Polyethylene glycol-modified sol-gel synthesis of ZnTiO3(n)- quartz composite microspheres for enhanced photocatalytic degradation of Reactive Brilliant Red X–3B

Zinc titanate-quartz composite microspheres were synthesized via a sol-gel route, and polyethylene glycol was used to reduce ZnTiO 3 crystal aggregation and to promote the photocatalytic activity of the ZnTiO 3 (n)-SiO 2 composites. The crystallite size of ZnTiO 3 was found to decrease from 37.8 nm (ZnTiO 3 (0)-SiO 2 ) to 27.2 nm (ZnTiO 3 (2.5)-SiO 2 ) with increasing polyethylene glycol amount. Many free fine ZnTiO 3 particles were obtained in the composites after the removal of polyethylene glycol during calcination . The bandgap energies of ZnTiO 3 (0)-SiO 2 , ZnTiO 3 (0.5)-SiO 2 , ZnTiO 3 (1.5)-SiO 2 and ZnTiO 3 (2.5)-SiO 2 were measured as 3.49, 3.71, 3.89 and 3.54 eV, respectively. Both the pore volumes and the surface areas of ZnTiO 3 (0.5)-SiO 2 and ZnTiO 3 (1.5)-SiO 2 were found to be enlarged compared to those of ZnTiO 3 (0)-SiO 2 . Polyethylene glycol can significantly enhance the photocatalytic activity of ZnTiO 3 (n)-SiO 2 composites. In terms of hydroxyl radical production, the composites follow the sequence ZnTiO 3 (1.5)-SiO 2 , ZnTiO 3 (0.5)-SiO 2 , ZnTiO 3 (2.5)-SiO 2 and ZnTiO 3 (0)-SiO 2 . The RBR X–3B degradation rate constants for ZnTiO 3 (1.5)-SiO 2 , ZnTiO 3 (0.5)-SiO 2 and ZnTiO 3 (0)-SiO 2 were calculated as 0.02474, 0.02201 and 0.01777 min −1 , respectively. A total of 89.5% of RBR X–3B molecules were degraded on ZnTiO 3 (1.5)-SiO 2 after 80 min of reaction, leading to the decomposition of major organic groups in the dye.