Investigating A New Energy-Efficient Hybrid Ion Exchange-Nanofiltration (HIX-NF) Desalination Process

0853124 sengupta海水淡化是能源密集型的。一个典型的海水反渗透（RO）工厂需要1.5至2.5千瓦时（kwh）的电力来生产1立方米的处理水；而热蒸馏装置则需要5到10倍以上。该项目的主要目标是开发一种新的混合离子交换-纳滤（HIX-NF）工艺，该工艺有可能将海水淡化的能耗降低两到三倍，适用于大范围的给水盐度。所提出的工艺在其方法上是创新的，因为它在膜处理之前部分地改变了给水化学。具体来说，它通过可逆的阴离子交换过程将盐水中的主要阴离子氯离子转化为硫酸盐，而不需要任何再生剂。因此，反渗透膜可以被纳滤膜完全取代，从而显著降低能量需求。此外，与反渗透相比，纳滤膜更坚固，不易受污染，HIX-NF工艺有可能进一步浓缩废水，从而减少一次性盐水的体积。本研究的主要挑战在于设计和完善可逆的硫酸盐-氯离子交换过程，这是HIX-NF过程的重要组成部分。对于每一种半咸淡水/海水成分，阴离子交换剂都有独特的硫酸盐/氯化物选择性（即分离因子值），以维持HIX-NF过程。目前关于离子交换基础的知识和我们的相关工作强烈表明，通过改变胺官能团的大小，可以极大地操纵二价硫酸盐和单价氯化物之间的相对亲和力，以获得最佳的工艺性能。在本项目中，将对以下三种给水盐度进行严格的实验研究，以覆盖HIX-NF工艺的整个范围：6,000 mg/l, 12,000 mg/l和30,000 mg/l NaCl浓度。两名研究生（一名博士和一名硕士）将参与该项目。私家侦探计划从毕业班中招收一名女学生。私家侦探在利哈伊山谷的自由高中的科学课上讲授与水有关的课程。由于其全球吸引力，海水淡化将继续成为高中生的相关和有趣的话题。

0853124SenguptaWater desalination is energy-intensive. A typical seawater reverse osmosis (RO) plant requires 1.5 to 2.5 kilowatt hours (kwh) of electricity to produce 1 m3 of treated water; a thermal distillation plant requires five to ten times more. The principal objective of this project is to develop a new hybrid ion exchange-nanofiltration (HIX-NF) process that has the potential to reduce energy consumption of water desalination by two to three times for a wide range of feed water salinities. The proposed process is innovative in its approach for it partially alters the feed water chemistry prior to the membrane treatment. Specifically, it converts chloride, the predominant anion in salt water, into sulfate through a reversible anion exchange process without requiring any regenerant. As a result, RO membranes can be replaced altogether by NF membranes resulting in a marked reduction in energy requirement. Also, NF membrane is more robust and less susceptible to fouling compared to RO, the HIX-NF process has the potential to concentrate the reject stream further, thus reducing the volume of disposable brine. The primary challenge of this research lies in engineering and perfecting the reversible sulfate-chloride anion exchange process, a significant component of the HIX-NF process. For every brackish/sea water composition, there remains a unique sulfate/chloride selectivity (i.e., separation factor value) for anion exchangers to sustain the HIX-NF process. The present body of knowledge on ion exchange fundamentals and our related work strongly suggest that by changing the sizes of the amine functional groups, the relative affinity between divalent sulfate and monovalent chloride can be greatly manipulated for an optimal process performance. In this project, rigorous experimental studies will be conducted with the three following feed water salinities to cover the entire range for the HIX-NF process: 6,000 mg/l, 12,000 mg/l and 30,000 mg/l NaCl concentrations. Two graduate students (one doctoral and one MS) will work on the project. The P.I. plans to recruit one female student from the graduating class. The P.I. gives water related lectures in science classes of Freedom High School in the Lehigh Valley. Due to its global appeal, desalination will continue to be a relevant and interesting topic for high school students.