查看更多>>摘要：? 2022 Elsevier B.V.Food-borne aflatoxins impede the path of current agriculture and worsened the food safety problem, thus researches on prevention and detoxification of aflatoxins by biological, chemical and physical technologies have become hot spots in food safety and agriculture fields. Recently, efficient preservative based on phytochemicals with nano formulation is considered a versatile and green approach to control aflatoxin contamination. In this study, fabrication of a series of nano-emulsions based on American mint and pectinata essential oils via high pressure homogenization is presented. Their morphology and stability via dynamic light scattering and scanning electron microscopy were explored. All these nano-emulsions, namely MNEO 1–5, exhibited obviously growth inhibition effect towards Aspergillus aflatoxiformans with ED50 values of 5.18 ± 0.56, 4.70 ± 0.83, 6.37 ± 0.55, 6.65 ± 0.79 and 8.89 ± 0.90 mg g?1, respectively. Moreover, cell membrane damage assays showed that interactions between MNEO and cell membrane of A. aflatoxiformans resulted in increased electronic conductivity and cell death. To demonstrate prevention effect, a storage simulation experiment was designed on peanut seeds to determine the AFB1 control efficacy of nano-emulsions in hot and wet environments, and both the nano-emulsions displayed remarkable prevention effect after the preservation with AFB1 protection at 86.06–94.00%. For realistic management of pathogens and mycotoxins, bio-active EOs with nano-formulation capable of adapting to complex environment may help to innovate important key source technologies for food processing and preservation in future.
查看更多>>摘要：? 2022 Elsevier B.V.As a high-strength biomass composite material, the development of bamboo scrimber (BS) was limited by its flammable characteristics. In this study, different immersion orders of ammonium polyphosphate (10 wt%, APP solution) for bamboo bundles were selected in order to evaluate its influence on the interphase behavior, mechanical and combustion properties of BS. The flattened bamboo bundles, phenol-formaldehyde (PF) and APP solution were utilized to fabricate the BSs. The interphase behavior of the treated bamboo bundles was characterized by the contact angle measurement, Fourier transform infrared spectroscopy (FTIR) analysis, fluorescence microscope and SEM-EDS measurement. Thermogravimetric analysis, limiting oxygen index (LOI), mechanical properties before and after combustion test were assessed for various BSs. The results showed that significantly increased equilibrium contact angle of PF droplet on the surface of bamboo after immersed in APP solution while the decrement was for APP solution droplet on the surface of bamboo after immersed in PF. Varied intensities of chemical bonds and distribution forms of APP and PF were observed for the treated BSs depending on the immersion orders. These variations have a great effect on the mechanical and combustion properties. No significant decrement of compressive strength and bending strength was observed for APP-treated BSs with different immersion orders compared with the control sample. Higher compressive strength, bending strength, and modulus of elasticity (MOE) were found for the APP-PF-BS with increments of 31.60%, 21.70%, and 29.01%, respectively. Significantly increased thermal stability was observed for bamboo bundles after immersed in APP and PF especially for the temperature over 300 °C. After the combustion test (duration of 40 min), a higher LOI of 35.4, retention rates of mechanical properties of 39.96–78.97%, and lower mass loss of 15.93% were obtained for the PF-APP-BS. Finally, the immersion order of low concentration of APP solution has a great effect on the interphase behavior, mechanical and combustion properties of BSs, which plays a significant role in the optimized fabrication of fire-resistant BSs.
查看更多>>摘要：? 2022 Elsevier B.V.A biphasic solvent system consisting of ionic liquids (IL) and petroleum ethers was applied in the extraction of Eucommia ulmoides gum (EUG) from pericarp. Effects of IL and extraction parameters on the yield and purity of EUG were investigated. The results showed that the addition of IL could enhance the yield and purity of EUG extracted from pericarp comparing with the traditional alike pretreatment method. FTIR, XRD and 1H NMR characterization conformed the chemical structure of EUG. DSC analysis reviewed the partial destruction of crystal structure and the disappearance of β-crystal phase of EUG extracted by biphasic solvent system, resulting in the decrease of the melting point and increase of glass transition temperature. Moreover, the extracted EUG exhibited high tensile strength of 27.68 MPa, excellent elongation at break of 1069%, and thus high toughness of 181.45 MJ?m?3. Additionally, the excellent reusability of IL and petroleum ethers showed the extraction method of the biphasic solvent system promise as a feasible method to replace the traditional alkali pretreatment.
查看更多>>摘要：? 2022 Elsevier B.V.Currently, the main problems in cellulose conversion to glucose are the low enzymatic hydrolysis efficiency and the high cellulase cost. In this study, cellulose I allomorph substrates were from p-toluenesulfonic acid (PT), dilute sulfuric acid (DA) and sulfite (SP) treated cellulose substrates, and cellulose II allomorph were prepared by mercerization. XRD, NMR, FTIR and molecular docking were used to investigate the effect of cellulose allomorphs on hydrolysis efficiency. The results showed that cellulose II allomorph had a lower cellulase adsorption capacity and higher hydrolysis efficiency. This was because cellulose II allomorph owned gt conformation, and less tg and gg conformations of C-6 hydroxymethyl, causing the reduction of interchain hydrogen bonds and the increase in hydrolysis efficiency (PT, DA and SP: from 62.04%, 65.62% and 63.21% to 83.23%, 89.24% and 87.65%, respectively). This study provided theoretical supports for further understanding the effect of cellulose allomorphs on enzymatic hydrolysis.
查看更多>>摘要：? 2022 Elsevier B.V.Dilute acid and alkaline pretreatments are commonly used to fractionate lignocellulosic biomass for its conversion into biofuels and renewable materials. In the current work, we compare the structure and morphology of one and two-step alkaline and acid pretreated sugarcane bagasse (SCB) and differences in their enzymatic hydrolysis rates and yields. We used physical techniques such as nuclear magnetic resonance (NMR) and X-ray diffraction to shed light on physical and morphological changes introduced by the pretreatments in SCB. We also applied solid state NMR procedures which allowed us to separate xylan structural conformations inside pretreated plant biomass samples. Our results reveal that practically all xylan in two-step “alkaline first” (NaOH 1% + H2SO4 1%) pretreated samples adopts two-fold ribbon-like conformation, tightly associated with crystalline cellulose. On the contrary, a main part of xylan in the SCB samples after “acid first” (H2SO4 1% + NaOH 1%) combined pretreatment has a three-fold screw conformation characteristic of xylan bound to lignin. Modifications in the biomass composition, physical structure and xylan conformation introduced by the alternative pretreatments contribute to the observed differences in the enzymatic hydrolysis rates and yields. These results could be relevant for analysis and optimization of pretreatments and enzymatic hydrolysis of lignocellulosic biomass in general.
查看更多>>摘要：? 2022 Elsevier B.V.In response to the global environmental issues over inorganic additives in lubrication process in solving friction and wear challenges. There is growing interest in the development of polymer additives, particularly bio-polymer, to address the issues given by friction and wear of contact surfaces exposed to boundary and mixed lubrication regimes. The investigation employed a unidirectional ball on disc tribo-tester machine. Using rapeseed lubricant as a base oil sample, this study examined the effect of bio-based Eichhornia crassipes carboxylmethyl cellulose (EC-CMC) polymer to inorganic polyphosphate as well as mixing the two to determine their synergetic and antagonistic effect on reducing friction and wear. The additives were tested for tribological enhancement in terms of friction and wear reduction, and load-carrying effect. Scanning Electron Microscope (SEM) and energy dispersive x-ray (EDX) spectroscopy were used to examine the substrate morphology and elemental distribution of worn surfaces. Introducing 1 wt% EC-CMC, 1 wt% polyphosphate, and 1 wt% EC-CMC + 1 wt% polyphosphate into the base lubricant resulted in improved lubricant performance and reduced friction and wear. However, as compared to base rapeseed oil, the polyphosphate sample provided the best friction (44.8%), while EC-CMC gives better wear reduction (0.3073). The higher the operating capacity, the better the tribological properties of nanoparticles, according to the findings. The best tribofilm creation performance, notably with EC-CMC, is achieved when a load of 100 N is applied, resulted in outstanding tribological performance. When compared to polyphosphate, the strong and efficient nature of EC-CMC results in excellent shear stability.
查看更多>>摘要：? 2022The paper presents the synthesis of novel adsorbents in spherical form based on divinylbenzene, ethylene glycol dimethylacrylate and triethoxyvinylsilane, and lignin or its modified form with ZrO2 and SiO2, as hybrid materials of well-defined microstructural factors. In the first stage of the experiment, lignin was mechanochemically combined with the inorganic oxides in form of zirconia and silica. Then, the obtained material was used as a modifier in the preparation of the functionalized polymeric microspheres using the suspension polymerization method. To confirm the chemical structure of the lignin-based hybrid modifiers and the polymeric sorbents, ATR-FTIR and XPS spectroscopy as well as SEM analysis were performed. In addition, the parameters of the porous structure were determined. It was shown that mainly physical interactions occur between the inorganic and organic components, resulting in the formation of class I hybrid systems. Subsequently, the functionalized polymeric microspheres were used as effective sorbents of hazardous C.I. Basic Yellow 2 (BY2) and C.I. Basic Blue 3 (BB3) days from textile wastewaters. Equilibrium data for the sorption of BY2 and BB3 by the newly designed adsorbents show that Freundlich isotherm model describes the experimental data more appropriate than the Langmuir or Dubinin–Radushkevich ones. The Freundlich constant related to adsorption capability, kF, enlarged with rising amount of lignin, zirconia and silica, from 42.3 to 83.5 mg1–1/n L1/n/g for BB3 and from 11.1 to 45.7 mg1–1/n L1/n/g for BY2. Kinetic studies revealed favorable uptake of 50 mg/L BB3 during the first 60 min of phase contact time, compared with BY2. Anionic and non-ionic surfactants (0.25 g/L) and NaCl (25 g/L) slightly decreased dyes (50 mg/L) sorption from dyeing baths, and their retention was significantly reduced when a cationic surfactant was present in the bath. Desorption of BB3 and BY2 dyes from the hybrids, with yield in the ranges 20.8–32.0% and 24.8–99.0% respectively, was achieved applying 1 M HCl in the presence of 50% v/v methanol.
查看更多>>摘要：? 2022 Elsevier B.V.Lignin is the second most abundant natural polymer that exhibits a complex structure with various amounts of aliphatic and phenolic hydroxides. The use of lignin as a source of polyol to make lignin-based polyurethanes (PUs) has been the subject of intense studies in recent years. It is well known that there is a difference in reactivity between aliphatic and aromatic hydroxyl groups towards isocyanates. For simple model systems using conventional fossil-fuel based polyols the overall kinetics are well known. However, unveiling the complex kinetic behavior obtained when combining an isocyanate with lignin derived components exhibiting different types of hydroxyl groups is challenging. Therefore, an in-depth investigation using lignin model compounds and lignin hydrogenolysis oil to elucidate these differences of reactivity is presented and will be invaluable towards the development of lignin-based PUs. Understanding the kinetics involved will lead to optimized synthetic protocols and a higher valorization potential for lignin-based PUs. In this work, various monolignol model compounds are studied concerning their reactivity to aliphatic and aromatic isocyanates. Isothermal experiments revealed the kinetic rate constants and reaction orders while non-isothermal DSC was used to obtain the activation energies through the Friedman isoconversion model-free-kinetics (MFK) approach. These results were confirmed with FT-IR and 1H NMR. It was found that in all cases, aliphatic hydroxide groups react the fastest with aromatic isocyanates while aromatic hydroxide groups react the slowest with aromatic isocyanates. Reactions with aliphatic isocyanates, independent of the hydroxyl type, fall in between these extremes shown by the aromatic isocyanates. Apparent activation energies ranging from 55.2 kJ·mol-1 to 39.5 kJ·mol-1 were found with corresponding reaction rate constants ranging from 5.19·10-3 M1?n s-1 to 1.04·10-3 M1?n s-1. The presented work will be a capstone for the further valorization of lignin as a material for renewable PUs.
查看更多>>摘要：? 2022 Elsevier B.V.Paper mulberry wood contains a high cellulose content of 59%, making it a potentially excellent feedstock for recovery of fermentable sugar used in bioethanol production. This potential was usefully exploited by establishing the optimal phosphoric acid plus hydrogen peroxide pretreatment of its woods using the response surface methodology. Pretreatment temperature, H3PO4 proportion in pretreatment mixture, and time significantly corelated with the removal of non-cellulosic polymers, cellulose recovery, enzymatic hydrolysis of the recovered cellulose, and glucose yield. At the optimized conditions of 34.7 ?C, 71.3% w/w H3PO4 proportion (the corresponding H2O2 proportion of 4.84% w/w), and 3.3 h, there were 97% biomass delignification, 100% hemicellulose removal, and high recovery of a cellulose-rich substrate characterized by decreased crystallinity, enhanced porosity, and complete glucose digestibility. The obtained high glucose yield of 493 mg/g raw wood was comparable to the best-reported yields from short-rotation woody energy crops.
查看更多>>摘要：? 2022 Elsevier B.V.The acid/alkali pretreatment of windmill palm fiber (WPF) and the application of high voltage electrostatic force (HVEF) technology were used to prepare WPF-reinforced laminated veneer lumber (LVL). The effects of acid/alkali pretreatment on the surface morphology, chemical composition, crystallinity and mechanical properties of WPF were investigated. Moreover, the effects of intensity of HVEF on chemical composition and wettability of WPF were analyzed. Based on the mechanical experiment of WPF reinforced LVL composites, the mechanism of acid/alkali pretreatment and HVEF for the reinforcement of the composite was systematically clarified. The results showed alkali treatment efficiently removed silica particles and cuticles on the fiber surface and produced windmill palm fiber with relatively high Young's modulus and tensile strength (increased by 167.07% and 26.52%, respectively). After HVEF treatment, the increase of surface-active groups (- OH and - CHO) led to the increase of surface oxidation degree and water contact angle of WPF. Under the synergistic effect of acid/alkali pretreatment and HVEF, the interfacial properties between the adhesive and WPF were improved. This study showed that the synergistic effect of acid/alkali pretreatment and HVEF not only broaden the application scope of WPF, but also provide insights into the engineering of LVL production.
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