Hybrid electrodialysis

Grebenuyak VD, Cheborateva RD, Linkov NA, and Linkov VM. Electro membrane extraction of Zn from Na-containing solutions using hybrid electrodialysis—ion exchange method. Desalination 1998 115 255-263. 

Leading Examples Electrodialysis has its greatest use in removing salts from brackish water, where feed salinity is around 0.05-0.5 percent. For producing high-purity water, ED can economically reduce solute levels to extremely low levels as a hybrid process in combination with an ion-exchange bed. ED is not economical for the produc tion of potable water from seawater. Paradoxically, it is also used for the concentration of seawater from 3.5 to 20 percent salt. The concentration of monovalent ions and selective removal of divalent ions from seawater uses special membranes. This process is unique to Japan, where by law it is used to produce essentially all of its domestic table salt. ED is very widely used for deashing whey, where the desalted product is a useful food additive, especially for baby food. 

Membrane operation is a specific, but not exotic, operation. In fact it is a hybrid of classical heat and mass transfer processes (Figure 4.1). Direct contact mass transfer operations tend to reach equilibrium due to a difference of chemical potential between two phases that are put into contact. In the same way, temperature equilibrium is aimed at during heat transfer operations, for which driving force is a temperature gradient. In contrast, for membrane operations, by using the specific properties of separation of the thin layer material that constitutes the membrane, under the particular driving force that is applied, it is possible to deviate from the equilibrium that prevails at fluid-to-fluid interphase with classical direct contact mass exchange systems and to reorientate the mass transfer properties. In particular, this is the case with classical operations such as microfiltration (MF), ultrafiltration (UF), reverse osmosis (RO), gas separation (GS), pervaporation (PV), dialysis (DI) or electrodialysis (ED), for which a few characteristics are recalled in Table 4.1. 

Tremendous opportunity exists for hybrid processes consisting solely of membrane processes or a combination of membrane and non-membrane processes. Of the large number of potential combinations, studies of several are reported in the literature including nanofiltration with reverse osmosis [99] nanofiltration with electrodialysis [100] ultrafiltration with nanofiltration and reverse osmosis [101] ultrafiltration with membrane distillation [102] nanofiltration with reverse osmosis and a microfiltration membrane-based sorbent [103] microfiltration with flotation [104] microfiltration and ultrafiltration with ozone and activated carbon adsorption [105] and membrane processes with photocatalysis [106-107]. Despite the activity in this area, a comprehensive approach to designing hybrid systems does not exist future work would benefit from the development of such a design framework. 

Another process entails using electrodialysis to treat RO reject from brackish water. A RO-EDR-CrystaUiser/setder-UF-WAIV hybrid process achieved 98% recovery in... 

Electrodeionization (EDI) is a hybrid process combining ion-exchange with electrodialysis by introducing ion-exchange resins into the electrodialysis chambers. The combination allows for treating very dilute electrolyte solutions, while the ion-exchange resin beads inside the chambers... 

Mahmoud, A. Hoadley, A.F. (2012) An evaluation of a hybrid ion exchange electrodialysis process in the recovery of heavy metals from simulated dilute industrial wastewater. Water Research, 46, 3364-3376. 

Nataraj, S.K., Sridhar, S., Shaikha, I.N., Reddy, D.S. Aminabhavi, T.M. (2007) Membrane-based micro-filtration/electrodialysis hybrid process for the treatment of paper industry wastewater. Separation and Purification Technology, 57, 185-192. 

Spoor, P.B., Koene, L. Janssen, L.J.J. (2002b) Potential and concentration gradients in a hybrid ion-exchange/electrodialysis cell. Journal of Applied Electrochemistry, 32, 369-377. 

Tran, A.T.K., Zhang, Y., Jullok, N., Meesschaert, B., Pinoy, L. Van der Bruggen, B. (2012) RO concentrate treatment by a hybrid system consisting of a pellet reactor and electrodialysis. Chemical Engineering Science, 79, 228-238. 

Sadyrbaeva (2011) proposed a novel method, called hybrid liquid membrane-electrodialysis process (HLM-electrodialysis), for Mn(II) extraction from sulfuric acid solutions. 

Sadyrbaeva, T.Zh. (2011) Hybrid liquid membrane-electrodialysis process for extraction of manganese(II). 

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