Sol-gel synthesis of La0·05Mg0·95TiO3/SiO2 microspheres for photocatalytic degradation of azophloxine

Lanthanum doped MgTiO 3 (La–MgTiO 3 ; n (La): n (Mg) = 0.05:0.95) was synthesized using a sol–gel method, and a layer of this material was supported on quartz microspheres to produce La–MgTiO 3 ( x% )/SiO 2 microspheres (LMTO( x% )/SiO 2 ; where x% represents the weight fraction of La–MgTiO 3 in the microspheres). The crystal size of MgTiO 3 decreased from 43.4 nm in La–MgTiO 3 to 29.2 nm in LMTO( 20 % )/SiO 2 , and the bandgap energies increased from 3.34 eV (La–MgTiO 3 ) to 3.91 eV (LMTO( 20 % )/SiO 2 ). The supported La–MgTiO 3 contributed the most to the total surface area of the LMTO( x% )/SiO 2 microspheres; further, the specific surface area of the microspheres decreased with decreasing La–MgTiO 3 content. The photoluminescence intensity of the microspheres was significantly lower than that of La–MgTiO 3 . The activity of La–MgTiO 3 was enhanced after loading onto the quartz microspheres. The maximum photocatalytic activity was obtained using LMTO( 40 % )/SiO 2 , while the azophloxine degradation efficiency slightly decreased after five reaction cycles.