ZnO-Immobilized mesoporous hollow silica spheres (ZnO/xMHSS; x ¼ 15, 30, 50 molar ratio of Zn/Si) were synthesized and examined as photocatalysts toward the degradation of sodium dodecylbenzenesulfonate (SDBS). The hollow structures of MHSS and ZnO-immobilized MHSS composite were evidenced by transmission electron microscopy analysis. X-ray diffraction results confirmed the presence of ZnO and a mesoporous structure in the synthesized materials. N 2 adsorption-desorption analysis also depicted the formation of a mesoporous structure and the increased surface area for the ZnO/xMHSS materials. Fourier transform infrared spectroscopy analysis revealed the formation of Si-O-Zn bonds due to interaction between ZnO and MHSS. The photocatalytic testing results indicated that all the ZnO/xMHSS materials showed improved efficiencies of 10-21 % toward the photodegradation of SDBS when compared with bare ZnO. Among the prepared materials, ZnO/15MHSS was the best photocatalyst, which photodegraded 68 % SDBS after 1 h reaction. The kinetic study demonstrated that the photocatalytic reaction followed the second-order model.

Highly crystalline ZnO/mesoporous hollow silica sphere (MHSS) composites have been successfully synthesized through an impregnation method at 323K without applying calcination. Three composites of different Zn/Si molar ratios of 1:2, 1:1, and 2:1 were prepared. X-Ray diffraction patterns confirmed the presence of highly crystalline ZnO in the materials. A layer of ZnO was formed on the MHSS as evidenced by field emission scanning electron microscopy analysis. Transmission electron microscopy analysis verified the mesoporous structure in ZnO/MHSS composites. N2 adsorption–desorption analysis indicated a type IV isotherm for 1ZnO/2MHSS and 1ZnO/1MHSS samples, confirming the presence of mesopores in the ZnO layer. It has been demonstrated that all the ZnO/MHSS composites exhibit a high photocatalytic activity towards sodium dodecylbenzenesulfonate degradation compared with bare ZnO under UV irradiation. A kinetic study showed that the photodegradation followed a second order model. Among the prepared composites, 1ZnO/1MHSS recorded the highest reaction rate of 6.03×10−3mM−1min−1 which is attributed to a high crystallinity and the monodispersity of a high amount of ZnO on MHSS.