Thermo-responsive nonionic amphiphilic copolymers as draw solutes in forward osmosis process for high-salinity water reclamation
Thermo-responsive nonionic amphiphilic copolymers as draw solutes in forward osmosis process for high-salinity water reclamation
Recently, thermo-responsive nonionic amphiphilic copolymers have shown a great potential as forward osmosis (FO) draw solutes for high-salinity water desalination and zero-liquid discharge (ZLD). However, the relationship between the copolymer structural properties and key characteristics as draw solutes, as well as copolymer's chemical stability after regeneration have not been much studied. In this work, we systematically investigated poly (ethylene oxide)-block-poly (propylene oxide)-block-poly (ethylene oxide) (PEO-PPO-PEO) copolymers as draw solute. The results showed that the PEO segments significantly influenced the viscosity, osmotic pressure and lowest phase separation temperature of the copolymer aqueous solutions. Among four commercial copolymers studied, Pluronic® L35 with moderate molecular weight (Mn 1,900 Da), 50% PEO, and relatively high hydrophilic-lipophilic balance (HLB) showed the best draw solution (DS) performance. It also showed great stability in physiochemical properties and draw capacity after more than ten cycles of regeneration. On the other hand, despite the fact that membrane fouling was observed due to the use of copolymer DS, the FO flux (∼1.2 L m‒2 h‒1, as similar with the virgin membrane) was not affected when high-salinity feedwater such as seawater RO brine was applied. Overall, our study has provided a more comprehensive understanding on the characteristics of nonionic amphiphilic copolymer DS and showcased the promise of copolymer-driven FO process in high-salinity water desalination and ZLD.
Draw solute, Forward osmosis (FO), High-salinity water desalination, Nonionic amphiphilic copolymer, Thermo-responsive, Zero-liquid discharge (ZLD)
Xu, Yilin
1ee73e6a-94ac-4a27-ab2c-16f4bbb95fdf
Wang, Yi Ning
3a06a4c4-af75-4895-a7c5-163cb29a65a0
Chong, Jeng Yi
2f9ead94-86f2-4e20-9e67-75f10759555b
Wang, Rong
fd4ca2d0-78f2-40c2-aad1-355e7f3f3022
22 June 2022
Xu, Yilin
1ee73e6a-94ac-4a27-ab2c-16f4bbb95fdf
Wang, Yi Ning
3a06a4c4-af75-4895-a7c5-163cb29a65a0
Chong, Jeng Yi
2f9ead94-86f2-4e20-9e67-75f10759555b
Wang, Rong
fd4ca2d0-78f2-40c2-aad1-355e7f3f3022
Xu, Yilin, Wang, Yi Ning, Chong, Jeng Yi and Wang, Rong
(2022)
Thermo-responsive nonionic amphiphilic copolymers as draw solutes in forward osmosis process for high-salinity water reclamation.
Water Research, 221, [118768].
(doi:10.1016/j.watres.2022.118768).
Abstract
Recently, thermo-responsive nonionic amphiphilic copolymers have shown a great potential as forward osmosis (FO) draw solutes for high-salinity water desalination and zero-liquid discharge (ZLD). However, the relationship between the copolymer structural properties and key characteristics as draw solutes, as well as copolymer's chemical stability after regeneration have not been much studied. In this work, we systematically investigated poly (ethylene oxide)-block-poly (propylene oxide)-block-poly (ethylene oxide) (PEO-PPO-PEO) copolymers as draw solute. The results showed that the PEO segments significantly influenced the viscosity, osmotic pressure and lowest phase separation temperature of the copolymer aqueous solutions. Among four commercial copolymers studied, Pluronic® L35 with moderate molecular weight (Mn 1,900 Da), 50% PEO, and relatively high hydrophilic-lipophilic balance (HLB) showed the best draw solution (DS) performance. It also showed great stability in physiochemical properties and draw capacity after more than ten cycles of regeneration. On the other hand, despite the fact that membrane fouling was observed due to the use of copolymer DS, the FO flux (∼1.2 L m‒2 h‒1, as similar with the virgin membrane) was not affected when high-salinity feedwater such as seawater RO brine was applied. Overall, our study has provided a more comprehensive understanding on the characteristics of nonionic amphiphilic copolymer DS and showcased the promise of copolymer-driven FO process in high-salinity water desalination and ZLD.
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More information
Accepted/In Press date: 15 June 2022
e-pub ahead of print date: 16 June 2022
Published date: 22 June 2022
Additional Information:
Funding Information:
We acknowledge funding (S16-1309-NRF-Water-RCFS) support from Singapore Economic Development Board, Singapore, to the Singapore Membrane Technology Centre, Singapore. Appreciate Dr Daniel Yee Fan Ng for developing the in-house made TFC FO hollow fiber membranes. We also acknowledge Dr Yunbo Lv and Ms Janelle Ru Ying Ng from Nanyang Environment and Water Research Institute Analytics Cluster, Nanyang Technological University, Singapore, for the guidance of operating XPS and GPC.
Keywords:
Draw solute, Forward osmosis (FO), High-salinity water desalination, Nonionic amphiphilic copolymer, Thermo-responsive, Zero-liquid discharge (ZLD)
Identifiers
Local EPrints ID: 486391
URI: http://eprints.soton.ac.uk/id/eprint/486391
ISSN: 0043-1354
PURE UUID: 1f773851-f310-4779-877d-c3d5cf9d2ae1
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Date deposited: 19 Jan 2024 17:31
Last modified: 18 Mar 2024 04:18
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Contributors
Author:
Yilin Xu
Author:
Yi Ning Wang
Author:
Jeng Yi Chong
Author:
Rong Wang
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