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Spontaneous, proton- and electrophile- catalysed hydrolysis of 1,5- anhydrocellobiitol : models for the reduction of cellulose degree of polymerisation in papermaking fibres

In this project, the kinetics of the spontaneous, proton- and electrophile-catalysed hydrolyses of the Cl-Ol bond in the cellulose model compound 1,5-anhydrocellobiitol were measured at various temperatures (125.0-220.0°C). Sealed capillary tubes containing the substrate (and catalyst where applicable) in various buffer solutions were opened after various exposures and analysed with HPLC-RI or HPAE-PAD. For the spontaneous, specific-acid-cata1ysed and AlIII-catalysed hydrolyses, apparent first-order rate constants and activation energies were calculated, showing the relative significance of these reactions at ambient temperatures. Efficient e1ectrophilic catalysis by AlIII over H+ catalysis of the hydrolysis of the model was demonstrated, with important implications for the degradation of "rosin-alum" sized paper and other papers containing AlIII. The loss of cellulose DP as a function of time was modelled under several conditions using the af Ekenstam equation. The loss of cellulose DP under kraft pulping conditions was shown to be due significantly to the spontaneous hydrolysis mechanism. A simple equation was derived for expressing the specific rate constant as a function of pH for the hydrolysis of cellulose (modelled with 1,5-anhydrocellobiitol). This equation is applicable from very acidic conditions to -pH 12.3.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:602433
Date January 2004
CreatorsBaty, John William
PublisherUniversity of Manchester
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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