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Author:Niinivaara, Elina
Title:Amine catalysed HOC1 treatment for birch pulp
Koivusellun amiinikatalysoitu HOCl-käsittely
Publication type:Master's thesis
Publication year:2012
Pages:85 s. + liitt. 6      Language:   eng
Department/School:Puunjalostustekniikan laitos
Main subject:Puunjalostuksen kemia   (Puu-19)
Supervisor:Vuorinen, Tapani
Instructor:Lehtimaa, Tuula ; Kovasin, Kari
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto  2250   | Archive
Keywords:tertiary amine
catalysis
hypochlorous acid
hexenuronic acid
tertiääriamiini
katalyysi
alikloorihapoke
heksenuronihappo
Abstract (eng): The presence of hexenuronic acid (HexA) in pulp is disadvantageous.
It has been found to cause an increased consumption of electrophilic bleaching chemicals, scaling in bleaching equipment and aid in the yellowing of pulp/paper, among others.
Although methods such as hot acid hydrolysis exist with which to remove HexA, tertiary amine catalysis may have the potential to provide an alternative and equally, if not more, efficient method.

The first objective of this work was to explore the possibility of using the tertiary amine, 1,4-diazabicyclo(2.2.2]octane (Dabco), to catalyse the removal of hexenuronic acid using hypochlorous acid.
The second objective was to determine the possibility of bleaching oxygen delignified birch pulp to full brightness using two four-stage bleaching sequences.
The sequences that were the focus of this thesis were A-EOP-D1-P and Dabco/H-EOP-D1-P.
The sequence used as a reference was D0-EOP-D1-Ep-D2.

The theoretical section of this thesis will describe the different components of wood, provide an introduction on kraft pulping and bleaching, describe the benefits of hexenuronic acid removal and will introduce the concept of tertiary amine catalysis.

In the experimental section, two major topics were considered.
The first of these was the optimization of the use of Dabco according to four key parameters; temperature, active chlorine charge, Dabco dosage and ph.
The second was the exploration of the two four stage bleaching sequences already mentioned.

It was found that Dabco was capable of extensively increasing the HexA removal potential of hypochlorous acid through a chlorammonium cation formed between Dabco and hypochlorous acid.
The system was also capable of removing lignin from the pulp.
As of yet, the four-stage bleaching sequences explored in this thesis were not able to bleach the oxygen delignified birch pulp to full brightness.
Abstract (fin): Massankeiton aikana muodostuva heksenuronihappo (HexA) on haitallista sillä se lisää elektrofiilisten valkaisukemikaalien kulutusta, aiheuttaa valkaisulaitteiston likaantumista sekä massan/paperin jälkikellertymistä.
Olemassa olevien keinojen lisäksi tertiäärinen amiinikatalyysi voi tarjota HexA:n poistamiseen vähintään yhtä tehokkaan vaihtoehtoisen menetelmän.

Tämän työn tavoitteena oli tutkia tertiäärisen amiinin, 1,4-diatsabisyklo[2.2.2]oktaani (Dabco), ja alikloorihapokkeen yhdistelmän katalyyttisia vaikutuksia HexA:n poistossa.
Toisena tavoitteena oli selvittää mahdollisuus valkaista happidelignifioitua koivumassaa täyteen vaaleuteen käyttämällä kahta nelivaiheista valkaisusekvenssiä.

Työn teoriaosassa perehdytään puun eri komponentteihin, sulfaattisellun valmistuksen ja valkaisun perusteisiin, heksenuronihapon poistamisen hyötyihin sekä tertiääriamiinikatalyysin perusteisiin.

Työn kokeellisessa osassa Dabcon käyttöä HexA:n poistossa optimoitiin neljän päämuuttujan avulla: Lämpötila, aktiivikloorin annostus, Dabcon annostus sekä pH.
Työssä ilmeni, että klorammonium kationin, jota syntyy Dabcon ja alikloorihapokkeen välisessä reaktiossa, avulla on mahdollista vaikuttaa HexA:n määrään massassa.
Samalla pystyttiin myös vähentämään ligniinin määrää massassa.

Kokeellisessa osassa tarkasteltiin myös kahta valkaisusekvenssiä, A-EOP-D1-P ja Dabco/H-EOP-D1-P, Referenssisekvenssinä käytettiin D0-EOP-D1-Ep-D2.
Näillä valkaisusekvensseillä ei kuitenkaan tämän työn reunaehdoilla pystytty valkaisemaan happidelignifioitua koivumassaa täyteen vaaleuteen.
ED:2012-05-11
INSSI record number: 44468
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