Semi-pilot scale fluidized bed reactor for removal of a textile dye through heterogeneous Fenton process using natural pyrite

Abstract: The ability of fluidized bed Fenton oxidation of Acid Yellow 36 (AY36) as an azo dye was investigated applying natural pyrite (NP) particles in a recirculating semi-pilot system. X-ray diffraction, scanning electron microscopy and Brunauer–Emmett–Teller techniques were carried out for characterization of the pyrite. The decolorization percentage of AY36 in NP/H₂O₂ procedure has been noticeably affected by operational conditions. The decolorization percentage of 92% was observed for the AY36 decolorization (15 mg/L) at the optimized conditions as suspension pH 4, 2 mM H₂O₂ and 0.6 g/L NP after 120 min of the process time. The decolorization rate in whole of the runs obeyed the pseudo-first-order kinetic with proper correlation coefficients (R² ≥ 0.98). The low leached iron amount, repeated reusability in the milder pH and the recirculation mode with adequate mix were the substantial benefits of the NP/H₂O₂ utilization. Graphical abstract: Schematic of designed fluidized bed reactor for heterogeneous Fenton process.