Recovering phenol as high purity crystals from dilute aqueous solutions by pervaporation

•Phenol crystal is obtained from dilute aqueous solution by pervaporation.•A novel coupling process is proposed separation of conjugate solution.•Residual concentration is far lower than that of complete condensation process.•Phase separation and further purification operations are not required.

A new process to produce high purity phenol crystal from dilute aqueous solutions based on pervaporation–crystallization coupling (PVCC) was reported. Our approach to modifying the permeate condenser was to replace the traditional single condenser for complete condensation and collection of permeate with a two-stage condenser where the first stage was used for crystallization of phenol while the second stage was to condense and collect the remaining permeate. The phenol crystal obtained in the crystallizer was found to be of the same purity as that of commercial reagent phenol. The pervaporation experiments showed that the phenol crystals collected in the crystallizer accounted for about 79.9–89.2% of the total amount of phenol permeated through the membrane for a feed concentration of 6000–10,000 ppm at an operating temperature of 65 °C. This is of particular interest from an application point of view as high purity phenol crystals were obtained directly from dilute aqueous solutions by pervaporation alone.