Mechanism of decolorization of acid fuchsin by means of fixed iron ion and graphite electrode.

Fe fixed with sodium alginate gel beads (Fe³⁺-SA) was successfully synthesized. The application of the electro-Fenton (EF) technique using Fe³⁺-SA for the degradation of acid fuchsin (AF) was investigated. The decolorization of AF by EF with Fe³⁺-SA and homogeneous Fe³⁺ was studied, which confirmed that the EF with Fe³⁺-SA could attain higher color removal rate (98.2%). Redox of Fe³⁺-SA and homogeneous Fe³⁺ were also examined by cyclic voltammetry. Influencing factors on AF decolorization including pH, current density, initial AF concentration, Fe³⁺-SA dosage, Cl– concentration, were investigated by conducting batch experiments. The results showed that AF could be decolorized effectively in a wide pH range of 3–11. pH, applied current density, initial AF concentration, H₂O₂/Fe^3+-SA ratio, and the addition of Cl– affected AF decolorization. The pseudo-first-order kinetic model can accurately describe the AF decolorization process. In addition, 100 mg/L AF was treated by EF with Fe³⁺-SA for 4 h to evaluate total organic carbon (TOC) removal, mineralization current efficiency, and specific energy consumption. The properties of Fe³⁺-SA, and Fe³⁺-SA after EF reaction (Fe³⁺-SA/EF) were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray photo-electron spectrometry. The iron content in AF solution before and after EF was measured by inductively coupled plasma atomic emission spectroscopy. Ion chromatography analyzed the change in inorganic salt during EF and ultraviolet–visible spectroscopy studied the decolorizing mechanism. [ABSTRACT FROM AUTHOR]