TY - JOUR
T1 - Competitive electrosorption of fluoride and chloride in capacitive deionization
T2 - Role of membrane
AU - Pang, Tianting
AU - Marken, Frank
AU - Zhang, Dengsong
AU - Shen, Junjie
AU - Xie, Ming
PY - 2024/10/22
Y1 - 2024/10/22
N2 - Fluoride removal from solutions containing mixed monovalent ions, particularly F– and Cl–, is challenging due to fluoride’s high electronegativity, large hydration radius, and high hydration energy. This study investigates the performance of capacitive deionization (CDI) and membrane capacitive deionization (MCDI), focusing on initial concentrations, applied constant voltages, and different types of membranes. Membrane integration enhanced adsorption capacity and removal rate and minimized Faradaic reactions. However, these membranes were unable to enhance fluoride selectivity and achieve selective fluoride removal. Increasing initial concentrations was not a viable approach to enhance adsorption capacity since higher concentrations resulted in decreased removal rates. Although raising applied constant voltages improved both adsorption capacities and fluoride selectivity, detrimental Faradaic reactions occurred during the adsorption and desorption processes, decreasing energy efficiency. pH changes in CDI cells increased during the adsorption process and decreased during the desorption process at high applied voltages, resulting in a decrease in anion adsorption capacity and current efficiency. The pH change trend in MCDI was opposite, causing the increase of anion adsorption capacity. These findings offer valuable insights for improving membrane technologies in wastewater treatment and selective fluoride removal.
AB - Fluoride removal from solutions containing mixed monovalent ions, particularly F– and Cl–, is challenging due to fluoride’s high electronegativity, large hydration radius, and high hydration energy. This study investigates the performance of capacitive deionization (CDI) and membrane capacitive deionization (MCDI), focusing on initial concentrations, applied constant voltages, and different types of membranes. Membrane integration enhanced adsorption capacity and removal rate and minimized Faradaic reactions. However, these membranes were unable to enhance fluoride selectivity and achieve selective fluoride removal. Increasing initial concentrations was not a viable approach to enhance adsorption capacity since higher concentrations resulted in decreased removal rates. Although raising applied constant voltages improved both adsorption capacities and fluoride selectivity, detrimental Faradaic reactions occurred during the adsorption and desorption processes, decreasing energy efficiency. pH changes in CDI cells increased during the adsorption process and decreased during the desorption process at high applied voltages, resulting in a decrease in anion adsorption capacity and current efficiency. The pH change trend in MCDI was opposite, causing the increase of anion adsorption capacity. These findings offer valuable insights for improving membrane technologies in wastewater treatment and selective fluoride removal.
U2 - 10.1021/acsestwater.4c00711
DO - 10.1021/acsestwater.4c00711
M3 - Article
SN - 2690-0637
JO - ACS ES and T Water
JF - ACS ES and T Water
ER -