Catalytic adsorptive elimination of deleterious contaminant in a pilot fluidised-bed reactor by granulated Fe3O4/Cu-MOF/cellulose nanocomposites: RSM optimisation and CFD approach

A novel catalyst was synthesised in a way that it could be applied in simultaneous adsorption and heterogeneous Fenton processes. The granulated Fe₃O₄/CuBDC/Cellulose nanocomposites were synthesised with a novel in-situ granulation method in a rotary autoclave reactor, and they were efficient in the removal of a detrimental trisazo dye, direct blue 71 (DB71). The catalysts were characterised by various analyses. In order to fulfill the expectation from the catalysts traits, many parameters were evaluated meticulously such as the effect of modification of Fe₃O₄ nanoparticles, the ratio of Fe₃O₄ to CuBDC in the nanocomposite, the stability of the catalyst, and diverse catalyst characterisations (SEM, EDX, FTIR, XRD, BET, XPS). The rotating speed of the autoclave was optimised by carrying out computational fluid dynamics (CFD) simulations; 60 rpm rotating speed was selected among the other ones to achieve catalysts that were more homogeneous. Moreover, the dye elimination process was conducted in a pilot fluidised bed reactor. The impacts of three diverse parameters on the removal efficiency were assessed by response surface method (RSM) to optimise them, 96.85% dye removal was achieved in a 30-min process (the initial DB71 concentration = 10 mg/L, the H₂O₂ concentration = 8.55 mM, and the catalyst dosage = 7.12 g/L). The study of the dye elimination mechanism and thermodynamics of the process indicated endothermic, spontaneous, favourable, and physical adsorption of DB71 on the catalysts. Reutilisation of granulated catalysts at least for ten treatment cycles without regeneration process incorporating high and stable degradation efficiency (11% performance reduction), exhibited the exceeding performance of the highly durable well-designed catalysts in the simultaneous adsorption and heterogeneous Fenton processes.