Biosorption of Nitrophenol from Aqueous Mixture of Phenolic Compounds Using Sawdust of Parkia biglobosa

The present study investigated the potential of sawdust of Parkia biglobosa, an agroforestry by-product, for the removal of 4-Nitrophenol (4NP), from its aqueous solutions (singly) and in combination with phenol (binary) and chlorophenol (ternary). The effects of sawdust dose, initial concentration of phenolics and pH of the solution on the adsorption were investigated through batch adsorption experiments. Five isotherm models were employed to describe the equilibrium experimental data. The adsorption kinetics and thermodynamics were also studied. The equilibrium time for the sorption was observed to be 720 min, while the optimum dose was 0.500 g. The kinetics of the adsorption could be best described by the pseudo-second order model, while Freundlich isotherm gave the best fit in all the systems studied. The thermodynamics of the adsorption revealed that the process was not spontaneous at low temperatures as ∆G was positive; but it was endothermic in the single, binary and ternary systems.