Transport of organic solutes in ion-exchange membranes: Mechanisms and influence of solvent ionic composition

WATER RESEARCH

卷:190

Article

Ma, Lingshan¹  Gutierrez, Leonardo^1,2  Verbeke, Rhea³  D'Haese, Arnout¹  Waqas, Muhammad¹  Dickmann, Marcel⁴  Helm, Ricardo⁴  Vankelecom, Ivo³  Verliefde, Arne¹  Cornelissen, Emile^1,5 

[1] Univ Ghent, Particle & Interfacial Technol Grp, Ghent, Belgium

[2] Univ Pacifico, Fac Mar & Medio Ambiente, Guayaquil, Ecuador

[3] Katholieke Univ Leuven, Ctr Membrane Separat Adsorpt Catalysis & Spect Su, Membrane Technol Grp, Leuven, Belgium

[4] Univ Bundeswehr Munchen, Inst Angew Phys & Messtech, Munich, Germany

[5] KWR Water Res Inst, Nieuwegein, Netherlands

关键词: Ion-exchange membranes;    Organic solutes;    Transport mechanism;    Selective separation;    Influence of salts;   

DOI  :  10.1016/j.watres.2020.116756

来源: Elsevier

【 摘 要 】

Ion-exchange membrane (IEM)-based processes are used in the industry or in the drinking water production to achieve selective separation. The transport mechanisms of organic solutes/micropollutants (i.e., paracetamol, clofibric acid, and atenolol) at a single-membrane level in diffusion cells were similar to that of salts (i.e., diffusion, convection, and electromigration). The presence of an equal concentration of salts at both sides of the membrane slightly decreased the transport of organics due to lower diffusion coefficients of organics in salts and the increase of hindrance and/or decrease of partitioning in the membrane phase. In the presence of a salt gradient, diffusion was the main transport mechanism for non-charged organics, while the counter-transport of salts promoted the transport of charged organics through electromigration (electroneutrality). Conversely, the co-transport of salts hindered the transport of charged organics, where diffusion was the main transport mechanism of the latter. Although convection played a role in the transport of non-charged organics, its influence on the charged solutes was minimal due to the dominant electromigration. Positron annihilation lifetime spectroscopy showed a bimodal size distribution of free-volume elements of IEMs, with both classes of free-volume elements contributing to salt transport, while larger organics can only transport through the larger class. (c) 2020 Elsevier Ltd. All rights reserved.

【 授权许可】

Free