McDermott, Sinead (2010) Polypyrrole Modified with Macrocycles for the Detection of Aqueous Pollutants and Carbon Membranes for the Separation of Gases. PhD thesis, National University of Ireland Maynooth.
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Abstract
The development of environmental technologies and their applications in
aqueous and gaseous systems are essential in combating pollution. The
formation and detailed characterisation of a polypyrrole (PPy) film modified
with anionic macrocycles of either sulfonated-bcyclodextrin (sul-bCD) or
sulfonated-calix[4]arene (sul-calix[4]) were carried out. These composite
modified electrodes were used as electrochemical sensors for the detection of
the harmful herbicide, paraquat. These polymer films were highly conducting
and due to the immobilisation of the large anionic dopants within the PPy
matrix they exhibited cation exchange behaviour on reduction. Cyclic
voltammetry (CV), differential pulse voltammetry (DPV) and constant potential
amperometry (CPA) were the techniques employed to evaluate the sensitivity of
PPy/sul-bCD and PPy/sul-calix[4] towards the redox states of MV2+, MV+ and
MV0 of paraquat. A limit of detection of 1.28 ´ 10-5 mol dm-3 and 3.48 ´ 10-6 mol
dm-3 for the reduction of MV2+ was evaluated using CPA for PPy/sul-bCD and
PPy/sul-calix[4], respectively.
Additional studies were carried out to probe the nature of the complex
interaction between the macrocyclic structures of sul-bCD and sul-calix[4] and
the analytes, paraquat and diquat. Electrochemical and spectroscopic
techniques were used to quantify the association constant, Ka. The data obtained
from these techniques was consistent with electrostatic interactions as the
major driving force in complex formation. In the case of the sul-calix[4] system
the magnitude of Ka was influenced by ionic strength. The Ka values decreased
from 106 to 103 mol-1 dm3 for the complex of diquat and sul-calix[4] in the
absence and presence of 0.1 mol dm-3 Na2SO4, respectively.
Carbon molecular sieve membranes (CMSMs) were employed for the separation
of gases. CMSMs displayed selective permeation of CO2 over N2 by a factor of
24.7:1.0. Reduction in the permeability of the membrane was observed with
aging. This was restored using an electro-regeneration procedure.
Item Type: | Thesis (PhD) |
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Keywords: | Polypyrrole; Macrocycles; Aqueous Pollutants; Carbon Membranes; Separation of Gases; |
Academic Unit: | Faculty of Science and Engineering > Chemistry |
Item ID: | 2264 |
Depositing User: | IR eTheses |
Date Deposited: | 19 Nov 2010 11:44 |
URI: | https://mu.eprints-hosting.org/id/eprint/2264 |
Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
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