Tefluthrin Sorption to Mineral Particles: Role of Particle Organic Coatings

Abstract

The sorption of tefluthrin was studied on “pure” clay minerals and those that had been coated with aquatic humic substances over a mass percent carbon range of 0.02 to 2.15. Tefluthrin sorption onto humic-coated minerals was significantly greater than on to the clean minerals and increased with increasing quantities of sorbed humic substances. Humic acid, the most aromatic coating, was the strongest sorbent, followed by fulvic acid, hydrophilic macromolecular acid and natural coatings on estuarine suspended particles. This shows the significant impact of humic coatings on the sorptive capacity of mineral particles. The sorption was linear, also consistent with the operation of a partition process. The partition coefficient normalised to organic carbon (K_oc) after deduction of the contribution from the clean mineral, ranged from 120000 to 770000 and was highest for the most aromatic humic acid fraction.     

Chemical Imaging for PAH Analysis in Particulate Materials

Abstract

Chemical imaging is a new analytical science, related to a combination of spatial and chemical resolutions. Several new chemical imaging tools have been developed and applied to environmental analysis. The advantages of such methods, which provide simultaneous morphological/geometrical and chemical speciation, are pointed out and exemplified in several environmental analytical applications. These include fast analysis of PAH contaminated aerosols at low concentrations, analysis of contaminated quartz sand particles, as well as improvement of laser induced fluorescence detection of PAH compounds in natural water, in the presence of various microparticles. It is shown that chemical imaging has a considerable potential in environmental applications and can provide detailed and unique information when particulate materials are concerned.     

悬式绝缘子的形状优化

本文将带自适应运动极限的序列线性规划法应用于悬式绝缘子瓷头的形状优化问题中。建立了优化的数学模型;给出了相应的算法;分析了优化计算的结果;为悬式绝缘子的形状优化设计提供了可行的有效手段。     

The influence of impurity formation on electron inelastic scattering of suspended graphene

This study reports on controlling the formation of nanoimpurities on suspended graphene to investigate the inelastic scattering of electrons using a two‐phonon Raman process. Results were analyzed by transmission electron microscopy (TEM) and scanning Raman spectroscopy in the same region of suspended graphene. The findings revealed that the area with a higher concentration of impurities shown in the TEM image corresponds directly to the area with a lower integrated intensity and a wider full width at half maximum in the Raman mapping of the 2D band and vice versa. The same trend is also apparent in the 2D′ and D + D″ bands. In conclusion, the results are explained by an increase in the electronic scattering rate due to impurities, which affects two‐phonon Raman scattering. Combining the TEM image and Raman mapping image effectively demonstrates how electron behavior is affected by the distribution of impurities in graphene systems. Copyright © 2012 John Wiley & Sons, Ltd.     

Determination of 3-nitroaniline in water samples by directly suspended droplet three-phase liquid-phase microextraction using 18-crown-6 ether and high-performance liquid chromatography

Liquid–liquid–liquid microextraction (LLLME) with directly suspended droplet in high-performance liquid chromatography (HPLC) has been applied as a new, rapid and easy method for the determination of 3-nitroaniline in environmental water samples. The target compound was extracted from the aqueous sample solution (donor phase, pH 13) into an organic phase and then was back-extracted into a directly suspended droplet of an acidic aqueous solution (acceptor phase, pH 0.3). In this method, without using a microsyringe as supporting device, an aqueous large droplet is freely suspended at the top-center position of an immiscible organic solvent, which is laid over the aqueous sample solution while being agitated. Then, the droplet was withdrawn into the microsyringe and directly was injected into the HPLC system with UV detection at 227 nm. Up to 148-fold enrichment of the analyte could be obtained under the optimal conditions [i.e. donor phase: 0.1 M sodium hydroxide solution (4.5 mL); organic phase: o-xylene/1-octanol (90:10, v/v; 250 μL); acceptor phase: 0.5 M hydrochloric acid and 500 mM 18-crown-6 ether (6 μL); extraction time: 60 s; back-extraction time: 6 min and stirring rate: 600 rpm]. The limit of detection was 1 μg/L (n = 7) and the relative standard deviation (RSD, n = 5) was 4.9 at S/N = 3. The calibration graph was linear in the range of 5–1500 μg/L with r = 0.9983. All experiments were carried out at room temperature (22 ± 0.5 °C).     

Determination of Mercury(II) in Drinking Water by Total Reflection X-ray Fluorescence Spectrometry and Liquid–Liquid Microextraction

The total reflection X-ray fluorescence determination of mercury(II) in drinking water at concentrations of 7?×?10^?2 to 3.0?µg/L is reported. The mercury(II) preconcentration protocol includes directly suspended droplet microextraction with benzene as a molecular iodine complex. The proposed approach is highly selective. The elements Cr, Mn, Fe, Co, Ni, Zn, and Pb at concentrations up to 0.1?g/L did not interfere with the extraction of trace mercury(II). The method is characterized by high sensitivity (limit of detection of 21?ng/L) and suitable reproducibility (relative standard deviation of 0.12 for 100?ng/L). The accuracy of the results was confirmed by recovery and the method of standard addition.     

快速原子吸收法测定蔬菜样品中微量铜

本文描述了蔬菜悬浮液直接进样非火焰原子吸收法测定微量钢的方法,讨论了样品的粉碎、匀浆及进样技术,研究了原子化温度程序等实验条件,并通过对各种蔬菜中微量铜测定的结果与常规法结果比较,确立了方法的可行性。     

Affinity separation of enzymes from mixtures containing suspended solids

Agarose beads containing immobilized enzymes or affinity ligands have been made magnetically responsive by adsorbing freshly precipitated magnetite on their surface. These beads are used for affinity adsorption of proteins from complex mixtures containing suspended solids. The magnetically responsive beads and the unwanted (diamagnetic) solids are then separated by magnetic filtration. This magnetic adsorption scheme for direct affinity separation of enzymes from mixtures containing suspended solids is compared with a similar, but nonmagnetic, scheme in which the affinity matrix is supported on fiberglass cloth. The enzyme is allowed to adsorb in this matrix, and the matrix is simply removed physically from the suspension to achieve separation from the unwanted solids. The two methods seem comparable in their ability to separate a desired enzymatic activity. The magnetic methods are technically the more complex of the two, but are significantly the more rapid. The efficiency of separation of diamagnetic and ferrimagnetic solids in these biological systems by high gradient magnetic filtration is good.     

Application of capillary gas chromatography to environmental analysis

Routine analytical methods for benzo[a]pyrene and nitroarenes in airborne particulates are presented. Benzo[a]pyrene in airborne particulates was easily analyzed by a capillary GC/NCIMS. Analysis time was about 10 min and analytical values obtained by this method agreed well with those by HPLC/spectrofluorometry. Nineteen nitroarenes were analyzed by capillary GC/FTD following a simple clean-up procedure. Fifteen out of 19 nitroarenes analyzed were mutagenic for Salmonella typhimurium TA100 and TA98, and 4 nitroarenes were carcinogenic to experimental animals.     

Bridging the gap between membrane bio-reactor (MBR) pilot and plant studies

An integrated numerical approach was developed and implemented to study the hydrodynamic characteristics of pilot and plant systems of membrane bio-reactor (MBR). The approach incorporated Eulerian multiphase model, porous medium scheme, and also successfully took into account the vertically dependent filtration flux and the effect of mixed liquor suspended solids (MLSS) on mixed liquor viscosity. Utilizing this integrated numerical approach, a clear distinction of up-flow and down-flow regions within the pilot single module had been simulated. The simulated mixed liquor velocity and air hold-up agreed well with published experimental measurements and theoretical estimation, respectively. However, when a total of 160 modules were consolidated into an actual plant operation (i.e. Plant A), the average mixed liquor and air velocities of each module encountered a drop of approximately 50–80% lower compared to the pilot system. This implied that an approach applicable for the studies on both pilot and plant simulations was essential to identify and subsequently improve the problem. One example of optimization was by enlarging the tank size for the plant system (i.e. Plant B). With this minor design modification, the mixed liquor and air velocities were improved by 50% and noticeable up-flow and down-flow circulations were achieved.