Surface nano-aggregation and photocatalytic activity of TiO2 on H-type activated carbons

The main objective of this work is to detect any associative or synergistic effects between TiO₂ and activated carbon in 4-chlorophenol photodegradation. Different activated carbons (AC) were prepared from Tabebuia pentaphyla wood by means of physical activation with CO₂ or by extensive carbonization under N₂ flow at temperatures from 450 °C up to 1000 °C during 1 h. Results indicate a clear correlation between photocatalytic activities of titania with texture and surface chemistry of AC. Kinetic results of 4-chlorophenol photodegradation indicate that for most of mixed TiO₂ and AC solids a synergistic effect between both solids is observed. Surface nano-aggregation of TiO₂ on AC was observed by scanning electronic microscopy and dispersion of TiO₂ nanoparticles was improved as a function of more basic surface pH of AC. In conclusion, an increase of electronic density in carbon support clearly introduces an enhancement in titania's photoactivity for 4CP photodegradation. This beneficial effect indicates that it is possible to obtain clean water in a much shorter period of time by employing some selected AC in conjunction with TiO₂.