ISOTHERMS STUDY OF CONGO RED BIOSORPTION EQUILIBRIUM USING FIR (ABIES NORDMANNIANA) SAWDUST BIOMASS

摘要

In this work, biosorption of Congo Red (CR) anionic dye, from synthetic aqueous solution using fir tree (Abies nordmanniana) sawdust biomass (FSB) (Transylvanian forests, Romania) was investigated. The considered biomass was characterized using Scanning Electronic Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The effects of the initial biomass quantity and stirring rate over the biosorption process were considered. The biosorption equilibrium data were correlated with the most used isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich). Maximum adsorption capacity calculated using the Langmuir model was 28.1±0.1 mg/g. From Dubinin-Radushkevich isotherm the free energy of the system E = 0.326 kJ/mol was determined, whose value indicates a physisorption process. Also for this model, the coefficient of determination had the highest value (R~2 = 0.994). All these results indicate that Abies nordmanniana can be used as a cost effective biosorbent for the removal of CR dye from aqueous solutions.