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Master Thesis the Haloperoxidase-DABCO System

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Master Thesis the Haloperoxidase-DABCO System UNIVERSITY OF COPENH AGEN FACULTY OF SCIENCE Master Thesis Valentin Waschulin The Haloperoxidase-DABCO System Exploring a Novel Method of Enzymatic Pulp Bleaching Name of department: Department of Geosciences and Natural Resource Management, Forest, Nature and Biomass Author: Valentin Waschulin Title / Subtitle: The Haloperoxidase-DABCO System: Exploring a Novel Method of Enzymatic Pulp Bleaching Academic advisor: Prof. Claus Felby Industrial advisors: Pedro Loureiro Submitted: 18. September 2016 2/79 Acknowledgements I want to express my thanks to Prof. Claus Felby for the opportunity of performing my Master Thesis at his chair, and Henrik Lund for providing me with the possibility of performing the thesis work at the Technical Industries department at Novozymes A/S, Denmark. I want to thank Pedro Loureiro for providing supervision, detailed expertise and great scientific discussions throughout the time of the thesis. I also want to thank all the scientists and associates at the department for discussion, advice and hands-on help in the laboratory; in particular Owik Herold-Majumdar for guidance and discussion concerning the model compound work. Finally, I want to thank my parents Susanne and Georg and my sister Laura for supporting me throughout my studies in Denmark. 3/79 Abstract A novel approach for cellulosic pulp bleaching and hexenuronic acid (HexA) removal using a haloperoxidase (Hap) and a tertiary amine catalyst (DABCO) was tested on oxygen-delignified eucalypt kraft pulp. In a buffered system (pH 4,5, 60°C), high brightness gain, good response to peroxide-reinforced alkaline extraction and more than 80% HexA removal were achieved, while preserving cellulose integrity. In an optimized, but non-buffered system, Hap/DABCO was compared to the non-enzymatic HOCl treatment and an inferior performance of the former was found. At the same brightness level, HOCl treatment performed superior in terms of HexA and kappa number reduction. Hydrogen peroxide was proposed as most likely playing a role in contributing to the brightening during Hap/DABCO treatment. Organochlorine formation was measured and found to be much higher than reference chlorine dioxide treatments. It was concluded that the problem of organochlorine formation must be solved for this technology to be used in the future. Danish Abstract I denne afhandling undersøges en ny enzymatisk proces til blegning af cellulosepulp og fjernelse af hexenuronic acid (HexA). I processen indgår en haloperoxidase (Hap) og en tertiær amin (DABCO) der testes på oxygen-delignificeret eukalyptus kraft pulp. Ved at køre processen ved konstant pH (pH 4,5; 60°C) sås en øget lyshed samt en god respons på peroxid-alkalisk ekstraktion hvor mere end 80% HexA fjernelse opnået, uden at cellulose strukturen blev nedbrudt. I et optimeret, men ikke-bufret system, blev Hap/DABCO-systemet sammenlignet med en ikke- enzymatisk HOCl behandling, og en mindre effekt af Hap/DABCO-systemet blev fundet. På samme niveau af lyshed var HOCl behandlingen overlegen i forhold til reduktion af HexA og kappanummer. Hydrogenperoxid og ikke kun den enzymatiske oxidation kan være medvirkende til blegningen under Hap/DABCO behandling. Organochlor-dannelse blev målt og vurderet at være meget højere end reference-behandlinger med chloridoxid. Det blev konkluderet, at problemet med dannelse af organochlor skal løses før en fremtidig anvendelse af Hap/DABCO teknologien. 4/79 List of abbreviations List of abbreviations mM Millimolar mmol Millimole ISO International Organization for Standardization DABCO 1,4-diazabicyclo[2.2.2]octane ECF Elemental chlorine free TCF Totally chlorine free O Oxygen stage D Chlorine dioxide stage E Alkaline extraction Ep Alkaline extraction reinforced with hydrogen peroxide COD Chemical oxygen demand mg Milligram MQ Milli-Q water dH2O Deionized water LC Liquid chromatography GC Gas chromatography MS Mass spectrometry odp Oven dry pulp % odp Weight percentage of the amount of oven dry pulp odt Oven dry ton (of pulp) OX Organic halogens AOX Adsorbable organic halogens cP Centipoise T Temperature DM Dry matter DM% Percentage of dry matter HexA Hexenuronic acid °C Degree Celsius T Temperature Hap Haloperoxidase PET Polyethylene terephthalate BSTFA N,O-Bis(trimethylsilyl)trifluoroacetamide TMCS Trimethylchlorosilane DHBQ Dihydroxybenzoquinone; IUPAC: 2,5-dihydroxycyclohexa-2,5-diene-1,4-dione SAL Sinapaldehyde IUPAC: 3-(4-Hydroxy-3,5-dimethoxyphenyl)prop-2-enaI 5/79 List of abbreviations 6/79 Table of Contents Table of Contents Abstract ........................................................................................................................................................... 4 Danish Abstract ............................................................................................................................................... 4 List of abbreviations ........................................................................................................................................ 5 Table of Contents ............................................................................................................................................ 7 1 Aim and Scope ........................................................................................................................................ 9 2 Introduction and background ............................................................................................................... 11 2.1 The pulp and paper industry ..................................................................................................... 11 2.2 The Raw Material: Cellulose and Lignin .................................................................................... 11 2.3 Kraft Pulping ............................................................................................................................... 13 2.4 Bleaching: Development and current technology ..................................................................... 14 2.4.1 D-stage chemistry .............................................................................................................. 14 2.4.2 Ep chemistry ....................................................................................................................... 15 2.5 Hexenuronic acids: A side product of kraft pulping.................................................................. 16 2.6 Catalytic bleaching ..................................................................................................................... 17 2.6.1 Tertiary amine catalysis of HOCl reactions ....................................................................... 17 2.6.2 Catalyic bleaching and removal of hexenuronic acid ....................................................... 19 2.7 Pulp mill effluents and the environment ................................................................................... 21 2.7.1 Organochlorine compounds ............................................................................................... 22 2.8 Selected paper and pulp properties .......................................................................................... 23 2.8.1 Brightness ........................................................................................................................... 23 2.8.2 Strength .............................................................................................................................. 24 2.8.3 Viscosity .............................................................................................................................. 24 2.8.4 Yield .................................................................................................................................... 24 2.9 Enzyme applications in pulp and paper .................................................................................... 24 2.9.1 Hydrolytic enzymes ............................................................................................................ 25 2.9.2 Laccases and peroxidases .................................................................................................. 25 2.10 Haloperoxidases ......................................................................................................................... 26 2.10.1 Vanadium haloperoxidases ................................................................................................ 27 2.10.2 Curvularia haloperoxidases ................................................................................................ 28 2.10.3 Biotechnological applications of VHPOs ............................................................................. 28 2.11 The haloperoxidase – DABCO system ....................................................................................... 29 3 Materials and Methods .......................................................................................................................... 30 3.1 Materials ..................................................................................................................................... 30 3.1.1 Enzyme ............................................................................................................................... 30 3.1.2 Equipment .......................................................................................................................... 30 3.2 Methods .....................................................................................................................................
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