Statistical physics modeling and interpretation of the adsorption of dye remazol black B on natural and carbonized biomasses

Abstract

Natural and carbonized pine-fruit shells (NPFS, and CPFS) were employed to study the adsorption of remazol black B dye (RBB) from aqueous solution. A theoretical analysis of the adsorption systems was performed via the statistical physics modeling of the experimental dye adsorption isotherms at 298–323 K and pH 3. Results showed that the adsorbent CPFS outperformed adsorbent NFPS for water decolorization. A multilayer advanced statistical physics model, which included monolayer and double layer adsorption scenarios, was employed to understand the RBB dye adsorption mechanism. Modeling analysis suggested that around two and three adsorbate layers were formed depending on the adsorption (i.e., adsorbent + dye RBB) systems at high temperature. The calculation of the linked dye molecules per leading adsorption site varied from 0.83 to 1.86 and from 1.10 to 2.88 for systems RBB-NPFS and RBB-CPFS, respectively. These results suggested that the dye RBB dye could be adsorbed on NPFS and CPFS surfaces via a non-horizontal orientation at tested operating conditions where the dye molecule aggregation phenomenon was present. Estimated adsorption energies confirmed an endothermic physisorption process for RBB dye removal. In summary, the statistical physics analysis provided a reliable interpretation of the adsorption mechanism of this textile pollutant on tested adsorbents.