Investigation and Characterization of Synthesis Conditions on Sucrose-ammonium Dihydrogen Phosphate (SADP) Adhesive: Bond Performance and Chemical Transformation

Fully Bio-Based Adhesive from Tannin and Sucrose for Plywood Manufacturing with High Performances

Fully bio-based adhesives are beneficial to reduce the dependence of the wood adhesive industry on synthetic resins based on petrochemical resources and enhance the market competitiveness of adhesives. A fully bio-based wood adhesive composed of tannin and sucrose was developed and successfully used in the preparation of plywood. Effects of the preparation technology on the bonding strength and water resistance of plywood were investigated, and the properties of the adhesive were analyzed by Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG) and X-ray diffraction (XRD) in this study. The results showed that: (1) Compared with other biomass adhesives, tannin-sucrose adhesive had the characteristics of high-solid content and low viscosity, which had the potential to prepare particleboard and fiberboard. (2) A proper mass ratio of tannin to sucrose was key to obtaining a tannin-sucrose adhesive with better properties. (3) The optimum preparation process of tannin-sucrose adhesive for plywood was as follows: hot-pressing temperature of 210 °C, hot-pressing time of 1.2 min/mm, m(tannin):m(sucrose) of 60:40 and adhesive loading of 160 g/m². Under these conditions, the water-resistant bonding strength of the plywood was 0.89 MPa, which met the strength requirements of the Type II standard of plywood in GB/T 17657-2013. (4) The hot-pressing temperature played a decisive role in the tannin-sucrose adhesive, and the good performance of the plywood was maintained when the temperature was 210 °C or above. Thus, the prepared tannin-sucrose adhesive had high-bonding strength, good water resistance and thermal stability.

Fabrication of superhydrophobic Enteromorpha-derived carbon aerogels via NH4H2PO4 modification for multi-behavioral oil/water separation

Hydrophobic and oleophilic biomass-based block materials are considered to be highly promising candidates used for oil/water separation. However, the crucial hydrophobic modification process often involves various toxic and hazardous organic substances or requires high energy inputs. Inspired by the flame retardant principle of phosphorus-containing flame retardants, herein, an Enteromorpha-derived carbon (ADP-EP) aerogel with a water contact angle of 144.2° was prepared by successive freeze-shaping, freeze-drying and low-temperature carbonization treatment (300 °C), using NH₄H₂PO₄ (ADP) as a modifier. The results demonstrated that the introduction of NH₄H₂PO₄ could largely facilitate the removal of oxygenated groups from the pristine EP aerogels and enhance their surface roughness, thereby achieving surface hydrophobic modification. Featuring intrinsic low density, rich porosity and strong lipophilicity, the as-fabricated ADP-EP aerogels exhibited exceptional performance in both oil spill adsorption (~140 g/g) and water-in-oil emulsion separation. Moreover, the good reusability for oil uptake was also realized thanks to its robust mechanical compressibility and thermal stability. This work provides a facile, economical and eco-friendly route to obtain a desirable hydrophobic/oleophilic surface.

Insight in the Recent Application of Polyphenols From Biomass

Biomass polyphenols are bio-active macromolecules with distinct chemical structures in a variety of biomass. In recent years, the study of biomass polyphenols and their application in food and medicine fields has become a research hotspot, which predominantly focuses on the preparation, purification, structural identifications, and measurements of biological activities. Many studies describe methodologies for extraction and application of polyphenols, but comprehensive work to review its physiological activities like drugs and health products are lacking. This paper comprehensively unlocks the bioactivities of antioxidant, antibacterial, antitumor, anticancer, neuroprotection, control of blood sugar, regulation of blood fat, and promotion of gastrointestinal health functions of polyphenols from different biomass sources. This review will serve as an illuminating resource for the global scientific community, especially for those who are actively working to promote the advances of the polyphenols research field.

Extraction and Application of Natural Rutin From Sophora japonica to Prepare the Novel Fluorescent Sensor for Detection of Copper Ions

Rutin (R), a representative flavonoid found in various biomasses, can be used to prepare different fluorescent sensors for environmental, biological and medical fields. In this work, the natural R in Sophora japonica was extracted and purified to prepare fluorescent-responding sensor systems intended to recognize copper ions with both strong selectivity as well as appropriate sensitivity. Results showed that neat R had no obvious fluorescent emission peak in PBS buffer solution. However, when R and (2-hydroxypropyl)-β-cyclodextrin (CD) were introduced within buffer solution, fluorescent emission intensity was significantly increased due to the resultant R-CD inclusion complex. In addition, the formed R-CD inclusion complex was shown to behave as the aforementioned fluorescent sensor for copper ions through a mechanism of quenched fluorescent emission intensity when R-CD became bound with copper ions. The binding constant value for R-CD with copper ions was 1.33 × 10⁶, allowing for quantification of copper ions between the concentration range of 1.0 × 10^–7–4.2 × 10^–6mol⋅L^–1. Furthermore, the minimum detection limit was found to be 3.5 × 10^–8mol⋅L^–1. This work showed the prepared R-CD inclusion complex was both highly selective and strongly sensitive toward copper ions, indicating that this system could be applied into various fields where copper ions are of concern.

Insight into understanding the performance of deep eutectic solvent pretreatment on improving enzymatic digestibility of bamboo residues

Deep eutectic solvent (DES) is a promising pretreatment for improving enzymatic digestibility of lignocellulosic material by altering the physicochemical properties. However, few work has been done to quantitatively analysis the physicochemical properties changes of lignocellulosic material with enzymatic digestibility. In this work, DES pretreatment with different molar ratios of choline chloride/lactic acid was carried out on bamboo residues and respective enzymatic digestibility was investigated and linearly fitted with corresponding physicochemical features changes of the pretreated bamboo residues. Results showed that enzymatic digestibility of DES-pretreated bamboo residues was enhanced with the increasing molar ratio of choline chloride/lactic acid, which was due to DES pretreatment's ability to remove lignin and xylan, reduce the degree of polymerization of cellulose, enhance the crystallite size of cellulose, and improve cellulose accessibility. Several compelling linear correlations (R2 = 0.6-0.9) were observable between enzymatic digestibility and these changes of physicochemical properties, demonstrating how DES pretreatment improve the enzymatic digestibility.

Effect of Coating Process on Performance of Reversible Thermochromic Waterborne Coatings for Chinese Fir

The effect of the coating process on the properties of reversible thermochromic waterborne coating on the surface of Chinese fir was examined. The results demonstrated that the most critical process parameter affecting the color difference and gloss of the coating was the way of adding thermochromic ink. The coating process had little influence on the adhesion, impact resistance adding, liquid resistance, and original properties of the coating. There was no obvious gloss variation in the coating under different coating processes. For the (3+3) layered coatings, when the thermochromic ink was added to the topcoats, the discoloration performance was the most obvious and the comprehensive performance of coating was better. Meanwhile, the gloss was 55.6%, the adhesion grade was grade 0, the impact resistance was 5.0 kg·cm, the liquid resistance grade of the coating to sodium chloride, ethanol and detergent was grade 1, and the liquid resistance grade to red ink was grade 3. The discoloration performance of the coating was stable under the conditions of aging and time change. This study provides new insight into preparing thermochromic intelligent waterborne wood coatings with potential practical applications on Chinese fir wood surfaces, and also lays a foundation for its application in furniture engineering.

Investigation of Synthesis Mechanism, Optimal Hot-Pressing Conditions, and Curing Behavior of Sucrose and Ammonium Dihydrogen Phosphate Adhesive

In this study, a further investigation was carried out on the synthesis mechanism, optimal manufacturing conditions, and curing behavior of a sucrose-ammonium dihydrogen phosphate (SADP) adhesive. The results of ¹³C nuclear magnetic resonance (NMR) spectroscopy confirmed that SADP was composed of 5-hydroxymethylfurfural (5-HMF), deoxyfructosazine (DOF), amino compounds, Schiff base, monosaccharides, and oligosaccharide. The optimal hot-pressing conditions were a hot-pressing temperature of 170 °C, a hot-pressing time of 7 min, and a spread rate of 120 g/m². The wet shear strength of plywood bonded at optimal manufacturing conditions met the requirements of China National Standard (GB/T 9846-2015). Thermal analysis and insoluble mass proportion measurements showed that the main curing behavior of the SADP adhesive occurred at curing temperatures higher than 145 °C, and more than 50% insoluble mass was formed when the heating time was longer than 5 min. Fourier-transform infrared spectroscopy (FT-IR) indicated that cross-linking of the cured adhesive was promoted by prolonging the heating time. In addition, pyrolysis gas chromatography and mass spectrometry (Py-GC/MS) confirmed that the cured SADP adhesive was composed of furan and nitrogen-containing compounds.