Preparation of Biochar from Sugarcane By-product Filter Mud by Slow Pyrolysis and Its Use Like Adsorbent

Abstract

This paper presents an alternative treatment of the filter mud residue derived from sugar and ethanol industries. Slow pyrolysis, at 400 °C, in a batch reactor was carried out to obtain biochar, without activation, aiming at using it as adsorbent for methylene blue and methyl violet 10B (crystal violet) dyes that were chosen as standards to verify the efficiency of biochar in adsorption of cationic organic dyes. The residue was characterized in terms of elemental analysis, trace elements, and thermogravimetry. The biochar was characterized by scanning electron microscopy, thermogravimetric, chemical analysis and determination of specific surface area and porosity. The specific surface area determined by the BET method was 19.80 m2 g−1, the specific pore volume 0.087 cm3 g−1 and the pore diameter 172 A (mesoporous biochar). The equilibrium isotherms and kinetics of methylene blue and crystal violet dyes adsorption from aqueous solutions on biochar were investigated. The equilibrium adsorption data were analyzed by the Langmuir and Freundlich isotherm models. The results showed that the best fit was achieved with the Freundlich isotherm. The adsorption kinetic data were well described by the pseudo-second order model. This biochar acting as an adsorbent has a high removal rate of cationic organic dyes.