Development of novel nanocomposite membranes for hybrid forward osmosis processes

清洁水是一种稀缺资源，因为地球上现有的水中只有2.5%适合人类直接饮用。与此同时，不断增长的世界人口、工业化、农业和污染极大地增加了对水的需求。这导致了水危机，这是21世纪的重大挑战之一。膜过程，特别是反渗透(RO)，现在是用于海水和咸水淡化的主要分离技术。反渗透是一种压力驱动的过程，在这个过程中，给水的泵送压力高于给水和渗透液之间的渗透压差，允许纯水渗透，而盐类被拒绝。反渗透膜脱盐是目前解决水危机的最佳方案。然而，这仍然是一项昂贵的技术，许多第三世界国家负担不起。在正向渗透(FO)中，正是渗透压力的差异(进料是在常压下)促使水从进料(可能是废水)渗透到更浓缩的提取液中。如果提取的溶液是海水，FO过程会将其稀释，使后续的反渗透不那么耗能，也不太容易出现结垢和结垢问题。FO不能是一个独立的海水淡化过程。然而，将反渗透和反渗透相结合形成复合工艺，可以显著降低膜淡化纯水的成本。不幸的是，尽管商业反渗透膜的数量很多，但目前可用的反渗透膜不足以满足这种混合工艺的需要。拟议的研究计划应对这一挑战。这项提议的核心是获得一种新型的薄膜纳米复合(TFN)FO膜，在优化的同时为混合工艺优化RO膜。我们还将引入一种新的基于动态FO测试的膜表征方法来评估渗透膜的结构参数。新方法代表了这一研究领域的根本性转变。TFN膜将使用纯净和功能化的纤维素纳米晶，即安全的纳米颗粒，这种纳米颗粒在加拿大大量存在。苦咸水的淡化对油砂工业至关重要。混合FO-RO工艺在加拿大的另一个关键应用是去除废水中的重金属，这对我们的采矿、铜冶炼和纺织行业至关重要。最后，通过该项目培训的学生将获得独特的技能组合，在科学和工程的交叉点上具有扎实的基础知识，并具有动手实践经验。他们将成为该领域的领导者，使加拿大对膜分离技术的贡献得到认可和相关。

Clean water is a scarce resource because only 2.5% of all the water present on Earth is suitable for direct human consumption. Simultaneously, the growing world population, industrialization, agriculture, and pollution have dramatically increased water demand. This has led to a water crisis, one of the grand challenges of the 21st century. Membrane processes, in particular reverse osmosis (RO), are now the primary separation technology used in seawater and brackish water desalination. RO is a pressure-driven process in which the feedwater is pumped at a pressure higher than the osmotic pressure difference between the feed and permeate, allowing pure water to permeate while salts are rejected. Water desalination by RO membranes is currently the best solution to tackle the water crisis. However, it is still an expensive technology, which is not affordable by many third world countries. In forward osmosis (FO), it is the difference in osmotic pressure (feed is at ambient pressure) that drives water permeation from feed (could be wastewater) to a more concentrated draw solution. If the draw solution is seawater, the FO process will dilute it, making subsequent RO less energy-intensive and less prone to fouling and scaling problems. FO cannot be a stand-alone desalination process. However, combining RO with FO into a hybrid process could significantly reduce pure water cost by membrane desalination. Unfortunately, despite the abundance of commercial RO membranes, currently available FO membranes are not adequate for such a hybrid process. The proposed research program addresses this challenge. This proposal's heart is the approach to a novel thin-film nanocomposite (TFN) FO membrane, optimized while simultaneously optimizing the RO membrane for the hybrid process. We will also introduce a new membrane characterization method based on dynamic FO tests to evaluate the osmotic membrane's structural parameter. The new method represents the fundamental shift in this research field. TFN membranes will utilize pure and functionalized cellulose nanocrystals, i.e., safe nanoparticles, which and abundant in Canada. Desalination of brackish water is vital for the oil sand industry. Another critical application of hybrid FO-RO processes in the Canadian context is removing heavy metals from wastewaters, vital for our mining, copper smelter and textile industries. Finally, students trained through this program will gain a unique combination of skills, strong fundamentals at the intersection of science and engineering, with hands-on practical experience. They will become leaders in the field, making Canada contributions to membrane separation technology recognizable and relevant.