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Indexed by:期刊论文

Date of Publication:2017-04-01

Journal:DESALINATION AND WATER TREATMENT

Included Journals:SCIE

Volume:71

Page Number:280-288

ISSN No.:1944-3994

Key Words:Electric-sensitive; PVA/PAAc hydrogels; Forward osmosis; Draw agent

Abstract:In this study, electric-sensitive poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAAc) hydrogels were fabricated as draw agent for forward osmosis. By controlling the amounts of cross-linker, chemical crosslinked method integrated with freezing-thawing was adopted, and prepared hydrogels were denoted as PVA3M0.25, PVA3M0.5, PVA3M1.0 and PVA3M1.5. The mass retention ratio examination indicated that PVA/PAAc hydrogels were sensitive to subtle electric stimuli; thus, they could shrink and release water under non-contacted electric field. And swelling ratio experiment suggested that PVA3M1.0 had relatively higher swelling ratio. Swelling exponent n value was above 0.5, which indicated that the swelling process belonged to the non-Fickian diffusion and water absorbing mechanism was more complex. Besides, swelling-deswelling behavior analysis showed that hydrogels could restore the original state in the next swelling experiment when the hydrogels released water under non-contacted electric field. Thus PVA3M0.5 and PVA3M1.0 were selected as draw agent for forward osmosis; by using deionized water and 2,000 ppm NaCl solution as feed solution, the initial water fluxes obtained were 1.04, 0.72, 0.73 and 0.54 LMH, respectively, with hydrogels against the active layer of membrane. Therefore, using electric-sensitive hydrogels as draw agent can eliminate reverse salt leakage and reduce the complexity of the operation in forward osmosis process.