A process for removing a solvent from a first solution, said process
comprising positioning a selective membrane between the first solution
and a second solution having a higher osmotic potential than the first
solution, such that solvent from the first solution passes across the
membrane to dilute the second solution, and extracting solvent from the
second solution, wherein the membrane has an average pore size of at
least 10 Angstroms, and wherein the second solution contains solute
species that are too large to pass through the pores of the membrane.