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关键词： Typha angustifolia biochar   Surface oxidation   Carboxyl coordination   Heavy metal sorption  

摘要： Biochars treated with acids always presented enhanced sorption capacities for heavy metals. Biochars pyrolyzed at various temperatures have different compositions and present different oxidation states for the acid treatment. To optimize the surface oxidation of biochars, an appropriate pyrolysis temperature of biomass is of great importance. In this work, raw biochars prepared from Typha angustifolia at 300, 400, 450, 500 and 600 degrees C were oxidized by HNO3. The function of HNO3 mainly focused on the surface oxidation of biochars rather than the creation of micropores in matrixes. Biochars pyrolyzed at the higher temperature were more difficult to be oxidized by the acid. The HNO3-activated biochars (NABCs) enriched Pb(II) and Cd(II) under various geochemical conditions including contact time, pH, ionic strengths, coexisting HA, initial heavy metal concentrations and temperatures. NABCs exhibited excellent sorption capacities (i.e., 232.6 mg/g for Pb(II), 88.9 mg/g for Cd(II) at pH 5.0 and 298 K) which were 6.9 and 5.5 times higher than these of untreated biochars. The maximum uptake capacities toward Pb(II) and Cd(II) showed an excellent linearity with the values of [O-C--O content x Surface area], demonstrating the essential role of the surface O-C--O species to coordinate heavy metals. NABCs could be well reused for six cycles through desorption using the acid pickling.

关键词： Calcium carbonate  

摘要： The use of pyrolysis oils from demolition woods is an interesting option to produce fuels or chemicals from waste wood. This work investigated the effect of paints and varnish that contain various potential contaminants on the properties of bio-oils obtained by thermal pyrolysis of wood or after ex situ catalysis of the pyrolysis vapors using a HZSM-5 catalyst. The paints and varnish were analyzed, and their main components were identified. Clean beech wood samples were impregnated with commercial paints and varnish and also individually with the main inorganic compounds (TiO2, CaCO3, and BaSO4) found in the paints and varnish. These contaminated wood samples were pyrolyzed, and the gas, liquid, and solid products formed were thoroughly characterized and compared to the products obtained from clean wood. The results show that the mineral contaminants remained in the chars and that the pyrolysis oils obtained by thermal pyrolysis were not significantly modified by the presence of contaminants on the wood. In ex-situ-catalyzed pyrolysis experiments, the HZSM-5 catalyst promoted the formation of some fully deoxygenated aromatic compounds, which were not obtained without a catalyst. However, the bio-oil produced from wood impregnated with commercial paints and varnish contained less fully deoxygenated compounds. This effect was not related to the mineral compounds present in the paints and varnish and could originate from the polymeric organic components present in their formulations.

关键词： Anthocyanins  

摘要： While identified by the respective flavylium cation, anthocyanins are much more than this molecule. The flavylium cation (generally appearing only at very acidic pH values) is one of the molecules of a complex sequence of pH dependent molecular species reversibly interconnected by different chemical reactions. These species include the red flavylium cation, purple quinoidal base and blue or bluish anionic quinoidal bases. At the common pH of the vacuoles of simpler anthocyanins, the red flavylium cation is present only at very acidic pH values and at moderately acidic pHs there is no significant colour of the purple quinoidal base. Moreover, the blue or bluish anionic quinoidal base appearing around neutral pH values is not stable. Intermolecular (copigmentation) and intramolecular (in acylated anthocyanins) interactions increase the colour hue and yield bathochromic shifts in the absorption bands, permitting to extend the pH domain of the flavylium cation and increase the mole fraction of the quinoidal bases. Metal complexation is another strategy. In particular, the Al3+ cation plays an essential role in the blue colour of hydrangea. The most sophisticated structures are however the metaloanthocyanins, such as the one that gives the blue colour of commelina communis, constituted of six anthocyanins, six flavanones and two metals. In this work we discuss how physical chemical tools are indispensable to account for the chemical behaviour of these complex systems. The experimental procedures and the equations needed to calculate all equilibrium constants of anthocyanins and the consequent pH dependent mole fraction distributions in the absence or presence of copigments are described in detail. Reverse pH jumps monitored by stopped flow have been shown to be an indispensable tool to calculate these parameters.

关键词： Ozone   ozonated oils   total unsaturation   ozonation degree   H-1 NMR spectroscopy   FT-IR spectroscopy  

摘要： The aim of this investigation was to evaluate the modification of physicochemical properties (viscosity and density) of four vegetable oils (grapeseed, sunflower, avocado, and olive) during ozonation, and to relate such variation with the ozonation kinetics, the ozonation degree, and the ozonation by-products distribution. During ozonation, the monitorization of the double bonds' decomposition and accumulation of ozonation by-products yields defined the relationship between the ozonation degree and the physicochemical properties of the ozonated oils. The ozonated oils were characterized by FT-IR and H-1 NMR. The ozonation degree was determined by the measurement of the total unsaturation (TU);this method quantified the substrate reactive with ozone contained in oils. During the ozonation, the variation of viscosity, density, and ozonation by-products exhibited differences among the studied oils, which was effectively correlated to the corresponding ozonation degree. These were characterized by the observed reaction rate constants obtained by a parametric algorithm based on the application of a nonlinear least mean square method.

关键词： antibiotic resistance genes   composting   dynamics   indicator   microbial communities  

摘要： Composting alters manure-derived antibiotic resistance genes (ARGs) to a certain extent, which is largely dependent upon the composting phase, manure type, microbial phylogeny, and physicochemical properties. However, little is known about how these determinants influence the fate and dynamics of ARGs as well as the mechanisms underlying the ecological process of ARGs during composting. Here, we investigated the temporal patterns of ARGs and their correlations with a series of physicochemical, genetic, and microbial properties during pilot-scale composting of chicken, maggot, bovine, and swine manure. We detected 237 ARGs, 71 of which were co-occurring across all four composting processes and accounted for >80% of the sum of resistome abundance. In support of this ARG co-occurrence, variance partition analyses demonstrated that the manure type explained less resistome variations (5.6%) than the composting phase (21.6%). During the phase-driven resistome dynamics, ARGs showed divergent variations in abundance, and certain beta-lactams and multidrug ARGs were consistently enriched across multiple manure composting processes. Correlation analyses all led to the conclusion that the divergent ARG variations during composting were attributable to the unequal effects of physicochemical properties, mobile elements, and succession of indigenous microbiota, whereas antibiotic residues' effects were marginal. Ultimately, this study determines the relative importance of various key determinants in the phase-driven divergence of ARGs during multiple manure composting processes and demonstrates a clear need to evaluate risks posed by enriched ARGs toward their receiving environments.

关键词： Electrolytes  

摘要： We report the physicochemical and electrochemical properties of various concentrations of potassium and lithium acetate (OAc) electrolytes from dilute to near saturation as well as mixed potassium/lithium acetate (32 m KOAc + 8 m LiOAc). The electrochemical stability window varied in the order of Pt < Au < highly ordered pyrolytic graphite (HOPG) < glassy carbon electrodes, and expanded when the salt concentration increased reaching 3.5 V in the dual cation water-in-salt electrolyte. This increase was due to the shift in the onset potential of the hydrogen evolution and oxygen evolution reactions to more negative and positive potential values, respectively. It is noteworthy that there is a larger shift in the onset potential of the oxygen evolution on the Pt electrode. The capacitance at the potential of zero charge of the HOPG electrode was found to be about 4 mu F cm(-2) and almost independent of the electrolyte concentration while the potential of zero charge shifted to more negative values upon increasing the acetate salt concentration. Using ferricyanide and ferrocene methanol as redox probes, their redox potential, ion transport and electron transfer kinetics in acetate-based electrolytes were investigated. The apparent redox potential shifted in the opposite direction;to more positive and negative values for ferricyanide and ferrocene methanol redox systems, respectively. A significant decrease in the diffusion coefficient of ferricyanide ions, i.e. 4 orders of magnitude, was observed in the dual cation water-in-salt compared to a dilute single salt electrolyte. High viscosities might be partially responsible for the decrease of the heterogeneous rate constants obtained for the redox probes but other factors such as interactions with water, electrolyte ions and electrodes might be at play as well.

关键词： 物理化学   课程考核改革   过程考核  

摘要： 物理化学是四大化学中理论性最强的一门课程,针对传统物理化学考核中存在的问题,本文将过程评价与结果评价融合进行了初步探究。结果表明,增强过程考核能显著提高学生学习物理化学课程的兴趣及培养学生分析问题和解决问题的能力。

关键词： CFs-ZnO复合材料   锂电池负极   循环电容量  

摘要： 文章首先采用微尺寸的沸石咪唑骨架(ZIF-8)为包覆材料前驱体,在碳纤维(CFs)中引入氧化锌(ZnO)材料,通过常温搅拌、高温煅烧制备出CFs-ZnO复合材料。然后经过常规的物化实验后对材料进行观察。结果表明,发现纳米结构的ZnO颗粒包覆在ZIF-8碳纤维表面,该材料用于锂电池负极材料时,材料多孔特性在1800 mAg^(-1)电流密度下、900次循环后仍可维持400 mAhg^(-1)的超高容量。最后得出结论,CFs-ZnO的优良电化学性能本质是纳米级的包覆材料以及多孔结构和CFs自身高电导率,此性能使电池储能发电性能显著提升。

关键词： 三全育人   物理化学实验   教学改革实践  

摘要： 物理化学实验具有综合测量的特点,其原理和方法对各相关专业的专业实验及科学研究具有普遍的指导意义,课程教学对于培养学生的科学品德、科学思维和创新精神,使学生获得终生的发展能力具有重要作用。本文基于立德树人的指导思想,探讨“三全育人”理念在物理化学实验课程教学改革中的应用,提出思政教育贯穿课程教学主线,团队协作的全员育人、注重过程的全程育人和多种方式的全方位育人的教学实践,以期对课程教学改革进行有益探索。

关键词： 物理化学   课程思政   教学思考   课堂应用   学生品质引导  

摘要： 推进专业课程与课程思政理念相融合是落实高校立德树人根本任务的重要举措与要求。物理化作为化学类专业必修课程,对学生培养有着不可替代的作用。从在物理化学教学过程中的思考、课程思政在物理化学课堂的应用以及物理化学课程思政对学生思想品质的引导三方面论述物理化学课程思政对于高校人才培养的积极作用。