Understanding the mechanism of carbonization and KOH activation of polyaniline leading to enhanced electrosorption performance

Author(s)

Zornitta, Rafael L. ^[1] ; Barcelos, Kamilla M. ^[1] ; Nogueira, Francisco G. E. ^[1] ; Ruotolo, Luis A. M. ^[1]

Affiliation

^[1] Univ Fed Sao Carlos, Dept Chem Engn, Rod Washington Luiz Km 235, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Carbon; v. 156, p. 346-358, JAN 2020.
• Web of Science Citations: 0

Abstract

Capacitive deionization (CDI) emerged as a new water desalination technology in which ions are removed from brackish water by being attracted and stored in two polarized electrodes. The electrode material plays a very important role affecting other fundamental parameters such as the salt adsorption capacity (SAC), conductivity, desalination kinetics, and energy consumption. Typically, the CDI electrodes are carbon-based materials, fulfilling requirements such as high specific surface area (SSA), chemical stability, and conductivity. Here, we make a comprehensive study of the variables involved in the polyaniline activated carbons (PAC) preparation. A new mechanism is proposed to explain how the carbonization/activation conditions have influence on textural properties (SSA and pore volume) of PAC. We found that carbonization at temperatures <= 600 degrees C are mandatory to provide more KOH-reactive carbon intermediates due to their turbostratic structure. After activation at 850 degrees C, remarkable pore volume (2.30 cm(3)/g) and SSA (similar to 3600m(2)/g) were achieved, which has direct influence on promoting high electrode capacitance (213 F/g), SAC (22.2 mg/g), and charge efficiency (81%). This SAC is among the highest values reported for CDI desalination using carbon electrodes. This work enlightens the mechanism to achieve high performance activated carbons providing a promising electrode material for CDI desalination. (C) 2019 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 15/26593-3 - Desalination using capacitive deionization: development of new electrodes and process optimization
• Grantee: Rafael Linzmeyer Zornitta
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 17/19838-5 - DESALINATION AND SEPARATION OF AMINO ACIDS BY ELECTROSSORPTION USING ELECTRODES OF ACTIVATED GRAPHENE
• Grantee: Luis Augusto Martins Ruotolo
• Support Opportunities: Regular Research Grants