Transport and Permeation

Generally speaking, two principal mechanisms operate in the biology of membrane processes, such as membrane transport and permeation. One involves a network of active sites and operates by metabolic energy, and it is referred to as active another is directed by passive diffusion, and it is called passive. This passive mechanism is determined by various aspects of lipid dynamics and lipid-protein interactions, and it can be described in quantitative terms of chemical and phase equilibrium and molecular physics. However, in the highly anisotropic... 

M. R. Weisner and P. Aptel, Mass transport and permeate flux and fouling in pressure-driven processes. In Water Treatment Membrane Processes, P. E. Odendaal, M. R. Wiesner, and J. Mallevialle (eds.), McGraw-Hill, New York, pp. 4.1. 30 (1996). 

Chellam S., Wiesner M.R, (1997), Particle back-transport and permeate flux behaviour in crossflow membrane filters. Environmental Science and Technology, 31, 3, 819-824. 

For measuring the respiratory activity of the bacteria they used 5.0 mM K3[Fe (CN)6l hydrophilic mediator added to the PBS buffer electrolyte. The mediator after passing through the cell membrane could interfere with the respiration cycle and got reduced. As the formed [Fe(CN)6]" diffused back to the buffer through the gap, its mass flow could be detected recording the amperometric current at 0.6 V electrode potential. In this case the oxidative current depends on the transport and permeation rate of the mediator as well as on the metabolic activity of the culture. 

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