The Practical Utility of Imidazolium Hydrogen Sulfate Ionic Liquid in Fabrication of Lignin-Based Spheres: Structure Characteristic and Antibacterial Activity.

In this study, lignin-based spherical particles (Lig-IL) with the use of 1-(propoxymethyl)-1H-imidazolium hydrogen sulfate were prepared in different biopolymer and ionic liquid (IL) weight ratios. The application of IL during the preparation of spherical particles is an innovative method, which may be beneficial for further applications. The particles were obtained with the use of the soft-templating method and their chemical, structural and morphological characterization was performed. The spherical shape of products and their size (91-615 nm) was confirmed with the use of scanning electron microscopy (SEM) images and the particle size distribution results. The attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra were analyzed to identify functional groups of all precursors and produced material and it was confirmed, that all materials exhibit characteristic hydroxyl and carboxylic groups, but the presence of carbonyl group was detected. Moreover, the zeta potential analysis was performed to evaluate the electrokinetic behavior of obtained materials. It was confirmed, that all materials are colloidally stable in pH above 4. Produced lignin-based spherical particles were used for evaluation of their antibacterial properties. Particles were tested against Staphylococcus aureus (S. aureus), a gram-positive bacterium, and Escherichia coli (E. coli), a gram-negative one. It was observed, that only the material with the highest addition of IL showed the antibacterial properties against both strains. A reduction of 50% in the number of microorganisms was observed for particles with the addition of hydrogen sulfate ionic liquid in a 1:1 ratio after 1 h. However, all prepared materials exhibited the antibacterial activity against a gram-positive bacterium.

Development of functional lignin-based spherical particles for the removal of vanadium(V) from an aqueous system.

A new type of functional lignin-based spherical particles (L-CTAB) prepared with the use of hexadecyltrimethylammonium bromide (CTAB) was applied as an effective biosorbent for removing vanadium(V) ions. The porous structure, characteristic functional groups, electrokinetic stability, morphology and size of the L-CTAB particles were examined. The conditions of removal were also investigated, including pH (2-12), sorbent mass (0.1-0.5 g), concentration (10-100 mg/dm3), phase contact time (1-240 min) and temperature (293-333 K). At pH 5.0 the maximum sorption percentage (%S) of V(V) was 45%, while at pH 2.0 it was 32%. The maximum sorption capacity of V(V) for L-CTAB was found to be 10.79 mg/g. The kinetic data indicate that the sorption followed the pseudo-second-order and film diffusion models. Sorption equilibrium for V(V) ions removal by L-CTAB was reached after 60 min at the initial concentrations 10 and 50 mg/dm3. It has been shown that the adsorption of V(V) ions on the surface of L-CTAB is a heterogeneous, endothermic and spontaneous reaction, as evidenced by the calculated values of thermodynamic parameters - free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) - for the tested systems at different temperatures. HCl solutions, used as an L-CTAB regeneration agent, quantitatively eluted V(V) ions.

Lignin-Based Spherical Structures and Their Use for Improvement of Cilazapril Stability in Solid State.

Biopolymer-based spherical particles exhibit unique properties including narrow sizes and many functional groups on their surfaces. Therefore, they show great potential for application in many scientific and industrial processes. The main aim of this study was to prepare lignin-based spherical particles with the use of a cationic surfactant, hexadecyl(trimethyl)ammonium bromide (CTAB). In the first step, different preparation procedures were tested with varying parameters, including biopolymer and surfactant ratios, lignin filtration, and experimental time. The morphological and dispersion characteristics of the materials were determined to select the best samples with the most promising properties, which could then be tested for their acute toxicity. It was observed that almost all materials were characterized by spherical shapes in micro- and nanosizes. The sample with the best physicochemical properties was used for further analysis and then tested for medical applications: the improvement of the stability of a drug molecule, cilazapril (CIL). The formulated material (CIL@LC-2a 1:1 wt./wt.) exhibited outstanding properties and significantly improved the stability of cilazapril as tested in conditions of increased temperature and humidity. Lignin spherical particles may be employed as a promising material for shielding other active compounds from decomposition.

Catalyst-free activation of kraft lignin in air using hydrogen sulfate ionic liquids.

In this research we use ionic liquids in combination with mild process conditions to provide a selective increase in the content of carbonyl groups in the kraft lignin structure. Such modification can improve the properties of the pristine biopolymer. In this study, aromatic substituted ionic liquids were synthesized using [C4C1Im][HSO4] as a template structure. The substituents were intended to increase the affinity of the ionic liquid to the aromatic structure of kraft lignin, and to increase access to the oxidizing agent, which was atmospheric oxygen. [Benzyl(C2OC1)Im][HSO4] and [benzylC4Im][HSO4] activate the surface of the biopolymer more effectively than [C4C1Im][HSO4]. This was confirmed based on X-ray photoelectron spectroscopy, which showed the content of CO groups to be almost doubled compared with unmodified lignin. The analysis also revealed targeting of the hydroxyl groups of lignin to the carboxyl groups during activation in [C4C1Im][HSO4].

Development of Acidic Imidazolium Ionic Liquids for Activation of Kraft Lignin by Controlled Oxidation: Comprehensive Evaluation and Practical Utility.

A novel, eco-friendly method for the activation of lignin by controlled oxidation was studied. The results obtained for six acidic imidazolium ionic liquids containing the hydrogen sulfate anion were compared. The key goal of this research was to increase the content of carbonyl groups in the lignin structure because these may play the main role in the transport of protons and electrons in active materials for electrochemical applications. By means of a variety of analytical techniques (FTIR, 13 C CP/MAS NMR, and X-ray photoelectron spectroscopy; selected reactions to determine the presence of carbonyl groups; SEM; zeta-potential analysis; thermogravimetric analysis/differential thermogravimetric analysis; and porous structure analysis), it was determined that the product obtained after treatment with 3-cyclohexyloxymethy-1-methylimidazolium hydrogen sulfate had favorable properties, in terms of the target application. Electrochemical tests proved that the obtained materials could be used as anodes in lithium batteries. The results show that the activation of lignin with ionic liquids can increase its capacity and maintain stability.

Functional Hybrid Materials Based on Manganese Dioxide and Lignin Activated by Ionic Liquids and Their Application in the Production of Lithium Ion Batteries.

Kraft lignin (KL) was activated using selected ionic liquids (ILs). The activated form of the biopolymer, due to the presence of carbonyl groups, can be used in electrochemical tests. To increase the application potential of the system in electrochemistry, activated lignin forms were combined with manganese dioxide, and the most important physicochemical and morphological-microstructural properties of the novel, functional hybrid systems were determined using Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), scanning electron microscopy (SEM), zeta potential analysis, thermal stability (TGA/DTG) and porous structure analysis. An investigation was also made of the practical application of the hybrid materials in the production of lithium ion batteries. The capacity of the anode (MnO2/activated lignin), working at a low current regime of 50 mA·g-1, was ca. 610 mAh·g-1, while a current of 1000 mA·g-1 resulted in a capacity of 570 mAh·g-1. Superior cyclic stability and rate capability indicate that this may be a promising electrode material for use in high-performance lithium ion batteries.