Operational Parameters, Kinetics and Energy Consumption of Chloride Removal by Graphene as a Capacitive Deionization Sorbent
J. Environ. Nanotechnol., Volume 14, No 1 (2025) pp. 371-378
Abstract
Capacitive deionization (CDI), a novel and emerging technology provides a solution to the conventional difficulties linked to desalination. The optimum benefits can be harnessed from the technology if a proper electrode material is chosen and its influential parameters are enhanced. The primary objective of the work is to enhance the maximum chloride removal efficiency of graphene employed in flow-by CDI cells by varying flow rate, voltage, pH, electrode spacing, and electrolyte concentration. The secondary objective is to assess the energy consumption and the rate-limiting period for optimal operational conditions. Results show that 95.8% of chloride can be effectively reduced by employing graphene as a CDI electrode. However, this removal efficiency was achieved by maintaining the applied voltage, flow rate, electrolytic concentration, pH, and electrode spacing at 2.36 V, 2 mg/L, 250 mg/L, 5.67, and 0.84 cm, respectively. Isotherm studies reveal that the electrosorption of chloride onto graphene follows the Freundlich isotherm. An increase in flow rate, voltage, duration, and electrode distance, proportionally increases the energy consumption, exclusive of an increase in electrolytic concentration.
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Reference
Algurainy, Y., and Call, D.F., Asymmetrical removal of sodium and chloride in flow through capacitive deionization, Water Res., 183, 116044 (2020).
https://doi.org/10.1016/j.watres.2020.116044
Angizi, S., Hong, L., Huang, X., Selvaganapathy, R. P., and Kruse, P., Graphene versus concentrated aqueous electrolytes: the role of the electrochemical double layer in determining the screening length of an electrolyte, npj 2D Mater Appl., 7, 67 (2023).
https://doi.org/10.1038/s41699-023-00431-y
Alkhadra, M. A., Xiao Su., Matthew E. Suss., Huanhuan Tian., Eric N. Guyes., Amit N. Shocron., Kameron M. Conforti., Pedro de Souza, J., Nayeong Kim., Michele Tedesco., Khoiruddin Khoiruddin., Gede Wenten, I., Juan G. Santiago, Alan Hatton,T. and Martin Z. Bazant, Electrochemical Methods for Water Purification, Ion Separations, and Energy Conversion, Chem. Rev., 122 (16), 13547-13635 (2022).
https://doi.org/10.1021/acs.chemrev.1c00396
Diaz, P., Gonzalez, Z., Grand, M., Menendez, R., Santamaria, R. and Blanco, C., Evaluating capacitive deionization for water desalination by direct determination of chloride ions, Desalination, 344, 396-401 (2014).
https://doi.org/10.1016/j.desal.2014.04.013
Oladunni, J., Zain, J.H., Hai, A., Banat, F., Bharath, G. and Alhseinat, E., A comprehensive review on recently developed carbon-based nanocomposites for capacitive deionization: from theory to practice, Sep. Purif. Technol., 207, 291–320 (2018).
https://doi.org/10.1016/j.seppur.2018.06.046
Pauline, S., and Venkatesan,G., Influence of solvent and its concentration on binding graphene with substrate in electric double layer capacitance, DESALIN WATER TREAT., 145, 134–142 (2019).
https://doi.org/10.5004/dwt.2019.23707
Porada, S., Zhao, R., Wal, V. D. A., Presser, V., and Biesheuvel, P. M., Review on the science and technology of water desalination by capacitive deionization, Prog. Mater. Sci., 58(8), 1388-1442 (2013).
https://doi.org/10.1016/j.pmatsci.2013.03.005
Qi, Y., Peng, W., Zhang, W., Jing, Y. and Hu L., A Cross-Scale Framework for Modelling Chloride Ions Diffusion in C-S-H: Combined Effects of Slip, Electric Double Layer and Ion Correlation, Mater., 15(22), 8253, (2022).
https://doi.org/10.3390/ma15228253
Rafael, L. Z., Julio, J. L., Marc, A. A. and Luís, A. M. R., Effect of electrode properties and operational parameters on capacitive deionization using low-cost commercial carbons, Sep. Purif. Technol.., 158, 39-52 (2016).
https://doi.org/10.1016/j.seppur.2015.11.043
Salleh, N. A., Kheawhomb, S., Hamidc, N. A. A., Rahimand, W., and Mohamad, A. A., Electrode polymer binders for supercapacitor applications: A review, JMR&T., 23, 3470-3491 (2023).
https://doi.org/10.1016/j.jmrt.2023.02.013
Shulga, Y. M., Kabachkov, E. N., Korepanov, V. I., Khodos, I. I., Kovalev, D.Y., Melezhik, A.V., Tkachev, A. G., and Gustev, G. L., The concentration of c(sp3) atoms and properties of an activated carbon with over 3000 m2/g bet surface area, Nanomater., 11(5), 1324 (2021).
https://doi.org/10.3390/nano11051324
Sufiani, O., Sahini, M. G., and Elisadiki, J., Towards attaining SDG 6: The opportunities available for capacitive deionization technology to provide clean water to the African population, Environ. Res., 216 (3), 114671 (2023).
https://doi.org/10.1016/j.envres.2022.114671
Vareda, J. P., On validity, physical meaning, mechanism insights and regression of adsorption kinetic models, J. Mol. Liq., 376, 121416 (2023).
https://doi.org/10.1016/j.molliq.2023.121416
Venkatesan, G. and Pauline S., Influence of Chemical, Electrochemical Exfoliation, Hydrophilic, and Hydrophobic Binder on the Sorption Capacity of Graphene in Capacitive Deionization, J. Environ. Eng., 148(7), 04022033 (2022).
https://doi.org/10.1061/(ASCE)EE.1943-7870.0001999
Zhang, C., He, Di., Ma, J., Tang, W., and Waite, D. T., Faradaic reactions in capacitive deionization (CDI) - problems and possibilities: A review, Water Res., 128, 314-330 (2018).
