Effects of Pressure from High-Pressure Homogenization on the Performance of Soybean Flour Based-Adhesive

A green and sustainable soybean flour (SF) adhesive is considered as a potential alternative to toxic formaldehyde-based resins. Nevertheless, poor bond stability and low bonding strength is caused by the uneven size distribution and low reactivity of SF. Herein, SF adhesives with excellent and stable performance are synthesized via the synergistic action of high-pressure homogenization (HPH) treatment by incorporating a green crosslinker. Specifically, an even distribution of the SF particles is obtained after the HPH treatment, from which large soy protein molecules are broken to several small and even single protein molecules. In this way, the adhesion stability is improved. Additionally, more active groups buried in proteins are exposed after the HPH treatment due to the unfolding of the protein molecules. Therefore, a more reactive SF is obtained and thus forms a denser crosslinking structure of resultant the adhesive, providing an increase in bonding strength. Particularly, the effects of homogenizing pressure on the adhesive performance are investigated. The results show that a 215.6% increase of wet bonding strength (1.01 MPa) is obtained after the HPH treatment with a homogenizing pressure of 20 MPa, meeting the standards (GB/T 9846-2015) for interior applications.     

Stabilization of bio-oil over a low cost dolomite catalyst

A low cost alkaline catalyst of dolomite (CaMg(CO₃)₂) was used to stabilize acacia sawdust bio-oil mixed with methanol. The upgrading efficiency was evaluated in terms of the total acid number (TAN) and viscosity. A change in the dolomite calcination temperature from 700 to 900 °C led to a significant change in the TAN and viscosity of the methanol-added bio-oil. Dolomite activated at higher temperatures had larger amounts of active CaO and MgO species due to the enhanced decarboxylation of calcium and magnesium carbonates. An increase in the dolomite content (1-5 wt%) decreased the TAN value of bio-oil remarkably. A thermal aging test of the methanol-added bio-oil upgraded using dolomite (calcined at 900 °C) at 50 °C for 24 h was carried out by storing the bio-oil at 80 °C for one week. Although the TAN value increased after the aging process, it was still lower than the TAN of raw bio-oil. In addition, increasing the methanol content (10-30 wt%) decreased the TAN and viscosity of the bio-oil significantly.     

Optimization of Enzymatic Hydrolysis of Chicken Fat in Emulsion by Response Surface Methodology

Chicken fat in an emulsion prepared with mechanical shearing and high pressure homogenization (HPH) was hydrolyzed using Candida cylindracea lipase. A homogenization pressure of 50 MPa, which can generate smaller droplets and higher hydrolysis efficiency than mechanical shearing, was fixed to prepare the emulsion for hydrolysis optimization. Response surface methodology (RSM) was applied to study the effect of temperature, enzyme loading, shaking rate and reaction time on the hydrolysis process. The results showed that all three-second-order polynomial models adequately fitted the experimental data. Additionally, hydrolysis parameters for the optimal yields of free oleic and linoleic acids were also obtained using the desirability function: a temperature of 38 °C, an enzyme loading of 0.48% (g/g fat basis), a shaking rate of 100 rpm and a reaction time of 80 min. Under the optimal conditions, the yields of free oleic and linoleic acids were predicted as being 0.470 and 0.118 g/g fat with recoveries of 94.6 and 93.7%, respectively. During the hydrolysis process, the particle size increased with concomitant boosting of the degree of hydrolysis and the stability of the emulsion system was gradually undermined by this reaction process.     

Upgrading of bio-oil in supercritical ethanol: Catalysts screening,solvent recovery and catalyst stability study

Supercritical upgrading of bio-oil is an effective method to upgrade bio-oil. In this paper, upgrading of bio-oil was carried out in supercritical ethanol with the aim of catalyst selection, reducing solvent consumption and catalyst stability study. Compared with Ru/HZSM-5, C-supported catalysts (Pt/C, Pd/C, and Ru/C) gave better catalytic performance. Over the C-supported catalysts, the heating value increased from 21.45 MJ/kg to about 30 MJ/kg and the pH value increased from 3.13 to about 5.5. The relative content of desired products reached as high as 80% over Ru/C. The ratio of ethanol to bio-oil was further reduced to about 1:1 by solvent recovery and reutilization. The relative content of desired products particularly that of esters increased with the recovered solvent. Catalytic stability study of Ru/C showed that the relative content of desired products decreased gradually with the number of catalyst recycle times while the consumption of hydrogen decreased mainly in the first recycle. Coke deposition and sintering of metal particles were the main reasons for the deactivation of Ru/C.     

假酸浆子胶质的乳化性评价

评价了假酸浆子胶质的乳化性。结果表明,假酸浆子胶质能降低油水界面张力;乳状液稳定性随胶质质量浓度增加而增强,加油量增多而下降。乳化温度和贮存温度越高,乳状液越不稳定。胶质溶液pH改变胶质溶液的黏度进而影响乳状液稳定性。pH=3时,胶质溶液乳化活性(emulsion ability,EA)和乳化稳定性(emulsionstability index,ESI)达最高值,分别为1.247和63.353 h。乳状液粒径随质量浓度和均质压力增大而减小。均质压力过大会导致乳状液放置后易聚集而不稳定,合适的均质压力为5 MPa。     

小球藻热解油在Ni-Cu/ZrO2催化剂上的加氢脱氧

在小型固定床反应器中以Ni-Cu/ZrO₂为催化剂,对小球藻热解油进行催化加氢脱氧,以改善生物油性能。利用XRD、H₂-TPR、TG、NH₃-TPD等技术对催化剂进行了结构表征。结果表明,Cu的加入有效促进了Ni-Cu/ZrO₂催化剂活性相的表面分散,提高了该催化剂对小球藻热解油加氢脱氧反应的催化活性。在2 MPa、350 ℃反应条件下,随Cu/Ni的增大,Ni-Cu/ZrO₂的催化活性先升高后降低,Cu/Ni质量比为0.40时的催化性能最好,连续运行3 h后所得精制生物油脱氧率达82.0%。Ni-Cu/ZrO₂催化剂在反应过程中,表面结焦少,活性粒子及催化剂性能稳定,连续运行24 h后所得精制生物油脱氧率依然维持在77.0%以上。小球藻热解油经催化加氢脱氧所得的精制生物油,低位热值由31.5 MJ·kg^-1提高至35.0 MJ·kg^-1,40℃运动黏度由20.5 mm²·s^-1降至9.5 mm²·s^-1,且油品中水分更易于脱除。精制生物油中高级脂肪酸的含量减少,油品稳定性大幅提高。     

Stabilization of oils by microencapsulation with heated protein-glucose syrup mixtures

The use of proteins [whey protein isolate (WPI) or soy protein isolate (SPI) in combination with dried glucose syrup (DGS) for stabilization of microencapsulated spray-dried emulsions containing tuna oil, palm stearin, or a tuna oil-palm stearin blend was investigated. Pre-emulsions containing heated (100°C/30 min) protein-DGS mixtures and oils at oil/protein ratios of 0.75∶1 to 4.5∶1 were homogenized at two passes (35+10 or 18+8 MPa) and spray-dried to produce 20–60% oil powders. Microencapsulation efficiency decreased at lower homogenization pressure and as the oil load in the powder was increased beyond 50% but was independent of the type of oil encapsulated and the total solids (TS) content of the emulsions (24–33% TS) prior to drying. Oxidative stabilities of the powders, as indicated by headspace propanal values and PV after 4 wk of storage at 23°C, generally decreased with increasing oil content and homogenization pressure but increased with increasing TS of the emulsion prior to drying. Powder containing palm stearin was more stable to oxidation than powders containing a 1∶1 ratio of palm stearin and tuna oil or only tuna oil. Heated WPI-DGS formulations were superior to corresponding formulations stabilized by heated SPI-DGS, producing spray-dried powders with higher microencapsulation efficiency and superior oxidative stability.     

La改性多级孔HZSM-5在线催化提质生物油

采用Na₂CO₃溶液对HZSM-5分子筛进行预处理，然后采用浸渍法对预处理后的HZSM-5进行不同负载量的La改性，通过XRD、BET、SEM-EDS和Py-IR等方法对改性前后的HZSM-5进行表征。利用改性前后的HZSM-5在两段式固定床反应器上进行生物质热解产物在线催化实验，对得到的生物油有机相进行理化特性和组成成分分析。结果表明，经过Na₂CO₃溶液处理后，使HZSM-5分子筛形成了含有微-介孔的多级孔孔道结构，La的改性未改变HZSM-5的MFI结构，但改变了分子筛的酸分布。随着La负载量的增加，生物油有机相产率、密度、运动黏度及氧含量先减小后增加，含氧化合物和羰基类化合物含量同样呈现先减小后增加的变化趋势。经过最佳质量分数为5%的La负载后的多级孔HZSM-5分子筛制得的生物油中，有机相高位热值高达37.7 MJ/kg，烃类物质含量达到了49.86%，含氧化合物和羰基类化合物含量分别减少了32.43%和57.03%。     

Influence of alcohol addition on properties of bio-oil produced from fast pyrolysis of eucalyptus bark in a free-fall reactor

Fast pyrolysis of eucalyptus bark was carried out in a free-fall pyrolysis unit at different temperatures ranging from 400 to 550 °C to produce bio-oil, char and gas. The bio-oil produced at optimum temperature was mixed with alcohols with an aim to improve its properties. The results showed that the maximum bio-oil yield of 64.65 wt% on dry biomass basis could be obtained at the pyrolysis temperature of 500 °C. The addition of a small proportion (2.5–10%) of alcohol into the bio-oil could improve its viscosity, stability and heating value. These effects were further enhanced when increasing the alcohol.     

High Pressure Processing of Lipase (Thermomyces lanuginosus): Kinetics and Structure Assessment

Lipases are highly demanded enzymes, used to synthesize high commercial value products in food, pharmaceutical, cosmetic, textile, paper, and detergent industries. The effect of high pressure processing (HPP) on Thermomyces lanuginosus lipase is studied at 0.1, 100, and 300 MPa and 25 °C. Kinetics is assessed after HPP treatment in three sets of time series: 0–25, 51–75, and 101–112 min. Conformational change of lipase is studied by infrared attenuated total reflectance (ATR)–FTIR spectra deconvolution and 1D ¹H NMR. Pressure treatment lead to changes in enzymatic activity from 51 to 75 and from 101 to 112 min. Treated enzyme at 300 MPa has the highest activity (≈twofold higher than untreated lipase). Statistical difference in activity (p  > 0.05) is not found during the first 25 min. Lipase activity is best described by first‐order model (0–25 min) and zero‐order model (51–75 and 101–112 min). Lipase unfolding is evident at 100 MPa due to an increase of β‐turns and β‐sheet components. Pressurized enzyme at 300 MPa enhances its activity from 51 to 112 min, due to an increase of β‐sheet and α‐helix structures (refolding). These findings impact directly on cost‐effectiveness of lipase catalyzed products manufacture. Practical Applications: Enzyme enhanced activity and stability improves the performance of manufacture processes. Assessment of structure changes of lipase induced by HPP lead to accurate parameter selection to increase stability and profitability of lipase catalyzed products processing. Pressure levels of 100 MPa led to enzyme unfolding, whereas 300 MPa causes improved activity and stability provoked by lipase refolding. Pressure treatment at 300 MPa of Thermomyces lanuginosus lipase is recommended for long term bioprocessing (≥112 min), which require increased activity and stability of the enzyme.     

Storage stability of polyamidoamine-epichlorohydrin resin and its effect on the properties of defatted soybean flour-based adhesives

A polyamidoamine (PA) without introducing epichlorohydrin, and two epichlorohydrin-modified polyamidoamine (PAE) samples with solid contents of 12% (PAE-12) and 25% (PAE-25) were synthesized, and their short-term storage stabilities, evaluated at intervals of at least 3 months were assessed for chemical structure, viscosity, pH, thermal degradation behavior, crystalline degree and wet bond strength. The results showed that PA was stable during storage for 98 days, while PAE-12 had better storage stability than PAE-25. PAE was active due to complex side reactions, as the number of azetidinium groups within PAE significantly decreased resulting from the ring open reaction after storage for 42–56 days, leading to decreased crosslinking degree and thermal stability, and increased crystalline content of defatted soy flour (DSF)-PAE adhesives. Thus, the wet bond strength of the corresponding plywood decreased with the increasing storage time of PAE-12 and PAE-25, and finally decreased to 1.05 MPa and 0.66 MPa after storage for 98 days, respectively. In order to ensure the water resistance of DSF-PAE adhesives, the preferable application time at room temperature is 3 months for PAE-12 and 4 weeks for PAE-25.     

Investigation of rapid conversion of switchgrass in subcritical water

The reaction characteristics of switchgrass conversion in subcritical water were investigated using a batch reactor under conditions of rapid rising to 250–350 °C and pressure of 20 MPa, with reaction times varying from 1–300 s. The effects of temperature and reaction time on product distribution and yields of chemical products were investigated. High conversion of switchgrass (90 wt.% on dry biomass basis) can be obtained in less than 60 s under a relative lower reaction temperature of 350 °C, compared with that in a switchgrass flash pyrolysis process where switchgrass conversion achieves only 58.9–78.8 wt.% in temperature range of 450–550 °C. The yield of water solubles (WS) can reach 37 wt.% after reaction for 1 s at 250 °C. The increases in temperature and reaction time lead to increases of the biomass conversion and the yield of gas, while WS yield decreases by secondary decomposition reactions. Many lignin-derived compounds were identified by GC-MS analysis and could well be recovered in methanol solubles (MS). Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis of methanol insolubles (MI) indicated that the lignocellulosic matrix could be significantly decomposed, and no char formation was observed, while many lignin structures were left in the MI products. These results provide important information for recovering value-added chemicals from energy crops and biomass waste.     

An in situ reduction approach for bio-oil hydroprocessing

An in situ reduction treatment, combination of reduction and esterification, was investigated to refine bio-oil. Over Raney Ni and zeolites-supported noble metal (Pd and Ru) catalysts, the reductant formic acid decomposed into hydrogen and carbon dioxide, and then hydrogen reduced the bio-oil while compressible CO₂ dissolved in methanol to form a CO₂-CH₃OH expanded liquid. The results showed that Raney Ni and zeolites-supported Ru were highly active in this heterogeneous catalytic system. The reactions preformed at 150-230 °C for 5-7 h would give a better upgraded bio-oil with a high yield of 80-90 wt.%. The unsaturated components in bio-oil were reduced substantially without obvious coke formation, and the oxygen content was lowered by ca. 5 wt.%. Organic acids were converted into esters through the esterification with methanol, and the properties of hydrogenated bio-oil were improved: the pH value increased from 2.17 to ca. 4.5; the higher heating value approached to 22 MJ/kg, and the viscosity decreased from 5.31 to ca. 4.0 mm²/s.     

Effects of temperature,reaction time,atmosphere, and catalyst on hydrothermal liquefaction of Chlorella

Hydrothermal liquefaction (HTL) is the direct conversion of wet biomass into bio-oil at high temperature (200–400°C) and high pressure (10–25 MPa). In this work, we investigated HTL with 4.5 g of Chlorella and 45 ml of water/ethanol (1:1 vol. ratio) in a 100 ml reactor. Bio-oils produced are characterized via elemental analysis, thermogravimetric analysis, and gas chromatography–mass spectrometry (GC–MS). HTL of Chlorella was investigated at 240 and 250°C for 0 and 15 min under an air or H₂ atmosphere and with and without 5% zeolite Y. Temperature increased the bio-oil yield from 38.75% at 240°C to 43.04% at 250°C for 15 min reaction time. Longer reaction time increased the bio-oil yield at 250°C from 39.14% for 0 min to 43.04% for 15 min. The H₂ atmosphere had a significant effect for HTL at 240°C. Zeolite Y increased the bio-oil yield significantly from 32.03% to 43.06% at 250°C for 0 min. The carbon content of bio-oil increased with the temperature while the oxygen content decreased. The boiling point distribution of bio-oils in the range of 110–300°C varies with temperature, and atmosphere. At 240°C for 15 min, the 110–300°C range increased from 31.19% in air (240-15-air) to 39.25% in H₂ (240-15-H₂). The H₂ atmosphere increased the content of hydrocarbons, alcohols, and esters from 69.61% in air (240-0-air) to 82.83% in H₂ (240-0-H₂). Overall, temperature, reaction time, atmosphere, and catalyst all significantly influenced the yield and/or quality of bio-oils from HTL of Chlorella.     

Effect of Homogenization Pressure and Oil Load on the Emulsion Properties and the Oil Retention of Microencapsulated Basil Essential Oil (Ocimum basilicum L.)

The objective of this work was to evaluate the influence of oil concentration and homogenization pressure on the emulsion and particle properties during the microencapsulation of basil essential oil by spray drying, using gum arabic as the wall material. Experiments were planned according a 2² rotational central composite design. The independent variables were oil concentration with respect to total solids (10–25%) and homogenization pressure (0–100 MPa). Emulsions were analyzed for droplet mean diameter, stability, and viscosity, and particles were analyzed for oil retention, moisture content, particle size, and morphology. Emulsion viscosity was not affected by any of the independent variables. The increase in the homogenization pressure from 0 to 100 MPa resulted in smaller emulsion droplet size (down to 0.40 µm) and, consequently, higher oil retention (up to 95%). On the other hand, higher oil loads (25%) resulted in poorer oil retention (51.22%). Microencapsulation of basil essential oil using gum arabic as the wall material proved to be a suitable process to obtain powdered basil essential oil, presenting great oil retention with the use of lower oil concentration and higher homogenization pressure.     

Visualization of the Drop Deformation and Break‐Up Process in a High Pressure Homogenizer

For the creation of sub‐micron emulsions in fluids of low viscosity the high pressure homogenizer (HPH) is usually chosen. One way of obtaining deeper knowledge of exactly what happens in the active region is to visualize it. In this work, a drop deformation and break‐up visualization system based on a modified Particle Image Velocimetry (PIV) system is described. The system reproduces the gap in a HPH and has been used with pressures up to 18 MPa and drops as small as 5 μm. The optics of the system are analyzed taking into account limiting factors such as the lens resolving power, the focal depth, and the duration of the laser pulses. It is shown that it is possible to resolve drops down to a few μm moving in excess of 100 m/s, and that the main limitations are the resolving power and in the focal depth of the objectives. Examples are shown from capillary drop creation and from the deformation and break‐up of drops in a HPH. It can be concluded that in a HPH, the drops are only deformed to a limited extent in the inlet of the gap, and that all drop break‐up occurs far downstream of the gap.     

Effect of Alcohol in Starch-Thickened Fillings on the Storage Stability of Dark Chocolate Pralines

Commercial praline shells made from dark chocolate were filled with a mixture of invert sugar syrup, wine distillate and sucrose, which was adjusted to a viscosity of approximately 4 Pa·s by addition of pregelatinized starch. The pralines which also contained malt extract were subjected to storage at 20 and 24 °C. The liquefaction rate induced by enzymes of the malt extract depended on ethanol (0–15% w/w) and moisture content (approximately 30%) of the filling, and on storage temperature. The decay of apparent viscosity immediately after adding malt extract was delayed when ethanol was present in the filling, implying that viscosity stability after mixing and during subsequent processing is improved. Softening of the praline shells and fat bloom formation also depended on the ethanol concentration of the filling. A cross-comparison with praline shells which were filled with pure invert sugar syrup implies that the enzymes of the malt extract do not exhibit a negative influence on praline shell firmness. Electron micrographs give evidence that ethanol in contact with chocolate causes structural damage which results in a partial solubilization of praline shells.     

Optimization of supercritical CO2 extraction of Anastatica hierochuntica

Response surface methodology (RSM) was applied to optimize the variables affecting the supercritical carbon dioxide (SC-CO₂) extraction of non-polar compounds from Anastatica hierochuntica using the Central Composite Design technique (CCD). Independent variables were temperature (32–46 °C) and pressure (22–46 MPa). Dependent variables were the percentage of the content of hexadecanoic acid, 9,12-octadecadienoic acid, heneicosane and heptacosane. Pressure was the most significant parameter that affected the content of the compounds. The hexadecanoic and 9,12-octadecadienoic content decreased while heneicosane and heptacosane increased with pressure. A number of choices can be run either at low pressure and low temperature or at low pressure and high temperature in order to optimize extraction of the selected compounds. Extraction either at low temperature (33 °C) and low pressure (25.6 MPa), or at high temperature (42 °C) and low pressure (22.0 MPa) maximized the yield of hexadecanoic, 9,12-octedecanoic, heneicosane and heptacosane.     

玉米秸秆棒状燃料热解过程和产物特征研究

以玉米秸秆棒状燃料为原料,在固定床反应器上探究热解温度对玉米秸秆棒状燃料热解过程和热解产品性质的影响。研究发现,随着热解温度的升高,热解气体产量增加,固体炭产量逐渐减少,生物油产量先增后减在450℃时达到最大值35.61%。对固体炭进行工业分析,发现其灰分含量较高;FT-IR分析表明:玉米秸秆棒状燃料的热解反应主要发生在650℃之前;SEM图显示断截面表现为蜂窝状的孔结构。生物油的GC-MS分析表明:在250~750℃下生物油的组成主要是呋喃、酮、醛和酚类等含氧化合物,其中酚类和呋喃类化合物是含量最多的物质;而在850~950℃下以多环芳烃类化合物为主。热解气的主要组成是CO₂、CO、CH₄和H₂,同时有少量的C₂H_n化合物,在250~450℃范围内,气体的主要组成是CO和CO₂,随着温度升高,CO、H₂、CH₄和C₂H_n逐渐增加,热解气的热值逐渐增加,在650℃下气体产品的热值已达到13.05 MJ/m³,当温度大于650℃后,热值增加速率变慢。     

Catalytic depolymerisation and conversion of Kraft lignin into liquid products using near-critical water

A high-pressure pilot plant was developed to study the conversion of LignoBoost Kraft lignin into bio-oil and chemicals in near-critical water (350 °C, 25 MPa). The conversion takes place in a continuous fixed-bed catalytic reactor (500 cm³) filled with ZrO₂ pellets. Lignin (mass fraction of approximately 5.5%) is dispersed in an aqueous solution containing K₂CO₃ (from 0.4% to 2.2%) and phenol (approximately 4.1%). The feed flow rate is 1 kg/h (reactor residence time 11 min) and the reaction mixture is recirculated internally at a rate of approximately 10 kg/h. The products consist of an aqueous phase, containing phenolic chemicals, and a bio-oil, showing an increased heat value (32 MJ/kg) with respect to the lignin feed. The 1-ring aromatic compounds produced in the process are mainly anisoles, alkylphenols, guaiacols and catechols: their overall yield increases from 17% to 27% (dry lignin basis) as K₂CO₃ is increased.