Photocatalytic degradation of methyl orange by Bi 20 TiO 32 –montmorillonite composite

Abstract

To solve the problem of methyl orange (MO) dye wastewater pollution, TiO2–montmorillonite composite (TiO2–MMT) and Bi20TiO32–montmorillonite composite (Bi20TiO32–MMT) were synthesised by the sol–gel method, and they were used for photocatalytic degradation of MO solution. The results showed that TiO2 in TiO2–MMT existed as the anatase type, and Bi20TiO32 in Bi20TiO32–MMT existed as the tetragonal crystal type. When the dosage of the composite was 0.50 g/l, the initial concentration of the MO solution was 20 mg/l, and the pH was 3, the decolourisation rate of MO solution using TiO2–MMT treating was 87.11%, and it reached 98.50% after Bi20TiO32–MMT treating. When Bi20TiO32–MMT was reused four times, the decolourisation rate of the MO solution was only reduced by 3.5%. The photocatalytic degradation between MO solution and Bi20TiO32–MMT complied with the pseudo-first-order kinetic equation. Holes and superoxide radicals interacted directly with MO during photocatalytic degradation, which reduced the probability of hole–electron recombination, and improved the photocatalytic degradation property of Bi20TiO32–MMT. Bi20TiO32–MMT has excellent stability property, which makes it a good composite in the treatment of dye wastewater.