Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China.
NUS Graduate School for Integrative Science and Engineering, National University of Singapore, Singapore 119077, Singapore.
Environ Sci Technol. 2021 Oct 19;55(20):14156-14164. doi: 10.1021/acs.est.1c04443. Epub 2021 Oct 1.
Although membrane distillation (MD) has been identified as a promising technology to treat hypersaline wastewaters, its practical applications face two prominent challenges: membrane wetting and fouling. Herein, we report a facile and scalable approach for fabricating a Janus MD membrane comprising a dense polyvinyl alcohol (PVA) surface layer and a hydrophobic polyvinylidene fluoride (PVDF) membrane substrate. By testing the Janus membrane in direct contact MD experiments using feeds containing a sodium dodecyl sulfate (SDS) surfactant or/and mineral oil, we demonstrated that the dense Janus membrane can simultaneously resist wetting and fouling. This method represents the simplest approach to date for fabricating MD membranes with simultaneous wetting and fouling resistance. Importantly, we also unveil the mechanism of wetting resistance by measuring the breakthrough pressure and surfactant permeation (through the PVA layer) and found that wetting resistance imparted by a dense hydrophilic layer is attributable to capillary pressure. This new insight will potentially change the paradigm of fabricating wetting-resistant membranes and enable robust applications of MD and other membrane contactor processes facing challenges of pore wetting or/and membrane fouling.
尽管膜蒸馏（MD）已被确定为处理高盐废水的有前途的技术，但其实用化应用面临两个突出的挑战：膜润湿和污染。在此，我们报告了一种简便且可扩展的方法来制造包含致密聚乙烯醇（PVA）表面层和疏水性聚偏二氟乙烯（PVDF）膜基底的 Janus MD 膜。通过使用含有十二烷基硫酸钠（SDS）表面活性剂和/或矿物油的进料在直接接触 MD 实验中测试 Janus 膜，我们证明了致密的 Janus 膜可以同时抵抗润湿和污染。这种方法是迄今为止制造具有同时抗润湿和污染阻力的 MD 膜的最简单方法。重要的是，我们还通过测量突破压力和表面活性剂渗透（通过 PVA 层）来揭示抗润湿的机制，并发现由致密亲水性层赋予的抗润湿能力归因于毛细压力。这一新的见解将有可能改变制造抗润湿膜的范例，并使 MD 和其他膜接触器工艺在面临孔润湿或/和膜污染挑战时能够实现稳健的应用。
