Evaluating boron removal from aqueous solutions using membrane capacitive deionization (MCDI): Efficacy and limitations
Journal
Journal of Environmental Chemical Engineering
Journal Volume
12
Journal Issue
3
ISSN
2213-3437
Date Issued
2024-06
Author(s)
DOI
10.1016/j.jece.2024.113104
Abstract
In the present study, the feasibility of employing activated carbon-based membrane capacitive deionization (MCDI) for boron removal was systematically evaluated under various conditions, including different applied voltages, pH levels, initial boron concentrations, and boron-to-chloride molar ratios. When the pH of the solution exceeds 9, borate ions with a negative charge become the predominant species, facilitating easier removal during the charging period of both capacitive deionization (CDI) and MCDI. As demonstrated, MCDI can achieve a relatively higher mean deionization capacity of 2.84±0.19 mg/g at 1.2 V and pH 11, associated with a corresponding high charge efficiency of 99% and low energy consumption of 0.04 kWh/m3. More specifically, the results revealed a significant improvement in boron removal performance with the incorporation of ion exchange membranes into CDI. Additionally, MCDI exhibited considerably higher selectivity of boron over chloride ions compared to CDI, attributed to the charge promotion effect. However, the selectivity coefficient of boron over chloride was still need to be improved, identified as the primary constraint of MCDI. With the same ionic charge, chloride with smaller hydrated radius compared to boron was preferentially electrosorbed, thereby suppressing the electrosorption of borate ions. These findings suggest potential future directions for the treatment of boron in practical applications such as seawater desalination and wastewater reclamation in the semiconductor industry.
Subjects
Boron removal
Electrosorption selectivity
Low energy consumption
Membrane capacitive deionization
Publisher
Elsevier BV
Description
Article number 113104
Type
journal article