Science & Tech

A promising solution to improve the surface hydrophobicity of hydrophobic membranes

A promising solution to improve the surface hydrophobicity of hydrophobic membranes
Credit: Jun Pan et al, Frontiers of Chemical Science and Engineering (2022)

As many chemists know, the membrane distillation (MD) course of has gained rising recognition and a spotlight for saline remedy, particularly due to its extraordinarily excessive salt rejection (the theoretical worth as much as 100%). In MD, the hydrophobic membrane serves as a core and important a part of realizing two-phase separation. However, the prevailing membrane wetting phenomenon at all times restricts the long-term secure operation and separation effectivity.

Zhaoliang Cui, a professor from the College of Chemical Engineering of Nanjing Tech University, and colleagues have discovered one promising resolution to resolve this drawback by making ready hydrophobic poly(vinlidene fluoride-co-hexafluoro propylene) (PVDF-HFP) copolymer membrane to enhance floor hydrophobicity. Their research was printed on-line in Frontiers of Chemical Science and Engineering on March 28, 2022.

In this research, one hydrophobic fluorinated polymer materials, PVDF-HFP, was chosen because the membrane materials to arrange porous membrane for membrane distillation utility. The thermally induced section separation (TIPS) technique was employed to arrange the membrane, which is a typical fabrication technique. In order to lower hurt from the volatilization of used solvent at a excessive temperature in the course of the TIPS course of, the inexperienced and environmentally pleasant diluent acetyl tributyl citrate (ATBC) was used.

According to the section diagram of PVDF-HFP/ATBC system, there was a large liquid-liquid section area among the many vary of ready polymer concentrations (25-40 wt%), indicating {that a} liquid-liquid section separation happens. As a outcome, a last bi-continuous construction might be obtained. The pore connectivity, permeability and mechanical properties of such a construction will profit the mass switch in the course of the separation course of. The floor contact angle, porosity, tensile energy and elongation at breaks of the ready membranes on this research had been as much as 123.87o, 60.43%, 5.89 MPa and 396.85%, respectively.

Then the ready PVDF-HFP membranes had been utilized within the membrane distillation course of treating 3.5 wt% NaCl saline. Firstly, the bottom desalination efficiency was examined at totally different feed temperatures, which confirmed that the permeate flux remained proportional to the feed temperature. This is in keeping with frequent information. Moreover, for an extended testing interval, the ready membrane had a secure membrane distillation flux and was not wetted (the permeated conductivity was at all times round 2–3 mS·cm−1). These are all thrilling and satisfying outcomes.

Cui and his crew will proceed their research on the preparation of hydrophobic or super-hydrophobic membranes for membrane distillation purposes. They hope to arrange sufficient practical hydrophobic membranes to attain the ultimate aim of zero liquid discharge of wasted saline to have the ability to recycle the commercial uncooked supplies and water sources.

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More info:
Jun Pan et al, Poly(vinylidene fluoride-co-hexafluoro propylene) membranes ready through thermally induced section separation and utility in direct contact membrane distillation, Frontiers of Chemical Science and Engineering (2022). DOI: 10.1007/s11705-021-2098-y

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A promising resolution to enhance the floor hydrophobicity of hydrophobic membranes (2022, May 11)
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