ABSTRACT
The extent of binding of 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD), 2,3, 7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), and 2,4,5,2’,4’,5’-hexachlorobiphenyl (HCB) to unmodified clay, hydroxy aluminum-clay, and humic acid-hydroxy aluminum-clay is described. The initial set of experiments was performed with OCDD in water-THF binary solution to establish the effects of the amount of organic carbon on the sorbent; the surface area of the sorbent; and the microporosity of the sorbent on the value of the linear partition coefficient for different sorbents. Ancillary experiments carried out in our laboratory show that humic acid in solution binds strongly to OCDD. Therefore, the source of humic acid may not be responsible for the poor binding affinity of OCDD to the surface-bound humic acid. A comparison between the binding affinity of humic acid-alumina and hydroxy aluminum-clay shows that the microporosity of the sorbent has the most profound effect on the binding affinity of the sorbent toward OCDD.
