Hsu Chih-Hao, Ma Canghai, Bui Ngoc, Song Zhuonan, Wilson Aaron D, Kostecki Robert, Diederichsen Kyle M, McCloskey Bryan D, Urban Jeffrey J
The Molecular Foundry and Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
Idaho National Laboratory, P.O. Box 1625 MS 2208, Idaho Falls, Idaho 83415, United States.
ACS Omega. 2019 Feb 27;4(2):4296-4303. doi: 10.1021/acsomega.8b02827. eCollection 2019 Feb 28.
Forward osmosis (FO) has emerged as a new technology for desalination and exhibits potentials for applications where reverse osmosis is incapable or uneconomical for treating streams with high salinity or fouling propensity. However, most of current draw agents in FO are salts and difficult to be recycled cost- and energy-effectively. In this work, we demonstrate a new and facile approach to efficiently recover water from the FO process with enhanced water purity by using a binary ion liquid/hydrogel system. The hybrid ion liquid/hydrogel draw solution system demonstrated in this work synergistically leverages the thermoresponsive properties of both the ionic liquid (IL) and hydrogel to improve the overall FO performance. Our findings corroborate that the hydrogel mitigates the water flux decline of the IL as the draw agent and provide a ready route to contiguously and effectively regenerate water from the FO process. Such a route allows for an efficient recovery of water from the draw solute/water mixture with enhanced water purity, compared with conventional thermal treating of lower critical solution temperature IL draw solute/water. Furthermore, hydrogels can be used in a continuous and readily recyclable process to recover water without heating the entire draw solute/water mixture. Our design principles open the door to use low-grade/waste heat or solar energy to regenerate draw agents and potentially reduce energy in the FO process considerably.
正向渗透（FO）已成为一种用于海水淡化的新技术，在反渗透无法处理或处理高盐度或易结垢水流不经济的应用中展现出潜力。然而，目前FO中的大多数汲取剂都是盐，难以经济高效地回收利用。在这项工作中，我们展示了一种新的简便方法，通过使用二元离子液体/水凝胶系统，从FO过程中高效回收水并提高水的纯度。本文展示的混合离子液体/水凝胶汲取溶液系统协同利用了离子液体（IL）和水凝胶的热响应特性，以改善整体FO性能。我们的研究结果证实，水凝胶减轻了作为汲取剂的IL的水通量下降，并为从FO过程中连续有效地再生水提供了一条现成的途径。与对较低临界溶液温度的IL汲取溶质/水混合物进行传统热处理相比，这样一条途径能够从汲取溶质/水混合物中高效回收水并提高水的纯度。此外，水凝胶可用于连续且易于回收的过程中，无需加热整个汲取溶质/水混合物即可回收水。我们的设计原则为利用低品位/废热或太阳能再生汲取剂打开了大门，并有可能大幅降低FO过程中的能源消耗。
