Adsorption of Methylene Blue on Lignocellulosic Plant Materials

Abstract

A comparative study of the sorption properties of lignocellulosic plant materials (aspen and pine wood and wheat straw) is performed using the cationic dye methylene blue (MB). Experimental data on the adsorption of MB from water solutions are described by the Langmuir model. It is established that the isotherms of MB adsorption on softwood and hardwood samples are almost the same and the maximum sorption capacity is 26.4 ± 0.7 mg/g. The amount of MB adsorbed by wheat samples at the same equilibrium concentrations is greater and reaches a maximum of ~46 mg/g. The estimated specific surface area accessible to dye molecules is 52 m²/g for the wood and 91 m²/g for the straw. It is shown that the ozonation of aspen wood reduces the affinity of the adsorbent surface toward MB but has no effect on its adsorption capacity.