Enhancing the performance of microbial desalination cells using δMnO2/graphene nanocomposite as a cathode catalyst

• Published in: Journal of water reuse and desalination 2020-09, Vol.10 (3), p.214-226
• Main Authors: Elawwad, Abdelsalam, Ragab, Mostafa, Hamdy, Ahmed, Husein, Dalal Z.
• Format: Article
• Language: English
• Subjects: Carbon; Catalysts; cathode catalyst; Cathodes; Cells; Chemical oxygen demand; Desalination; Electrodes; Electrolytes; Fuel cells; Graphene; Graphite; Heavy metals; High temperature; Manganese dioxide; Maximum power; Membranes; Metals; microbial desalination cells; Microorganisms; mno2/g nanocomposite; Nanocomposites; Nanomaterials; Oxidation; Oxygen requirement; Performance enhancement; Platinum; Platinum metals; Reactors; Saline water; Water desalting; Water treatment
• ISSN: 2220-1319; 2408-9370
• DOI: 10.2166/wrd.2020.011

In this work, δMnO2 was anchored into graphene nanosheets via a mediated simple and eco-friendly approach to be used as a potential low-cost cathodic catalyst in microbial desalination cells (MDC). MnO2/G based MDC revealed a faster start-up and stable performance during the operation compared with the catalyst-free control MDC. The average chemical oxygen demand (COD) removal efficiencies were 85.11 ± 5.13 and 86.20 ± 4.85% and average columbic efficiencies throughout the operation cycles were 1.52 ± 0.32% and 0.70 ± 0.35% for MnO2/G based reactor and control reactor, respectively. The average desalination efficiencies were 15.67 ± 3.32 and 13.21 ± 2.61% for MnO2/G based reactor and control reactor, respectively. The superior catalytic performance of MnO2/G based cathode improved current generation which is the key desalination stimulus. MnO2/G based reactor revealed a lower internal resistance of 430 Ω compared with 485 Ω for the catalyst-free control reactor and, similarly, the maximum power densities were found to be 12.5 and 6.5 mW/m2, respectively. MnO2/G catalyst offered an improved MDC performance, however, still with uncompetitive performance in comparison with platinum group metals catalysts.