Forward osmosis across an ionic membrane in a shell and tube apparatus for desalination applications
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Although 70% of the world’s surface is covered by water, water scarcity is a major problem in many parts of the world. Lack of freshwater availability lowers the quality of life and hampers economic development in such regions. Extracting clean water from saltwater by the process of desalination offers a potential solution to alleviate water stress. ☐ One such process of desalination is forward osmosis. Forward osmosis employs a semipermeable membrane and the natural osmotic pressure to separate impurities from water. This thesis investigates the forward osmosis performance of an ionic semipermeable membrane manufactured and provided by Xergy Inc. Here, forward osmosis represents the first step in a larger project that aims to purify water using a two-step process: forward osmosis followed by vacuum pervaporation. The project calls for the use of an ionic liquid to draw fresh water from saltwater, however, we employ potassium acetate solution as a functionally similar yet economical substitute. Tests reported here were conducted using a shell and tube type apparatus with 3% saltwater and potassium acetate solution flowing on opposite sides of an ionic membrane formed into tubes. The concentration of potassium acetate solution was measured as a function of time to record the rate of water transport across the ionic membrane, and thereby estimate the effectiveness of the forward osmosis process.
Description
Keywords
Forward osmosis, Water stress, Desalination, Clean water, Water purification, Vacuum pervaporation