Transmission of sodium chloride in PDMS membrane during Pervaporation based on polymer relaxation

Zuo, Chengye; Xu, Shuainan; Ding, Xiaobin; Jin, Wanqin; Xing, Weihong; Ke, Xuebin

Abstract

Polydimethylsiloxane (PDMS) composite membrane is used for treating pharmaceutical wastewater containing NaCl and solvent. In this study, the influence of feed concentrations of NaCl and isobutanol, process temperature and membrane microstructures on salt rejection are evaluated. Microstructures of PDMS membrane before and after separation are characterized by nuclear magnetic resonance (NMR), energy dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Positron annihilation life-time spectroscopy (PALS). The PV results show that NaCl will not spontaneously enter PDMS membrane without isobutanol. However, while NaCl feed concentration is 13 wt%, salt rejection of PDMS membrane drops from 100% to 99.09% with increasing feed concentration of isobutanol (up to 7 wt%). On the contrary, a higher temperature increases salt rejection of PDMS membrane and NaCl permeation through PDMS membrane is not through a vapor permeate process. Due to the relaxation of PDMS polymer chain, when PDMS cross-linking ratio is 0.1, the salt rejection increases from 99.87% to 100% with its thickness increasing from 10 μm to 17.5 μm. While the cross-linking ratio rises to 0.2, the salt rejection is 100% with the PDMS layer thickness of 10 μm. The relationship between relaxation of polymer chains and transport of NaCl in PDMS membrane is an excellent guidance and will be beneficial for the treatment of saline organic wastewater.

Citation

Zuo, C., Xu, S., Ding, X., Jin, W., Xing, W., & Ke, X. (2022). Transmission of sodium chloride in PDMS membrane during Pervaporation based on polymer relaxation. Journal of membrane science, 659, Article 120812. https://doi.org/10.1016/j.memsci.2022.120812

• Journal Article Type: Article
• Acceptance Date: Jul 8, 2022
• Online Publication Date: Jul 16, 2022
• Publication Date: Oct 5, 2022
• Deposit Date: Aug 30, 2022
• Publicly Available Date: Aug 30, 2022
• Journal: Journal of Membrane Science
• Print ISSN: 0376-7388
• Electronic ISSN: 1873-3123
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 659
• Article Number: 120812
• DOI: https://doi.org/10.1016/j.memsci.2022.120812
• Keywords: Salt rejection; Isobutanol; Polydimethylsiloxane membrane; Pervaporation; Polymer relaxation
• Public URL: https://hull-repository.worktribe.com/output/4041527