2017 Fiscal Year Annual Research Report
Enhanced energy harvesting by reverse electrodialysis in aligned mesoporous silica SBA-15 thin films
| Project/Area Number |
16K18024
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| Research Institution | The University of Tokyo |
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Principal Investigator |
黄 ジュンホ 東京大学, 大学院工学系研究科(工学部), 特任研究員 (60772978)
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| Project Period (FY) |
2016-04-01 – 2018-03-31
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| Keywords | Ion-selective transport / Nanofluidics / Mesoporous silica / Energy harvesting / Salinity gradient / Osmotic energy / Reverse electrodialysis / Thermal effect |
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| Outline of Annual Research Achievements |
The thermal dependence of salinity-gradient-driven energy conversion by reverse electrodialysis using a mesoporous silica thin film with pores ca. 2-3 nm in diameter was studied in a temperature range of 293-333 K. As the temperature increases, the surface charge density of mesopores increases owing to an increase in the zeta potential of the pore walls, which in turn increases the concentration of counter-ions in the electrical double layer. The ion mobility also increases with increasing temperature owing to a decrease in the liquid viscosity. As a result, the temperature increase improves the ion conductance of mesopores both in the surface-charge-governed regime at low ion concentrations and in the bulk regime at high ion concentrations. However, further increases in temperature induce bubble nucleation. In particular, in highly concentrated salt solutions, hydrophobic patches appear on the pore surfaces because of the salting-out effect and mask the surface charge. The weakened polarity in mesopores allows more co-ions to enter them, decreasing the potential difference across the film, resulting in a serious deterioration of the energy conversion efficiency. The thermal dependence of the performance characteristics of mesoporous-silica-based nanofluidic devices was also evaluated.
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