Characterization of internal and external concentration polarizations during forward osmosis processes

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• 作者：Yiben Gao^a ; ^b ; Yi-Ning Wang^a ; ^b ; Weiyi Li^a ; ^b ; Chuyang Y. Tang^b ; ^c ; ^{tangc@hku.hk" class="auth_mail}
• 关键词：Forward osmosis ; Structural parameter ; Internal concentration polarization ; External concentration polarization
• 刊名：Desalination
• 出版年：1 April, 2014
• 年：2014
• 卷：338
• 期：Complete
• 页码：65-73
• 全文大小：1720 K

文摘

Forward osmosis (FO) is an emerging technology showing promising future in fields of water/wastewater reclamation, desalination and energy production. However, the efficiency of such process can be adversely affected by internal concentration polarization (ICP), which is usually characterized by the structural parameter, S value. In this work, we established three independent testing methods in reverse osmosis (RO) mode to evaluate the S value, namely the J_v-method, the R_s-method and the R_t-method, relying on the measurements of RO water flux, salt rejection and trace contaminant (boron in this work) rejection, respectively. S values achieved by three methods showed good agreement with that obtained by the conventional FO water flux fitting method. Among the three approaches, the R_s-method exhibited a much smaller deviation and it was demonstrated successfully that this method can be used to estimate the value of the solute permeability graphically at the same time. In addition, the R_s-method showed the feasibility to study ICP and external concentration polarization (ECP) interpretively.