Layered double hydroxide pillared by Paratungstate A ion, Mg 12 Al 6(OH) 36 (W 7O 24 )·4H 2O, was prepared via anion exchange reaction of the synthetic precursor, Mg 4Al 2(OH) 12 TA· x H 2O(TA 2- =terephthalate), and W 7O 6- 24 ion. Trace aqueous organochlorine pesticide, hexachlorocyclohexane, was totally degraded and mineralized into CO 2 and HCl by irradiating a suspension of Mg 12 Al 6(OH) 36 (W 7O 24 )·4H 2O and HCH in the near UV area. The model and pathway for the photocatalytic degradation of HCH on the Mg 12 Al 6(OH) 36 (W 7O 24 )· 4H 2O were proposed, indicating that the interlayer space is the reaction field, and that photogeneration of OH · radicals are responsible for degradation pathway.
