Mass transfer involves the net movement of mass from one location to another due to a driving force such as a difference in concentration gradient. It finds extensive application in chemical engineering due to its application in crude oil refining, petrochemical separation and extraction processes. In general, the random motion of molecules causes a net transfer of mass from an area of high concentration to an area of low concentration. For separation processes, thermodynamics determines the extent of separation, while mass transfer determines the rate at which the separation will occur. Это и многое другое вы найдете в книге An Introduction to Mass Transfer Operations for Chemical Engineers (Cecil Coutinho)