Abstract: The development and modification of existing processes for the abatement of pollutants in the environment is a continuous exercise. In this regard, the importance of wastewater treatment before its eventual discharge into the environment cannot be overemphasized. Adsorption process has been widely accepted as an efficient method and research is ongoing on the possible application of agricultural residues as adsorbents in wastewater treatment. This study investigates the potential of Parkia biglobosa sawdust in removing reactive black 5 dye from aqueous solutions in single and binary dye systems. Several works have been conducted on the adsorption of reactive dyes but reports on their adsorption as a component of a mixture of dyes is scanty. The sawdust, collected from a local sawmill was thoroughly washed, dried and characterized using Fourier Transform-Infrared (FT-IR) spectrophotometer and Scanning Electron Microscope (SEM). Batch adsorption experiments were conducted to determine the effects of adsorbent dose, initial concentration and pH of the dye solution. Five isotherm models were employed in the interpretation of the equilibrium experiments. Kinetics and thermodynamics of the adsorption processes were also studied. The results indicate the presence of functional groups which could be potential adsorption sites for interaction with the dye on the sawdust. The kinetics of the adsorption in both single and binary systems could best be described by the pseudo-second order model and Langmuir gave the best fit for the equilibrium adsorption data (R2>0.94). The maximum monolayer adsorption capacity of the adsorbent for the dye was low (2.21 mg/G) with no significant difference in the 2 systems. The adsorption processes in all the systems were spontaneous with ΔG becoming increasingly more negative (-0.15-2.81 kJ/mol) as temperature increases. The enthalpy change (ΔH) for the sorption in both systems was positive, indicating that the process was endothermic, the change in entropy (ΔS) was also positive an indication of increased disorderliness on the surface of the adsorbent.
Giwa Abdurrahim Adebisi, Aderibigbe Deborah Olubunmi, Wewers Francois and Bello Isah Adewale, 2018. Biosorption of Reactive Black 5 in Binary Dye Mixture onto Sawdust of Parkia biglobosa. Research Journal of Applied Sciences, 13: 704-710.