Synergetic adsorption and photo-Fenton degradation of methylene blue by ZnFe2O4/SiO2 magnetic double-mesoporous-shelled hollow spheres.

Adsorption and Fenton technologies have been widely employed to deal with wastewater. ZnFe2O4/SiO2 magnetic double-mesoporous-shelled hollow spheres (MDSHSs) were feasibly synthesized by a solvothermal method. The as-synthesized MDSHSs show excellent adsorption and selectivity for methylene blue (MB), which it took about only 1 min to reach the adsorption equilibrium. About 50% MB was removed by adsorption, and other 50% MB was degraded under further photo-Fenton process. Effects of experimental conditions on the adsorption and photo-Fenton process were investigated. The mechanisms of MDSHSs formation and photo-Fenton process were proposed. Total organic carbon (TOC) reduction reached as high as 90% with 60 mg/L of MB for 90 min. The experimental results indicated that MDSHSs exhibit a remarkable adsorption and catalytic activity for photo-Fenton process in a wide pH range of 3.3-11.0. Simultaneously, the composite shows an excellent stability and reusability.