Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", Aghia Paraskevi, 15341 Attica, Greece.
School of Mechanical Engineering, National Technical University of Athens, Zografou, 15780 Attica, Greece.
ACS Appl Mater Interfaces. 2023 Apr 12;15(14):18493-18504. doi: 10.1021/acsami.3c00535. Epub 2023 Mar 29.
Superhydrophobicity has only recently become a requirement in membrane fabrication and modification. Superhydrophobic membranes have shown improved flux performance and scaling resistance in long-term membrane distillation (MD) operations compared to simply hydrophobic membranes. Here, we introduce plasma micro- and nanotexturing followed by plasma deposition as a novel, dry, and green method for superhydrophobic membrane fabrication. Using plasma micro- and nanotexturing, commercial membranes, both hydrophobic and hydrophilic, are transformed to superhydrophobic featuring water static contact angles (WSCA) greater than 150° and contact angle hysteresis lower than 10°. To this direction, hydrophobic polytetrafluoroethylene (PTFE) and hydrophilic cellulose acetate (CA) membranes are transformed to superhydrophobic. The superhydrophobic PTFE membranes showed enhanced water flux in standard air gap membrane distillation and more stable performance compared to the commercial ones for at least 48 h continuous operation, with salt rejection >99.99%. Additionally, their performance and high salt rejection remained stable, when low surface tension solutions containing sodium dodecyl sulfate (SDS) and NaCl (down to 35 mN/m) were used, showcasing their antiwetting properties. The improved performance is attributed to superhydrophobicity and increased pore size after plasma micro- and nanotexturing. More importantly, CA membranes, which are initially unsuitable for MD due to their hydrophilic nature (WSCA ≈ 40°), showed excellent performance with stable flux and salt rejection >99.2% again for at least 48 h, demonstrating the effectiveness of the proposed method for wetting control in membranes regardless of their initial wetting properties.
超疏水性最近才成为膜制造和修饰的要求。与简单的疏水性膜相比，超疏水性膜在长期膜蒸馏 (MD) 操作中表现出了更高的通量性能和抗结垢性。在这里，我们介绍了等离子体微纳结构化处理和随后的等离子体沉积，这是一种新颖的、干燥的、绿色的超疏水性膜制造方法。使用等离子体微纳结构化处理，商业疏水性和亲水性膜都可以转变为具有大于 150°水静态接触角 (WSCA) 和低于 10°接触角滞后的超疏水性。为此，我们将疏水性聚四氟乙烯 (PTFE) 和亲水性醋酸纤维素 (CA) 膜转变为超疏水性。超疏水性 PTFE 膜在标准空气隙膜蒸馏中表现出更高的水通量，与商业膜相比，其连续运行至少 48 小时的性能更稳定，盐截留率 >99.99%。此外，当使用表面张力低的含有十二烷基硫酸钠 (SDS) 和 NaCl 的溶液 (低至 35 mN/m) 时，其性能和高盐截留率仍然稳定，表现出其抗湿性能。性能的提高归因于等离子体微纳结构化处理后超疏水性和孔径增大。更重要的是，由于初始亲水性 (WSCA ≈ 40°)，CA 膜最初不适合 MD，但经过等离子体微纳结构化处理后表现出优异的性能，稳定通量和盐截留率 >99.2%，至少 48 小时，证明了该方法在膜润湿控制中的有效性，无论其初始润湿性质如何。
