SORPTION AND PERMEATION OF ORGANIC ENVIRONMENTAL CONTAMINANTS THROUGHPVC GEOMEMBRANES

The effect of penetrant diffusion on the barrier properties of PVC geo membranes have been determined for the following organic environmental contaminants: benzene, dichloromethane, and trichloroethylene. The me mbranes experienced swelling to a degree which depends on the type of penetrant used. Some dissolution may occur, and in general we are deal ing with Case II transport. The experimental work was performed with a n ASTM-cell, a Cahn balance, and an in-house built gravity (G-) cell. Those instruments generated comparable data on breakthrough times. The obtained diffusion coefficients as well as the breakthrough times obe yed an Arrhenius-type relation over the temperature range studied. Liq uid sorption of the various penetrants modified the geomembrane struct ure. Membrane surface pretreatment with different contaminants influen ces the subsequent transport of organic penetrants through PVC geomemb ranes. That is to say: the induced swelling, as result of membrane con tact with one penetrant, is likely to alter the system free volume, al lowing for a different rate of mass transport for subsequent penetrant s. (C) 1997 John Wiley & Sons, Inc.