Recovery of Pentachlorophenol from Aqueous Solution via Silicone Rubber Membrane

Although pentachlorophenol (PCP) has been widely employed as a biocide for over 60 years, its production and use are currently severely curtailed in many countries due to its extreme toxicity. In recent years, the contamination of both soil and surface waters by PCP has become a concern. In this study the permeation characteristics of PCP penetrating silicone rubber membranes (SRM) were studied, in order to determine the feasibility of separation of PCP from water via the permeation and chemical desorption (PCD) method. It was found that efficient separation and recovery of PCP could be obtained using an acidic feed solution and an alkaline recovery solution. The permeation rate of PCP into the SRM was optimized when the feed solution was maintained at a pH of 4 or lower. The SRM thickness did not significantly affect the permeation rate, indicating that the rate determining step for the process is the initial movement of the PCP into the SRM. The activation energy for the penetration process was determined to be quite high, and thus thermal controls will play an important role in the recovery of PCP by this method. The membrane distribution coefficient (mc) for PCP moving into SRM was large and showed a strong correlation to permeation rates reported previously, confirming that PCD is a suitable technique for the separation and recovery of PCP from aqueous solution.