Synthèse et caractérisation des charbons actifs ferromagnétiques à partir des épluchures de manioc (manihot dulcis) : Application à l’adsorption du bleu de méthylène en solution aqueuse.

Abstract

This work aimed at preparing Ferromagnetic Activated Carbon from Cassava Peel. It has been prepared by chemical activation of cassava peel powder impregnated by FeCl3 in a temperature range of 500, 650 and 800°C, an impregnation ratio of (R=3.750%) by weight and a resident time of 120 min. Some characterization have been done on the raw material namely: proximate and ultimate analysis, X- Ray Fluorescence (XRF), Scanning Electron Microscope (SEM) associated to Energy Dispersive X ray (EDX), Fourier Transform Infra red Spectroscopy (FTIR), X ray Diffraction (XRD) and nitrogen adsorption at 77 K. The ferromagnetic activated carbon obtained has been characterized by the aforementioned methods followed by Iodine number method, Methylene Blue number, and the capture rate. It has been shown that the synthesis of ferromagnetic activated carbon by the chemical activation method led to activated carbon with mixed porosity, in other words, it contained micropores and mesopores with a specific surface (BET) of 405.890 m2 /g and a total pore volume of 0.1076 cm3/g for an impregnation report of 3.750% of FeCl3, a resident time of 120 min, temperature of 800°C, heating rate of 10°C/min compared to the precursor that has a specific surface area of 2.496 m2/g and a pore volume of 0.004 cm3/g. It has been found from this study that the pyrolysis temperature has an important effect on the magnetic properties of CAFEM3. These magnetic properties might be due to the presence of iron oxides such as magnetite (Fe3O4) and maghemite (ℽ-Fe2O3) formed during the pyrolysis of biomass impregnated with FeCl3. The efficacity of the material has been tested on the removal of dyes (Methylene blue) from aqueous solution by varying some parameters such as contact time, pH, adsorbent dose and concentration. From the results obtained, pseudo-second order model fitted well for the adsorption kinetic of Methylene blue. The separation factor value (RL) from Langmuir model was between 0< RL< 1 and n= 1.548 from Freundlich model indicated a favourable adsorption. Hence, CAFEM3, possessing a porous structure, induced a good adsorption capacity. It could be find then as a good low cost material for the treatment of waste water because it is easy to prepare and is available and can be recover easily from aqueous solution by simple application of a magnetic field.