Synthesis of CuAPTPP-TDI-TiO2 Conjugated Microspheres and its Photocatalytic Activity

The metal complex 5-(4-aminopheny1)-10,15,20-triphenylporphyrin copper (CuAPTPP) was covalently linked on the surface of TiO2 microspheres by using toluene disocyanate (TDI) as a bridging bond unit. The hydroxyl group (-OH) of TiO2 microspheres surface and the amino group (-NH2) of CuAPTPP reacted respectively with the active -NCO groups of TDI to form a surface conjugated microsphere CuAPTPP-TDI-TiO2 that was confirmed by FT-IR spectra. The CuAPTPP-TDI-TiO2 microspheres were characterized with UV-visible, elemental analysis, XRD, SEM, and UV-Vis diffuse reflectance spectra. The effect of amounts of linked TDI on the performance of photocatalytic microspheres was discussed, and the optimal molar ratio of TDI:TiO2 was established. The photocatalytic activity of CuAPTPP-TDI-TiO2 was evaluated using the photocatalytic degradation of methylene blue (MB) under visible-light irradiation. The results showed that, TDI, as a bond unit, was used to form a steady chemical brigdging bond linking CuAPTPP and the surface of TiO2 microspheres, and the prepared catalyst exhibited higher photocatalytic activity under visible-light irradiation for MB degradation. The degradation rate of 20 mg/L MB could reach 98.7% under Xe lamp (150 W) irradiation in 120 min. The degradation of MB followed the first-order reaction model under visible light irradiation, and the rate constant of 5.1 x10(-2) min(-1) and the half-life of 11.3 min were achieved. And the new photocatalyst can be recycled for 4 times, remaining 90.0% MB degradation rate.