffusion might existed in the process ofremoving hardness ions.mainly mesoporosities were the factors,which controlled theadsorption rate in greater porosity, The higher the mesoporosities,the more adsorptioncapability,The longer adsorption time will be needed.