Use of semiconducting manganese (IV) oxide particulate system as a photocatalyst: photoassisted bleaching of some dyes.

The most serious polluters of environment are industries like textiles, tannery, electroplating and pulp and paper etc. Photocatalytic degradation has been considered to be an effective process for degradation of organic pollutants, which are present in the effluents released by these industries. The photocatalytic degradation was carried out on some cationic dyes (Methylene blue, azure B and toluidine blue) in the presence of semiconducting manganese (IV) oxide and it was observed spectrophotometrically. The effects of various operating variables like pH, concentration of dyes, amount of semiconductor, light intensity, particle size, stirring etc. were also observed on the rate of the reaction. A tentative mechanism has also been proposed for this photocatalytic bleaching.