Experimental determination and theoretical correlation for the solubilities of dicarboxylic acid esters in supercritical carbon dioxide

The synthesis of high molecular weight esters such as bis (2-ethylhexyl) sebacate is of significance for its use as a lubricant. This ester is synthesized by the transesterification of dimethyl sebacate with 2-ethylhexanol. Therefore, the solubilities of bis (2-ethylhexyl) sebacate and dimethyl sebacate were determined at 308-328 K at pressures of 10-18 MPa in supercritical carbon dioxide. The solubility of dimethyl sebacate was always higher than bis (2-ethylhexyl) sebacate at a given temperature and pressure. The Mendez-Teja model was used to verify the self-consistency of data. Further, a new semi-empirical model with three parameters was developed using the solution theory coupled with Wilson activity coefficient. This model was used to correlate the experimental data of this work and solubilities of many high molecular weight esters reported in the literature. (C) 2015 Elsevier B.V. All rights reserved.

Comparative studies of AOT and NaDEHP by fluorescence technique and z-potential (ζ) measurements

The aggregation behaviors of two surfactants with the same hydrophobic tail, sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP), have been investigated by the fluorescence technique and z-potential (ζ) measurements. Five fine peaks of the pyrene molecule fluorescence spectroscopy appear in the surfactant solution, and the micropolarity at which pyrene locates is monitored from the intensity ratio of the first (I1) and the third peak (I3). A wide peak around 475 nm, the emission spectra of the excimer of pyrene molecules, is observed in the NaDEHP solution, while this is not found for the AOT system. The value of I1/I3 decreases in a more limited concentration range for the AOT system than for NaDEHP, indicating that small aggregates can be more easily formed by NaDEHP molecules. The z-potential results for the aggregates formed by the two surfactants show that the interaction between AOT and PVP is stronger than that between NaDEHP and PVP.

Sediment Quality in Puget Sound Year 3 - Southern Puget Sound

As a component of a three-year cooperative effort of the Washington State Department of Ecology and the National Oceanic and Atmospheric Administration, surficial sediment samples from 100 locations in southern Puget Sound were collected in 1999 to determine their relative quality based on measures of toxicity, chemical contamination, and benthic infaunal assemblage structure. The survey encompassed an area of approximately 858 km2, ranging from East and Colvos Passages south to Oakland Bay, and including Hood Canal. Toxic responses were most severe in some of the industrialized waterways of Tacoma’s Commencement Bay. Other industrialized harbors in which sediments induced toxic responses on smaller scales included the Port of Olympia, Oakland Bay at Shelton, Gig Harbor, Port Ludlow, and Port Gamble. Based on the methods selected for this survey, the spatial extent of toxicity for the southern Puget Sound survey area was 0% of the total survey area for amphipod survival, 5.7% for urchin fertilization, 0.2% for microbial bioluminescence, and 5- 38% with the cytochrome P450 HRGS assay. Measurements of trace metals, PAHs, PCBs, chlorinated pesticides, other organic chemicals, and other characteristics of the sediments, indicated that 20 of the 100 samples collected had one or more chemical concentrations that exceeded applicable, effects-based sediment guidelines and/or Washington State standards. Chemical contamination was highest in eight samples collected in or near the industrialized waterways of Commencement Bay. Samples from the Thea Foss and Middle Waterways were primarily contaminated with a mixture of PAHs and trace metals, whereas those from Hylebos Waterway were contaminated with chlorinated organic hydrocarbons. The remaining 12 samples with elevated chemical concentrations primarily had high levels of other chemicals, including bis(2-ethylhexyl) phthalate, benzoic acid, benzyl alcohol, and phenol. The characteristics of benthic infaunal assemblages in south Puget Sound differed considerably among locations and habitat types throughout the study area. In general, many of the small embayments and inlets throughout the study area had infaunal assemblages with relatively low total abundance, taxa richness, evenness, and dominance values, although total abundance values were very high in some cases, typically due to high abundance of one organism such as the polychaete Aphelochaeta sp. N1. The majority of the samples collected from passages, outer embayments, and larger bodies of water tended to have infaunal assemblages with higher total abundance, taxa richness, evenness, and dominance values. Two samples collected in the Port of Olympia near a superfund cleanup site had no living organisms in them. A weight-of-evidence approach used to simultaneously examine all three “sediment quality triad” parameters, identified 11 stations (representing 4.4 km2, 0.5% of the total study area) with sediment toxicity, chemical contamination, and altered benthos (i.e., degraded sediment quality), 36 stations (493.5 km2, 57.5% total study area) with no toxicity or chemical contamination (i.e., high sediment quality), 35 stations (274.1 km2, 32.0% total study area) with one impaired sediment triad parameter (i.e., intermediate/high sediment quality), and 18 stations (85.7km2, 10.0% total study area) with two impaired sediment parameters (i.e., intermediate/degraded quality sediments). Generally, upon comparison, the number of stations with degraded sediments based upon the sediment quality triad of data was slightly greater in the central Puget Sound than in the northern and southern Puget Sound study areas, with the percent of the total study area degraded in each region decreasing from central to north to south (2.8, 1.3 and 0.5%, respectively). Overall, the sediments collected in Puget Sound during the combined 1997-1999 surveys were among the least contaminated relative to other marine bays and estuaries studied by NOAA using equivalent methods. (PDF contains 351 pages)

Measurement of two-photon excitation cross-section of a new symmetric-type fluorene derivative

A new dye, 2,7-bis(4-methoxystyryl)-9,9-bis(2-ethylhexyl)-9H-fluorene, has been synthesized, which is a D-pi-D symmetrical-type fluorene derivative. The two-photon absorption (TPA) of this new dye has been experimentally studied by comparable two-photon-induced fluorescence method. This new dye has a TPA cross-section of 84 x 10(-50) cm(4) s/photon at 790 nm/13 fs. (c) 2004 Elsevier GmbH. All rights reserved.

Two- and three-photon absorption in a novel fluorene-based compound

A novel symmetrical charge transfer fluorene-based compound 2,7-bis (4-methoxystyryl)-9, 9-bis (2-ethylhexyl)-9H-fluorene (abbreviated as BMOSF) was synthesized and its nonlinear absorption was investigated using two different laser systems: a 140-fs, 800-nm Ti:sapphire laser operating at 1-kHz repetition rate and a 38-ps, 1064-nm Nd:YAG pulsed laser operating at 10-Hz repetition rate, respectively. Unique nonlinear absorption properties in this new compound were observed that rise from multiphoton absorption. The nonlinear absorption coefficients were measured to be 6.02

两种新型芴类衍生物的三光子吸收特性研究

研究了两种新型芴类衍生物9，9-二(2-乙基已基)-2，7-二咔唑-9H-芴(简记为DCZF)和9，9-二(2-乙基已基)-2，7-二(2-(4-甲氧基)苯-2，1-乙烯基)芴(简记为BMOSF)在N，N-二甲基甲酰胺(DMF)中的线性吸收和单光子荧光行为，并用脉冲宽度为38ps，重复频率为10Hz的1064 nm Nd：YAG脉冲激光研究了两种化合物的三光子吸收性质．结果表明：两种新材料的最大线性吸收峰分别位于330和380nm，吸收区域覆盖了270-420nm波段．两种化合物的荧光带位于蓝-紫区，中心

一种新型芴类衍生物的光谱性质研究

合成了具有大π共轭性的对称型芴类衍生物9，9-二（2-乙基已基）-2，7-（2-（4-甲氧基）苯-2，1-乙烯基）芴（简写为MO-F1u—MO）。通过元素分析、质谱、紫外-可见光谱和红外光谱对其进行了表征。测试了该染料在乙腈、二氯甲烷、四氢呋喃和正己烷4种不同极性溶剂中的线性吸收光谱和单光子荧光谱。结果发现溶剂效应对吸收光谱和荧光光谱表现出不同程度的影响，对产生这些光谱行为的主要原因进行了讨论。

ANTHROPOGENIC ORGANIC CONTAMINANTS IN WATER AND SURFACE SEDIMENTS OF LARGE SHALLOW EUTROPHIC CHAOHU LAKE, CHINA

To characterize the contamination of anthropogenic organic contaminants in the aquatic environment of Chaohu Lake, China, 7 samples for both water and surface sediment were collected in the lake. Organic contaminants were extracted by solid phase extraction (SPE) and Soxhlet extraction from the water and surface sediment samples, respectively, and then analyzed by GC-MS. One hundred and twenty kinds of organic chemicals were detected in these samples including phenol, benzene series, benzaldehydes, ethanol, polycyclic aromatic hydrocarbons (PAHs), sulfur compounds, alcoholic halides, amines, ketones, esters, alkenes and alkanes. Among them, 13 kinds of chemicals were identified as priority pollutants listed by the U.S. Environmental Protection Agency (EPA), such as phthalate esters (PAEs) and PAHs. Besides, the concentrations of 19 of PAEs and PAHs including, priority pollutants identified were also determined. Bis(2-ethylhexyl)phthalate, the predominant component of the analyzed pollutants, was in the range from 72.34 ng g(-1) DW to 613.71 ng g(-1) DW, 14.80 ng L-1 to 47.05 ng L-1 in sediment and water, respectively. The results indicated that the northwest part of the lake was heavily polluted by domestic and industrial wastewater.

Distribution of 25 semi-volatile organic compounds of two urban lakes in Wuhan, China

In this study, the levels of 25 semi-volatile organic compounds (SVOCs) were measured in samples of water, suspended particulate matter (SPM) and sediment from two urban lakes in Wuhan, China. The total concentrations of 25 SVOCs varied from 529.4 to 2168.9 ng/L, 120.7 to 22543.7 ng/g dry weight and 1577.3 to 61579.6 ng/g dry wt. in water, SPM and sediment, respectively. The concentration of SVOCs in SPM was 9-10 times higher than that in water, and the concentration of SVOCs in sediment 1.5-2 times higher than that in SPM. The level of total SVOC25 in the samples from Moshuihu Lake was higher than that in Yuehu Lake. Among the 25 SVOCs, phthalate compounds were on the highest level in all observed samples ranging between 441.9-1831.2 ng/L, 116.3-17566.8 ng/g, dry wt. and 6432.8-48177.6 ng/g dry wt. in water, SPM and sediment, respectively. Bis(2-ethylhexyl)phthalate, the predominant component of the analyzed pollutants, was in the range from 246.7 to 537.5 ng/l, 51.2 to 15540.0 ng/g dry wt. and 468.2 to 45010.3 ng/g dry wt. in water, SPM and sediment, respectively. The content of PAHs, dinitrotoluene and isophoton in sediment was higher than that in water and SPM at most of the locations. The possible sources of the pollutants and their inter-relation with human activities were discussed.

Determination of phthalate acid esters plasticizers in plastic by ultrasonic solvent extraction combined with solid-phase microextraction using calix[4]arene fiber

Ultrasonic solvent extraction combined with solid-phase microextraction (SPME) with calix[4]arene/hydroxy-terminated silicone (C[4]/OHTSO) oil coated fiber was used to extract phthalate acid esters (PAEs) plasticizers in plastic, such as blood bags, transfusion tubing, food packaging bag, and mineral water bottle for analysis by gas chromatography (GC). Both extraction parameters (i.e. extraction time, extraction temperature, ionic strength) and conditions of the thermal desorption in a GC injector were optimized by analysis of eight phthalates. The fiber shows wonderful sensitivity and selectivity to the tested compounds. Owing to its high thermal stability (380 degreesC), the carryover effect that often encountered when using conventional fibers can be reduced by appropriately enhancing the injector temperature. The method showed linear response over two to four orders of magnitude with correlation coefficients (r) better than 0.996, and limits of detection (LOD) ranged between 0.006 and 0.084 mug l(-1). The relative standard deviation values obtained were less than or equal to 10%. bis-2-Ethylhexyl phthalate (DEHP) was the sole analyte detected in these plastics and recoveries were in the ranges 95.5-101.4% in all the samples. (C) 2004 Elsevier B.V. All rights reserved.

Reversed micelle formation in a model liquid-liquid extraction system

The formation of reversed micelles and the roles of extractant and extracted complexes were investigated in the Cyanex923/n-heptane/H2SO4 system. Interfacial tension (gamma), electrical conductivity (kappa), and water content measurements showed that Cyanex923 had a tendency to self-assemble, forming reversed micelles. The changes in electrical conductivity with concentration of H2SO4 in the organic phase (CH2SO4,(0)) exhibited an S-type curve: a correlation was found between the change in electrical conductivity and the water content as a function of CH2SO4,(0),.

Aqueous solution of anionic surfactants mixed with soils show a synergistic reduction in surface tension

Water retention and transport in soils is dependent upon the surface tension of the aqueous phase. Surfactants present in aqueous solution reduce the surface tension of aqueous phase. In soil–water systems, this can result in water drainage and reductions in field capacity and hydraulic conductivity. In this investigation, the surface tension of surfactant solutions mixed with soil—in a constant fixed ratio—was measured as a function of surfactant concentration. Two anionic surfactants were used: sodium dodecyl sulphate and sodium bis (2-ethylhexyl) sulfosuccinate. Two soils were also used—a clay soil and a sandy soil. The key observation made by this investigation was that the addition of soil to the surfactant solution provided a further component of surface tension reduction. Neither soil sample reduced the surface tension of water when surfactant was absent from the aqueous phase, though both soils released soil organic matter at low surfactant concentrations as shown by measurement of the chemical oxygen demand of the supernatant solutions. Furthermore, both surfactants were shown to be weakly adsorbed by soil as shown by the use of a methylene blue assay. It is therefore proposed that the additional reduction in surface tension arises from synergistic interactions between the surfactants and dissolved soil organic matter.

Citrate selective electrodes for the flow injection analysis of soft drinks, beers and pharmaceutical products

Aiming the establishment of simple and accurate readings of citric acid (CA) in complex samples, citrate (CIT) selective electrodes with tubular configuration and polymeric membranes plus a quaternary ammonium ion exchanger were constructed. Several selective membranes were prepared for this purpose, having distinct mediator solvents (with quite different polarities) and, in some cases, p-tert-octylphenol (TOP) as additive. The latter was used regarding a possible increase in selectivity. The general working characteristics of all prepared electrodes were evaluated in a low dispersion flow injection analysis (FIA) manifold by injecting 500µl of citrate standard solutions into an ionic strength (IS) adjuster carrier (10−2 mol l−1) flowing at 3ml min−1. Good potentiometric response, with an average slope and a repeatability of 61.9mV per decade and ±0.8%, respectively, resulted from selective membranes comprising additive and bis(2-ethylhexyl)sebacate (bEHS) as mediator solvent. The same membranes conducted as well to the best selectivity characteristics, assessed by the separated solutions method and for several chemical species, such as chloride, nitrate, ascorbate, glucose, fructose and sucrose. Pharmaceutical preparations, soft drinks and beers were analyzed under conditions that enabled simultaneous pH and ionic strength adjustment (pH = 3.2; ionic strength = 10−2 mol l−1), and the attained results agreed well with the used reference method (relative error < 4%). The above experimental conditions promoted a significant increase in sensitivity of the potentiometric response, with a supra-Nernstian slope of 80.2mV per decade, and allowed the analysis of about 90 samples per hour, with a relative standard deviation <1.0%.

Mono, di and polynuclear Cu(II)-azido complexes incorporating N,N,N reduced Schiff base: syntheses, structure and magnetic behavior

Three kinds of copper(II) azide complexes have been synthesised in excellent yields by reacting Cu(ClO4)(2) . 6H(2)O with N,N-bis(2-pyridylmethyl)amine (L-1); N-(2-pyridylmethyl)-N',N'-dimethylethylenediamine (L-2); and N-(2-pyridylmethyl)-N',N'-diethylethylenediamine (L-3), respectively, in the presence of slight excess of sodium azide. They are the monomeric Cu(L-1)(N-3)(ClO4) (1), the end-to-end diazido-bridged Cu-2(L-2)(2)(mu-1,3-N-3)(2)(ClO4)(2) (2) and the single azido-bridged (mu-1,3-) 1D chain [Cu(L-3)(mu-1,3-N-3)](n)(ClO4)(n) (3). The crystal and molecular structures of these complexes have been solved. The variable temperature magnetic moments of type 2 and type 3 complexes were studied. Temperature dependent susceptibility for 2 was fitted using the Bleaney-Bowers expression which led to the parameters J = -3.43 cm(-1) and R = 1 X 10(-5). The magnetic data for 3 were fitted to Baker's expression for S = 1/2 and the parameters obtained were J = 1.6 cm(-1) and R = 3.2 x 10(-4). Crystal data are as follows. Cu(L-1)(N-3)(ClO4): Chemical formula, C12H13ClN6O4Cu; crystal system, monoclinic; space group, P2(1)/c; a = 8.788(12), b = 13.045(15), c = 14.213(15) Angstrom; beta = 102.960(10)degrees; Z = 4. Cu(L-2)(mu-N-3)(ClO4): Chemical formula. C10H17ClN6O4Cu: crystal system, monoclinic; space group, P2(1)/c; a = 10.790(12), b = 8.568(9), c = 16.651(17) Angstrom; beta = 102.360(10)degrees; Z = 4. [Cu(L-3)(mu-N-3)](ClO4): Chemical formula, C12H21ClN6O4Cu; crystal system, monoclinic; space group, P2(1)/c; a = 12.331(14), b = 7.804(9), c = 18.64(2) Angstrom; beta = 103.405(10)degrees; Z = 4. (C) 2004 Elsevier B.V. All rights reserved.

Recovery of lactoferrin and lactoperoxidase from sweet whey using colloidal gas aphrons (CGAs) generated from an anionic surfactant, AOT

The recovery of lactoferrin and lactoperoxidase from sweet whey was studied using colloidal gas aphrons (CGAs), which are surfactant-stabilized microbubbles (10-100 mum). CGAs are generated by intense stirring (8000 rpm for 10 min) of the anionic surfactant AOT (sodium bis-2-ethylhexyl sulfosuccinate). A volume of CGAs (10-30 mL) is mixed with a given volume of whey (1 - 10 mL), and the mixture is allowed to separate into two phases: the aphron (top) phase and the liquid (bottom) phase. Each of the phases is analyzed by SDS-PAGE and surfactant colorimetric assay. A statistical experimental design has been developed to assess the effect of different process parameters including pH, ionic strength, the concentration of surfactant in the CGAs generating solution, the volume of CGAs and the volume of whey on separation efficiency. As expected pH, ionic strength and the volume of whey (i.e. the amount of total protein in the starting material) are the main factors influencing the partitioning of the Lf(.)Lp fraction into the aphron phase. Moreover, it has been demonstrated that best separation performance was achieved at pH = 4 and ionic strength = 0.1 mol/L i.e., with conditions favoring electrostatic interactions between target proteins and CGAs (recovery was 90% and the concentration of lactoferrin and lactoperoxidase in the aphron phase was 25 times higher than that in the liquid phase), whereas conditions favoring hydrophobic interactions (pH close to pI and high ionic strength) led to lower performance. However, under these conditions, as confirmed by zeta potential measurements, the adsorption of both target proteins and contaminant proteins is favored. Thus, low selectivity is achieved at all of the studied conditions. These results confirm the initial hypothesis that CGAs act as ion exchangers and that the selectivity of the process can be manipulated by changing main operating parameters such as type of surfactant, pH and ionic strength.