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关键词： Biomass   Condensation   Reactivity   Biofuels   Pyrolysis  

摘要： The study aims to realize the recycling of the heavier portion of bio-oil produced in pyrolysis to achieve a higher char yield in a two-stage fixed bed. Simultaneously, the influence of condensation temperature in the second-stage reactor on the obtained char yield was probed as well. For further investigation on the physicochemical properties of char samples, ultimate analysis, N-2 adsorption-desorption measurements, Raman spectroscopy, and Fourier-transform infrared spectroscopy analysis were conducted. In addition, the reactivity of char samples in air was determined using a thermogravimetric analyzer. The results suggested that the char samples produced by the recycling of heavy oil resulted in a relatively high yield. Simultaneously, different condensation temperatures of the second layer during pyrolysis had a significant impact on the experimental results: as the temperature increased, the char yield and the O/C molar ratio decreased, whereas the value of I-G/I-ALL increased. Finally, it was found that the increase of condensation temperature in the second layer led to the decline of char reactivity. The dimensionless index (DI) was used to show the physicochemical properties of char, and a linear relationship between the oxidation activity index and DI was achieved, which could be used to predict the char reactivity based on the physicochemical properties for industrial applications.

关键词： Deformation   Fluids   Shale   Clay   Minerals  

摘要： Hydraulic fracturing of unconventional hydrocarbon resources involves the sequential injection of a high-pressure, particle-laden fluid with varying pH's to make commercial production viable in low permeability rocks. This process both requires and produces extraordinary volumes of water. The water used for hydraulic fracturing is typically fresh, whereas "flowback" water is typically saline with a variety of additives which complicate safe disposal. As production operations continue to expand, there is an increasing interest in treating and reusing this high-salinity produced water for further fracturing. Here we review the relevant transport and geochemical properties of shales, and critically analyze the impact of water chemistry (including produced water) on these properties. We discuss five major geochemical mechanisms that are prominently involved in the temporal and spatial evolution of fractures during the stimulation and production phase: shale softening, mineral dissolution, mineral precipitation, fines migration, and wettability alteration. A higher salinity fluid creates both benefits and complications in controlling these mechanisms. For example, higher salinity fluid inhibits clay dispersion, but simultaneously requires more additives to achieve appropriate viscosity for proppant emplacement. In total this review highlights the nuances of enhanced hydrogeochemical shale stimulation in relation to the choice of fracturing fluid chemistry.

关键词： Bacterial cellulose   Antimicrobial   Nanocomposite   Chitosan   Edible film  

摘要： Antimicrobial film is one of the most promising active packaging materials that can maintain the quality and extend the shelf life of food products. It can be prepared by incorporating antimicrobial agents into films. In this work, antimicrobial films were fabricated by blending bacterial cellulose (BC) suspension as a matrix, chitosan as a natural antimicrobial agent, carboxymethyl cellulose (CMC) as a homogeniser and glycerol as a plasticiser. All components were mixed and degassed before casting and drying at 40 degrees C in an oven. As a control, film without chitosan was also cast. Scanning electron microscopy (SEM) revealed smooth and dense surface morphologies for BC-based films containing chitosan. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of chitosan in BC-based films, while X-ray diffraction (XRD) revealed that adding chitosan influenced their crystallinity. Furthermore, incorporating chitosan increased the insoluble matter and water vapour transmission rate (WVTR) of the films. The tensile strength was slightly increased, while the elongation at break was slightly decreased by adding chitosan. Antimicrobial testing demonstrated that incorporating chitosan into BC-based films successfully reduced the growth of microbes. Based on this result, BC/chitosan films can be considered as a potential candidate for antimicrobial films.

关键词： Nicotinic acid   SDC   CTAB   CMC   thermodynamic parameters  

摘要： Aggregation behavior of anionic bio-surfactant;sodium deoxycholate (SDC) and cationic surfactant;cetyltrimethylammonium bromide (CTAB) and their mixtures at different mole fractions, alpha(SDC) = (0.90026, 0.88416, and 0.69438) has been examined in water as well as in aqueous solutions of nicotinic acid at (298.15, 308.15, and 318.15) K by employing various techniques such as conductivity, density, sound velocity, UV-visible spectroscopy, and dynamic light scattering (DLS) studies. From the critical micelle concentration (CMC) and the degree of ionization (alpha) of micelle, thermodynamic parameters {standard Gibbs free energy (), enthalpy (), and entropy () of micellization} have been evaluated and analyzed for surfactants studied in water and in (1, 2, and 3) x 10(-4) mol kg(-1) nicotinic acid((aq)) solutions at (298.15, 308.15, and 318.15) K. The CMC values for both the pure and mixed (SDC + CTAB) surfactants were found to increase with increase in concentration of nicotinic acid. The partial specific volume (phi(v)), isentropic compressibility (kappa(s)), and partial specific isentropic compressibility (phi(kappa)) were estimated from density and speed of sound data. UV-vis absorption spectra of 1 x 10(-4) mol kg(-1) nicotinic acid((aq)) solutions were also recorded in presence of surfactants studied at alpha(SDC) = (0.90026, 0.88416, 0.69438) and T = 298.15 K. Hydrodynamic diameters (D-h) of micellar aggregates for both pure and mixed surfactants were analyzed through the DLS studies performed at 298.15 K. The results from all the studies suggest the supremacy of both hydrophobic and electrostatic interactions between the nicotinic acid and the mixed micellar aggregates. [GRAPHICS] .

关键词： Physico-chemical properties   Jouyban-Acree model   Viscosity   Density   Dielectric constant   Surface tension   Refractive index   Speed of sound   Solvatochromic parameter   Molar volume   Isentropic compressibility  

摘要： The applicability of Jouyban-Acree model for representing the physicochemical properties (PCPs) of binary liquid mixtures at various temperatures was reviewed. The PCPs include viscosity, density, dielectric constant, surface tension, refractive index, speed of sound, solvatochromic parameter, molar volume and isentropic compressibility. Numerous mathematical models were reported for modeling PCP data of binary mixtures and their different appearances are somehow confusing for the users whereas our developed model employs a single algorithm for all PCP data. Accuracies of some of the models were compared with those of the Jouyban-Acree model. Advantages and disadvantages of the model were discussed and some generally trained versions of the Jouyban-Acree model for predicting PCP data were summerized. (C) 2020 Elsevier B.V. All rights reserved.

关键词： 物理化学   纳米ZnO立方体   高氯酸铵   热分解   HTPE推进剂   燃烧性能  

摘要： 为改善高氯酸铵(AP)的性能,从而改善复合固体推进剂的燃烧性能,采用AP辅助的金属有机骨架结构(MOF)热分解法合成纳米ZnO立方体催化剂(n-ZnO/cube);采用XRD、FESEM、TEM等对其形貌进行了表征,分析了其比表面积和孔径分布;采用TG-DTA分析了其对AP热分解的影响;将其加入到HTPE推进剂中,测试了其对推进剂工艺性能、安全性能、力学性能及燃烧性能的影响。结果表明,n-ZnO/cube催化剂具有大的比表面积(70.5m2/g)和大量的孔道结构,将AP热分解的高温分解峰从413℃降至279℃,放热量从584J/g增至1520J/g,分解活化能从151.1kJ/mol降至65.3kJ/mol;将质量分数2%的n-ZnO/cube加入到HTPE推进剂中,推进剂的燃速(20℃,6.86MPa)从12.01mm/s提高到16.16mm/s,工艺性能、安全性能、力学性能、燃速压强指数(0.42,20℃,3~16MPa)、燃速温度敏感系数(2.02×10^(-3)℃^(-1),-55~70℃,6.86MPa)均未受到明显影响,表明纳米ZnO立方体结构对AP热分解表现出良好的催化性能,是HTPE推进剂的一种具有潜力的燃烧调节剂。

关键词： 课程思政   辩证唯物主义   物质观   《物理化学》  

摘要： 在建设新时代具有中国特色社会主义的大背景下,高校思想政治教育刻不容缓,思政教育应融入到每一门课程中。本文阐述了在《物理化学》绪论部分的授课过程中,结合马克思主义哲学辩证唯物主义的有关原理,深入浅出地揭示物质的物理运动和化学运动的关系,以及《物理化学》的本质含义、研究对象、研究内容等,同时向学生传递科学的世界观。

关键词： Sisal solid waste   alkaline pretreatment   physicochemical characterization   biorefinery  

摘要： Solid waste from sisal fiber is a great candidate for biorefinery feedstock and material for composite production. However, sisal solid waste needs to be pre-treated before being used for such application. One of pretreatment method is chemical pretreatment process using alkaline solution. Alkaline pretreatment can improve the digestibility and physicochemical properties of this lignocellulosic material. The aim of this study was to characterize the in natura and alkali pretreated sisal solid waste in order to evaluate their potential as biorefinery feedstock and material for composite production. The chemical characterization showed that the pretreatment resulted in an increase in cellulose content, which is in agreement with the results of infrared spectra. The DRX pattern and thermal characterization showed a crystallinity degree increase and thermal stability improving, respectively, indicating a partial removal of the amorphous fraction of the lignocellulosic material. The SEM analysis showed that the pretreatment increased the sisal solid waste superficial area, due to extractives removing. These results contributed to elucidate the potential uses of the lignocellulosic material from sisal and how the dilute alkaline pretreatment affected its composition and physicochemical properties.

关键词： Indoor microbiota   Lisbon   Exposure assessment   Inhaled dose   Vehicle cabin  

摘要： Commuters are exposed to a variety of physicochemical and microbiological pollutants that can lead to adverse health effects. This study aims to evaluate the indoor air quality (IAQ) in cars, buses and trains in Lisbon, to estimate inhaled doses while commuting and to evaluate the impacts of cleaning and ventilation on the IAQ. Particulate matter with diameter lower than 1, 2.5 and 10 mu m (PM1, PM2.5 and PM10), black carbon (BC), carbon monoxide (CO), carbon dioxide (CO2) volatile organic compounds (VOCs), formaldehyde (CH2O) and total airborne bacteria and fungi were measured and bacterial isolates were identified. Results showed that the type of ventilation is the main factor affecting the IAQ in vehicle cabins. Under the fan off condition, the concentration of BC was lower, but the concentration of gases such as CO2, CO and VOC tended to accumulate rapidly. When the ventilation was used, the coarse particles were filtered originating the decrease of indoor concentrations. Commuters travelling in trains received the lowest dose for all chemical pollutants, except VOC, mainly because railways are further away from the direct vehicular emissions. Commuters travelling in cars without ventilation received the highest inhaled dose for almost all pollutants despite having the lowest travel duration. Airborne microbiota was highly affected by the occupancy of the vehicles and therefore, the fungi and bacterial loads were higher in trains and buses. Most of the isolated species were human associated bacteria and some of the most abundant species have been linked to respiratory tract infections. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： PBL教学模式   物理化学   教学研究  

摘要： 在高校物理化学的教学中,需要关注学生的主体地位,对学生的能力进行培养。基于PBL教学模式下,强调通过问题解读促进物理化学学科核心素养的达成,并要在教学过程中重视学生生活经验的调动和学生熟悉的生活情境的创设。文章针对PBL教学模式的价值进行分析,探讨在物理化学教学中如何进行PBL教学模式的应用。