Nanoscale Zero-Valent Iron Supported on Biochar: Characterization and Reactivity for Degradation of Acid Orange 7 from Aqueous Solution

The nanoscale zero-valent iron supported on biochar (B-nZVI) was prepared by liquid-phase reduction method and used for the removal of acid orange 7 (AO(7)). The structure of composited B-nZVI was characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area analysis. nZVI was well dispersed on the surface of biochar with a specific surface area 52.21 m(2)/g, and no obvious aggregation was observed. Batch experiments demonstrated that the degradation of AO(7) (20 mg/L) by B-nZVI (2 g/L) at initial pH 2 reached 98.3 % within 10 min. There was a good linearity (r(2)=0.99) between k(obs) and B-nZVI dosage. The reductive cleavage of the azo group in AO(7) to amino group may be the dominant stage. This study demonstrated that B-nZVI has the potential to be a promising material for the removal of azo dyes.