Doctoral theses of the School of Chemical Engineering are available in the open access repository maintained by Aalto, Aaltodoc.
Public defence in Bioproduct Technology, M.Sc. Daryna Diment
Advances in lignin engineering by developing structure–property–performance correlation to enable bio-based alternatives to fossil materials
Public defence from the Aalto University School of Chemical Engineering, Department of Bioproducts and Biosystems
Public defence from the Aalto University School of Chemical Engineering, Department of Bioproducts and Biosystems
Title of the thesis:
Thesis defender: Daryna Diment
Opponent: Prof. Yuki Tobimatsu, Kyoto University, Japan
Custos: Prof. Michael Hummel, Aalto University School of Chemical Engineering
The global push toward a green transition has intensified interest in lignin as a bio-based alternative to fossil-derived materials. Lignin is an abundant, non-toxic, biodegradable, and economically attractive biopolymer with rich structural functionality. However, its complex and heterogeneous structure has significantly limited its widespread utilization in high-value applications. This doctoral thesis addresses these challenges through lignin engineering. This approach enables the targeted design of lignin and lignin-carbohydrate complexes (LCCs) tailored for specific applications. The approach is based on the structure–property–performance correlation that link lignin structure to its resulting properties and performance. By providing a systematic framework to correlate lignin structure with application-relevant behavior, this research supports the development of tailor-made lignin as a viable, sustainable alternative to conventional fossil-based materials. Lignin engineering involves selective chemical modification of targeted functional groups while keeping others constant, followed by comprehensive property and performance evaluation. That said, it allowed to investigate how specific functional groups affect the physicochemical behavior of lignin and its performance in methylene blue adsorption. At the same time, tailor-made LCCs with superior properties were produced through optimized biorefineries as optimal processing conditions were identified, achieving LCC yields of 8–15 wt% and carbohydrate contents up to 60/100 Ar. Additionally, lignin and LCCs demonstrated potent antioxidant properties which were employed in a fully bio-based lignocellulosic UV-protective films that block up to 92% of UV rays when lignin is incorporated in 1.5 wt%. Additionally, a novel fast screening method for the determination of antioxidant properties of lignin has been developed by evaluating the impact of the solvent, time, and the type of substrate on the antioxidant activity using a well-established 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. This work highlights the versatility of lignin and its great potential for iincorporation into applications where strong UV and antioxidant protection are required without posing any environmental concern. As a consolidated outcome, these findings will advance lignin engineering and accelerate its wider utilization in various industrial applications catalyzing the transition toward sustainable solutions.
Key words: lignin modification, AqSO biorefinery, lignin-carbohydrate complexes, NMR spectroscopy, antioxidant activity, glass transition temperature, UV-blocking efficiency
Thesis available for public display 7 days prior to the defence at .
Contact:
email address: daryna.diment@aalto.fi
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Doctoral theses of the School of Chemical Engineering
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