|M.Sc Student||Shocron Amit|
|Subject||The Effect of Surface Transport On Water Desalination|
By Capacitive Deionization
|Department||Department of Mechanical Engineering||Supervisor||Assistant Professor Matthew E. Suss|
|Full Thesis text|
Capacitive deionization (CDI) is a technology in which water is desalinated by ion
electrosorption into the electric double layers (EDLs) of charging porous electrodes.
In recent years significant advances have been made in modeling the charge and salt
dynamics in a CDI cell, but the possible effect of surface transport within diffuse
EDLs on these dynamics has not been investigated. We here present theory which
includes surface transport in describing the dynamics of a charging CDI cell. We
investigated the effect of surface transport using macroscopic 1D models and also
local 2D models to probe the effect of multi-scale pore structure. Through our
numerical solution to the presented models, the possible effect of surface transport on
the CDI process is elucidated. While at some model conditions surface transport
enhances the rate of CDI cell charging, counter-intuitively this additional transport
pathway is found to slow down cell charging at other model conditions.
In the second part of this thesis, we present the development of a 1D model simulating
the salt and charge dynamics in a flow-through electrode CDI cell, and show a
comparison to experimental results. A boundary condition analysis reveals that
appropriate simulation of the cell requires use of upstream and downstream reservoirs
in the model domain at conditions of low and moderate Peclet numbers. The
comparison to experimental equilibrium results agree at low voltage conditions, but
model to experiment results for salt storage diverge at cell voltages above 0.5 V.