Research Projects

A continuous electrochemical approach namely Flow-Electrodes Capacitive Deionization (FCDI) was recently introduced for brackish or hypersaline water treatment and resource recovery. FCDI resembles other energy sources such as electrochemical flow capacitors and semi-solid fuel cells. It can also be integrated with redox flow batteries and flow capacitors. FCDI eliminates the constraints of conventional desalination technologies e.g., reverse osmosis (RO), multistage flush distillation and capacitive deionization (CDI). It is more energy efficient and has compact structure compared to RO. FCDI works on the principle of ion adsorption on flowable electrode’s surface. The continuous replacement of flow electrodes in FCDI leads to higher salt removal rate compared to CDI. The electrolyte for flow electrodes dissolves the particle electrode material and facilitates the flow of the slurry. Hence, it plays a vital role in electrode’s capacitive performance and determination of ohmic resistance of the cell. Electronic conductivity, viscosity and salinity of electrode slurry are the key factors while choosing an appropriate electrolyte. In view of the disadvantages of aqueous and organic electrolytes, the proposed work aims at development of sustainable deep eutectic solvents (DESs) as host electrolyte for carbon nanotubes (CNT: SWCNT/MWCNT) based flow electrodes for FCDI. DESs are considered as emerging solvents having comparable physicochemical properties to ionic liquids with lower cost of synthesis. Lower volatility and non-flammability bring about several applications of DESs in chemistry and chemical engineering research. DESs consist of two groups: hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) associated together through hydrogen bonds. The constituent solvent has lower melting point than the individual HBA and HBD. The feasible association between several HBAs and HBDs gives the advantage of preparation of a DES according to their application. The work focuses on synthesis of DES comprising of organic salts e.g., NaBF₄, NaPF₆ or NaNO₃ as HBA and N-methylacetamide, ethylene glycol or glycerol as HBD. The study involves synthesis of low viscous DES to reduce pumping cost of electrode slurry. The work plan includes synthesis and physical characterization of DESs and further preparation of flow electrode and electrochemical characterization of FCDI device. Moreover, the work can be extended to regeneration of flow electrode materials.