Evaluation of sono-assisted solar/Fenton process for indigo carmine degradation over magnetic ZnO-Fe3O4 supported Tunisian kaolinite clay

This study reports a novel ZnO-Fe3O4 supported natural Tunisian kaolinite clay as a photocatalyst (denoted herein as ZnO-Fe3O4/Kal) magnetic separation. The ZnO-Fe3O4/Kal was prepared using the hydro-thermal following by sol-gel methods. This material was assayed in the degradation of Indigo Carmine in an aqueous solution, as a model of organic dye, using sono-Fenton under solar irradiation. The effect of pH, catalyst amount, H2O2 concentration, initial IC concentration, and the presence of inorganic ions were studied and then optimized. Under optimum experimental, the complete degradation of IC (50 mg/L) was achieved in 100 min of irradiation time. By applying the combination of ultrasonic waves and US irradiation, a synergistic effect was observed in the presence of ZnO-Fe3O4/Kal, and the synergy value was found to 53.84%. UV-vis and total organic carbon (TOC) measurements indicated required longer reaction times were for achieving IC mineralization 97.45%. The importance of this work is that a simple external magnetic field can easily separate the ZnO-Fe3O4/Kal. This material also has a strong catalytic activity after five successive uses.

Automated summary

This study introduces a novel ZnO-Fe3O4/Kal photocatalyst for the degradation of organic dyes, achieving complete degradation under optimized conditions. By combining sono-Fenton with solar irradiation, a synergistic effect was observed, and the material could be easily separated using an external magnetic field. The material also showed strong catalytic activity after multiple uses.