Preparation Of Carbon Aerogel Microspheres And Its Properties For Capacitive Deionization

Carbon aerogel microsphere(CA microsphere)is a novel carbon aerogel material,which can be prepared by emulsion polymerization of resorcinol�formaldehyde(RF)in a slightly basic aqueous solution via an ambient drying technology,followed by carbonizing at a high temperature under a nitrogen atmosphere.Compared with the traditional supercritical drying,there is no solvent exchange process that the cost of production is low and fabrication procedure is uncomplicated via using ambient drying method.From this aspect,CA microspheres prepared by ambient drying technology pose ideal electrode materials if its appropriate pore size distribution(PSD)and available surface area can meet the demand of CDI application.In this work,CA microspheres prepared by emulsion polymerization and an ambient drying technology were firstly applied to the CDI application.The process of preparing carbon aerogel microspheres was studied.Among them,through using the cyclic voltammetry test,scanning electron microscopy(SEM),cyclic voltammetry,X-ray diffraction(XRD),and N2 adsorption test to study the effects of parameters such as R/C and RF solution density on the morphology,pore structure and electrochemical performance of the sample.The capacitive property of CA microspheres electrodes are further examined by deionization experiments on Na Cl solution.The effect of specific salt-adsorption capacity of the CDI systems is also evaluated under different solution concentrations(500-650 mg/L)and applied voltages(0.8-1.4 V).The performance of electrosorption with different microspheres was explored.The electrosorption and electrodesorption procedures displayed the stability and regeneration of CAmicropheres electrodes.Through the research of the above content,the mainly conclusion of this article was as follows:(1)Carbon aerogel microspheres can be successfully prepared by emulsion(1)Carbon aerogel microspheres can be successfully prepared by emulsion polymerization and ambient drying technology,and the obtained carbon aerogel microspheres have uniform particle size distribution,good dispersibility and high balling rate.According to the results of experimental,the optimized preparation parameters are as follows: catalyst capacity(R/C=500),RF solution theoretical density=0.6 g/ml;used RF solution was used as a raw material in the industrial-scale production of carbon aerogel microspheres prepared by emulsion polymerization and atmospheric drying.The production process is simple,the preparation time is short,the yield is high and the single batch production can reach 5kg.The super capacitor prepared by this sample is of excellent performance.(2)Through investigation of literature and experiments,it was found that when carbon aerogel was used as electrode material to prepare the electrode,the PVDF was selected as binder,and the electrode was prepared with the ratio of 7:2:1.The results showed that electrode has good adhesion;in the experiment,an CDI device was successfully constructed,including CDI unit cell,an electric conductivity meter,a peristaltic pump and a stabilized voltage supply.In this system,the prepared electrode sheet is assembled into a CDI device.The Na Cl solution was controlled by the peristaltic pump and flowed through the CDI unit cell.The variation of Na Cl solution conductivity was measured by the conductivity meter.(3)CDI experiments used Na Cl solution to simulate seawater.Due to the conductivity linearly increases with the increasing concentration of Na Cl solution,the concentration of Na Cl solution was determined by measuring conductivity of the solution.(4)The effect of applied voltage and initial concentration on electrode adsorption performance was investigated.The experimental results showed that the optimal applied voltage was 1.2V,the optimal initial concentration was 500mg/L.(5)The electro-adsorption measurements results of carbon aerogel microspheres with different catalysts show that the R/C=500 sample has the fastest adsorption rate,the highest adsorption capacity and the best electrode regeneration effect;the electro-adsorption measurements results of carbon aerogel microspheres with different theoretical shows that the theoretical density=0.6 g/ml of the sample has the fastest adsorption rate,the highest adsorption capacity and electrode regeneration effect.Therefore,the samples prepared with theoretical density of 0.6 g/ml,R/C=500 was more suitable as electrode material for electrosorption.(6)The electrode regeneration performance was an important property of electrosorption.The test results show that the regeneration performance of the microsphere sample was relatively stable in several cycles of desorption and desorption,and the time of desorption is short and the repeatability of the curve was good.Therefore,when the carbon aerogel microspheres were used as electrode materials in electrosorption,the electrosorption/desorption processes were both stable and eversible processes and the electrodes had long service lives.