Sugarcane Biowaste-Derived Biochars as Capacitive Deionization Electrodes for Brackish Water Desalination and Water-Softening Applications

Author(s)

Lado, Julio J. ^{[1, 2]} ; Zornitta, Rafael L. ^{[1, 3]} ; Vazquez Rodriguez, Ines ^[2] ; Barcelos, Kamila Malverdi ^[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

^[2] Madrid Inst Adv Studies, IMDEA Energy, Electrochem Proc Unit, Avda Ramon Sagra, 3 Parque Tecnol Mostoles, Madrid 28935 - Spain

^[3] Wageningen Univ, Lab Organ Chem, Stippeneng 4, NL-6708 WE Wageningen - Netherlands

• Document type: Journal article
• Source: ACS SUSTAINABLE CHEMISTRY & ENGINEERING; v. 7, n. 23, p. 18992-19004, DEC 2 2019.
• Web of Science Citations: 0

Abstract

The sugarcane ethanol industry is currently generating an intensive amount of biowaste while consuming significant water resources. In this work, sugarcane bagasse fly ash (SCBFA), a major biowaste with high amounts of fixed carbon, is employed as a precursor for activated carbon (SCBFA-AC) production. Here, SCBFA-ACs are valorized as the main component of carbon electrodes employed in capacitive deionization (CDI), an emerging desalination technology. In this way, an abundant and low-cost biowaste could be used as a green alternative to treat the water. Different activation methods of SCBFA were explored obtaining SCBFA-AC with a broad spectrum of structural and chemical properties. The electrochemical characterization of SCBFA-AC showed the positive impact of large surface areas, good combination of micro- and mesopores, and the presence of surface functional groups on specific capacitances (117 F g(-1)). Subsequently, CDI and membrane CDI experiments showed the importance of ion-exchange membranes on improving charge efficiency values (from 5-30 to 80-95%) and consequently, salt adsorption capacity, SAC, from approximate to 5 to 22 mg g(-1). This SAC value, one of the highest ever obtained with biowaste electrodes, only suffered a slight reduction (19 mg g(-1)) after 70 CDI cycles. Finally, SCBFA electrodes were successfully tested for water-softening applications, reaching 15 mg g(-1) when operating using CaCl2 solutions instead of NaCl. This study represents a great example of the water-energy-food nexus in the framework of the circular economy. (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
• FAPESP's process: 15/16107-4 - Desalination by capacitive deionization: development of new electrodes and process optimization
• Grantee: Luis Augusto Martins Ruotolo
• Support Opportunities: Regular Research Grants