The effect of material properties and scaling on wetting of membranes used in membrane distillation

开发高能效的处理方法来处理非传统水源将有助于解决全球水资源短缺问题。膜蒸馏可以处理高盐度和/或高度污染的沃茨，对于这些水，常规处理方法是不切实际的。膜蒸馏使用由废热和/或太阳热能提供的低级能量来蒸发（而不是煮沸）非饮用水流。膜允许水蒸气通过，同时限制液态水及其溶解的溶质的渗透。 膜蒸馏过程的设计涉及许多简化的假设，特别是膜对液态水及其溶解的溶质是不可渗透的。然而，随着时间的推移，溶解的溶质在膜上形成结垢层，损害膜排除液态水和溶质的能力。本项目将开发一个新的模型，以解决膜蒸馏过程的性能，这是符合长期运行的实际，非均相膜。本项目将开发一个新的模型，液体入口压力，包括操作条件，膜化学，不对称膜性能，和结垢层的影响。该模型将结合实验，探测内部和蒸馏侧膜性能孔润湿，简单和复杂的进料溶液化学，并考虑单组分和多组分的缩放条件。将考虑商业膜和改变疏水性与亲水性的新型聚合物膜。扩展的Washburn方法将量化多孔膜的内部疏水性。技术经济评估将量化高性能膜在高盐度应用中的关键影响。该项目将支持研究生和博士后培训，同时还将教育推广扩大到代表性不足和低收入的高中学生，使他们了解节能水生产。该项目将使更好的性能，预测和识别膜设计的改进，具有挑战性的，高盐度的应用，接近零液体排放。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Development of energy-efficient treatment methods to treat nonconventional water sources will help to address global water scarcity. Membrane distillation can treat high-salinity and/or highly contaminated waters, for which conventional treatment processes are impractical. Membrane distillation uses low-grade energy, supplied from waste heat and/or solar thermal energy, to vaporize (rather than boil) non-potable water streams. The membrane allows water vapor to pass, while restricting permeation of liquid water and its dissolved solutes. Design of membrane distillation processes involves a number of simplifying assumptions, in particular, that the membrane is impermeable to liquid water and its dissolved solutes. However, with time, dissolved solutes form a scaling layer on the membrane, compromising the ability of the membrane to exclude liquid water and solutes. This project will develop a new model to address the performance of membrane distillation processes that is consistent with long-term operation of practical, heterogeneous membranes.This project will develop a new model for liquid entry pressure that incorporates operating conditions, membrane chemistry, asymmetric membrane properties, and the effect of a scaling layer. The model will incorporate experiments that probe internal and distillate-side membrane properties on pore wetting, simple and complex feed solution chemistries, and consider both single- and multi-component scaling conditions. Both commercial membranes and novel polymer membranes that vary hydrophobicity versus hydrophilicity will be considered. An extended Washburn method will quantify the internal hydrophobicity of the porous membranes. A techno-economic assessment will quantify the key impacts of high-performance membranes for high-salinity applications. The project will support graduate and postdoctoral training, while also expanding educational outreach to underrepresented and low-income high school students on energy-efficient water production. The project will enable better performance, prediction, and identification of membrane design improvements for challenging, high-salinity applications that approach zero liquid discharge.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.