Efficient Photodegradation of Organics in Acidic Solution by ZnO–Smectite Hybrids

Zinc oxide has been immobilized in layered clay minerals (natural montmorillonite and synthetic saponite) by ion exchange and simultaneous oxidation. The products exhibit blueshifted absorption bands (onsets at 346 and 374 nm for the montmorillonite and saponite systems, respectively) compared with that of bulk zinc oxide (393 nm), thereby showing the formation of zinc oxide nanoparticles. The samples are characterized by the broad photoluminescence centered at 545 nm for zinc oxide in montmorillonite and the relatively sharp and strong photoluminescence observed at 436 nm for zinc oxide in saponite. The photocatalytic activities of the ZnO–smectite hybrids towards the decomposition of an aqueous solution of Methylene Blue were examined and revealed that both catalysts function even in acidic solution, which is an advantage of nanoparticles (ZnO in the present case) supported on smectites.