(460c) Electrosorption of Ions by Novel Mesoporous Carbon Materials

The formation of an electrical double layer (EDL) near a charged surface has significance in many electrochemical processes, including electrosorption of ions from brackish water and energy storage in batteries and supercapacitors. Electrosorption of ions from aqueous solutions is utilized in capacitive deionization (CDI) for water desalination. Porous, nanostructured carbon materials are suitable for electrosorption due to their high specific surface area and low electrical resistivity. The main objective of the present work is to study the basic mechanisms involved in the electrosorption of ions from aqueous solutions and synthesize durable and efficient mesoporous carbon materials for application in the CDI process and energy storage devices. The results obtained in the study suggest that the mesoporous carbon materials synthesized at Oak Ridge National Laboratory via a self-assembly method exhibit a higher ion removal capacity with faster deionization rates over the conventional carbon aerogel. The effect of temperature on EDL formation in aqueous solutions is also investigated as it has implications in the desalination of produced water from the oil/gas industry. Mesoporous carbon exhibits a higher capacitance and a faster electrosorption rate in cyclic voltammetry (CV) experiments at 40°C than at room temperature. In the CDI experiments, higher sorption and regeneration rates are also observed at a higher temperature (40°C) as compared to room temperature. Canonical Monte Carlo (CMC) simulation results show that the EDL thickness is greater at 50°C than at room temperature, which validates the increase in electrosorption capacitance observed in CV and CDI experiments. In situ neutron imaging and scattering experiments reveal information on ion transport in the pores of the mesoporous carbon.