Comparison of photocatalytic efficiencies of TiO2 in suspended and immobilised form for the photocatalytic degradation of nitrobenzenesulfonic acids

The photocatalytic efficiency of TiO2 immobilised on various supports (glass, cement, red brick and inorganic fibres), using different techniques (sputtering, sol–gel dip-coating, patented method for inorganic fibres), are compared with the photocatalytic efficiency of TiO2 Degussa P25 in suspension 2 g l−1, for the degradation of 3-nitrobenzenesulfonic acid (3-NBSA) and 4-nitrotoluenesulfonic acid (4-NTSA). In all cases, the fixation of TiO2 on solid supports appreciably reduces the photocatalytic efficiency. The best results were obtained with TiO2 on inorganic fibres.