Suchergebnisse

The effectiveness of granular activated carbon (GAC) for carcinogenic volatile organic compounds (cVOCs) has not been evaluated in the low‐ to submicrogram per liter range. Rapid small‐scale column tests were used to determine the GAC performance at empty bed contact times (EBCTs) of 7.5 and 15 min for 13 cVOCs at a target influent concentration of 5 μg/L in a typical groundwater matrix. Breakthrough was assessed for vinyl chloride, dichloromethane, 1,1‐dichloroethane (1,1 DCA), 1,2‐dichloroethane (1,2 DCA), 1,2‐dichloropropane, carbon tetrachloride, 1,3‐butadiene, 1,1,1,2‐tetrachloroethane, 1,2,3‐trichloropropane, trichloroethylene, and tetrachloroethylene. The throughput to breakthrough was found to be linearly correlated to capacities calculated with single‐solute equilibrium isotherm parameters. Modest decreases, 9–13% on average, in throughput to 50 and 75% breakthrough were found when the EBCT was increased from 7.5 to 15 min. The carbon use rate (CUR), when scaled to simulate full‐scale adsorption, indicated that GAC would be a viable technology for seven of the cVOCs evaluated, with a CUR threshold of less than 0.2 lb/1,000 gal. It may be possible to use 1,1 DCA and 1,2 DCA as surrogates for assessing chemicals near the feasibility limit.

AbstractTo assess the practical implications of various bottle materials used in anion exchange (IX) or granular activated carbon (GAC) isotherm experiments, adsorption of seven per‐ and polyfluoroalkyl substances (PFAS) onto three common bottle materials (silanized glass, polypropylene, and high‐density polyethylene [HDPE]) were screened. Results were similar between bottle materials; therefore, only HDPE was used in a detailed bottle material isotherm study with 11 PFAS. For each PFAS, an HDPE bottle isotherm was generated with equilibrium liquid phase concentrations relevant to drinking water (<2000 ng/L). Percent PFAS recoveries between 90% and 103%, 85% and 114%, and 54% and 108% were determined for perfluoro‐2‐propoxypropanoic acid (GenX), five perfluoroalkyl carboxylic acids, and five perfluoroalkyl sulfonic acids (PFSA), respectively. These results indicated only the five PFSA adsorbed to the HDPE bottles in a concentration‐dependent manner. Furthermore, linear isomer versions of two PFSA exhibited greater adsorption. For each PFSA studied, a linear isotherm was generated and used to develop guidance for conducting future IX and GAC isotherm studies. Specifically, the minimum initial isotherm concentration was established such that a maximum 1% loss would be expected to the HDPE bottles, resulting in required initial concentrations of the five PFSA between 21 and 75 times that of the design isotherm liquid equilibrium concentration.Article Impact StatementAssesses the practical implications of per‐ and polyfluoroalkyl substances adsorption to various bottle materials used in environmental sampling and isotherm experiments.