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dc.contributor.advisorZhao, Huijun
dc.contributor.advisorTeasdale, Peter
dc.contributor.authorLi, Weijia
dc.date.accessioned2018-01-23T02:56:09Z
dc.date.available2018-01-23T02:56:09Z
dc.date.issued2004
dc.identifier.doi10.25904/1912/2018
dc.identifier.urihttp://hdl.handle.net/10072/367741
dc.description.abstractThe recently developed technique of diffusive gradients in thin films (DGT) for speciation measurement of analytes in the environment was further developed through the development of series of new binding phases including poly(acrylamide-co-acrylic acid) copolymer hydrogel (PAM-PAA), poly(acrylamidoglycolic acid-co-acrylamide) (PAAGA-PAM) hydrogel, the Whatman P81 cellulose phosphate ion exchange membrane (P81) and a liquid binding phase of poly(4-styrenesulfonate) (PSS). A new diffusion layer, cellulose dialysis membrane, was also employed for the liquid binding phase DGT. PAM-PAA copolymer hydrogel was prepared by the controlled hydrolysis of polyacrylamide (PAM) in an alkaline solution of 10% sodium hydroxide. The capacity of the copolymer hydrogel to bind various metal ions was tested under a range of uptake conditions. Ions such as Cu2+ and Cd2+ were bound more strongly to the copolymer hydrogel than the competing ions such as Na+, K+, Ca2+ and Mg2+. Metals bound to the copolymer hydrogel can be efficiently eluted in 2 M HNO3 solution (>94%). Application of this new binding material to DGT technique was validated in a synthetic lake water (Windermere, Lake District, UK) with a recovery of 99.0% for Cu2+. PAAGA-PAM hydrogel was prepared by copolymerising 2-acrylamidoglycolic acid with acrylamide. The metal ion binding properties of the hydrogel were characterised for Cu2+, Cd2+ and competing ions under various experimental conditions. The hydrogel was shown to bind Cu2+ and Cd2+ strongly under non-competitive binding conditions, with binding capacities of 5.3 and 5.1 micromol cm-2, respectively. The binding capacity of each metal decreased, under competitive binding conditions (with a range of metal ions present at 17.8 mN), to 1.3 and 0.17 micromol cm-2, respectively, indicating a strong selective binding towards Cu2+. The metal ions were readily recovered (>94%) by eluting with 2 M HNO3. Finally, the copolymer hydrogel was tested as a binding phase with the DGT technique. A linear mass vs. time relationship was observed for Cu2+ in Windermere water with a recovery of close to 100%. The use of a commercially available solid ion exchange membrane (P81) as the binding phase in DGT analysis was demonstrated. P81 is a strong cation exchange membrane. Its performance characteristics as a new binding phase in DGT measurement of Cu2+ and Cd2+ were systematically investigated. Several advantages over the conventional ion exchange resin-embedded hydrogel based binding phases used in DGT were observed. These include: simple preparation, ease of handling, and reusability. The binding phase preferentially binds to transition metal ions rather than competing ions. Within the optimum pH range (pH 4.0 - 9.0), the maximum non-competitive binding capacities of the membrane for Cu2+ and Cd2+ were 3.22 and 3.07 micromol cm-2, respectively. The suitability of the new membrane-based binding phase for DGT applications was validated experimentally. The results demonstrated excellent agreement with theoretically predicted trends. The reusability of this binding phase was also investigated. Application of a liquid binding phase and a dialysis membrane diffusive layer were proposed for the first time. The binding phase was a 0.020 M solution of poly(4-styrenesulfonate) (PSS) polyelectrolyte using a specially designed DGT device. The binding properties of Cd2+, Cu2+, and a range of alkali and alkaline earth metal ions to the PSS solution were characterised. The PSS behaved like a cation exchanger with preferential binding to Cd2+ (6.0 micromole ml-1, log K = 9.0) and Cu2+ (2.5 micromole ml-1, log K = 8.1) under competitive binding conditions. The DGT devices were successfully validated for Cd2+ and Cu2+ in Windermere water. The speciation performance of the solid and liquid binding phases developed in this study was investigated in solutions containing ethylenediaminetetraacetic acid disodium salt (EDTA), humic acid (HA), glucose (GL), dodecylbenzenesulfonic acid (DBS) and tannic acid (TA) with Cu2+ and Cd2+. The ratios of labile metals over total metals were at good agreement with calculated theoretical values using Stability Constants Database. The results indicated that the DGT-labile concentration measured by DGT with these binding phases is essentially free metal ion concentration in the sample. All newly developed DGT binding phases were successfully applied for environmental speciation. The field deployments were carried out in both freshwater and salt-water test sites.
dc.languageEnglish
dc.publisherGriffith University
dc.publisher.placeBrisbane
dc.rights.copyrightThe author owns the copyright in this thesis, unless stated otherwise.
dc.subject.keywordsthin films
dc.subject.keywordsdiffusive gradients in thin films
dc.subject.keywordsDGT
dc.subject.keywordsspeciation
dc.subject.keywordsmeasurement
dc.subject.keywordsbinding phases
dc.subject.keywordsion exchange
dc.subject.keywordstrace metals
dc.subject.keywordswater quality measurement
dc.subject.keywordscopper
dc.subject.keywordscadmium
dc.titleDevelopment of New Binding Phases for Speciation Measurements of Trace Metals with the Diffusive Gradients in Thin Films Technique
dc.typeGriffith thesis
gro.rights.copyrightThe author owns the copyright in this thesis, unless stated otherwise.
gro.hasfulltextFull Text
dc.contributor.otheradvisorJohn, Richard
dc.rights.accessRightsPublic
gro.identifier.gurtIDgu1315954979168
gro.identifier.ADTnumberadt-QGU20040504.150905
gro.source.ADTshelfnoADT0
gro.source.GURTshelfnoGURT
gro.thesis.degreelevelThesis (PhD Doctorate)
gro.thesis.degreeprogramDoctor of Philosophy (PhD)
gro.departmentSchool of Environmental and Applied Science
gro.griffith.authorLi, Weijia


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