Removal of rhodamine B dye from aqueous solution by electro-Fenton process using iron-doped mesoporous silica as a heterogeneous catalyst.

In the current study, Rhodamine B (RhB) dye was removed by electro-Fenton (EF) process using iron-doped SBA-15 (Fe-SBA-15; SBA: Santa Barbara Amorphous) mesoporous silica as a heterogeneous catalyst. This catalyst was prepared with the help of ferric nitrate nonahydrate as a forerunner by wet impregnation method. Various techniques of characterization such as XRD and N2 adsorption-desorption isotherms were performed to confirm the presence of iron particles in the pores of the catalyst. These characterization methods were also used to examine the morphological properties and textural arrangement of the synthesized material. In the batch study of EF process, 750 mL working volume of RhB dye was taken. Anode and cathode used in the process were graphite electrodes respectively with effective area of 25 cm2 each. To maximise the process efficiency, the effect of initial pH, applied voltage, electrode spacing, the concentration of supporting electrolyte and Fe-SBA-15 dosage were investigated and optimized. The optimum conditions obtained were pH of 2, voltage of 8 V, an electrode spacing of 3 cm and Fe-SBA-15 dosage of 15 mg L-1. At the end of 3 h electrolysis, maximum RhB removal of 97.7% and TOC removal of 35.1% were achieved for 10 mg L-1 RhB concentration. In a batch study with real wastewater, 97% of color and 39% of TOC were removed at optimum conditions. Utilization of EF heterogeneous catalyst Fe-SBA-15 is an alternative technique for the elimination of dyes from solution.