| 1. |
- Budnyak, Tetyana, et al.
(author)
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LignoPhot : Conversion of hydrolysis lignin into the photoactive hybrid lignin/Bi4O5Br2/BiOBr composite for simultaneous dyes oxidation and Co2+ and Ni2+ recycling
- 2021
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In: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 279
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Journal article (peer-reviewed)abstract
- Valorization of lignin is still an open question and lignin has therefore remained an underutilized biomaterial. This situation is even more pronounced for hydrolysis lignin, which is characterized by a highly condensed and excessively cross-linked structure. We demonstrate the synthesis of photoactive lignin/Bi4O5Br2/BiOBr bio-inorganic composites consisting of a lignin substrate that is coated by semiconducting nanosheets. The XPS analysis reveals that growing these nanosheets on lignin instead on cellulose prevents the formation of Bi5+ ions at the surface region, yielding thus a modified hetero-junction Bi4O5Br2/BiOBr. The material contains 18.9% of Bi4O5Br2/BiOBr and is effective for the photocatalytic degradation of cationic methylene blue (MB) and zwitterionic rhodamine B (RhB) dyes under light irradiation. Lignin/Bi4O5Br2/BiOBr decreases the dye concentration from 80 mg L-1 to 12.3 mg L-1 for RhB (85%) and from 80 mg L-1 to 4.4 mg L-1 for MB (95%). Complementary to the dye degradation, the lignin as a main component of the composite, was found to be efficient and rapid biosorbent for nickel, lead, and cobalt ions. The low cost, stability and ability to simultaneously photo-oxidize organic dyes and adsorb metal ions, make the photoactive lignin/Bi4O5Br2/BiOBr composite a prospective material for textile wastewaters remediation and metal ions recycling.
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| 2. |
- Budnyak, Tetyana M., et al.
(author)
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Electrostatic Deposition of the Oxidized Kraft Lignin onto the Surface of Aminosilicas : Thermal and Structural Characteristics of Hybrid Materials
- 2019
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:27, s. 22530-22539
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Journal article (peer-reviewed)abstract
- In recent years, functional polymeric compounds have been widely used to modify the silica surface, which allows one to obtain the corresponding organomineral composites for broad application prospects. In this case, lignin-a cross-linked polyphenolic macromolecule-is of great interest according to its valuable properties and possible surplus as a by-product of pulp and paper industry and various biorefinery processes. Hybrid materials based on kraft softwood lignin and silica were obtained via the electrostatic attraction of oxidized lignin to the aminosilica surface with different porosities, which were prepared by the amination of the commercial silica gel with an average pore diameter of 6 nm, and the silica prepared in the lab with the oxidized kraft lignin and lignin-silica samples with an average pore diameter of 38 nm was investigated by physicochemical methods: two-dimensional nuclear magnetic resonance (NMR), P-31 NMR, Fourier transform infrared spectroscopy, thermogravimetric analysis in nitrogen and air atmosphere, scanning electron microscopy, and adsorption methods. After oxidation, the content of carboxylic groups almost doubled in the oxidized lignin, compared to that in the native one (0.74 mmol/g against 0.44 mmol/g, respectively). The lignin content was deposited onto the surface of aminosilica, depending on the porosity of the silica material and on the content of amino groups on its surface, giving lignin-aminosilica with 20% higher lignin content than the lignin-aminosilica gel. Both types of lignin-silica composites demonstrate a high sorptive capacity toward crystal violet dye. The suggested approach is an easy and low-cost way of synthesis of lignin-silica composites with unique properties. Such composites have a great potential for use as adsorbents in wastewater treatment processes.
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| 3. |
- Budnyak, Tetyana M., et al.
(author)
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Membrane-Filtered Kraft Lignin-Silica Hybrids as Bio-Based Sorbents for Cobalt(II) Ion Recycling
- 2020
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:19, s. 10847-10856
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Journal article (peer-reviewed)abstract
- Efficient and sustainable recycling of cobalt(II) is of increasing importance to support technological development in energy storage and electric vehicle industries. A composite material based on membrane-filtered lignin deposited on nanoporous silica microparticles was found to be an effective and sustainable sorbent for cobalt(II) removal. This bio-based sorbent exhibited a high sorption capacity, fast kinetics toward cobalt(II) adsorption, and good reusability. The adsorption capacity was 18 mg Co(II) per gram of dry adsorbent at room temperature (22 degrees C) at near-neutral pH, three times higher than that of the summarized capacity of lignin or silica starting materials. The kinetics study showed that 90 min is sufficient for effective cobalt(II) extraction by the composite sorbent. The pseudo-second-order kinetics and Freundlich isotherm models fitted well with experimentally obtained data and confirmed heterogeneity of adsorption sites. The promising potential of the lignin-silica composites for industrial applications in the cobalt recovering process was confirmed by high values of desorption in mildly acidic solutions.
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| 4. |
- Budnyak, Tetyana M., et al.
(author)
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Methylene Blue dye sorption by hybrid materials from technical lignins
- 2018
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In: Journal of Environmental Chemical Engineering. - : Elsevier. - 2213-3437. ; 6:4, s. 4997-5007
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Journal article (peer-reviewed)abstract
- New hybrid sorbents were synthesized from technical lignins and silica and were applied for the removal of Methylene Blue dye (MB) from aqueous solution. Kraft softwood lignins from LignoBoost (LBL) and CleanFlowBlack (CFBL) processes were used to understand the influence of molecular weight and functionality of initial lignins on the properties of the final hybrids. The synthesized materials were applied as adsorbents for the removal of MB from aqueous solutions. The effects of parameters such as contact time, initial concentration of dye and initial pH on the adsorption capacity were evaluated. The hybrids exhibited higher adsorption capacity than the initial macromolecules of lignin with respect to MB. The hybrid based on CFBL exhibited an adsorption capacity of 60 mg/g; this value was 30% higher than the capacity of the hybrid based on LBL, which was 41.6 mg/g. Lignin hybrid materials extract 80-99% of the dye in a pH range from 3 to 10. The equilibrium and kinetic characteristics of MB uptake by the hybrids followed the Langmuir isotherm model and pseudosecond-order model, rather than the Freundlich and Temkin models, the pseudo-first-order or the intraparticle diffusion model. The attachment of the dye to the hybrid surface was confirmed via FE-SEM and FTIR spectroscopy. The mechanism for MB adsorption was proposed. Due to the high values of regeneration efficiency of the surface of both lignin-silica hybrid materials in 0.1 M HCl (up to 75%) and ethanol (99%), they could be applied as effective sorbents in industrial wastewater treatment processes.
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| 5. |
- Dogaris, Ioannis, et al.
(author)
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Polyelectrolyte complexes based on a novel and sustainable hemicellulose-rich lignosulphonate for drug delivery applications
- 2024
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In: Drug Delivery and Translational Research. - 2190-393X .- 2190-3948.
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Journal article (peer-reviewed)abstract
- Polyelectrolyte complexes (PECs) are polymeric structures formed by the self-assembly of oppositely charged polymers. Novel biomaterials based on PECs are currently under investigation as drug delivery systems, among other applications. This strategy leverages the ability of PECs to entrap drugs under mild conditions and control their release. In this study, we combined a novel and sustainably produced hemicellulose-rich lignosulphonate polymer (EH, negatively charged) with polyethyleneimine (PEI) or chitosan (CH, positively charged) and agar for the development of drug-releasing PECs. A preliminary screening demonstrated the effect of several parameters (polyelectrolyte ratio, temperature, and type of polycation) on PECs formation. From this, selected formulations were further characterized in terms of thermal properties, surface morphology at the microscale, stability, and ability to load and release methylene blue (MB) as a model drug. EH/PEI complexes had a more pronounced gel-like behaviour compared to the EH/CH complexes. Differential scanning calorimetry (DSC) results supported the establishment of polymeric interactions during complexation. Overall, PECs' stability was positively affected by low pH, ratios close to 1:1, and the addition of agar. PECs with higher EH content showed a higher MB loading, likely promoted by stronger electrostatic interactions. The EH/CH formulation enriched with agar showed the best sustained release profile of MB during the first 30 h in a pH-dependent environment simulating the gastrointestinal tract. Overall, we defined the conditions to formulate novel PECs based on a sustainable hemicellulose-rich lignosulphonate for potential applications in drug delivery, which promotes the valuable synergy between sustainability and the biomedical field.
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| 6. |
- Esakkimuthu, Esakkiammal Sudha, et al.
(author)
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Multifunctional lignin-poly (lactic acid) biocomposites for packaging applications
- 2022
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In: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media SA. - 2296-4185. ; 10
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Journal article (peer-reviewed)abstract
- Lignin is the most abundant aromatic biopolymer with many promising features but also shortcomings as a filler in polymer blends. The main objective of this work was to improve the processability and compatibility of lignin with poly (lactic acid) (PLA) through etherification of lignin. Commercial kraft lignin (KL) and oxypropylated kraft lignin (OPKL) were blended with PLA at different weight percentages (1, 5, 10, 20, and 40%) followed by injection molding. Low lignin contents between 1 and 10% generally had a favorable impact on mechanical strength and moduli as well as functional properties of the PLA-based composites. Unmodified lignin with free phenolic hydroxyl groups rendered the composites with antioxidant activity, as measured by radical scavenging and lipid peroxidation tests. Incorporating 5–10% of KL or OPKL improved the thermal stability of the composites within the 300–350°C region. DSC analysis showed that the glass transition temperature values were systematically decreased upon addition of KL and OPKL into PLA polymer. However, low lignin contents of 1 and 5% decreased the cold crystallization temperature of PLA. The composites of KL and OPKL with PLA exhibited good stabilities in the migration test, with values of 17 mg kg−1 and 23 mg kg−1 even at higher lignin content 40%, i.e., well below the limit defined in a European standard (60 mg kg−1). These results suggest oxypropylated lignin as a functional filler in PLA for safe and functional food packaging and antioxidant applications.
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| 7. |
- Giummarella, Nicola, et al.
(author)
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New Structures in Eucalyptus Kraft Lignin with Complex Mechanistic Implications
- 2020
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In: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 8:29, s. 10983-10994
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Journal article (peer-reviewed)abstract
- Recent years have seen the development of technically feasible methods to retrieve kraft lignin from the black liquor as solids or liquids. This opens enormous opportunities to position kraft lignin as a renewable aromatic polymer precursor. However, the heterogeneity of kraft lignin is one major hurdle and manifests in its largely unknown molecular structure, which in recent years has drawn further attention. In this context, we herein studied the detailed structure of Eucalyptus kraft lignin with special emphasis on identifying new linkages signatory to retro-aldol and subsequent radical coupling reactions, which we recently showed to be a key reaction sequence contributing to the structure of spruce kraft lignin. In combination with novel model studies, we unequivocally identified new structures by advanced 2D NMR characterization of Eucalyptus kraft lignin, i.e., 3,5-tetramethoxy-para-diphenol, 3-dimethoxy-para-diphenol and small amounts of 3,5-dimethoxy-benzoquinone. These structures are signatory to retro-aldol followed by radical coupling reactions. The two diphenol structures were further quantified by 1D C-13 NMR at 9% of the interunit linkages in Eucalyptus kraft lignin, which was comparable to the amounts we previously identified in softwood kraft lignin (10%). Radical condensation of kraft lignin to form carbon-carbon bonds therefore does not discriminate between syringyl lignin and guaiacyl lignin units. We rationalize such indiscrimination to emanate from possibilities for radical couplings at unsubstituted C-1 in the formed syringol and guaiacol lignin as a result of the retro-aldol reaction.
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| 8. |
- Goliszek, Marta, et al.
(author)
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Synthesis of lignin-containing polymer hydrogels with tunable properties and their application in sorption of nickel(II) ions
- 2021
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In: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 164
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Journal article (peer-reviewed)abstract
- Polymer hydrogels with lignin in the form of microspheres have been synthesized and their properties were evaluated. Prior to the polymerization, hardwood lignin (Eucalyptus grandis) was modified with methacryloyl chloride, and unmodified lignin (L-N) and its methacrylic derivative (L-M) were polymerized with 2-hydroxyethyl methacrylate (HEMA) and divinylbenzene (DVB) in different ratios using suspension polymerization. The presence of characteristic functional groups in the synthesized hydrogels was confirmed using attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FT-IR) and NMR. Thermal properties were determined by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Swelling was studied in common organic solvents and distilled water. The shapes of the hydrogels were confirmed by scanning electron microscopy (SEM) and optical microscopy. The addition of lignin significantly increased the swelling ability of the hydrogels in water and acetone. The incorporation of methacrylated lignin into the structure of HEMA-DVB hydrogels increased their sorption of Ni(II) ions by 30 % showing that these hydrogels are a promising material for use in nickel removal and recovery, as well as contributing to a better utilization of lignin.
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| 9. |
- Moreno, Adrian, et al.
(author)
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Urushi as a Green Component for Thermally Curable Colloidal Lignin Particles and Hydrophobic Coatings
- 2023
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In: ACS Macro Letters. - 2161-1653. ; 12:6, s. 759-766
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Journal article (peer-reviewed)abstract
- Colloidal lignin nanoparticles are promising buildingblocks forsustainable functional materials. However, their instability in organicsolvents and aqueous alkali limits their applicability. Current stabilizationmethods require nonrenewable and toxic reagents or tedious workupprocedures. Here we show a method to prepare hybrid nanoparticlesusing only natural components. Urushi, a form of black oriental lacquer,and lignin are coaggregated to form hybrid particles, with Urushiacting as a sustainable component that stabilizes the particles viahydration barrier effect and thermally triggered internal cross-linking.The weight fractions of the two components can be adjusted to achievethe desired level of stabilization. Hybrid particles with Urushi content>25 wt % undergo interparticle cross-linking that produces multifunctionalhydrophobic protective coatings that improve the water resistanceof wood. This approach provides a sustainable and efficient methodfor stabilizing lignin nanoparticles and opens up neoteric possibilitiesfor the development of lignin-based advanced functional materials.
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| 10. |
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