EFFECT OF CONCENTRATION ON SORPTION OF DISSOLVED ORGANICS BY PVC, PTFE, AND STAINLESS-STEEL WELL CASINGS

This report examines sorption of low ppb levels of organic solutions b y polytetrafluoroethylene (PTFE), rigid polyvinyl chloride (PVC), and stainless steel 304 and 316 well casings. Nineteen organics were selec ted, including several munitions and chlorinated solvents. Compounds w ere selected to offer a range of physical properties, such as solubili ty in water, octanol/water partition coefficient, and molecular struct ure. When these results were compared with the results from a similar study conducted at ppm levels, the rate and extent of sorption by PTFE and PVC were the same as seen previously For almost all analytes. The re were no losses of any compounds associated with stainless steel. At these low levels (ppm and ppb), the rate of diffusion within the poly mer (PVC and PTFE) is independent of concentration. Only with PFTE are the rates rapid enough to be of concern when monitoring for some cont aminants in ground water. Tetrachloroethylene was the compound PTFE so rbed the most rapidly. The study showed that PVC well casings are suit able for monitoring low levels (ppm and ppb) of organics.