Nicolaus Copernicus University in Toruń , Faculty of Chemistry, 7 Gagarina Street, 87-100 Toruń, Poland.
Institut Europeen des Membranes, UMR 5635 , Place Eugene Bataillon, 34095 Montpellier cedex 5, France.
ACS Appl Mater Interfaces. 2016 Mar 23;8(11):7564-77. doi: 10.1021/acsami.6b00140. Epub 2016 Mar 9.
The combination of microscopic (atomic force microscopy and scanning electron microscopy) and goniometric (static and dynamic measurements) techniques, and surface characterization (surface free energy determination, critical surface tension, liquid entry pressure, hydraulic permeability) was implemented to discuss the influence of perfluoroalkylsilanes structure and grafting time on the physicochemistry of the created hydrophobic surfaces on the titania ceramic membranes of 5 kD and 300 kD. The impact of molecular structure of perfluoroalkylsilanes modifiers (possessing from 6 to 12 carbon atoms in the fluorinated part of the alkyl chain) and the time of the functionalization process in the range of 5 to 35 h was studied. Based on the scanning electron microscopy with energy-dispersive X-ray spectroscopy, it was found that the localization of grafting molecules depends on the membrane pore size (5 kD or 300 kD). In the case of 5 kD titania membranes, modifiers are attached mainly on the surface and only partially inside the membrane pores, whereas, for 300 kD membranes, the perfluoroalkylsilanes molecules are present within the whole porous structure of the membranes. The application of 4 various types of PFAS molecules enabled for interesting observations and remarks. It was explained how to obtain ceramic membrane surfaces with controlled material (contact angle, roughness, contact angle hysteresis) and separation properties. Highly hydrophobic surfaces with low values of contact angle hysteresis and low roughness were obtained. These surfaces possessed also low values of critical surface tension, which means that surfaces are highly resistant to wetting. This finding is crucial in membrane applicability in separation processes. The obtained and characterized hydrophobic membranes were subsequently applied in air-gap membrane distillation processes. All membranes were very efficient in MD processes, showing good transport and selective properties (∼99% of NaCl salt rejection). Depending on the membrane pore size and used modifiers, the permeate flux was in the range of 0.5-4.5 kg·m(-2)·h(-1) and 0.3-4.2 kg·m(-2)·h(-1) for 5 kD and 300 kD membranes, respectively.
采用微观（原子力显微镜和扫描电子显微镜）和测角（静态和动态测量）技术以及表面特性（表面自由能测定、临界表面张力、液体入口压力、水力渗透率）相结合的方法，讨论了全氟烷基硅烷结构和接枝时间对 5kD 和 300kD 二氧化钛陶瓷膜疏水性表面的理化性质的影响。研究了全氟烷基硅烷修饰剂（氟烷基链中含有 6 至 12 个碳原子）的分子结构和功能化过程（5 至 35 小时）对疏水性表面的影响。基于带有能量色散 X 射线光谱的扫描电子显微镜发现，接枝分子的定位取决于膜孔径（5kD 或 300kD）。对于 5kD 二氧化钛膜，修饰剂主要附着在表面上，仅部分附着在膜孔内，而对于 300kD 膜，全氟烷基硅烷分子存在于整个多孔膜结构中。应用 4 种不同类型的 PFAS 分子进行了有趣的观察和讨论。解释了如何获得具有可控材料（接触角、粗糙度、接触角滞后）和分离性能的陶瓷膜表面。获得了具有低接触角滞后和低粗糙度的高疏水性表面。这些表面还具有低临界表面张力值，这意味着表面具有高度的抗湿性。这一发现对于膜在分离过程中的应用至关重要。随后，获得并表征的疏水性膜被应用于气隙膜蒸馏过程中。所有膜在 MD 过程中都非常有效，表现出良好的传输和选择性特性（~99%的 NaCl 盐排斥）。根据膜孔径和使用的修饰剂，5kD 和 300kD 膜的渗透通量分别在 0.5-4.5kg·m(-2)·h(-1)和 0.3-4.2kg·m(-2)·h(-1)范围内。
