Abstract
•Methylene blue adsorption on a biomass was analyzed via theoretical physics-based calculations.•Role of biomass functionalities for dye adsorption was explained.•DFT simulation characterized the interactions between the methylene blue andbiomass surface.•Experimental and theoretical findings of dye adsorption on lignocellulosic biomass ere reported.
The adsorption of the methylene blue on the biomass obtained from brazilian berries seeds was studied. Experimental adsorption data and results of the physicochemical characterization of the adsorbent besides theoretical physics-based calculations were utilized to understand the dye adsorption mechanism. A monolayer adsorption model was proposed to simulate the dye adsorption assuming an interaction adsorbent + adsorbate via two different functional groups on biomass surface. This statistical physics model calculated the number of bonded MB dye molecules and the saturated adsorption capacity for both functional groups at different temperatures. For instance, the values of n1 and n2 were 0.34 and 0.51 at 298 K thus indicating that MB molecules interacted via a horizontal adsorption orientation with two and three functional groups of biomass surface. Calculations based on statistical physics and density functional theory characterized the role and relevance of proposed functional groups on dye adsorption including its thermodynamic parameters. Results demonstrated that the hydrogen and oxygen functionalities of biomass surface were the main responsible functional groups for dye adsorption. Therefore, this paper reports new findings to understand the adsorption mechanism of dye molecules on lignocellulosic biomasses.