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Antimicrobial materials from cellulose using environmentally friendly techniques
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.ORCID iD: 0000-0002-1656-1465
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The transition to a more biobased society introduces both new opportunities and new challenges as we replace nonrenewable materials with renewable alternatives. One important challenge will be to control microbial growth on materials, both to protect the materials from biological degradation and to prevent the spread of infections and toxins that can cause illness.

In this thesis, both existing and new types of cellulose-based materials were treated with environmentally friendly alternatives to usual biocides to prevent microbial growth and remove bacteria from water. Two types of antimicrobial systems were studied, and the antimicrobial effects were evaluated for bacteria and fungi using both model organisms and wild-type cultures.

The first antimicrobial approach employed was a nonleaching and contact-active layer-by-layer adsorption of polyelectrolytes to provide the cellulose fibers with a cationic surface charge, which attracts and captures bacteria onto the fiber surface. The study showed that paper filters with pores much larger than bacteria could remove more than 99.9 % of E. coli from water when used in filtration mode. The polyelectrolyte-modified materials showed a good antibacterial effect but did not prevent fungal growth.

The second approach was to utilize biobased compounds with antimicrobial properties, which were applied to cellulose fiber foam materials. Chitosan and extractives from birch bark were selected as biobased options for antimicrobial agents. Two types of cellulose fiber foam materials were developed and evaluated for their antimicrobial properties.

This thesis shows the importance of understanding both the application and the targeted microorganism when selecting an environmentally friendly antimicrobial system for treating biobased materials. It highlights that a good understanding of both material science and microbiology is important when designing new antimicrobial materials.

Abstract [sv]

Satsningen på ett mer biobaserat samhälle, där vi ersätter icke-förnybara material med förnyelsebara alternativ, är en pusselbit för en mer hållbar framtid samtidigt som den medför nya utmaningar. En viktig uppgift är att minska och kontrollera mikrobiell tillväxt, både för att skydda material från biologisk nedbrytning men också för att förhindra spridning av infektioner och toxiner.

Cellulosabaserade material har behandlats med miljövänliga alternativ till traditionella biocider för att förhindra mikrobiell tillväxt och för ta bort bakterier från vatten. Två typer av antimikrobiella system har använts varefter den antimikrobiella effekten mot både mögel och bakterier utvärderats, med hjälp av både modellorganismer och mikrobiella odlingar från naturen.

Den första typen av antimikrobiell metod som använts baseras på en kontakt-aktivt teknik. Cellulosafibrer har modifierats genom lager-på-lager polyelektrolytadsorption för att skapa en positiv ytladdning som kan attrahera och binda bakterier till fiberytan. Studien visar att modifierade pappersfilter, med porer som är mycket större än bakterier, kan filtrera bort mer än 99,9 % av E. coli från kontaminerat vatten. De polyelektrolyt-modifierade cellulosamaterialen påvisade goda antibakteriella egenskaper men förhindrade inte tillväxt av mögel.

Den andra metoden som undersökts var att tillsätta biobaserade ämnen med antimikrobiella egenskaper till cellulosabaserade fiberskum. Kitosan och extraktivämnen från björkbark valdes ut som miljövänliga alternativ till vanliga biocider. Två typer av cellulosabaserade fiberskum har tagits fram och utvärderats för deras antimikrobiella egenskaper.

Avhandlingen visar hur viktigt det är att veta hur materialet är tänkt att användas och vilken typ av mikroorganism som skall undvikas när man väljer antimikrobiell behandling av biobaserade material. God förståelse för både materialvetenskap och mikrobiologi är nödvändig när nya biobaserade material med antimikrobiella egenskaper skall designas.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2018. , p. 68
Series
TRITA-CBH-FOU ; 2018:57
Keywords [en]
Antibacterial, antifungal, cellulosic, mold, bacteria, biobased, bio-based, renewable, insulation, packaging, water treatment, water purification, paper filter, paper, membrane
Keywords [sv]
Antibakteriell, fungicid, mögel, antimögel, pappersfilter, vattenrening, membran, papper, bakterier, cellulosa, förpackning, isolering, förnyelsebar, biobaserade, nya material
National Category
Paper, Pulp and Fiber Technology Water Treatment Microbiology
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-238843ISBN: 978-91-7873-031-5 OAI: oai:DiVA.org:kth-238843DiVA, id: diva2:1262673
Public defence
2018-12-07, F3, Lindstedtsvägen 26, KTH Campus, Stockholm, 14:00 (English)
Opponent
Supervisors
Funder
ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 17-391Swedish Research Council Formas, 2014-00959
Note

QC 20181114

Available from: 2018-11-14 Created: 2018-11-12 Last updated: 2018-11-14Bibliographically approved
List of papers
1. Water Purification Using Functionalized Cellulosic Fibers with Nonleaching Bacteria Adsorbing Properties
Open this publication in new window or tab >>Water Purification Using Functionalized Cellulosic Fibers with Nonleaching Bacteria Adsorbing Properties
2017 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 13, p. 7616-7623Article in journal (Refereed) Published
Abstract [en]

 Portable purifi cation systems are easy ways to obtain clean drinking water when there is no large-scale water treatment available. In this study, the potential to purify water using bacteria adsorbing cellulosic fi bers, functionalized with polyelectrolytes according to the layer-by-layer method, is investigated. The adsorbed polyelectrolytes create a positive charge on the fi ber surface that physically attracts and bonds with bacteria. Three types of cellulosic materials have been modifi ed and tested for the bacterial removal capacity in water. The time, material-water ratio and bacterial concentration dependence, as well as the bacterial removal capacity in water from natural sources, have been evaluated. Freely dispersed bacteria adsorbing cellulosic fi bers can remove greater than 99.9% of Escherichia coli  from nonturbid water, with the most notable reduction occurring within the fi rst hour. A fi ltering approach using modifi ed cellulosic fi bers is desirable for purifi cation of natural water. An initial fi ltration test showed that polyelectrolyte multilayer modifi ed cellulosic fi bers can remove greater than 99% of bacteria from natural water. The bacteria adsorbing cellulosic fi bers do not leach any biocides, and it is an environmentally sustainable and cheap option for disposable water purification devices.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Keywords
cellulose, water treatment, water purification, layer by layer, multilayer adsorption, bacteria removing, Vattenrening, cellulosa, pappersmassa, multilager, bakterieadsorption
National Category
Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-218668 (URN)10.1021/acs.est.7b01153 (DOI)000405056200035 ()2-s2.0-85024408693 (Scopus ID)
Note

QC 20171204

Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2018-11-12Bibliographically approved
2. Cellulose-based water purification using paper filters modified with polyelectrolyte multilayers to remove bacteria from water through electrostatic interactions
Open this publication in new window or tab >>Cellulose-based water purification using paper filters modified with polyelectrolyte multilayers to remove bacteria from water through electrostatic interactions
2018 (English)In: Environmental Science: Water Research & Technology, ISSN 20531400Article in journal (Refereed) Published
Abstract [en]

Filtration is a common way to obtain pure drinking water by removing particles and microorganisms based on size exclusion. Cellulose-based filters are affordable and biobased option for the removal of particles but bacteria are usually too small to be removed by size exclusion alone. In this article, the surfaces of cellulose fibres in two types of commercial paper filters have been given a positive net charge to trap bacteria through electrostatic interactions without releasing any biocides. The fibres were modified with the cationic polyelectrolyte polyvinylamine polymer in single layers (1 L) or in multilayers together with the anionic polyelectrolyte polyacrylic acid (3 L or 5 L) using a water-based process at room temperature. Filtration tests show that all filters, using both types of filter papers and a number of layers, can physically remove more than 99.9% of E. coli from water and that the 3 L modified filters can remove more than 97% of cultivatable bacteria from natural water samples. The bacterial reduction increased with increasing number of filter sheets used for the filtration and the majority of the bacteria were trapped in the top sheets of the filter. The results show the potential for creating water purification filters from bio-based everyday consumable products with a simple modification process. The filters could be used in the future for point-of-use water purification that may be able to save lives without releasing bactericides.

Keywords
Cellulose, water treatment, paper filter, membrane, filter, antibacterial, remove bacteria, layer-by-layer, Cellulosa, pappersfilter, vattenrening, membran, lager-på-lager, antibakteriell
National Category
Water Treatment
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-238838 (URN)10.1039/C8EW00514A (DOI)
Funder
ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 17-391
Note

QC 20181112

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-12Bibliographically approved
3. Water-stable cellulose fiber foam with antimicrobial properties for bio based low-density materials
Open this publication in new window or tab >>Water-stable cellulose fiber foam with antimicrobial properties for bio based low-density materials
2018 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 4, p. 2599-2613Article in journal (Refereed) Published
Abstract [en]

New bio-based packaging materials are highly interesting for replacing conventional fossil based products for a more sustainable society. Water-stable cellulose fiber foams have been produced in a simple one-batch foam-forming process with drying under ambient conditions. The cellulose fiber foams have a low density (33–66 kg/m3) and can inhibit microbial growth; two highly valuable features for insulating packaging materials, especially in combination with stability in water. Cationic chitosan and/or polyvinylamine have been added during the foam-forming process to give the foams water-stability and antimicrobial properties. The structural and mechanical properties of the cellulose fiber foams have been studied and the antimicrobial properties have been evaluated with respect to both Escherichia coli, a common model bacteria and Aspergillus brasiliensis, a sporulating mold. The cellulose foams containing chitosan had both good water-stability and good antibacterial and antifungal properties, while the foams containing PVAm did disintegrate in water and did not inhibit fungal growth when nutrients were added to the foam, showing that it is possible to produce a bio-based foam material with the desired characters. This can be an interesting low-density packaging material for protection from both mechanical and microbial damage without using any toxic compounds.

Place, publisher, year, edition, pages
Springer Netherlands, 2018
Keywords
Antibacterial, Antifungal, Cellulosic, Chitosan, Citric acid, Insulation, Packaging, Polyvinylamine, Wet-stable
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-227639 (URN)10.1007/s10570-018-1738-y (DOI)000428925300032 ()2-s2.0-85042912355 (Scopus ID)
Note

QC 20180509

Available from: 2018-05-09 Created: 2018-05-09 Last updated: 2018-11-12Bibliographically approved
4. Cellulose fiber based fungal and water resistant insulation materials
Open this publication in new window or tab >>Cellulose fiber based fungal and water resistant insulation materials
2017 (English)In: International Journal of the Biology, Chemistry, Physics, and Technology of Wood, E-ISSN 1437-434XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

The development of thermal insulation materials from sustainable, natural fibrous materials is desirable.In the present study, cellulose fiber based insulation foams made of bleached chemi thermo mechanical pulp(CTMP) have been investigated. To improve water resistance, the foams were impregnated with hydrophobic extractives from the outer bark of birch (Betula verrucosa)and dried. The surface morphology of the foams and the distribution of the deposited particles from the extractives were observed by scanning electron microscopy (SEM).The modified foams showed improved water resistance, as they did not disintegrate after immersion in water for7 days, whereas the unmodified foam did. Compared to the unmodified foam, the modified foams absorbed 50%less moisture within 24 h. The modification had no negative effects on the thermal insulation properties, fungal resistance or compressive strength of the foams. The proposed approach is simple and can be easily integrated into plants working based on the biorefinery concept.

Place, publisher, year, edition, pages
Berlin, Germany: Walter de Gruyter, 2017
Keywords
biorefinery; birch bark; cellulose; fungal resistance; insulation; water resistance
National Category
Wood Science Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-205367 (URN)10.1515/hf-2016-0162 (DOI)000404721500013 ()2-s2.0-85023159213 (Scopus ID)
Projects
Energy-efficient cellulosic insulation products/panels for green building solutions
Funder
Swedish Research Council Formas
Note

QC 20170424

Available from: 2017-04-14 Created: 2017-04-14 Last updated: 2018-11-12Bibliographically approved

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