The permeate vapor was
condensed and collected.Two condensers were used for comparisons. One was a single stage condenser comprising of a Pyrex cold trap immersed in liquid nitrogen at about -196 1C (which is commonly used in pervaporation), and the other was a two-stage condenser comprising of two Pyrex cold traps in series that were immersed in a brine coolant solution (at about -15 1C) and liquid nitrogen, respectively The phenol crystals were obtained in the first stage of condenser (crystallizer), and the remaining permeate solution, still containing a certain amount of phenol, was collected in the second stage of the condenser.