Selective biosorption of silver ions from aqueous solution using chitosan-based biosorbents

Zhang, Meng (2015) Selective biosorption of silver ions from aqueous solution using chitosan-based biosorbents. Masters thesis, Memorial University of Newfoundland.

[img] [English] PDF - Accepted Version
Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.

Download (2MB)

Abstract

In this study, Ag⁺-imprinted thiourea/glutaraldehyde grafted O-carboxymethyl chitosan (ITG-OCMC) beads and Ag⁺-imprinted glutaraldehyde-crosslinked chitosan (IGCC) gel beads were synthesized to selectively adsorb Ag⁺ from bimetallic aqueous solutions containing the same molar concentration of Ag⁺ and Cu²⁺. Surface imprinting technology has been applied to achieve extremely high selectivity for Ag⁺ on the prepared sorbents by generating recognizable binding sites. For the ITG-OCMC beads, experimental results indicated that high degree of carboxymethylation and low level of crosslinking would help to achieve higher uptake capacity of Ag⁺. The maximum uptake of Ag⁺ was found to be 156.32 mg g⁻¹ at 40.0 °C with an initial Ag⁺ concentration of 160.50 mg L⁻¹ and the biosorbent dosage of 1.0000 g L⁻¹. Langmuir isotherm and Lagergren’s pseudo-second-order kinetics can be used to describe the sorption process of Ag⁺. Analyses from FTIR and XPS confirmed that selective adsorption of Ag⁺ took place on the surfaces of ITG-OCMC beads by chelation through >C=S, amine, carboxyl and hydroxyl groups. For the IGCC beads, the maximum uptake of Ag⁺ by the ion-imprinted chitosan beads was found to be 89.200 mg g⁻¹ at 25.0 °C with an initial Ag⁺ concentration of 352.95 mg L⁻¹ and the biosorbent dosage of 1.0000 g L⁻¹. The adsorption equilibrium and kinetics of Ag⁺ by IGCC beads can be better described by Langmuir isotherm and the intraparticle diffusion model. FTIR and XPS analyses suggested that amine functional groups involve the binding of Ag⁺ via complexation at higher solution pH (3.0 ≤ pH ≤ 5.0) and ion exchange at lower solution pH (1.0 ≤ pH <3.0).

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/11592
Item ID: 11592
Additional Information: Includes bibliographical references.
Keywords: Selective adsorption, Chitosan, Silver, Crosslinking, Imprinting
Department(s): Engineering and Applied Science, Faculty of
Date: October 2015
Date Type: Submission
Library of Congress Subject Heading: Chitosan--Synthesis; Sorbents; Silver ions--Absorption and adsorption; Ion exchange; Coating processes

Actions (login required)

View Item View Item

Downloads

Downloads per month over the past year

View more statistics