Characterization of the structural and dynamic changes of cell wall obtained by ultrasound-water and ultrasound-alkali treatments

MXene-Wood Composites: A Review of Fabrication, Properties, Applications, and Future Prospects

MXene is a cationic 2D material made of transition metal carbides known for its diverse structure and multifunctionality. It faces challenges like stacking, oxidation, and weak mechanical properties that limit its use. By integrating MXene with self-supporting porous materials, it can be stabilized and converted from fragile 2D sheets to strong 3D structures. Wood, due to its natural structure and stability, is ideal for depositing MXene, which adheres to wood via adsorption, hydrogen bonding, or reactions with wood fibers. New MXene-wood composites with improved functions have been created and show great potential for interdisciplinary research. This review covers preparation methods, applications, potential development, and challenges of MXene-wood composites, aiming to provide a research framework and progressive direction for their future development.

Ultrasound-assisted deep eutectic solvent extraction of flavonol glycosides from Ginkgo biloba: Optimization of efficiency and mechanism

Ultrasound-assisted extraction (UAE) is a technique that can enhance the efficiency of the extraction of bioactive ingredients. In previous work, ginkgo flavonol glycosides (GFG) were extracted using a deep eutectic solvent (DES). To further enhance mass transfer efficiency in this work, ultrasound-assisted deep eutectic solvent (UADES) was employed for GFG extraction. The optimal extraction parameters were determined to be the ultrasonic power 320 W, extraction time 63.6 min, and extraction temperature 32.5℃. The extraction yield of GFG reached 5.60 mg/g, surpassing that achieved through DES extraction. Notably, the extraction time was drastically shortened from 11.8 h to 63.6 min. The analysis of changes in micro-morphology, crystalline structure, and cellulose content of the phytoextraction solid residue revealed that the UADES effectively disrupted the crystalline regions of lignocellulose within the cell wall, and the ultrasound enhanced the solubilization of DES to lignocellulose, thus improving the efficiency of the extraction process.

Effects of ultrasonic-alkali integrated extraction combined with Mannesi reaction on the antimicrobial properties of rice straw lignin and enhancement strategies

Lignin is one of the most abundant and underused biopolymers in nature with limited antimicrobial activities. Herein, this work aimed to enhance the antimicrobial activity of lignin extracted from waste rice straw by ultrasonic-alkali integrated extraction (USP-AT) and modify the alkali lignin through Mannich reaction to improve its antimicrobial properties. The effects of ultrasonic pretreatment (USP) time on the chemical structure, morphology, antioxidant, and antibacterial activities of lignin were studied. The results demonstrated that the total phenolic content of USP-AT lignin was higher than that of lignin extracted by alkali treatment. Moreover, the antioxidant activity of USP-AT lignin was increased by 49.69 %-69.42 %. The antibacterial activity of USP-AT lignin against Escherichia coli and Staphylococcus aureus increased by more than 40 %. However, the antibacterial capacity of USP-AT lignin is far from meeting the requirements of antibacterial food packaging. The alkali lignin was modified by Mannich reaction in order to improve its antimicrobial properties against common spoilage microorganisms or pathogenic bacteria in food and packaging. The modified USP-AT lignin exhibit remarkable antimicrobial capacities to representative bacteria, molds, and yeasts. The antifungal capacity of modified USP-AT lignin against A. niger and P. citrinum were improved by more than 40 %.

Insights into the performance and mechanism of a reinforced lignocellulosic sorbent fabricated from sawdust biomass for multi-tasking application in enrofloxacin removal and monitoring

Natural lignocellulose-based materials have numerous strengths such as abundance, cheap price and biodegradability, which indicates a brilliant prospect for environmental protection. This work aimed to design an efficient sorbent (NaSS-PSD) by pine sawdust (PSD) for the surveillance and management of enrofloxacin (ENR). In the study, sodium styrenesulfonate (NaSS) was chosen as an effective monomer to ameliorate the performance of PSD by graft copolymerization. The removal of ENR by NaSS-PSD was enhanced in comparison with the ungrafted ones under investigated conditions. Pseudo-second-order and Temkin were the best-fitted models to describe the adsorption behavior. For the first time, NaSS-PSD was employed as a novel extractant of solid-phase extraction (SPE) and dispersive solid-phase microextraction (DSPME) to develop accurate, eco-friendly and economic analytical techniques for trace ENR determination. Good linearity and reproducibility were obtained. The limits of detection were 0.41 μg/L for DSPME-HPLC-DAD technique and 0.15 μg/L for SPE-HPLC-DAD technique. These two methods exhibited satisfying practicability when applied to quantify ENR residue in real waters. The study on interfacial interaction mechanism and preferential binding sites suggested that hydrogen bond and π-π interactions took the primary responsibility. Our work provides a good perspective for tailoring natural lignocellulosic biomass to be alternative adsorbents for emerging pollutants.

Extraction of insoluble soybean fiber by alternating ultrasonic/alkali and its improved superior physicochemical and functional properties

Okara, as a by-product of soybean processing, is rich in insoluble dietary fiber (IDF), which is a carbohydrate polymer with various insoluble polysaccharides. Nowadays, the extraction of IDF with excellent functional properties has become a research hotspot. In this work, we further proposed an alternating alkali/ultrasound method for the efficient extraction of IDF. The sequential treatments of alkali (A-ISF), alkali-ultrasonic (AU-ISF), ultrasonic-alkali (UA-ISF), ultrasonic-alkali-ultrasonic (UAU-ISF) and alkali-ultrasonic-alkali (AUA-ISF) were applied to extract insoluble soybean fiber (ISF). FTIR and XRD results proved the typical structure of ISFs, and TGA results demonstrated the improved thermal stability of UAU-ISF and AUA-ISF. Chemical composition measurement showed that UAU-ISF and AUA-ISF exhibited higher cellulose content (>83 %). SEM results revealed that ultrasonic treatment led to a decomposition of okara matrix and significant porous structure in ISFs with an amplified collapse effect, resulting in an increase of the pore size of ISFs, and strengthening the properties of UAU-ISF and AUA-ISF in higher water (>15 g/g)/oil (>12 g/g) holding capacities, cholesterol binding capacity (>36 mg/g), and cation exchange capacity (>0.3 mmol/g), thus providing new insights for the preparation of ISF with high functional properties that are beneficial for human intestinal health.

Fermentable sugar recovery from durian peel by using ultrasound-assisted chemical pretreatment

Durian peel, an abundant waste in Malaysia could be a potential substrate for fermentable sugar recovery for value-added biochemical production. Common pretreatment such as acid or alkaline pretreatment resulted in the need for extensive solid washing which generated wastewater. Herein, this study aims to introduce sonication on top of chemical pretreatment to destruct lignin and reduce the chemical usage during the durian peel pretreatment process. In this study, the morphology and the chemical composition of the pretreated durian peels were studied. The sugar yield produced from the chemical pretreatment and the combined ultrasound and chemical pretreatment were compared. The morphology and chemical structure of durian peels were investigated by Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR) analysis and X-ray diffraction (XRD). The SEM images showed that the structural change became more significant when sonication was introduced. Second, XRD profile indicated a relatively higher crystallinity index and FTIR spectra displayed a lower intensity of lignin and hemicellulose for ultrasound plus alkaline (UB) pretreatment as compared to acid, alkaline and ultrasound plus acid (UA) pretreatment. UB and UA pretreatment portrayed higher yield (376.60 ± 12.14 and 237.38 ± 3.96 mg reducing sugar/g dry biomass, respectively) than their controls without the application of ultrasound. Therefore, it could be concluded that ultrasound was able to intensify the fermentable sugar recovery from durian peel by inducing physical and chemical effect of cavitation to alter the morphology of durian peel. Fermentation of UB treated durian peel resulted in 2.68 mol hydrogen/mol consumed sugar and 131.56 mL/Lmedium/h of hydrogen productivity. This study is important because it will shed light on a way to handle durian waste disposal problems and generate fermentable sugars for the production of high value-added products.

How does ultrasound contribute to the migration of extractives inside Ailanthus altissima wood?

Extractives have an impact on the processing and commercial value of wood. Ultrasound is an environmentally friendly technology commonly employed to reduce the extractive content and thus enhance the permeability of wood. This study aimed to understand the migration mechanism of extractives inside wood during ultrasonic treatment, which may help to obtain the desired wood properties. The extractive distribution of Ailanthus altissima was observed by using stereo microscopy, optical microscopy, and scanning electron microscopy, the extractive content was determined, and the relationship between the concentration of water-soluble extractives and absorbance was measured using a UV/Vis spectrophotometer, and the migration model of extractives was studied using layered extraction by innovatively combining the weight and the absorbance methods. The results revealed that the extractives were predominantly distributed in the vessels and diminished after ultrasonic treatment. The extractive content gradually decreased over time (0 ∼ 5 h), with a rapid decline observed within the first 2 h. The concentration of the water-soluble extractives exhibited a proportional relationship with the absorbance. Through the comparison of the layered-extractive concentration, accumulating evidence suggested that the migration of the extractives was a dynamic process, which included the extractives migrating towards easy-extracted area, moving along the direction of ultrasound propagation inside the wood, and leaching out of wood during ultrasonic treatment.

Effect of NaOH Pretreatment on Permeability and Surface Properties of Three Wood Species

To improve the permeability of wood, three chemical reagents were used to pretreat Chinese fir, white oak, and poplar. Through a factorial experiment with the mass change rate of the wood as the indicator, NaOH was preliminarily selected as the pretreatment agent. Further orthogonal experiments were conducted to explore the effects of NaOH concentration, temperature, and treatment time on the mass change rate, dye uptake rate, transverse dye penetration rate, and color difference of the wood. A fuzzy, comprehensive analysis was used to optimize the pretreatment process. The results showed that after NaOH pretreatment, the highest mass change rates of Chinese fir, white oak, and poplar were 11.30, 10.66, and 8.53%, respectively. Compared with untreated wood, the dye uptake rate of three wood species increased by 1.05, 1.43, and 1.13 times, respectively; the radial dye penetration rate increased by 5.05, 4.14, and 3.38 times, respectively; and the tangential dye penetration rate increased by 3.91, 3.45, and 3.84 times, respectively. These findings indicate an enhancement in permeability for all three wood species following NaOH pretreatment. The brightness of the three wood species decreased after NaOH pretreatment, while the yellow and red colors increased in Chinese fir and poplar and decreased in white oak. Scanning electron microscopy showed that pits in the wood opened after pretreatment, while extractives decreased. Infrared spectroscopy analysis indicated varying degrees of extraction effects from NaOH pretreatment across the three wood species, along with increased active hydroxyl groups within the wood structure. X-ray diffraction analysis revealed that NaOH dissolved noncrystalline substances in wood, leading to improved crystallinity. These experimental findings provide essential data for future endeavors in wood pretreatment and subsequent staining processes.

The differences between the water- and alkaline-soluble Poria cocos polysaccharide: A review

Poria cocos (PC) refers to a fungal species which is also known as "Fuling" in China. For >2000 years, PC has demonstrated its therapeutic values as a kind of traditional medicine. It is believed that the various biological benefits created by PCs highly rely on the Poria cocos polysaccharide (PCP). This review recapitulates the recent progress made in PCP in four aspects: i) the methods of extraction, separation, and purification, ii) structural characterization and identification, iii) the related bioactivities and mechanism of action, and iv) structure-activity relationships. Through discussion about the objective as mentioned above, it can be found out that PCP is categorized into water-soluble polysaccharide (WPCP) and alkaline-soluble polysaccharide (APCP), which are totally different in structure and bioactivity. The structures of WPCP are multiplicity whose backbone can be (1,6)-α-galactan and (1,3)-β-mannoglucan etc. to perform various bioactivities including anti-tumor effect, anti-depressant effect, anti-Alzheimer effect, anti-atherosclerosis effect, hepatoprotection etc. The structures of APCP are much more single with backbone of (1,3)-β-D-glucan and the studies of activity concentrate on anti-tumor effect, anti-inflammatory effect and immunomodulation. Besides, the future opportunities of WPCP are primary structure identification. For APCP, scholars can focus on the conformation of polysaccharide and its relationship with activity.