Non-Isothermal Donnan-Dialysis: a novel method beyond iso-thermal Water pre-Treatment paradigm for Energy Reduction in desalination

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Desalination technology is able to harvest abundant water from the sea or other saline sources such as groundwater and industrial effluents. However, the energy-intensity (EI) of water treatment by desalination is an increasing environmental, economical, and societal concern in many regions. An important way to reduce the energy intensity is to employ large resources of waste heat or lowgrade heat for pretreatment in desalination plants. Another challenge in desalination is the fouling and scaling of membranes by divalent cationic species (e.g. Ca2+, Mg2+) which necessitates chemical dosing and pretreatment and limits the fraction of water recovered. Some existing pretreatment technologies employ the concentration gradient between a feed and concentrate solution(Donnan-dialysis) or direct ion-exchange with ion exchange resins (IEX). Although Donnan-Dialysis (D2) is an economical, simple technological, and energy-saving process, it is not applied widely in industry because of its slow kinetics. Here, it is proposed to accelerate the D2 kinetics by a Non-Isothermal D2 as a novel method beyond iso-thermal WATer pre-treatment for Energy Reductionin desalination (NID2WATER) via recycling the waste heat as an additional driving force. The Fellow will, firstly, develop a nanofluidic chip and then a D2 stack with ion-selective membranes to investigate the NID2 fundamentally and practically, respectively. Then, he will perform a theoretical study to interpret rigorously the experimental data. The project will not only provide a solution for recycling the waste heat from desalination plants that is harmful to the marine environment but also enhance our understanding of thermoosmosis through electrically charged membranes. It is expected that the experimental and theoretical study will contribute to the applications of desalination in meeting world food and water demand and in recovering valuable metals from desalination brines.