SUMMARY

Capacitive Deionization (CDI) is a novel separation-based technology for desalinating brackish water. By applying an electrical voltage difference, the salt ions are removed from water and temporarily stored in the porous carbon electrodes. Once the adsorption capacity is reached, the ions are released to regenerate the electrodes as reducing or reversing the electrical polarization. CDI is a promising alternative to the state-of-the-art desalination methods due to low energy consumption and economic cost. For improving desalination performance, the ion exchange membranes can be included to construct a membrane capacitive deionization (MCDI) cell.

This thesis explored the thermal effect on CDI and MCDI systems and demonstrated the change of electrochemical features and salt removal performance with increasing operating temperature. Moreover, the energy recovery for MCDI cell was examined at different operating conditions. Based on theoretical modeling and experimental results, this thesis creatively proposed a concept of heat combined MCDI cell, aiming to boost the recoverable energy by using waste heat. Additionally, it demonstrated that recycling the brine stream used for discharging the electrodes is able to enhance both freshwater and energy recovery.