Extraction, Characterization and Methyl Orange Sequestration Capacity of Cellulose Nanocrystals Derived from Sugarcane Bagasse: Experimental and Regression Modelling

The adsorption capacity of cellulose nanocrystals extracted from sugarcane bagasse using acid hydrolysis for methyl orange (MO) sequestration was investigated. The extracted nanocrystals were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and Fourier transform infra-red spectroscopy (FTIR). The cellulose nanocrystals were well identified by their features including well-defined pore spaces, predominant nano range of particles (0.045-0.082 μm), greater crystallinity index from 1.09 to 1.21, disappearance of peaks at 1736 and 1429 cm^-1 in FTIR, and higher carbon content. A Two-fold improvement in monolayer adsorption capacity was obtained for cellulose nanocrystals (432.17 mg g^-1), described by Langmuir isotherm, and for bagasse (170.99 mg g^-1), described by Freundlich isotherm. Adsorption processes on both adsorbents were spontaneous, exothermic and followed pseudosecond order kinetics. Polynomial regression models appropriately predicted equations through which the effects of different batch adsorption parameters on MO removal were described, even with descriptions better than the experimentally generated data.