Browsing by Author "Orzan, Eliott"

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Cellulose modified to host functionalities via facile cation exchange approach
(2024-05-15) Spiliopoulos, Panagiotis; Navarro, Saül Llàcer; Orzan, Eliott; Ghanbari, Reza; Pietschnig, Rudolf; Stilianu, Clemens; Spirk, Stefan; Schaefer, Andreas; Kádár, Roland; Nypelö, Tiina
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Properties of cellulose are typically functionalized by organic chemistry means. We progress an alternative facile way to functionalize cellulose by functional group counter-cation exchange. While ion-exchange is established for cellulose, it is far from exploited and understood beyond the most common cation, sodium. We build on our work that established the cation exchange for go-to alkali metal cations. We expand and further demonstrate the introduction of functional cations, namely, lanthanides. We show that cellulose nanocrystals (CNCs) carrying sulfate-half ester groups can acquire properties through the counter-cation exchange. Trivalent lanthanide cations europium (Eu3+), dysprosium (Dy3+) and gadolinium (Gd3+) were employed. The respective ions showed distinct differences in their ability of being coordinated by the sulfate groups; with Eu3+ fully saturating the sulfate groups while for Gd3+ and Dy3+, values of 82 and 41 % were determined by compositional analysis. CNCs functionalized with Eu3+ displayed red emission, those containing Dy3+ exhibited no optical functionality, while those with Gd3+ revealed significantly altered magnetic relaxation times. Using cation exchange to alter cellulose properties in various ways is a tremendous opportunity for modification of the abundant cellulose raw materials for a renewable future.
Role of intrinsic and extrinsic xylan in softwood kraft pulp fiber networks
(2024-01-01) Schaubeder, Jana B.; Spirk, Stefan; Fliri, Lukas; Orzan, Eliott; Biegler, Veronika; Palasingh, Chonnipa; Selinger, Julian; Bakhshi, Adelheid; Bauer, Wolfgang; Hirn, Ulrich; Nypelö, Tiina
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Xylan is primarily found in the secondary cell wall of plants providing strength and integrity. To take advantage of the reinforcing effect of xylan in papermaking, it is crucial to understand its role in pulp fibers, as it undergoes substantial changes during pulping. However, the contributions of xylan that is added afterwards (extrinsic) and xylan present after pulping (intrinsic) remain largely unexplored. Here, we partially degraded xylan from refined bleached softwood kraft pulp (BSKP) and adsorbed xylan onto BSKP. Enzymatic degradation of 1 % xylan resulted in an open hand sheet structure, while adsorption of 3 % xylan created a denser fiber network. The mechanical properties improved with adsorbed xylan, but decreased more significantly after enzymatic treatment. We propose that the enhancement in mechanical properties by adsorbed extrinsic xylan is due to increased fiber-fiber bonds and sheet density, while the deterioration in mechanical properties of the enzyme treated pulp is caused by the opposite effect. These findings suggest that xylan is decisive for fiber network strength. However, intrinsic xylan is more critical, and the same properties cannot be achieved by readsorbing xylan onto the fibers. Therefore, pulping parameters should be selected to preserve intrinsic xylan within the fibers to maintain paper strength.