Membrane solution interface, couple reactions

In this chapter, a novel interpretation of the membrane transport process elucidated based on a voltammetric concept and method is presented, and the important role of charge transfer reactions at aqueous-membrane interfaces in the membrane transport is emphasized [10,17,18]. Then, three respiration mimetic charge (ion or electron) transfer reactions observed by the present authors at the interface between an aqueous solution and an organic solution in the absence of any enzymes or proteins are introduced, and selective ion transfer reactions coupled with the electron transfer reactions are discussed [19-23]. The reaction processes of the charge transfer reactions and the energetic relations... 

Further development of the SLM-ionic liquid methodology has been coupled with lipase-catalyzed esterification and ester-hydrolysis reactions in the feed gas (interface 1) and receiving phase (interface 2), respectively, to facilitate selective transport of various organic acids with aryl groups (via their esters) from aqueous solutions by utilizing different substrate specificity of lipases in a SLM system (Fig. 5.6-11) [118]. In the enzymatic SLM systems a poly(propene) membrane with water-immiscible [RMIM][X] (R = butyl, hexyl, octyl and X = [PFe]" and [(CF3S02)2N] ) ionic liquid phases were used. 

Non-linear phenomena such as temporal oscillations and chemical waves in the case of chemical reactions are governed by the autocatalytic reaction (positive feedback) and reaction where the product of autocatalysis is destroyed by some other species (negative feedback). Of course in the case of chemical waves (spatio-temporal oscillations), diffusion does play a role, and the concept of reaction diffusion equation is evoked to predict the dependence of velocity of chemical waves on different parameters. In this chapter, we propose to discuss electrical potential oscillations generated due to coupling of volume flux, solute flux and electric current through solid-liquid interface (membrane systems), liquid-liquid interface, solid-liquid-liquid interface (density oscillator) and liquid-liquid-vapour interface. 

If there is no redox couple in the analyzed solution, potentiometric measurements are not influenced by the existence of an electronic conductivity in the SIC. The voltage is fixed only by the ionic exchange reaction at the interface between the SIC and the analyzed solution. Typical examples are Ag2S-based membranes. 

Proteins can be preferentially precipitated from solution using a technique known as electrodialysis coupled with the use of bipolar manbranes. The application is based on the specific properties of electrolysis (redox reactions at the electrodes) coupled with membrane action (Bazinet et al, 1998) resulting in either electro-acidificalion or electro-alkalinization. A bipolar membrane is a composite membrane consisting of a cation exchange layer and an anion exchange layer which can spUt solvents (water and methanol, so far) into H and OH7 CHjO at the interface under reverse potential bias (Xu and Huang, 2008). 

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