Preparation Of Porous Carbon Matearials And Their Properties Of Electrosorption

Electrosorption is a new method of water treatment in recent years which has advantages such as low cost, regeneration and no secondary pollution. Formed double electrode layer at surface of electrode is its principle. So the electrode materials are important to electrosorption. Porous carbon materials are suitable for its electrode because it has high specific surface area, conductivity and stability. In this paper, activated carbon and carbon aerogels were used as electrode materials of electrosorption, and the relationship between electrosorption and pore structure has been studied. The main experimental conclusions are as follows:1. Deashing the active carbon with nitric acid. Then modified active carbon by water vapor and fabricated it into electrodes for electrosorption. The electrosorption performance was tested in the electrosorption system. The results showed that the specific surface area and pole volume were enhanced by secondary activation, and the adsorption volume increase from 2.92mg/g to 4.55mg/g. The effect of activation was influence by activation time and activation temperature. The active carbon can gain higher adsorption volume and efficient field when active under 850℃for 1 hour. High specific surface area activated carbon was used as electrode of electrosorption, the adsorption capacity increase with the rise of specific surface area, the activated carbon with specific surface area 3367 m2/g has biggest adsorption capacity 9.11mg/g. That means specific surface area is the most important properties for activated carbon electrosorption materials.2. Glucose was used as pore former to modify the structure of carbon aerogels that was prepared by resorcinol and formaldehyde. The organic gel was treated by soaking in acetone, supercritically drying and carbonized at 1000℃in inert atmosphere to made carbon aerogels. The pore structure and specific surface area of carbon aerogels was determined by SEM and BET methods. It was found that the specific surface area of carbon aerogels modified by glucose increased from 403.6 m2/g to 684.3 m2/g, and theirs pore distribution was changed. The average pore size decreased from 20.50 nm to 10.41 nm. Their electrochemical properties were characterized by constant current charge-discharge experiments, the result shows that the specific capacitances increase from 70.2 F/g to 115.2 F/g at the current of 1 mA. But the adsorption capacity released from 18.5 mg/g to 16.0 mg/g. That means pore diameter is also important to carbon aerogels electrosorption materials.3. Carbon aerogels made by phenol/resorcinol/formaldehyde and meta-cresol/resorcinol/formaldehyde was used as the electrodes for the electrosorption process. The adsorption capability was determined by specific surface area and average pore diameter. At the same loading, the adsorption volume of the unit increased with the rise of the final solid concentration. The sample made by meta-cresol/resorcinol/formaldehyde of 40wt% has best desalting performance (15.4mg/g) and shorter adsorption time because its high specific surface area (580.9 m2/g) and big average pore diameter (7.37nm). The adsorption volume of the unit increased with the rise of applied voltage and concentration of NaCl solution. The 1.5V is the most appropriate voltage for the CDI system.