Computational Simulation Studies of Membrane Fouling Mechanisms and Designing New Antifouling Membranes

饮用水短缺正成为世界上一个日益具有挑战性的问题。今天，约有11亿人，约占世界人口的六分之一，生活在没有足够安全饮用水的地区。使用膜分离过程可以去除水中的污染物。膜允许纯净水通过，同时保留污染物。然而，污染物可能会积聚并污染传统的膜技术。污染会降低膜的性能，需要定期清洗膜，并增加能源消耗。膜污染的机理以及造成膜污染的化学性质在分子水平上还没有被很好地理解。这一研究项目将推进一种广泛使用的聚合物膜的计算模型，并开发有效的模拟方法，以提供对污染机理的基本理解。该项目将使用新的计算工具来探索设计用于水净化的高性能、抗污染膜的策略。该项目针对膜污染的基本问题，并提出了通过表面改性设计抗污染膜的新策略，主要是通过接枝不同的两性离子涂层。研究目标包括：(1)开发聚酰胺膜和污染物的计算模型，其中膜表面模型能够基于现有的实验数据恰当地描述膜的表面化学和形态；(2)开发结合非平衡分子动力学筛选和平衡伞采样技术来准确地寻找膜-污染复杂系统的最低自由能污染位置和污染构型；以及(3)使用所开发的计算模型和工具进行广泛的分子模拟来研究表面改性聚酰胺膜及其抗污染性能，为防污染材料的分子设计提供新的策略。该项目为学生提供了一个获得基于模拟的工程和科学研究方面的教育和培训的重要机会。一名研究生将接受该项目的培训。本科生和高中生，包括女性和少数族裔学生，将通过机构暑期本科教育和研究计划的支持参与该计划。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The shortage of potable water is becoming an increasingly challenging issue in the world. Today, about 1.1 billion people, roughly one sixth of the world's population, live in areas without enough safe drinking water. Water contaminants can be removed using a membrane separation process. Membranes allow purified water to pass while retaining the contaminants. However, the contaminants can build up and foul conventional membrane technologies. Foulants reduce membrane performance, require regular membrane cleaning, and increase energy consumption. The mechanism by which membranes foul, and what chemical attributes contribute to membrane fouling, are not well understood on a fundamental molecular level. This research project will advance computational models for a widely used polymer membrane and develop efficient simulation methods to provide fundamental understanding of fouling mechanisms. The project will use the new computational tool to explore strategies of designing high-performance, antifouling membranes for water purification.This project targets fundamental questions of membrane fouling and proposes new strategies for designing antifouling membranes through surface modification, mainly by grafting different polyzwitterion coatings. Research objectives include: (1) developing computational models for polyamide membranes and foulants, in which the membrane surface model can properly represent the surface chemistry and morphology based on available experimental datasets; (2) developing a combined nonequilibrium molecular dynamics screening and equilibrium umbrella sampling technique to accurately search for the lowest free energy fouling sites and fouling configurations for a membrane-foulant complex system; and (3) using the developed computational models and tools to perform extensive molecular simulations to investigate surface modified polyamide membrane and its antifouling properties, proposing new strategies for the molecular design of antifouling materials. The project provides an important opportunity for students to obtain education and training in simulation-based engineering and science research. One graduate student will be trained in this project. Undergraduate and high school students, including women and minority students, will participate in the program through the support of institution summer undergraduate program for education and research.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.