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Membrane Water Treatment Volume 13, Number 6, December 2022 , pages 313-320 DOI: https://doi.org/10.12989/.2022.13.6.313 |
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Water transport through hydrophobic micro/nanoporous filtration membranes on different scales |
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Mian Wang and Yongbin Zhang
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| Abstract | ||
| Theoretical calculation results are presented for the enhancement of the water mass flow rate through the hydrophobic micro/nano pores in the membrane respectively on the micrometer and nanometer scales. The water-pore wall interfacial slippage is considered. When the pore diameter is critically low (less than 1.82nm), the water flow in the nanopore is non-continuum and described by the nanoscale flow equation; Otherwise, the water flow is essentially multiscale consisting of both the adsorbed boundary layer flow and the intermediate continuum water flow, and it is described by the multiscale flow equation. For no wall slippage, the calculated water flow rate through the pore is very close to the classical hydrodynamic theory calculation if the pore diameter (d) is larger than 1.0nm, however it is considerably smaller than the conventional calculation if d is less than 1.0nm because of the non-continuum effect of the water film. When the driving power loss on the pore is larger than the critical value, the wall slippage occurs, and it results in the different scales of the enhancement of the water flow rate through the pore which are strongly dependent on both the pore diameter and the driving power loss on the pore. Both the pressure drop and the critical power loss on the pore for starting the wall slippage are also strongly dependent on the pore diameter. | ||
| Key Words | ||
| hydrophobic wall; mass transfer; membrane; multiscale; nanopore; wall slippage | ||
| Address | ||
| Mian Wang: School of Electronic Engineering, Changzhou College of Information Technology, Changzhou, 213164, Jiangsu Province, China Yongbin Zhang: College of Mechanical Engineering, Changzhou University, Changzhou, 213164, Jiangsu Province, China | ||
