Improvement of the Swelling Properties of Ionic Hydrogels by the Incorporation of Hydrophobic, Elastic Microfibers for Forward Osmosis Applications

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• 作者：Ranwen Ou ; Huacheng Zhang ; Seungju Kim ; George P. Simon ; Hongjuan Hou ; Huanting Wang
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：56
• 期：2
• 页码：505-512
• 全文大小：494K
• ISSN：1520-5045

文摘

The swelling properties of hydrogels as draw agents have been identified as one of the key parameters in determining the performance of polymer hydrogel-driven forward osmosis process. We report here a new strategy to improve the swelling property of hydrogels by the introduction of structural inhomogeneity and compressive forces in an ionic hydrogel for the purpose of increasing forward osmosis water flux. This is achieved by incorporating a hydrophobic, elastic polyester (PET) hollow microfiber into an ionic hydrogel under a compressive force during the preparation of the composite hydrogel monolith. The forward osmosis water flux of the composite hydrogels increased with increasing the microfiber loading and compression pressure. The composite hydrogel with 50 wt% PET microfiber loading and 18 kPa compression pressure demonstrated the highest flux. The water flux of poly(NIPAM-co-SA)–PET microfiber composite prepared under 18 kPa compression (PN5S5–PET-0.5/0.5-18) and poly(sodium acrylate)–PET microfiber composite (PSA–PET-0.5/0.5-18) reached 3.0 and 5.0 LMH in the first 10 min, respectively, when their swelling ratio is 4. The water flux of the composites was twice as high as the pure hydrogel. The composite hydrogels were also better at maintaining high water fluxes for a long period. The water flux of PSA–PET-0.5/0.5-18 decreased from 3.5 to 1.4 LMH after 24 h forward osmosis test. The combination of hydrophilic ionic hydrogel and hydrophobic PET microfiber resulted in an extended, porous structure within the hydrogel because of their different wettability, while an additional relaxation force was preserved in the composites because of the compression pressure applied during the preparation. Both of these worked together to enhance the FO water flux and maintain it for an extended long period.