The adsorption of hexachlorobenzene on naturally occurring adsorbents in water.

To evaluate the distribution of hexachlorobenzene (HCB) between water and natural adsorbents, laboratory experiments were performed with 14C-labelled HCB, with quartz, kaolinite, illite, bentonite, peat, suspended particulate matter and activated sewage sludge as the natural adsorbents. HCB was bound mainly to organogenic adsorbents with distribution coefficients between 140 (for bentonite) and 28,000 (for activated sewage sludge). Desorption experiments showed that distilled water could remobilize up to 100% HCB from mineral adsorbents, but only 3% from activated sewage sludge. Using these values, basic parameters for the bioavailability of HCB in natural waters were estimated.