Anionic biopolymer derivatives and their performance in flocculation

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dc.contributor Helsingin yliopisto, Matemaattis-luonnontieteellinen tiedekunta, Kemian laitos fi
dc.contributor University of Helsinki, Faculty of Science, Department of Chemistry en
dc.contributor Helsingfors universitet, Matematisk-naturvetenskapliga fakulteten, Kemiska institutionen sv
dc.contributor.author Peltokoski, Brita
dc.date.issued 2018
dc.identifier.uri URN:NBN:fi-fe201804208681
dc.identifier.uri http://hdl.handle.net/10138/273580
dc.description.abstract The aim of the thesis is to identify and test anionic biopolymer derivatives in flocculation application. Several potential polysaccharides are listed in literature, but chemical modification is often needed to improve their performance in the selected application. Totally 28 polysaccharide derivatives were received from varying suppliers and screened by rheology and charge. The most potential biobased products in addition to synthetic polyacrylamide references were purified by dialysis and characterized by charge density, apparent viscosity in water and brine and intrinsic viscosity in brine. Xanthan gum, carboxymethyl cellulose and guar gum appeared to have the best combination of high viscosity and charge density. Xanthan gum revealed exceptional behavior in brine as its viscosity increases upon salt addition due to helix formation. This phenomenon opens numerous possibilities in brine applications. In the application testing 9 biopolymer derivatives representing 6 different types of polysaccharides in addition to two reference polyacrylamides were studied by flocculating bentonite. The evolution of flocs was monitored online with focused beam reflectance measurement. Xanthan gum, carboxymethyl cellulose and guar gum have the best performance in flocculation as expected based on the characterization results supporting the statement that size and charge are key parameters in flocculation performance. The biobased products fall behind in flocculation efficiency compared to polyacrylamides, but their performance can be improved by chemical modification. A quick thermal stability screening was also performed, and xanthan gum appeared to be even more thermally stable compared to the polyacrylamide reference in the selected environment. As a conclusion it is justified to claim that in the future the biobased products have a great potential to offer alternative solutions in the applications where synthetic fossil-based polymers are currently used. The recommended path forward is to find suitable modification mechanisms to increase the flocculation performance of xanthan gum, carboxymethyl cellulose and guar gum. Nucleophilic reaction of the saccharide oxygen is a typical example of chain modification for polysaccharide chemistry. Based on the results presented in this thesis, the future of biobased products from renewable resources looks promising. en
dc.language.iso eng
dc.publisher Helsingin yliopisto fi
dc.publisher University of Helsinki en
dc.publisher Helsingfors universitet sv
dc.title Anionic biopolymer derivatives and their performance in flocculation en
dc.type.ontasot pro gradu -tutkielmat fi
dc.type.ontasot master's thesis en
dc.type.ontasot pro gradu-avhandlingar sv
dc.subject.discipline Polymer Chemistry en
dc.subject.discipline Polymeerikemia fi
dc.subject.discipline Polymerkemi sv
dct.identifier.urn URN:NBN:fi-fe201804208681

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