ASSESSMENT OF THE COMPETITIVE ADSORPTION OF SOME HEAVY METAL IONS ONTO SOIL
ASSESSMENT OF THE COMPETITIVE ADSORPTION OF SOME HEAVY METAL IONS ONTO SOIL
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Date
2018-02
Authors
IDOWU, Opeyemi Elizabeth
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Abstract
This research work assessed the adsorption of Cd2+, Cr6+, Cu2+ and Pb2 in single-metal and multi-metal ions reaction systems onto a standard reference soil (NIST SRM 2709a). The effect of varying adsorbent dosage, contact time and initial concentration of the metal ions on the soil was examined and for most of the metals, the optimum conditions were attained at 20 mg/dm3 initial metal ion concentration, 1.0 g adsorbent dose and 2 hrs contact time. The highest percentage adsorption of Cd2+, Cr6+, Cu2+, and Pb2+obtained from their respective solutions were 92.22%, 56.71%, 99.57% and 97.11%. Equilibrium studies showed that the Freundlich isotherm had a better fit for the selected metals than Langmuir isotherm. The kinetics study revealed that all the selected metal ions followed the pseudo-second order model. The results of the experiments confirmed that adsorption from single-metal solution was more effective than adsorption under multi-metal conditions due to competitive effects. Also, the adsorption of the metals decreased with increase in the number of competing ions. Among the metal ions studied in the multi-metal system, Pb2+ was most preferably removed because of its high affinity to the soil surface. Metal affinity and capacity for the soil surface were found to increase with metal electronegativity Pb >Cu > Cd > Cr in the competitive systems. The results indicated that high removal efficiency could be achieved by the use of natural standard reference soil.
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A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA,
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD
OF
MASTER OF SCIENCE (ANALYTICAL CHEMISTRY)
DEPARTMENT OF CHEMISTRY,
FACULTY OF PHYSICAL SCIENCES,
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
ASSESSMENT,, COMPETITIVE ADSORPTION,, HEAVY METAL IONS ONTO,, SOIL