Semi-pilot scale fluidized-bed reactor applied for the Azo dye removal from seawater by granular heterogeneous fenton catalysts

Abstract

Not only is water an essential source for the existence of humans but also it is a necessity for creatures' life. Reutilizing wastewater is a salient way to conquer this rigor; many physical and chemical methods have been developed to treat wastewater, one of which is the advanced oxidation process (AOP). In this study, a heterogeneous Fenton reaction was employed to degrade a non-biodegradable organic contaminant (Direct Blue 71) from synthetic seawater. An unprecedented approach and a novel self-created autoclave were employed to synthesize granulated Fe3O4/Cellulose nanocomposites, which were applied in AOPs as catalysts. Characterization of prepared nanocomposites was investigated by various methods confirming that cellulose is uniformly covered by Fe3O4 nanoparticles. The AOP was carried out in two different kinds of batch and fluidized bed reactors. The impacts of three effectual parameters on the dye removal were weighed using response surface methodology (RSM). The obtained results for both systems demonstrated that exploiting 3.1 g/L catalysts besides the presence of 12.95 mM H2O2 could remove 33.12 mg/L dye entirely. In comparison to the batch reactor, only when the process was conducted in a fluidized bed reactor, did the elimination efficiency increase dramatically. Fluidization results indicated a significant enhancement in dye removal efficiency and a sensitive decrement in the degradation process time. The experimental results were in good agreement with the pseudo-first-order kinetic model and the fluidized bed reactor had a greater K value. The synthesized catalysts were biodegradable and they had an acceptable performance up to 6 cycles after each regeneration process.