It is desired to concentrate species A from a dilute mixture of solutes A and B dissolved in liquid water using a porous membrane. The membrane contains cylindrical pores in uniform parallel array. The separation factor (a) is defined as

α = D_Ae/D_Be

For solute A, the molecular weight is 142 g/gmole, molecular diameter is 2.0 nm, and the molar volume at boiling point is 233.7 cm³/gmole. For solute B, the molecular weight is 212 g/gmole, molecular diameter is 3.0 nm, and the molar volume at the boiling point is 347.4 cm³/gmole

a. Estimate the molecular diffusion coefficients of solute A and solute B in water at 293 K at infinite dilution.

b. Determine the pore diameter (dpore, units of nm) to achieve a separation factor of a = 3 for this process.