Degradation of azo dye in ozonation by noble metal supported mesoporous catalyst

The mesoporous catalyst was prepared by impregnating Ru noble metal on SBA-15 material and its performance was studied in catalytic ozonation reaction for degradation of reactive orange 4 (RO4) azo dye solution. The operational variables such as Ru (%) loadings on SBA-15, initial pH and ozone concentration are optimised in order to get maximum degradation efficiency. The reaction mechanism for catalytic ozonation was analysed by introducing t-butanol as radical scavenger. The colour of RO4 azo dye solution was completely removed after 21 min of catalytic ozonation reaction. The COD removal of 61.1% was achieved at optimised conditions of Ru loading of 0.25% on SBA-15, initial pH 9.0 and ozone concentration of 5 g/m(3). The addition of radical scavenger t-butanol in catalytic ozonation reaction indicated that the decolourisation mainly occurred through direct ozone molecular mechanism, whereas degradation of non-colourful groups and intermediates occurred through hydroxyl radical mechanism.