AMERICAN JOURNAL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
© 2014, Science Huβ, http://www.scihub.org/AJSIR
ISSN: 2153-649X, doi:10.5251/ajsir.2014.5.4.134.138
Mechanism of lead (ii) biosorption by delonix regia leaves and bark:
combined sorbent effect
Saratu Mamman and Tayelolu Olosunla
Department of Chemistry, University of Abuja, PMB 117, Abuja-Nigeria
mammansarah@yahoo.com and sunlagabt@yahoo.com
ABSTRACT
The toxicity of Pb(II) on living mechanisms has led to severe ecological and health issues. In this
paper, Delonix regia leaves (DRL), Delonix regia tree bark (DRB) have been used as
biosorbents for the removal of Lead (II) from aqueous solutions. The biosorption studies were
carried out using each biosorbent singly and the combination of the two in equimolar proportions
respectively. The concentrations of the metal ions adsorbed were determined by atomic
absorption spectroscopic (AAS) method. Biosorption experiments were performed as a function
of pH, contact time, particle size, biosorbent dosage, temperature, initial concentration of the
biosorbates. The maximum removal of Lead (II) was obtained at pH 5 after two hours. Biosorption
Kinetics data obtained in this study fitted satisfactorily to the pseudo-first-order rate equation for
all the biosorbents. The experimental equilibrium biosorption data were tested for Langmuir and
Freundlich models, and the Freundlich model fitted better for all the biosorbents with correlation
coefficient (R2) ranges 0.997 - 0.999. Thermodynamic parameters such as Gibbs free energy,
enthalpy and entropy evaluated from experimental data predict the nature of the biosorption,
revealed that biosorption of Lead (II) was exothermic. The optimum uptake of Lead (II) was
achieved at 25 0 C. The results show that a large proportion of Lead (II) were adsorbed at higher
percentage when the combined form of the biosorbents was used as compared to when the
biosorbents were used singly.
KeyWords: Mechanism, Biosorption , Lead (II), Sorbent, Delonix regia
© 2014, Science Huβ, http://www.scihub.org/AJSIR
ISSN: 2153-649X, doi:10.5251/ajsir.2014.5.4.134.138
Mechanism of lead (ii) biosorption by delonix regia leaves and bark:
combined sorbent effect
Saratu Mamman and Tayelolu Olosunla
Department of Chemistry, University of Abuja, PMB 117, Abuja-Nigeria
mammansarah@yahoo.com and sunlagabt@yahoo.com
ABSTRACT
The toxicity of Pb(II) on living mechanisms has led to severe ecological and health issues. In this
paper, Delonix regia leaves (DRL), Delonix regia tree bark (DRB) have been used as
biosorbents for the removal of Lead (II) from aqueous solutions. The biosorption studies were
carried out using each biosorbent singly and the combination of the two in equimolar proportions
respectively. The concentrations of the metal ions adsorbed were determined by atomic
absorption spectroscopic (AAS) method. Biosorption experiments were performed as a function
of pH, contact time, particle size, biosorbent dosage, temperature, initial concentration of the
biosorbates. The maximum removal of Lead (II) was obtained at pH 5 after two hours. Biosorption
Kinetics data obtained in this study fitted satisfactorily to the pseudo-first-order rate equation for
all the biosorbents. The experimental equilibrium biosorption data were tested for Langmuir and
Freundlich models, and the Freundlich model fitted better for all the biosorbents with correlation
coefficient (R2) ranges 0.997 - 0.999. Thermodynamic parameters such as Gibbs free energy,
enthalpy and entropy evaluated from experimental data predict the nature of the biosorption,
revealed that biosorption of Lead (II) was exothermic. The optimum uptake of Lead (II) was
achieved at 25 0 C. The results show that a large proportion of Lead (II) were adsorbed at higher
percentage when the combined form of the biosorbents was used as compared to when the
biosorbents were used singly.
KeyWords: Mechanism, Biosorption , Lead (II), Sorbent, Delonix regia
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