Enhanced, hydrophobic, fluorine-containing, thermally rearranged (TR) nanofiber membranes for desalination via membrane distillation

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Though membrane distillation (MD) has been considered as a promising desalination process, it is still required to develop a desirable membrane which has high water flux and long-term stability for practical use in the MD process. In our previous work, thermally rearranged nanofiber membranes (TR-NFMs), which exhibited high water flux (80kgm<SUP>−2</SUP> h<SUP>−</SUP> <SUP>1</SUP>) and salt rejection (> 99.99%) as well as outstanding long-term stability (more than 180h), were first introduced as a promising candidate for MD applications. However, nascent TR-NFM is susceptible to fluctuations in operating conditions due to insufficient liquid entry pressure with water (LEP<SUB>w</SUB>). In continuation of our enhanced hydrophobic TR-NFM study, we develop fluorine-containing thermally-rearranged nanofiber membranes (F-TR-NFMs) for MD applications for the first time. F-TR-NFMs showed enhanced hydrophobic properties such as high water contact angle (143°), high LEP<SUB>w</SUB> (1.3bar), and high effective evaporation area (EEA) due to the introduction of fluorine atoms in the backbone of the TR membrane. As the result, the developed F-TR-NFMs exhibited outstanding MD performance (114.8kgm<SUP>−2</SUP> h<SUP>−</SUP> <SUP>1</SUP> of water flux and > 99.99% of salt rejection at feed and permeate temperatures of 80°C and 20°C, respectively) and excellent energy efficiency (52.1% at feed and permeate temperatures of 50°C and 20°C, respectively). The long-term stability of F-TR-NFM is also investigated over more than 250h of operation time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fluorine-containing TR electrospun membrane exhibited improved contact angle and liquid entrance pressure. </LI> <LI> Fluorine-containing TR electrospun membrane also exhibited high water flux and stable long-term stability. </LI> <LI> Effective evaporation area (EEA) on the membrane surface was calculated with pore size and water contact angle. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>