Green microalga Chlorella vulgaris as a potential feedstock for biodiesel

BACKGROUND: A major bottleneck in microalgal biodiesel production is lipid content, which is often low in microalgal species. The present study examines Chlorella vulgaris as a potential feedstock for biodiesel by identifying and evaluating the relationships between the critical variables that enhance the lipid yield, and characterizes the biodiesel produced for various properties. RESULTS: Factors affecting lipid accumulation in a green microalga, Chlorella vulgaris were examined. Multifactor optimization raised the lipid pool to 55% dry cell weight against 9% control. When C. vulgaris cells pre‐grown in glucose (0.7%)‐supplemented medium were transferred to the optimized condition at the second stage, the lipid yield was boosted to 1974 mg L^?1, a value almost 20‐fold higher than for the control. The transesterified C. vulgaris oil showed the presence of ～82% saturated fatty acids, with palmitate and stearate as major components, thus highlighting the oxidative stability of C. vulgaris biodiesel. The fuel properties (density, viscosity, acid value, iodine value, calorific value, cetane index, ash and water contents) are comparable with the international (ASTM and EN) and Indian (IS) biodiesel standards. CONCLUSION: C. vulgaris biomass with 55% lipid content and adequate fuel properties is potentially a renewable feedstock for biodiesel. Copyright © 2011 Society of Chemical Industry     

Influence of laser irradiation on the optical and the mechanical properties of Makrofol‐DE polycarbonate

The effect of IR laser irradiation on the optical and the mechanical properties of Makrofol‐DE 1‐1 CC polycarbonate films were investigated. Three hundred microns‐thick films of Makrofol‐DE 1‐1 CC polycarbonate were irradiated with 0.00–10.40 J/cm² of Ga‐As laser pulses, 904 nm, 5 W, and 200‐ns pulse duration. Fourier transform infrared spectroscopy measurements showed that (C?O) groups degrade under laser irradiation at the studied fluence range. The aliphatic and aromatic (C? H) groups exhibited the same behavior, which can be attributed to nature of laser interaction with matter. The Makrofol samples exhibited degradation under the effect of laser irradiation up to 0.94 J/cm², where crosslinking mechanism started and continued until 7.07 J/cm². The refractive index had a minimum value at 0.94 J/cm² and maximum value at 7.07 J/cm² due to the degradation and crosslinking formation inside the sample, respectively. The decrease in elastic modulus, E, of Makrofol irradiated with 0.47–0.94 and 7.07–10.40 J/cm² indicates that the sample becomes more flexible, which results from the decrease in interatomic force constants. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

对比水泥对矿渣粉活性指数检测结果的影响研究

活性指数是评价粒化高炉矿渣粉性能的重要指标。采用不同对比水泥对矿渣粉活性指数进行了检测。结果表明,不同对比水泥对活性指数试验结果影响很大。本研究可为对比水泥生产及选用提供参考。     

Gel Permeation Chromatography with High Loads

Abstract

High loads on GPC columns usually lead to poor efficiency because of steep viscosity gradients. A great difference in density between solution and solvent can also cause excessive band broadening. However, under certain conditions good separations are achieved with loads of 150 mg/100 cc column volume and higher. Two mechanisms are proposed to explain this phenomenon. Secondary exclusion is caused by obstruction of pores to larger molecules by the more rapidly diffusing small molecules. It takes place predominantly with molecules of less than 2000 molecular weight in small pore gels. Incompatibility is caused by repulsive interaction between solute molecules and the polystyrene gel. It is observed with solutes which are chemically quite different from polystyrene, e.g., with polyvinyl acetate, and in a low to intermediate molecular weight range.     

The Effect of Dynamic Vulcanization on the Mechanical Properties of EPDM/PP Thermoplastic Elastomers

ABSTRACT

EPDM/PP blends were prepared by melt mixing using Brabender Plasticorder at 200°C and 100 rpm. The curative concentration was progressively increased from 1 to 3.5 phr EPDM in order to study the influence of dynamic vulcanization on the mechanical properties of the blend. The effectiveness of dynamic vulcanization was ascertained by Brabender torque Rheometry, the increase in crosslink density, and the reduction in swelling index as well. The mechanical properties were found to increase with sulfur up to 1.4 phr after which reversion occurred. Scanning electron micrographs were inspected to differentiate between the cured EPDM/PP TPEs and the uncured counterpart. The micrographs showed that the blended system contains two incompatible phases. This is evident in both the case of the dynamically cured sample where the EPDM phase remains as dispersed particles in the PP matrix, and in the case of the uncured blend where the EPDM and PP formed two continuous phases.     

Flow Characteristics and Dynamic Behavior of Polyamide 6/Acrylonitile Butadiene Styrene (PA6/ABS) Blends

The objective of this research was to investigate the effect of incorporation of maleic anhydride grafted acrylonitrile-butadiene-styrene (ABS-g-MAH) on rheological properties of PA6/ABS blends. Flow properties of the blends were examined by dynamic and capillary rheometers. The dynamic rheological analyses showed an increase in complex viscosity with the incorporation of a compatibilizer. The reduction of tan δ peaks showed enhanced interfacial interaction between PA6 and ABS phase, which resulted in the enhancement of melt strength. The power law index analysis showed that 1.5 wt.% resulted in minimum n and maximum K value for the blends while still retaining the pseudoplastics behavior necessary for plastics processing and prediction for the end use performance of the PA6/ABS blends.     

用于润滑油改性剂的乙丙共聚物J-0010的研究

根据国内油品市场的需要,通过研究考察了引发剂配比及工艺条件变化等对共聚反应的影响,得出共聚反应及共聚产物性能随上述诸因素的变化规律。结合吉林石化公司引进的乙丙橡胶生产工艺,分别进行了理化性能分析试验、模拟评定试验。成功开发了乙丙共聚物润滑油粘度指数改进剂产品J-0010及工艺。试验结果表明产品性能完全达到杜邦0125的水平。     

A particle‐scale index in the quantification of mixing of particles

Discrete element method (DEM) is a useful tool for obtaining details of mixing processes at a particle scale. It has been shown to satisfactorily describe the flow structure developed in bladed mixers. Here, the advantage is taken of the microstructure gained from DEM to evaluate how best to quantify the microstructure created by mixing. A particle‐scale mixing index (PSMI) is defined based on coordination numbers to represent the structure of a particle mixture. The mixture quality is then analyzed qualitatively and quantitatively in three different ways: a macroscopic mixing index based on the conventional approach, coordination number, and PSMI. Their effectiveness is examined based on DEM data generated for different particle loading arrangements and binary mixtures of particles with various volume fractions, size ratios, and density ratios. Unlike the two other methods, PSMI reveals in a straightforward manner whether a binary mixture of different particles is mixing or segregating over time, while being able to detect particle‐scale structural changes accompanying the mixing or segregation processes in all the mixtures investigated. Moreover, PSMI is promising in that it is not influenced by the size and number of samples, which afflict conventional mixing indexes. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Characterization of EfOM Fraction Responsible for Short-Term Fouling in Ultrafiltration

Based on our earlier diagnosis that hydrophobic and hydrophilic (HPO/HPI) acids are the primary cause of short-term fouling in the ultrafiltration of secondary effluent, the HPO/HPI acids were extracted and subsequently characterized in comparison with commercial organic materials. HPO/HPI acids isolated from secondary effluent contained significantly fewer complex mixtures than humic substances that have been implicated as the dominant foulants in the filtration of surface water using porous membranes. The physicochemical and spectroscopic characterization demonstrated that the aromaticity and apparent molecular weight of HPO/HPI acids were lower than that observed for other humic materials, while the oxygenated functional groups were relatively higher.     

核主成分分析-广义回归神经网络法研究——70种烷烃类有机化合物的气相色谱保留指数

利用核主成分分析法和广义回归神经网络研究了70种烷烃在固定相为角鲨烷,柱温50℃时的气相色谱保留指数。核主成分分析将70×8维的样品集降为51×3维,以减少计算量;降维后的样品集作为广义回归神经网络的训练集对色谱保留时间进行计算和预测。该方法的计算结果满足误差要求。