Green synthesis of magnetic biochars derived from biobased orange peel materials as sustainable heterogeneous catalytic supports for the Fenton process

In this work, two magnetite-biochar composite materials obtained via hydrothermal and co-precipitation methods to degrade dyes were evaluated. The two composite materials alongside their biochar precursor were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), Raman spectroscopy and N2 adsorption-desorption studies. Results of characterization showed a change in the amorphous structure of the biochar to a crystalline form after modification by both methods, the incorporation of magnetic particles into the carbonaceous matrix of the biochar precursor. In addition, the effect of solution pH, initial dye concentration H2O2 concentration, mass of composite material and the time of stirring on dye degradation were analysed by the response surface methodology. Both materials demonstrate appreciable sta-bility over repeated cycles and more interestingly, Fe3O4-BC2 retains its catalytic efficiency much more than Fe3O4-BC1. Statistical analysis of the degradation results by ANOVA revealed a good correlation between the five parameters and the expected response with coefficients of correlation very close to unity. The degradation of reactive red-198 in the presence of both materials is best described by the second order kinetic rate law.