Photo-Fenton discoloration of the azo dye X-3B over pillared bentonites containing iron.

Both Fe pillared bentonite (Fe-B) and Al-Fe pillared bentonite (Al/Fe-B) were prepared and used as heterogeneous catalysts for the photo-Fenton discoloration of azo dye X-3B under UV irradiation. The catalysts were characterized by XRD, BET and TEM. The effects of solution pH, H(2)O(2) concentration, dye concentration and catalyst loading on the rate of discoloration were investigated in detail. The results indicate that the Fe-B and Al/Fe-B have high BET surface area (114.6 and 194.2 m(2)/g, respectively). Both the heterogeneous photo-Fenton processes employing the Fe-B or the Al/Fe-B as catalyst exhibit higher photo-catalytic activity compared to their corresponding homogeneous photo-Fenton process. The amount of Fe ions leached from the Al/Fe-B into the solution is much lower than that leached from the Fe-B during the reaction process.