► Sub-/super-critical water–ethanol proved to be very effective for de-polymerization of organosolv lignin (OL). ► Ni10/AC and Ru10/γ-Al2O3 as catalysts effectively inhibited char formation, and ...increased degraded lignin (DL) yield. ► A high yield of DL (80.7%) with Mw (568g/mol) and Mn (181g/mol) was obtained at 340°C for 2h with Ni10/AC. ► OL phenol-formaldehyde resins (OLPF) and DLPF resins with OL/DL substituting up to 75% phenol were produced. ► Lignin-based PF resins have higher dry and wet tensile strength than PF resole resin when using as plywood adhesive.
The objective of this study was to produce green phenolic resins and adhesives using bio-phenolic compounds produced from lignin/forestry residuals. To produce bio-phenolic compounds, an organosolv lignin (OL) was catalytically degraded in 50/50 (v/v) water–ethanol and pure ethanol media under sub/supercritical condition in hydrogen atmosphere. Effects of lignin degradation process conditions (catalyst, temperature, type of reactor, etc.) on the yields and properties (molecular weights) of the degraded lignin (DL) products were examined in this study. The DL products were used to substitute for phenol in the synthesis of bio-phenol formaldehyde resins, denoted as degraded lignin phenol-formaldehyde (DLPF) resins, whose properties (such as viscosity, non-volatile contents, storage time, free formaldehyde contents, curing behavior, and thermal stability) were compared with pure PF resin and organosolv lignin phenol-formaldehyde (OLPF) resins. Plywood samples glued with the OLPF and DLPF adhesives with a phenol replacement ratio up to 75wt% showed higher dry and wet tensile strengths than those of PF adhesives. Although the OLPF adhesives have better bond strengths and thermal stability than DLPF adhesives, the DLPF resins have a lower free formaldehyde content and can be cured at a lower temperature.
Partitioning of trivalent actinides (An(III)) from lanthanides (Ln(III)) during Spent Nuclear Fuel (SNF) reprocessing presents a major challenge due to the exhibition of very similar chemical ...properties. Although an array of phenanthroline-based ligands have surfaced to solve this problem, the recently reported soft - hard-donor-combined N, N'-diethyl-N.N'-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) ligand has gained much attention. In this work, Et-Tol-DAPhen has been electronically modified with di and mono substitutions of phenol at the 4
th
and 5
th
positions. The structural properties and extraction abilities of these modified ligands have been studied using DFT calculations. The results reveal that the ligand (ETDP3) with diphenol substitutions at the 4
th
position has an excellent extraction capability with high selectivity toward Am(III) over Eu(III) ion. Electronic structure and bonding analyses provide insights into the nature of metal-ligand bonds in the ten coordinated ML(NO
3
)
3
complexes M = Am and Eu and convey that in all the complexes the M-O bonds are stronger than the M-N bonds. The quantum theory of atoms in molecules (QTAIM) reveals the weak C-H - O interactions in these ML(NO
3
)
3
complexes. The charge analysis explains the exceptional complexation behavior by determining the donor-acceptor interactions in the Am complexes. ΔΔG values obtained from thermodynamic analysis indicate the preferential selectivity of these ligands toward trivalent Am over Eu ions. Around 22% increased covalency is observed between M(NO
3
)
3
and L in the Am complexes compared to that of the Eu complexes. Overall, this computational study offers an understanding of how beneficial it is to have mono- and diphenol substitutions at the fourth and fifth position of the phenanthroline-based ligands for effective actinide/lanthanide separation.
Click chemistry is commonly used to prepare hydrogels, and chitosan-phenol prepared by using a Schiff base has been widely employed in the field of biomaterials. Chitosan-phenol is a derivative of ...chitosan; the phenol groups can disrupt both the inter- and intramolecular hydrogen bonds in chitosan, thereby reducing its crystallinity and improving its water solubility. In addition, chitosan-phenol exhibits various beneficial physiological functions. However, it is still unclear whether the degree of phenol substitution in the chitosan main chain affects the molecular interactions and structural properties of the self-healing hydrogels. To explore this issue, we investigated the molecular structure and network of self-healing hydrogels composed of chitosan-phenol with varying degrees of phenol substitution and dibenzaldehyde poly(ethylene oxide) (DB-PEO) using molecular dynamics simulations. We observed that when the degree of phenol substitution in the self-healing hydrogel was less than 15%, an increase in the degree of phenol substitution led to an increase in the interactions between chitosan-phenol and DB-PEO, and it enhanced the dynamic covalent bond cross-linking generated through the Schiff base reaction. However, when the degree of phenol substitution exceeded 15%, excessive phenol groups caused excessive intramolecular interactions within chitosan-phenol molecules, which reduced the binding between chitosan-phenol and DB-PEO. Our results revealed the influence of the degree of phenol substitution on the molecular structure of the self-healing hydrogels and showed an optimal degree of phenol substitution. These findings provide important insights for the future design of self-healing hydrogels based on chitosan and should help in enhancing the applicability of hydrogels in the field of biomedicine.
This article presents the results of the investigation of the properties of phenol-formaldehyde resin, obtained using the phenol-replacing fraction. A two-step method was developed for ...phenol-replacing fraction separation from liquid pyrolysis products with a yield up to 15%, and this fraction was used in the phenol-formaldehyde resin synthesis. Then, a work was conducted for the removal of neutrals from the modified phenol-formaldehyde resin with organic solvents, n-hexane and benzene. As a result, benzene was defined as a more efficient solvent because it removed more aromatics, like ethers and substituted phenols, that cannot react and worsen the glue line water resistance. Benzene dissolved 3.2% weight of the resin, and n-hexane dissolved 2.5% weight. The removal of neutrals increased the water resistance coefficient by more than 60%, so neutrals have a considerable effect on the resin properties. The results can be used for production of resin from renewable feedstock with the similar properties with the traditional resin.
