Removal of VOC from water by pervaporation with hollow-fiber silicone rubber membrane module

A pervaporation process was used to remove dissolved volatile organic compounds (VOC) (benzene and toluene) from water using a hollow-fiber membrane module of silicone rubber with a 60-mu m membrane thickness and 0.37-m(2) membrane area. The effect of water feed rate and feed temperature on removal efficiency was investigated. For a feed concentration of 200 ppm, the removal efficiency of benzene could reach 90% up to a water feed rate of 70 cm(3)/min, but the removal efficiency of toluene was only 72% at a water feed rate of 50 cm(3)/min. When the feed temperature was increased, the removal was more effective. A degassing experiment was performed to test the effect of dissolved air on the removal efficiency. The existence of dissolved air enhanced the removal efficiency of VOC from water. The permeabilities of VOC vapor with or without water vapor were measured by a vapor permeation experiment. With water vapor, the permeabilities of the VOC decreased. A calculation model based on the Henry constant and permeability was proposed and predicted the experimental results well.