1. Photochemical behavior of colloidal lignin particles under controlled UV exposure : balancing self-stabilization and degradationJulia Tomasich, Rene Alexander Herrera Diaz, Anna Malgorzata Sandak, Michael Harasek, Stefan Beisl, Oihana Gordobil, 2025, original scientific article Abstract: Colloidal Lignin Particles (CLPs), with their polyphenolic structure, are promising sustainable alternatives to chemical UV filters. This study investigates the photochemical behavior of CLPs under ultraviolet irradiation synthetized from five different technical raw lignins (Alkali, Organosolv, two Enzymatic Hydrolyzed and Softwood Kraft Lignin) via solvent-shift procedure. The suspensions were irradiated using a self-developed UV-pen set-up and a commercially available UV chamber, enabling controlled UV exposure over time. Variations in the physicochemical properties of irradiated colloidal lignin particles were characterized by Multi-Angle Dynamic Light Scattering (MADLS), Fourier Transform Infrared Spectroscopy (FTIR) coupled with chemometrics, UV–Vis spectroscopy, and High-Performance Size Exclusion Chromatography (HP-SEC). CLPs exhibited comparable responses after 14 days of UV exposure, with alterations in particle chemistry, particularly in the formation of new functional groups and molecular rearrangement. Moreover, the photochemical stability of CLPs was found to be highly dependent on both their concentration and the nature of the dispersion medium (aqueous, hexane-based, and solid-state). At higher concentrations (1.8 mg/mL), CLPs demonstrated effective self-stabilization, while lower concentrations led to rapid degradation, resulting in the disappearance of particles and the formation of low-molecular-weight fragments. Additionally, Minimal photochemical changes were observed in non-aqueous or solid-state environments due to restricted molecular mobility. These findings provide valuable insights into the degradation pathways and stability across different environmental contexts, which can contribute to understanding the potential environmental impact of CLPs in aquatic ecosystems.
Keywords: biobased materials, lignin colloidal particles, photodegradation, UV-irradiation, spectroscopy
Published in RUP: 09.09.2025; Views: 428; Downloads: 4
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2. Hybrid approach for wood modification : characterization and evaluation of weathering resistance of coatings on acetylated woodAnna Malgorzata Sandak, Edit Földvári-Nagy, Faksawat Poohphajai, Rene Alexander Herrera Diaz, Oihana Gordobil, Nežka Sajinčič, Veerapandian Ponnuchamy, Jakub Michal Sandak, 2021, original scientific article Keywords: wood modification, natural weathering, acetylation, coatings, service life performance, aesthetic
Published in RUP: 04.06.2021; Views: 2868; Downloads: 32
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3. Characterization of heritage objects with NIR hyperspectral imagingJakub Michal Sandak, Anna Malgorzata Sandak, Lea Legan, Klara Retko, Maša Kavčič, Janez Kosel, Faksawat Poohphajai, Rene Alexander Herrera Diaz, Veerapandian Ponnuchamy, Nežka Sajinčič, Črtomir Tavzes, Polonca Ropret, 2021, published scientific conference contribution abstract Keywords: hyperspectral imaging, cultural heritage, painted beehive panels
Published in RUP: 06.05.2021; Views: 3797; Downloads: 11
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5. Impact of drying process on kraft lignin : ligninwater interaction mechanism study by 2D NIR correlation spectroscopyOihana Gordobil, Rene Alexander Herrera Diaz, Faksawat Poohphajai, Jakub Michal Sandak, Anna Malgorzata Sandak, 2021, original scientific article Keywords: hardwood kraft lignin, drying temperature, DVS, NIR spectroscopy, 2D-COS
Published in RUP: 06.05.2021; Views: 3591; Downloads: 11
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6. Nondestructive evaluation of heritage object coatings with four hyperspectral imaging systemsJakub Michal Sandak, Anna Malgorzata Sandak, Lea Legan, Klara Retko, Maša Kavčič, Janez Kosel, Faksawat Poohphajai, Rene Alexander Herrera Diaz, Veerapandian Ponnuchamy, Nežka Sajinčič, Oihana Gordobil, Črtomir Tavzes, Polonca Ropret, 2021, original scientific article Keywords: hyperspectral imaging, cultural heritage, nondestructive testing, surface characterisation, painted beehive panels
Published in RUP: 06.05.2021; Views: 2516; Downloads: 49
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7. Fractionation of lignin using organic solvents : a combined experimental and theoretical studyVeerapandian Ponnuchamy, Oihana Gordobil, Rene Alexander Herrera Diaz, Anna Malgorzata Sandak, Jakub Michal Sandak, 2020, original scientific article Keywords: hardwood kraft lignin, fractionation, chemometrics, density functional theory, hydrogen bonds, noncovalent interactions
Published in RUP: 02.12.2020; Views: 3125; Downloads: 36
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8. Hydrophobization and photo-stabilization of radiata pinewood : the effect of the esterification on thermal and mechanical propertiesRene Alexander Herrera Diaz, Oihana Gordobil, Pedro L. Hoyos-Martinez, Anna Malgorzata Sandak, Jalel Labidi, 2020, original scientific article Keywords: wood esterification, fatty acids, hydrophobicity, photo-stability, mechanical properties, thermal oxidation
Published in RUP: 02.12.2020; Views: 3737; Downloads: 36
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10. Mapping of moisture on wood surface with hyperspectral imagingJakub Michal Sandak, Rene Alexander Herrera Diaz, Daniel Chuchała, Faksawat Poohphajai, Veerapandian Ponnuchamy, Nežka Sajinčič, Piotr Taubes, Kazimierz A. Orłowski, Anna Malgorzata Sandak, 2020, published scientific conference contribution abstract Published in RUP: 07.08.2020; Views: 3276; Downloads: 107
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