Consider the steady-state diffusion of a solute through a membranous sphere as shown in Figure6.35 (not given). Such a situation occurs when drugs are released from liposomes. The membrane is defined by the region between R0 and Ri. The solute concentration is highest at the core region. The spheres are placed in a large reservoir and the solute concentration in the bath is zero. Assume that the partition coefficient is one.
(a) State the steady-state form of the differential mass balance for diffusion in a sphere with no convection or reaction.
(b) State the boundary conditions
(c) Solve to obtain the concentration distribution in the membrane
(d) Determine the flux at r = R0