Development of capacitive deionization radial-flow cell for water softening

• Grant number: 23/08483-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2023
• End date: December 31, 2024
• Field of knowledge: Engineering - Chemical Engineering - Chemical Process Industries
• Principal Investigator: Luis Augusto Martins Ruotolo
• Grantee: Bruno Gomes Martins Alves
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated scholarship(s): 23/15868-8 - Tunning the surface chemistry of commercial activated carbon felt for improved asymmetric capacitive deionization, BE.EP.IC

Abstract

The exponential interest growth by capacitive deionization technology (CDI) has been motivated by its low energy cost and potential application for desalination and water softening. As a supercapacitor, CDI remove and store ions in the double electric layer formed when two electrodes are submitted to an electric field. In this project, CDI will be applied for water softening employing a radial flow cell, to be designed for water softening according to the concept developed in our research group of "permeation flow cell" which combines the flow-through e flow-by in order to achieve high efficiency and electrosorption rates. Aiming to obtain a feasible commercial cell, activated carbon felt will be used as electrode, since its high specific surface area and surface chemistry are appropriated for CDI applications. Considering the mass transfer and residence time variation in the radial direction, we propose the study of two flow patterns: (i) from the center to the edge of the electrode (u ×) and (ii) from the edge to the center of the electrode (u Ð). For each configuration, the effects of applied current and flow rate will be evaluated, in order to allow the understanding of the charge and mass transfer on the charge efficiency and ions removal rate. The proposal of the radial flow also aims to facilitate and reduce the time required in the electrode regeneration step, also decreasing the time of the electrosorption/desorption cycle, so increasing the water productivity. In another approach, but complementary, it was found, in preliminary tests, the necessity of introducing surface functional groups on the carbon surface in order to create surface charges that will minimize the co-ions effect, promoting the process improvement by using asymmetric electrodes. This part of the project is proposed to be developed in collaboration with a recognized research group abroad, through a BEPE/FAPESP project.