Phenol has a high boiling point (181.8 1C) and a higher melting point (40.1 1C) than water. Its solubility in water is 8.7 wt% at 25 1C. Phenol and water can form conjugate solutions that are partially miscible with each other (Balasubramanian and Mitra, 1979). The upper aqueous phase in the permeate decanter contains about 8.7 wt % of phenol and the lower organic phase contains about 28 wt% water when the overall phenol concentration in the permeate is higher than
8.7 wt% at ambient temperature (Böddeker et al., 1990; Hill and Malisoff, 1926). Above 65 1C, phenol and water are miscible in all proportions. Roualdes et al. (2003) observed that phenol component in permeate vapor desublimed to form crystals before reaching the cold trap during pervaporative phenol separation experiments. However, this phenomenon did not attract sufficient attention.