Comprehensive branching analysis of polyethylene by combined fractionation and thermal analysis

Linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) differ significantly in their branching types and branching distributions. For a comprehensive analysis, preparative temperature rising elution fractionation and/or preparative molar mass fractionation are used to fractionate typical LLDPE and LDPE bulk resins into narrowly distributed fractions. The chain structures of the bulk resins and their fractions are further analysed using SEC, crystallization analysis fractionation, DSC and high‐temperature HPLC to provide detailed information on short chain branching in LLDPE and long chain branching in LDPE. For LDPE it is shown that the multiple fractionation approach is a powerful source of sample libraries that may have similar molar masses and different branching structures or alternatively similar branching but different molar masses. The analysis of these library samples by thermal analysis provides a much deeper insight into the molecular heterogeneity of the samples compared to bulk sample analysis. © 2018 Society of Chemical Industry     

Observations on the use of iron(II) complexing agents to fractionate the total filterable iron in natural water samples

Analysis of filtered natural water samples using Fe(II) complexing agents (bathophenanthrolinedisulphonic acid, 2,2′-dipyridyl, ferrozine, TPTZ) and acetic acid-sodium acetate buffer (pH 4.6) showed that the absorbance of the iron(II) complex increased with time both in the presence and the absence of a reducing agent (ascorbic acid, hydroxylammonium chloride). Exposure of the samples to 0.1 M HCl (pH 1.3) for 1 h prior to the addition of the complexing reagents resulted in a stable iron concentration which was designated the acid-extractable fraction of the total filterable iron. The results have implications for the complexometric determination of iron fractions other than total iron after acid digestion.     

Evaluation of fly‐ash additive for removal of dissolved organic matter during soil aquifer treatment of wastewater treatment plant Peffluent

BACKGROUND: Fly‐ash (FA) additive was evaluated for enhanced removal of organic matter during soil aquifer treatment (SAT) of a wastewater treatment plant (WWTP) effluent in five 0.50 m length columns (diameter 0.1 m) in parallel. RESULTS: The characteristic behavior of dissolved organic matter (DOM) was examined for the stratum matrix configurations of both natural soil and a mixture of soil and FA. Incubation and fractionation experiments indicated that FA additive within the SAT columns would enhance the bulk adsorption of hydrophobic fractions, but decrease the biodegradation of the hydrophilic fraction simultaneously. The configuration design of an upper 0.25 m soil layer and a mixture of FA and soil underneath could make use of the functions of both FA adsorption and biodegradation within soil, which could lead to a further fractional removal of dissolved organic carbon (DOC) and trihalomethane formation potential (THMFP). Moreover, FA additive in the SAT columns could result in a significant decrease of tryptophan‐like aromatic proteins and fulvic‐like components (C?C and C?O related), while the setting of the top 25 cm soil layer would lead to a further reduction of oxygen‐containing functional groups. CONCLUSIONS: Based on the results, FA might serve as a supplementary material for enhancing the reduction of DOM during SAT operation. Copyright © 2010 Society of Chemical Industry     

Fractionation of urea-pretreated squid visceral oil ethyl esters

Ethyl esters of squid (Illex argentinus) visceral oil contained 11.8% eicosapentaenoic acid (EPA) and 14.9% docosahexaenoic acid (DHA). The esters were treated with urea to increase the contents of EPA and DHA. The non-urea complexing ethyl esters of squid visceral oil contained 28.2% EPA and 35.6% DHA. This mixture was fractionated by molecular distillation to further increase the EPA or DHA content. The fraction collected in the 110°C distillate had an EPA content of 39.0% with 0.26 g/100 g of cholesterol, while the 130°C distillate contained 65.6% DHA and 0.42 g/100 g of cholesterol. Ethyl esters prepared from visceral oil of squid Ommastrephes bartrami had 4.5% EPA and 12.7% DHA. After urea pretreatment, the EPA and DHA contents were raised to 10.1 and 30.0%, respectively. When this mixture was further fractionated by molecular distillation, 16.9% EPA with 0.35 g/100 g cholesterol was found in the 110°C distillate and 52.6% DHA with 0.70 g/100 g cholesterol was found in the 130°C distillate. Cholesterol in the squid visceral oil ethyl esters was concentrated in the final residue of molecular distillation when the polyunsaturated ethyl esters were enriched by the urea complexation method prior to molecular distillation. For example, the cholesterol content in the ethyl esters from O. bartrami squid visceral oil was 2.28 g/100 g originally. It was enriched to 64.15 g/100 g in the final residue from the molecular distillation.     

TREF在抗冲共聚聚丙烯研究中的应用

TREF技术是根据结晶性聚合物的结晶能力进行分级和表征的一项分析和制备技术,在聚烯烃非均匀性表征和窄组成分布样品的制备中有重要应用。文中主要介绍TREF技术的分级原理、装置以及在抗冲共聚聚丙烯研究中最新应用进展。     

Phytosterol Enrichment of Rice Bran Oil by a Supercritical Carbon Dioxide Fractionation Technique

Supercritical carbon dioxide (SC–CO₂) fractionation technique was evaluated as an alternative process for reducing the free‐fatty‐acid (FFA) content and minimizing the phytosterol loss of rice bran oil (RBO) during the process. The effects of pressure (20.5 to 32.0 MPa) and temperature (45 to 80 °C) for isothermal operation of the column on the composition of the resultant fractions were examined. Low‐pressure and high‐temperature conditions were found to be favorable for minimizing triglycerides (TG) and phytosterol losses during the FFA removal from crude RBO. Rice bran oil fractions with < 1% FFA, about 95% TG, and 0.35% free sterol with 1.8% oryzanol content could be obtained utilizing the described SC–CO₂ fractionation technique.     

Purification and identification of a novel cutinase from Coprinopsis cinerea by adsorptive bubble separation

A novel extracellular esterase was separated from culture supernatants of the basidiomycete Coprinopsis cinerea by means of foam fractionation. The parameters pH value, gas flow rate, addition of detergents, and the column design were varied to optimise the transport of the active enzyme into the foam phase. On the 70-mL scale, a recovery of activity of 79% with an enrichment factor of 10.5 was obtained at pH 7 and 20 mL air min⁻¹ within 15 min. The enriched enzyme was characterized biochemically by semi-native SDS-PAGE and IEF electrophoresis with activity staining. Peptide sequencing was performed after tryptic digestion by electrospray tandem mass spectrometry. Homology searches revealed significant similarities to cutinases of various ascomycetes and to C. cinerea genome data recently annotated as cutinases.     

Application of microfiltration to egg white depleted in ovomucin

Summary An attempt was made to reduce the microbial load of unpasteurized fresh egg white by using cross-flow microfiltration and a Tetra-Laval bactocatch installation. Cross-flow tangential microfiltration of liquid fresh egg white was not feasible as there was irreversible membrane clogging within a few minutes of operation. As membrane clogging could have been caused by ovomucin, this protein was removed from whole fresh egg white by increasing the salt strength and lowering the pH. Ovomucin-depleted egg white (ODEW) was successfully microfiltered on the same membrane. Compared to fresh egg white, ODEW had lower foaming and viscous properties, and these properties remained unchanged after bactofiltration. The reduction of microbial load was, however, relatively low.     

基于超临界流体萃取的悬浮床加氢尾油的分离与评价

 用超临界流体萃取分馏(SFEF)装置将克拉玛依渣油悬浮床加氢尾油（KMHR）分离为8个窄馏分和萃余残渣。测定并计算了馏出油的残炭及杂质脱除率，考察了窄馏分SARA族组成、残炭、密度、硫、氮、金属及平均结构参数等的递变规律，预测了窄馏分的裂化性能，并用XRD表征了甲苯不溶物的存在形态。结果表明，超临界流体萃取可以脱除尾油中全部沥青质及甲苯不溶物，质量分数99.5％以上的金属和70.4％以上的残炭富集到萃余残渣中。馏出油符合催化裂化或加氢裂化进料要求并具有优良的裂化性能。     

Food applications of trans fatty acid substitutes

The review outlines the increasing need to reduce trans fatty acids, and addresses the functionality issues of various trans free solutions through discussion of hydrogenation, interesterification, and fractionation, and their influence on fat crystallisation and solid fat content. Caution is urged not to focus solely on physio‐chemical aspects, but to approach trans free designing for specific food applications from a multidisciplinary angle. Examples of specific applications; margarines, shortenings and frying oils are given. The review also offers a glimpse into what the future trans free trends may hold.