Theoretical Analysis of Constant Voltage Mode Membrane Capacitive Deionization for Water Softening
Water softening is desirable to reduce scaling in water infrastructure and to meet industrial water quality needs and consumer preferences. Membrane capacitive deionization (MCDI) can preferentially adsorb divalent ions including calcium and magnesium and thus may be an attractive water softening te...
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MDPI AG
2021-03-01
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| Series: | Membranes |
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| Online Access: | https://www.mdpi.com/2077-0375/11/4/231 |
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| author | Xin Zhang Danny Reible |
| author_facet | Xin Zhang Danny Reible |
| author_sort | Xin Zhang |
| collection | DOAJ |
| description | Water softening is desirable to reduce scaling in water infrastructure and to meet industrial water quality needs and consumer preferences. Membrane capacitive deionization (MCDI) can preferentially adsorb divalent ions including calcium and magnesium and thus may be an attractive water softening technology. In this work, a process model incorporating ion exclusion effects was applied to investigate water softening performance including ion selectivity, ion removal efficiency and energy consumption in a constant voltage (CV) mode MCDI. Trade-offs between the simulated Ca<sup>2+</sup> selectivity and Ca<sup>2+</sup> removal efficiency under varying applied voltage and varying initial concentration ratio of Na<sup>+</sup> to Ca<sup>2+</sup> were observed. A cut-off CV mode, which was operated to maximize Ca<sup>2+</sup> removal efficiency per cycle, was found to lead to a specific energy consumption (SEC) of 0.061 kWh/mole removed Ca<sup>2+</sup> for partially softening industrial water and 0.077 kWh/m<sup>3</sup> removed Ca<sup>2+</sup> for slightly softening tap water at a water recovery of 0.5. This is an order of magnitude less than reported values for other softening techniques. MCDI should be explored more fully as an energy efficient means of water softening. |
| first_indexed | 2024-03-10T12:56:14Z |
| format | Article |
| id | doaj.art-8717f13d0dea4359bc65e4a23651bfac |
| institution | Directory Open Access Journal |
| issn | 2077-0375 |
| language | English |
| last_indexed | 2024-03-10T12:56:14Z |
| publishDate | 2021-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Membranes |
| spelling | doaj.art-8717f13d0dea4359bc65e4a23651bfac2023-11-21T11:54:50ZengMDPI AGMembranes2077-03752021-03-0111423110.3390/membranes11040231Theoretical Analysis of Constant Voltage Mode Membrane Capacitive Deionization for Water SofteningXin Zhang0Danny Reible1Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409-3121, USADepartment of Chemical Engineering, Texas Tech University, Lubbock, TX 79409-3121, USAWater softening is desirable to reduce scaling in water infrastructure and to meet industrial water quality needs and consumer preferences. Membrane capacitive deionization (MCDI) can preferentially adsorb divalent ions including calcium and magnesium and thus may be an attractive water softening technology. In this work, a process model incorporating ion exclusion effects was applied to investigate water softening performance including ion selectivity, ion removal efficiency and energy consumption in a constant voltage (CV) mode MCDI. Trade-offs between the simulated Ca<sup>2+</sup> selectivity and Ca<sup>2+</sup> removal efficiency under varying applied voltage and varying initial concentration ratio of Na<sup>+</sup> to Ca<sup>2+</sup> were observed. A cut-off CV mode, which was operated to maximize Ca<sup>2+</sup> removal efficiency per cycle, was found to lead to a specific energy consumption (SEC) of 0.061 kWh/mole removed Ca<sup>2+</sup> for partially softening industrial water and 0.077 kWh/m<sup>3</sup> removed Ca<sup>2+</sup> for slightly softening tap water at a water recovery of 0.5. This is an order of magnitude less than reported values for other softening techniques. MCDI should be explored more fully as an energy efficient means of water softening.https://www.mdpi.com/2077-0375/11/4/231water softeningmembrane capacitive deionization (MCDI)selectivitywater recoveryspecific energy consumption (SEC) |
| spellingShingle | Xin Zhang Danny Reible Theoretical Analysis of Constant Voltage Mode Membrane Capacitive Deionization for Water Softening Membranes water softening membrane capacitive deionization (MCDI) selectivity water recovery specific energy consumption (SEC) |
| title | Theoretical Analysis of Constant Voltage Mode Membrane Capacitive Deionization for Water Softening |
| title_full | Theoretical Analysis of Constant Voltage Mode Membrane Capacitive Deionization for Water Softening |
| title_fullStr | Theoretical Analysis of Constant Voltage Mode Membrane Capacitive Deionization for Water Softening |
| title_full_unstemmed | Theoretical Analysis of Constant Voltage Mode Membrane Capacitive Deionization for Water Softening |
| title_short | Theoretical Analysis of Constant Voltage Mode Membrane Capacitive Deionization for Water Softening |
| title_sort | theoretical analysis of constant voltage mode membrane capacitive deionization for water softening |
| topic | water softening membrane capacitive deionization (MCDI) selectivity water recovery specific energy consumption (SEC) |
| url | https://www.mdpi.com/2077-0375/11/4/231 |
| work_keys_str_mv | AT xinzhang theoreticalanalysisofconstantvoltagemodemembranecapacitivedeionizationforwatersoftening AT dannyreible theoreticalanalysisofconstantvoltagemodemembranecapacitivedeionizationforwatersoftening |