Sorption of Dibenzo-p-dioxin by Clay Minerals: Hypotheses for Interlayer Complexation.

Sorption of dibenzo-p-dioxin to smectite was studied using batch sorption technique, X-ray diffraction and Raman spectroscopy accompanied by quantum chemical calculations. Lower clay charge and interlayer cation hydration result in high affinity of dioxin, especially for Cs-saponite which effectively adsorbed dioxin from water, approaching 1 % (wt/wt). The basal spacing of Cs-saponite increased from 12 Ã… to 14.7 Ã… with dioxin loading demonstrated intercalation of dioxin into the clay interlayer. Raman spectra of dioxin associated with Cs-saponite showed significant enhancement of certain Raman lines, which were confirmed by quantum chemical calculations of simplified interlayer cation-dioxin complexations, indicated the formation of favorable electron acceptor-electron donor complexes between cation and dioxin molecule in the smectite interlayer.