Rotating diffusion cell theory

The published literature is not comprehensive in respect of the theory behind the operation of the RDC, therefore a full description of it is given here. The conventional RDC and clamp-RDC are shown in Figs. 6.2 and 6.3. The latter is very similar in construction to that used by David Leahy [28, 29, 30]. The RDC can be used with a variety of procedures for establishment of one of two liquid-liquid interfaces. 

The figure shows known diffusion layers and steady state concentration gradients. These are consequences of the thickness of the diffusion layers being known (calculable) and that the experiment is performed under steady-state conditions. This condition may break down if rates are very fast or slow or concentration in the donor phase is outside the range 0.5-100 mM (which does not apply to his work). At a particular rotation speed W (1 W 8 Hz for experimental reasons), the steady flux j (in mol m-2 s-1) is given by the following, 

1 sinner compartment O Outer compartment T Thermostarting jacket L Lid P Pulley C Clamp 

With the RDC, the concentrations at the surface C0,0rg and C0,aq are exactly described by the above equations because, in general, the thickness of the diffusion layer, z is given by 

The term PowC aq accounts for the back reaction. During most experiments C PowCc.aq- We replace (C,e,org - PCc,aq) by C for clarity but the calculation is explicit throughout the calculations and the interpretation of data. 

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