Date of Award

1-1-2001

Thesis Type

Masters

Document Type

Thesis

Divisions

Institute for Advanced Studies

Department

-

Institution

Universiti Malaya

Abstract

The primary objective of this study was to investigate the feasibility of using the immobilized biomass of Sargassum buccularia. a brown marine macro algae. to remove and recover copper ions in a fixed bed reactor by passive adsorption. This is commonly referred to as biosorpliun. Inactivated biomass of S. baccularia were chemically modified b) immobilizing it onto polyvinyl alcohol (PVA} as a support matrix. Spherical gel beads that were produced in this manner were subjected to mass transfer and equilibrium studies. The biosorption of copper is a bi-phasic process. with an initial fast phase for the first 2 hours followed by a slower second phase. Equilibrium was achieved after 20 hours of exposure. However, there was negligible uptake of copper by pure PVA beads. The effect of pH on biosorption equilibria was also investigated. Results indicate that copper uptake is pH dependent with higher uptake of copper at pH 6. Maximum binding capacity qₘₐₓ evaluated with Langmuir adsorption isotherm was 31.15 mg/g and 40.31 mg/g at pH 3 and pH 6 respectively. Both Langmuir and Freundlich adsorption isotherms characterized the experimental data well but Freundlich model exhibited a better fit at pH 6 than Langmuir does. To predict the adsorption profile of the immobilized biomass in a laboratory scale fixed bed reactor. a two parameter model was employed to characterize the breakthrough curve. The model was tested in various operating conditions and was able to model the entire breakthrough curve. Agreement between experimental and predicted values was favourable although minor deviations occurred at certain intervals. Reusability of the biosorbem in a fixed bed under multiple cycle of adsorption/desorption was also carried out. A bed depth of 13 cm with 1 mL/min and 20 mg/L of feed concentration was chosen. A total of three continuous cycles were studied using cthylencdiaminctctraacetic acid (EDTA) at various strengths as the desorbing agent. An elution efficiency greater than 90% indicated that copper ions were passively adsorbed onto the biomass surface and thus was easily extractable by EDTA. However. repeated exposure of the biosorbents to EOTA at 1. 4 and 6 mM reduced copper uptake in subsequent cycles. In this study. EDTA at 4 mM was found to be the optimum concentration to extract bound copper ions. At 6 mM. considerable damage was observed with copper uptake dramatically reduced. Scanning Electron Microscope (SEM) incorporating Energy Dispersive Analysis of X-ray (EDAX) was also conducted to assess the immobilized biomass surface. Both macrupores and micrupures were clearly observed with SEM indicating a very porous structure for the biomass immobilized with PVA. Ion exchange took place between copper ions and two divalent ions. From the EDAX spectrum. the two divalent ions were recognized as magnesium and calcium. Both are important constituents for cell wall and metabolic activities in the algae.

Initial

snms

Additional Information

Dissertation (M.A) -- Institute for Advanced Studies, Universiti Malaya, 2001.

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