Enhanced photocatalytic degradation of azo dyes using nano Fe3O4

Nanosized magnetic Fe3O4 synthesized via sonochemical route was used as a photocatalyst for the degradation of azo dyes, methyl red and congo red. The novelty of the photo catalyst is its easy recovery by magnetic force and its recycling ability due to its long-term stability, in addition to its cost effectiveness, non-toxicity and non-carcinogenicity. A detailed feasibility study has been carried out on the photocatalytic degradation of the azo dyes at various pH and at various concentrations of photocatalyst, dye and H2O2. The presence of photocatalyst is found to significantly accelerate the degradation of azo dyes and the optimal dosage is found to be 0.075 and 0.2 g/l for methyl red and congo red, respectively. Langmuir–Hinshelwood kinetic analysis revealed pseudo-first-order kinetics for the photocatalytic degradation of the dyes and the degradation products were identified using spectral analysis. The degradation study revealed the following order of reactivity: Photo-Fe3O4 > Photo-H2O2 > Fe3O4 > H2O2.