BIOSORPTION OF LEAD FROM AQUEOUS SOLUTION BY Ziziphus mauritiana SEED SHELLS
BIOSORPTION OF LEAD FROM AQUEOUS SOLUTION BY Ziziphus mauritiana SEED SHELLS
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Date
2016-11
Authors
BITIYONG, HOPE BABVOSHIA
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Abstract
Presence of heavy metals in the aquatic systems has become a serious problem. Lead is a metal which has been associated with various human activities However, it is also toxic to humans, with the most deleterious effects on the hemopoietic, nervous, reproductive systems and the urinary tract. Biosorption is potentially an attractive technology which utilizes biomass to sequester heavy metals from wastewater. Studies carried through the environmental biotechnology have shown that many biosorbents present in the nature have great capacity for removal of heavy metals. The aim of the present study was to utilize Ziziphus mauritiana Lam. seed shells for biosorption of Pb (II) ions from aqueous solutions. These seed shells were used for the biosorption Pb (II) ions from aqueous solution under batch mode. The concentration of Pb(II) ions sorbed was determined using atomic absorption spectrophotometry. The influence of biosorbent dose, initial lead (II) concentration, contact time, temperature, solution pH and agitation rate on the removal process, were investigated. Equilibrium studies, kinetics and thermodynamics of Pb (II) biosorption were also investigated. About 4 g of the adsorbent was obtained as the optimum biosorbent dose which showed a metal uptake capacity (qe) of 2112.03 mg g-1 for an initial metal ion concentration of 50 mg g-1. Increase in initial metal ion concentration led to a decrease in percentage removal efficiency of the Z. mauritania seed shells with 10 mg g-1 having the highest percentage Pb removal of 82.05%. The equilibrium contact time for the metal was found to be 60mins with 80.69 % uptake. At temperature of 70oC, the maximum percentage removal (89.48%) was observed. The optimum uptake of Pb (II) occurred at pH 7 with the highest percentage removal of 88.39%. Results of agitation rate showed a maximum uptake (85.18%) at 300 rpm. The equilibrium data was analyzed by the Freundlich and Langmuir adsorption isotherm models and was found to conform to the Freundlich isotherm with R2 value 0.952. The maximum adsorption capacity of the
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Z. mauritania seed shells for Pb (II) was 500 mg g-1. The kinetics of Pb (II) ion was modeled using pseudo-first-order and second-order models as well as the intraparticle diffusion model. It was shown that the adsorption could be described by the pseudo-second order kinetic model with R2 value 0.997. Thermodynamic parameters such as Gibbs free energy (ΔGo), enthalpy (ΔHo) as 15807.88 kJ/mol and entropy change of the biosorption (ΔSo) as 50.07 kJ/K/mol indicated that the biosorption process was endothermic in nature, spontaneous and feasible. FT-IR analysis of Z, mauritiana seed shells showed that O-H, C-O, C=O, C=N, NO2 are functional groups involved in the biosorption process. It was concluded that Z. mauritania seed shells can be used as an effective, low-cost and environmentally friendly biosorbent to remove Pb (II) ions from aqueous solutions
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POST GRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLMENT OF THE REQUIRMENT FOR THE AWARD
OF A
MASTER DEGREE IN BIOCHEMISTRY.
DEPARTMENT OF BIOCHEMISTRY,
FACULTY OF SCIENCE
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
BIOSORPTION,, LEAD,, AQUEOUS SOLUTION,, Ziziphus mauritiana,, SEED SHELLS,