第一作者：Farah Rahman Omi
通讯作者：Mohtada Sadrzadeh
通讯单位：加拿大阿尔伯塔大学
DOI:10.1016/j.seppur.2024.130083
在电-芬顿（EF）等高级氧化工艺（AOPs）中，处理浓度极低的新污染物（ECs）是一项重大挑战。将 EF 与膜蒸馏（MD）相结合可以浓缩进料溶液，从而改善反应动力学。我们的创新利用疏水性导电膜将 MD 与 EF 相结合，为连续脱水提供了可持续的解决方案，同时促进了 EF 反应。通过在聚四氟乙烯（PTFE）膜上使用银墨的简单 “喷涂和固化 ”方法制成的电活性膜具有高导电性（60000 S/cm）和水下疏油性。与单独使用 EF 相比，混合 EF-MD 在室温下的甲基橙（MO）降解率提高了 2.5 倍，总有机碳（TOC）降低了 3.4 倍。在去除 350 ppb 的布洛芬的测试中，EF-MD 在 20-60 °C 的温度范围内，在 2 小时的运行时间内实现了 81% 的降解。相比之下，仅 EF 就需要在 60 °C 下工作 6 小时以上才能达到类似的布洛芬降解水平。制作的 Ag-PTFE 膜可在低电位（-1 V）下运行，保持 10 mA 电流的稳定状态，因此是一种去除氨基甲酸乙酯的节能技术。此外，它还显示出卓越的抗生物污染特性，在 1 V 的电压下，它能使大肠杆菌完全失活，失活率大于 99%。Ag-PTFE 膜可以更大规模地制造，并能主动捕捉和降解通常对传统处理方法有抵抗力的有害微污染物。这样就能生产出更清洁、更安全的水，供人们饮用和排放到环境中。
Fig. 1. (A) Schematic image of Ag ink coating process on a PTFE membrane and a real picture of prepared Ag ink-coated PTFE membrane with a large surface area and (B) schematic presentation of hybrid MD-EF assembly with a cross-section image of the customized cell.
Fig. 2. FESEM images of (A) PTFE and (B) Ag-PTFE membranes at different magnifications of 20X and 2000X and (C) EDX mapping of Ag-PTFE membrane with corresponding C, F, and Ag contents. AFM images of PTFE membranes (D) ridge area (E) valley area; Ag-PTFE membrane(F) ridge area and (G) valley area. All the 3D images show root mean square roughness (Rq) and average roughness (Ra) of the surface.
Fig. 3. (A) XRD patterns and (B) TGA of both PTFE and Ag-PTFE membranes, XPS survey high-resolution spectrums of (C) C1s and (D) F1s for the PTFE membrane. XPS survey high-resolution spectrums of (E) C1s and (F) Ag3d for Ag-PTFE membrane, TEM cross-section images of the Ag-PTFE membrane, which were zoomed on the Ag ink coating top layer in (G) ridge and (H) valley areas, and water contact angles of (I) PTFE and (J) Ag-PTFE membranes.
Fig. 4. (A) Membrane stability assessments under different physical and chemical stresses using measurements of electrical conductivity and WCA. [The stability test conditions are: (1) Fresh Ag-PTFE membrane (2) Working as a cathode for 6hr at −1V (3) Working as an anode for 6hr at −1V (4) bath sonication for 1hr (5) Immersion in acidic solution at pH = 2 for 24hr and (6) Immersion in basic solution at pH = 10 for 24hr] The inside photograph shows a used Ag-PTFE membrane on which a 5 V DC electric potential difference was applied with a connected light bulb. (B) Zeta potentials of PTFE and AG-PTFE membranes in different pH values, and CV analyses using potassium hexacyanoferrate solution under (C) N2 and (D) air saturations.
Fig. 5. (A) Concentration of H2O2 produced by Ag-PTFE membrane as a function of electrolysis time, (B) calculated CE (%) values. Experimental conditions: [Na2SO4] = 50 mM, pH = 3, Ecell = -1 V, flow rate = 1 L/min.
Fig. 6. Water vapor flux and NaCl salt rejection in terms of conductivity (A) PTFE membrane (B) Ag-PTFE membrane; Water vapor flux and conductivity with feed solution containing a mixture of 3.5 % NaCl and 1 mM of SDS concentration of (C) PTFE membrane with static contact angle images taken with the 3.5 % NaCl and 1 mM SDS solution and (D) Ag-PTFE membrane with images of static contact angle using 3.5 % NaCl and 1 mM SDS solution; Water vapor flux and conductivity with feed solution containing a mixture of 3.5 % NaCl 1 g/L n-hexadecane oil and 1 mM of SDS surfactant of (E) PTFE membrane with the image showing a visible change of the membrane before and after 6 h run and (F) Ag-PTFE membrane with the image showing the front side and back side of the membrane after 6 h operational time.
在我们的研究中，我们利用简单有效的 “喷涂和固化 ”方法，在疏水性聚四氟乙烯膜上涂抹市售的银墨，从而制成了导电的银聚四氟乙烯膜。这种膜具有很高的导电性，即使在苛刻的条件下也能保持疏水性，因此适合大规模应用。银涂层还赋予了薄膜疏油特性，增强了它对表面活性剂和油附着物的抵抗力，这在涉及润湿和油水乳化的测试中尤为明显。将银-聚四氟乙烯膜集成到 EF-MD 混合系统中，可显著改善模型有机污染物甲基橙（MO）的降解，尤其是在高温条件下。与 EF-RT 相比，MD 促进的连续脱水进一步提高了 MO 的去除率（提高了 2.5 倍），这表明 EF-MD 组合工艺具有协同效应。值得注意的是，与 EF-RT 相比，EF-MD 对总有机碳 (TOC) 的去除率明显提高（提高了 3.4 倍），这表明热脱水对溶液中 MO 的完全降解动力学产生了有利影响。此外，EF-MD 系统中的 Ag-PTFE 膜加快了布洛芬（一种非甾体抗炎药物）的降解，仅在 2 小时内就达到了 81% 的去除率，突出了其降解新污染物（ECs）的效率。此外，集成的 EF-MD 技术还具有能耗低、有效防止生物污垢等优点。该系统依靠电化学反应产生羟基自由基，因此可以在较低的应用电压和电流下运行，从而降低了能源需求。此外，混合系统还可以利用低品位热资源加热给料溶液，进一步提高能效。此外，该系统即使在没有外加电场的情况下也能有效灭活微生物，这表明它在海水淡化、废水处理和资源回收等各种应用领域都具有潜力。如图 4A 所示，施加阳极电位可能会剥离银涂层。不过，能够承受阳极和阴极电位的电极将为广泛的电化学反应提供显著优势。
Farah Rahman Omi, Masoud Rastgar, Mojtaba Mohseni, Upasana Singh, Waralee Dilokekunakul, Robert Keller, David Wishart, Matthias Wessling, Chad Davis Vecitis, Mohtada Sadrzadeh, Removal of emerging contaminants from water using novel electroconductive membranes in a hybrid membrane distillation and electro-Fenton process, Separation and Purification Technology, 2025, https://doi.org/10.1016/j.seppur.2024.130083
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