Sol-gel synthesis of new TiO2/activated carbon photocatalyst and its application for degradation of tetracycline

Abstract A new efficient photocatalyst consisting of TiO 2 -activated carbon composite (TiO 2 /AC) was synthesized by sol-gel process and applied to decomposition of tetracycline (TC). Its properties and catalytic activity were evaluated in comparison with bare TiO 2 and P25, based on several characterization techniques and TC photodegradation kinetic studies. The results showed TiO 2 /AC has better structural and electronic features for photocatalysis; S BET of 129 m 2  g –1 , exclusively anatase phase, crystal size of 8.53 nm and band gap energy of 3.04 eV. The catalytic activity of the material was evaluated based on photodegradation kinetic studies of TC from aqueous solution (with initial concentration=50 mg L −1 and catalyst dosage=1.0 g L −1 ). Non-linear kinetic model of pseudo-first order were fitted to the resulting experimental data. The apparent first-order rate constant ( k app =42.9×10 –3  min –1 ) and half-life time ( t 1/2 =16.1 min) determined for TiO 2 /AC were better than those for P25 and bare TiO 2 . TC degradation by-products were investigated by HPLC-MS, showing TC was completely degraded after 75 min, producing fragments with m/z smaller than 150.