EXTRACTION OF THE METHYLENE BLUE DYE FROM SOLUTIONS WITH SYCAMORE BIOMASS SAWDUST

Abstract

The possibility of using the sawdust biomass of Platanus orientalis for the purification of model solutions from the dye "Methylene blue" (MG) was studied. Washed and dried sawdust fractions less than 1.0 mm were used. Adsorption studies were carried out under static conditions on model solutions. In experiments, the sorption capacity of the material under study was determined for native sawdust and modified with 3% H2SO4. It has been established that the sorption capacity of sawdust biomass is 0.26 mmol/g of MG for native biomass and 0.34 mmol/g for modified one. The specific surface of the sorption material, calculated through the Avogadro number, Na, and the cross-sectional area of the MG molecule, Q, was 0.28 m2/g for native biomass and 0.36 m2/g for the modified one. The efficiency of purification of the model solution from MG at the ratio of the mass of sawdust m to the initial concentration of the solution Сin (m/Cin) equal to 5 is 75% for the original sawdust and 86% for the modified ones; when the m/C ratio is changed to 8, the cleaning efficiency for native sawdust is 92%, and for modified sawdust it is 95%. Adsorption isotherms have been obtained, which, according to the IUPAC classification, characterize single-stage adsorption on microporous solid adsorbents. Mathematical processing of adsorption isotherms in the framework of the Langmuir, Freidlich, Dubinin-Radushkevich models showed that the adsorption process is most adequately described by the Freudlich model for both native (R2 = 0.9501) and modified (R2 = 0.9389) sawdust. The value of the Gibbs energy, ΔGo, kJ/mol·K, has a negative sign both for native (ΔGо = -7.237) and for modified ones (ΔGo = -19.568), which indicates a spontaneous flow of the process. Sorption capacity of sawdust biomass after treatment with acid increases from 0.26 to 0.34 mmol/g, i.e. by 30%.