Fluoride Removal from Brackish Groundwaters by Constant Current Capacitive Deionization (CDI).
Charging capacitive deionization (CDI) at constant voltage (CV) produces an effluent stream in which ion concentrations vary with time. Compared to CV, charging CDI at constant current (CC) has several advantages, particularly a stable and adjustable effluent ion concentration. In this work, the feasibility of removing fluoride from brackish groundwaters by single-pass constant-current (SPCC) CDI in both zero-volt and reverse-current desorption modes was investigated and a model developed to describe the selective electrosorption of fluoride and chloride. It was found that chloride is preferentially removed from the bulk solution during charging. Both experimental and theoretical results are presented showing effects of operating parameters, including adsorption/desorption current, pump flow rate and fluoride/chloride feed concentrations, on the effluent fluoride concentration, average fluoride adsorption rate and water recovery. Effects of design parameters are also discussed using the validated model. Finally, we describe a possible CDI assembly in which, under appropriate conditions, fluoride water quality targets can be met. The model developed here adequately describes the experimental results obtained and shows how change in the selected system design and operating conditions may impact treated water quality.
School of Civil and Environmental Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia.
Wangwang
W
Tang
School of Civil and Environmental Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia.
Peter
P
Kovalsky
Department of Municipal and Environmental Engineering, School of Civil Engineering, Beijing Jiaotong University , Beijing 100044, P. R. China.
Baichuan
B
Cao
School of Civil and Environmental Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia.
Di
D
He
School of Civil and Environmental Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia.
T David
TD
Waite
D000327:Adsorption; D004566:Electrodes; D005459:Fluorides; D060587:Groundwater; D018508:Water Purification
D005459:Fluorides