Degradation of methylene blue in a heterogeneous Fenton reaction catalyzed by chitosan crosslinked ferrous complex

A novel heterogeneous Fenton chitosan-Fe catalyst (CS-Fe), the ferrous ions coordinated by amino and hydroxyl groups of CS, was prepared and characterized by FT-IR and XRD. The decolorization of methylene blue (MB) was monitored by UV–vis spectra and chemical oxygen demand (COD). At the optimum reaction conditions, 10000 mg l−1 CS-Fe, 1200 mg l−1 H2O2, 30 °C, original pH, 120 mg l−1 MB, up to 99% color removal for MB was achieved at 30 min, superior to other Fenton systems. The study of COD removal and UV–vis spectra suggested that the uncompletely mineralization of MB occurs in the CS-Fe system. The concentration of Fe iron dissolved from CS-Fe was negligible relative to CS-Fe applied and the removal of MB remains as high as 90% after recycled five times, indicating that this novel heterogeneous Fenton catalyst is efficient for MB wastewater treatment. Moreover, almost 90% of color removal obtained after five cycles and low amount of dissolved iron were detected in solution, indicating that the catalyst has good stability.