Research Paper
Year: 2022 | Month: September | Volume: 9 | Issue: 9 | Pages: 1-12
DOI: https://doi.org/10.52403/ijrr.20220901
Biosorption of Cd (II), Pb (II) and Zn (II) from Aqueous Solutions using Garden Egg (Solanum Melongena) Leaf: Equilibrium, Kinetics and Thermodynamics
Ahmed Adebanjo1, Adesola Babarinde1, K. Moberuagba2, Moyosore Oyeti1
1Department of Chemical Sciences, Olabisi Onabanjo University, Ago-Iwoye, Nigeria.
2Department of Chemical Sciences, Tai Solarin University of Education, Ijagun Nigeria.
Corresponding Author: Ahmed Adebanjo
ABSTRACT
The prevalent problems associated with heavy metal contamination of the environment particularly underground and surface wastewater compel the need to work on economical means of mitigating the accumulation of heavy metals in the environment by espousing the heavy metal biosorption option. The choice of biosorption in this regard is hinged on the overall cost control of the process and its relative effective outcome compared to other means of diminishing heavy metal accumulation in the environment. Thus, the potential of Garden Egg (Solanum melongena) Leaf (GEL) to remove Cd(II), Pb(II) and Zn(II) from aqueous solutions through biosorption was studied. The influence of various process parameters such as pH, contact time, biomass dose and initial metal ion concentration was investigated using batch experiments to determine the efficiency of the biosorbent. The presence of ionizable functional groups (-N-H,-C≡N, C=O and –C-O) in the GEL were analyzed using Fourier Transform Infrared (FT-IR) which are responsible for the binding of the cations. The heat of the sorption process was estimated from Temkin Isothermal model and mean free energy were estimated from Dubinin-Radushkevich (D-R) model. The biosorption process revealed that the best pH for Cd(II), Pb(II) and Zn(II) adsorption was at pH 7. The kinetic studies showed that the biosorption process was best represented by pseudo-second order kinetics having the highest correlation coefficient (R2) of 0.9398, 0.9339 and 0.9398 for Cd(II), Pb(II) and Zn(II) respectively, among various kinetic models tested. Equilibrium data were better represented by Freundlich isotherm among Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) absorption isotherms. The Freundlich model appeared to have better regression coefficients among four Equilibrium data tested. The study on the effect of dosage showed that the dosage of the biomass significantly affected the uptake of the metal ions from solution. Thermodynamically, the biosorption of each of the metal ions was endothermic and the order of spontaneity of the biosorption process being Zn > Pb > Cd. However, positive change in entropy was observed for each and the order of disorder is Zn > Cd > Pb. The results indicate that Garden egg (Solanum melongena) leaf has a potential for the adsorption of Cd(ll), Pb(ll) and Zn(ll) and could be found useful in the treatment of industrial effluents.
Keywords: Biosorption; Heavy metals; Effluents; Garden egg; Thermodynamics; Kinetics.
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