Dry Fractionation of Cupuassu (Theobroma grandiflorum) Fat: Physical–Chemical Properties and Polymorphic Behavior

Physical chemical properties of cupuassu fat were modified by dry fractionation. Stearin and olein fractions were obtained at 29, 26, and 24 °C. Polymorphic behavior of unfractionated cupuassu fat (UCF) and its fractions were studied in situ by small-angle (SAXS) and wide-angle (WAXS) X-ray scattering using synchrotron light. Polymorphic transitions were followed in real time tempering samples with a thermal cycle. For UCF, the main polymorphic form crystallized under selected conditions was the β’₂. α and β’₁-forms appeared in trace amounts. β₂-form was obtained after storage at 25 °C for 3 months. Stearins obtained at 26 (S-26) and 24 °C (S-24) showed a similar polymorphic behavior. However, S-26 with improved physical properties might be more suitable for chocolate production or as a trans-fat alternative than UCF. Stearin fraction obtained at 29 °C (S-29) had a complex polymorphic behavior. The α-form was the first polymorphic form detected followed by β’₂-form. There was a polymorphic transition from α to β’₁-form but no transition between β’-forms. They were independent to each other showing fractionation in two different solid solutions. Increased contents of the triacylglycerols (TAG) SOA and SOB together with lower contents of SOO compared to UCF led to co-crystallization because there was no complete compatibility among all TAG present in S-29. β₁-form crystallized after storage forming crystals with a double-layer arrangement and a characteristic morphology. This form could be useful for accelerating crystallization process in melted liquid systems.     

渣油加氢装置分馏部分流程分析

以2.4 Mt/a渣油加氢装置分馏部分进料条件为基准,对单塔流程、双塔流程Ⅰ、双塔流程Ⅱ3种分馏方案进行模拟计算,并进行技术经济对比.结果表明,单塔流程投资和能耗均最小,但该流程需要设置酸性气压缩机,装置分馏部分长周期运行的可靠性略低.双塔流程通过设置汽提塔,提高了装置长周期运行的可靠性,降低了柴油产品中的硫化氢含量.其中双塔流程Ⅰ设备投资比单塔流程高50万元,单位原料油能耗比单塔流程高147.39MJ/t;双塔流程Ⅱ设备投资比单塔流程低150万元,单位原料油能耗比单塔流程高94.55 MJ/t.因此,双塔流程Ⅱ可在最大程度上提高装置分馏部分长周期运行的可靠性,节省设备投资.     

Bioanalytical and chemical assessment of the disinfection by-product formation potential: Role of organic matter

Disinfection by-products (DBP) formed from natural organic matter and disinfectants like chlorine and chloramine may cause adverse health effects. Here, we evaluate how the quantity and quality of natural organic matter and other precursors influence the formation of DBPs during chlorination and chloramination using a comprehensive approach including chemical analysis of regulated and emerging DBPs, total organic halogen quantification, organic matter characterisation and bioanalytical tools. In vitro bioassays allow us to assess the hazard potential of DBPs early in the chain of cellular events, when the DBPs react with their molecular target(s) and activate stress response and defence mechanisms. Given the reactive properties of known DBPs, a suite of bioassays targeting reactive modes of toxic action including genotoxicity and sensitive early warning endpoints such as protein damage and oxidative stress were evaluated in addition to cytotoxicity. Coagulated surface water was collected from three different drinking water treatment plants, along with reverse osmosis permeate from a desalination plant, and DBP formation potential was assessed after chlorination and chloramination. While effects were low or below the limit of detection before disinfection, the observed effects and DBP levels increased after disinfection and were generally higher after chlorination than after chloramination, indicating that chlorination forms higher concentrations of DBPs or more potent DBPs in the studied waters. Bacterial cytotoxicity, assessed using the bioluminescence inhibition assay, and induction of the oxidative stress response were the most sensitive endpoints, followed by genotoxicity. Source waters with higher dissolved organic carbon levels induced increased DBP formation and caused greater effects in the endpoints related to DNA damage repair, glutathione conjugation/protein damage and the Nrf2 oxidative stress response pathway after disinfection. Fractionation studies indicated that all molecular weight fractions of organic carbon contributed to the DBP formation potential, with the humic rich fractions forming the greatest amount of DBPs, while the low molecular weight fractions formed more brominated DBPs due to the high bromide to organic carbon ratio. The presence of higher bromide concentrations also led to a higher fraction of brominated DBPs as well as proportionally higher effects. This study demonstrates how a suite of analytical and bioanalytical tools can be used to effectively characterise the precursors and formation potential of DBPs.     

Assessing the aggregation behaviour of iron oxide nanoparticles under relevant environmental conditions using a multi-method approach

Iron nanoparticles are becoming increasingly popular for the treatment of contaminated soil and groundwater; however, their mobility and reactivity in subsurface environments are significantly affected by their tendency to aggregate. Assessing their stability under environmental conditions is crucial for determining their environmental fate. A multi-method approach (including different size-measurement techniques and the DLVO theory) was used to thoroughly characterise the behaviour of iron oxide nanoparticles (Fe₂O₃NPs) under environmentally relevant conditions. Although recent studies have demonstrated the importance of using a multi-method approach when characterising nanoparticles, the majority of current studies continue to use a single-method approach.Under some soil conditions (i.e. pH 7, 10 mM NaCl and 2 mM CaCl₂) and increasing particle concentration, Fe₂O₃NPs underwent extensive aggregation to form large aggregates (>1 μm). Coating the nanoparticles with dissolved organic matter (DOM) was investigated as an alternative “green” solution to overcoming the aggregation issue instead of using the more commonly proposed polyelectrolytes. At high concentrations, DOM effectively covered the surface of the Fe₂O₃NPs, thereby conferring negative surface charge on the particles across a wide range of pH values. This provided electrostatic stabilisation and considerably reduced the particle aggregation effect. DOM-coated Fe₂O₃NPs also proved to be more stable under high ionic strength conditions. The presence of CaCl₂, however, even at low concentrations, induced the aggregation of DOM-coated Fe₂O₃NPs, mainly via charge neutralisation and bridging. This has significant implications in regards to the reactivity and fate of these materials in the environment.     

Use of Palm Mid-Fraction in White Chocolate Formulation

Samples of two types of palm mid-fraction (PMF I, a commercial sample and PMF II, from a laboratory-scale acetone fractionation of PMF I) and a Malaysian deodorised cocoa butter sample were used as the main components in the fat phase for white chocolate formulation. The monounsaturatedtriacylglycerol contents of these fats were 853, 899 and 903 g kg⁻¹, respectively.All the fats had free fatty acid contents of less than 10 g kg⁻¹ and melting points in the range of 34·0–34·5°C. The solid fat content profiles for the three fats were very steep. Differential scanning calorimeter analyses showed that all the fats had two melting peaks, T1 and T2. Results of the study showed that the tempering time to produce a well-tempered chocolate using PMF I was longer than that using PMF II, whereas, the time to produce a well-tempered cocoa butter chocolate increased with increase in the tempering temperature. Chocolates made with PMF I and II were well tempered between 17 and 19°C and with cocoa butter at 23°C. Thermal analyses, carried out on the chocolate showed that PMF I and II produced three melting peaks, T1, T2′ and T2 whereas most of the cocoa butter chocolates exhibited only one melting peak, T2. Storage studies showed that most of the chocolates had good bloom resistance for up to 12 weeks storage.     

Studies of the comonomer distributions in low density polyethylenes using temperature rising elution fractionation and stepwise crystallization by DSC

The comonomer distributions of commercial linear low density polyethylenes (LLDPE) and linear very low density polyethylenes (VLDPE) produced with traditional high activity Ziegler–Natta (Z–N) catalysts were characterized by temperature rising elution fractionation (TREF). In order to develop faster characterization methods the polymers were also characterized using a segregation fractionation technique (SFT) based on a stepwise crystallization by differential scanning calorimetry (DSC). Comparative studies of SFT and TREF demonstrated that SFT provides an alternative tool for the relative qualitative analysis of the chemical composition distribution (CCD) and the technique is useful to characterize the heterogeneity in comonomer unit distribution. Lamellar thickness distributions can be calculated from the DSC endo-therms by applying the Thomson–Gibbs equation. The SFT technique was also applied to commercial single-site (metaliocene) LLDPE and VLDPE polymers. In spite of their more homogeneous structure compared with the Z–N copolymers, which contain many active sites, these single site copolymers also gave thermograms resolved into several peaks.     

Fractionation of oligomers of linear alphaolefins in a molecular evaporator

Oligomers of higher alphaolefins, mainly of 1-decene and 1-octene have important applications as synthetic lubricating oils or their components. The results of fractionation of polydecene, polyoctene, and polybutene oils in a wiped-film molecular evaporator, for the purpose of preparing narrow distillate cuts, are presented in the paper. Characteristics and properties of the fractions obtained are shown, and the possibilities for this distillation method in the fractionation of polyolefin oils discussed.     

哈尔滨气化厂油加氢工艺

采用对中油和轻油加氢精制以脱除油中的S、N、O等杂原子及对烯烃、芳烃、不饱和烃等加氢和脱氢过程,获得了汽油和柴油等产品并明显提高了油品质量。     

广州市地表堆积物中重金属含量分析研究

以地表堆积物中的Pb、Zn、Cu、Cd作为重点研究对象,在广州市分三个功能区(工业区、商业区、住宅区)进行地表堆积物样品的采集,从总含量、不同粒径级含量来分析堆积物中重金属的总体特性,并以研究结论为广州城市非点源的防治与管理提供理论依据。