Skip navigation

A spectroscopic investigation of the thermal decomposition of cellulose and alginic acid

A spectroscopic investigation of the thermal decomposition of cellulose and alginic acid

Coburn, Steven (2006) A spectroscopic investigation of the thermal decomposition of cellulose and alginic acid. PhD thesis, University of Greenwich.

[img] PDF
Steven_Coburn_2006.pdf - Published Version
Restricted to Repository staff only until 16 March 2019.
Available under License Creative Commons Attribution Non-commercial No Derivatives.

Download (27MB)

Abstract

The combustion and pyrolysis of biomass impacts directly on a number of areas such as, energy production, public health, environmental protection and feedstock for chemical production. This study investigated the thermal decomposition of two structurally similar polysaccharides – cellulose and alginic acid, arguably being the two largest sources of biomass on land and from the sea respectively. Despite the similarity in the two materials and applications, reviewing literature of the combustion and pyrolysis mechanisms of the two materials showed a relatively well-established framework of knowledge for cellulose, although there is still some lack of agreement in some areas. This contrasted with the almost total absence of any information on the thermal behaviour of alginic acid. The aim of the work reported in this thesis was to use the structural similarities and the mechanistic framework for cellulose to conduct a comparative investigation of the two materials.

Taking advantage of high throughput multivariate algorithms to process complex spectroscopic data produced by TGA-FTIR, a method was developed to identify infrared active volatile species generated above a detectable threshold during the thermal degradation process. The ability to plot an evolution profile of a selected compound in time- and/or temperature domain significantly enhanced the capabilities of a standard TGA-FTIR system for mechanistic investigations. With the technique established, the two materials were analysed under different heating rates (5, 10, 30, 60°C/min) under nitrogen and again under 10% oxygen in nitrogen. A reconstruction of the cellulose decomposition pathway was carried out using the data obtained from this work. Compared to the methods available in the scientific literature, the current method was a simpler and more efficient technique for providing information related to the thermal degradation behaviours of the sample materials. The application of the method to alginic acid revealed for the first time that this material responded differently and more sensitively to the presence of oxygen than did cellulose. Its decomposition pathway has a number of distinctive steps, in contrast to cellulose. To complement the analysis of the volatiles, the surface of charred residues of the two materials were also analysed by using attenuated total reflectance (ATR) infrared spectroscopy. This information was also used to deduce the combustion chemistry for the two materials.

Item Type: Thesis (PhD)
Additional Information: uk.bl.ethos.426475
Uncontrolled Keywords: polysaccharides, thermal decomposition, chemical decomposition,
Subjects: Q Science > QD Chemistry
Faculty / Department / Research Group: Faculty of Engineering & Science > Department of Pharmaceutical, Chemical & Environmental Sciences
Last Modified: 14 Feb 2018 12:58
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
URI: http://gala.gre.ac.uk/id/eprint/6134

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year

View more statistics