Date of Award

2002

Level of Access

Open-Access Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Civil Engineering

Advisor

Aria Amirbahman

Second Committee Member

Jean D. MacRae

Third Committee Member

William G. Davids

Abstract

This study describes the synthesis and characterization of thiol-grafted chitosan beads for use as mercury (Hg) adsorbents. Chitosan flakes were manipulated into beads using a phase inversion technique, then crosslinked to improve porosity and chemical stability. Cysteine was grafted onto the beads in order to improve the adsorption affinity of Hg to the beads. The beads possessed an average diameter of 3.2 mm, porosity of 0.9, specific surface are of -100 m21g, average pore size of -120 Angstroms, and specific gravity of 2. The beads exhibited a high adsorption capacity for Hg: 2,2.5,3.5 and 8 mmoVg dry at pH values of 2.2,4, 5,and 7, respectively. By comparison ungrafted chtosan had a capacity of -1.2 mmoVg dry at pH 4. Adsorption of Hg onto the beads was modeled using the Freundlich isotherm. Hg adsorption kinetics was modeled as radial diffusion into an infinite sphere. The beads exhibited a high initial uptake rate comparable to other published chitosan bead data followed by a slower uptake rate suggesting pore diffusion as the rate-determining step.

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