Submicron particle size and polymerization excess surfactant analysis by capillary hydrodynamic fractionation (CHDF)

The particle size distribution of a blend of two polymer latex monodisperse standards, 86 and 238 nm, has been measured by capillary hydrodynamic fractionation (CHDF). The particle size distributions obtained agreed well with the expected particle diameters. The relative amounts of the two standards in the blends were accurately measured at different blend ratios. The particle size distribution of a parenteral lipid sample was successfully measured. A soluble species was fractionated from latex standards smaller than 100nm. This soluble species appears to be excess surfactant used in the preparation of small size monodisperse latexes. The amount of excess surfactant increases as the particle diameter of the standard decreases.     

Effect of temperature programming on the performance of urea inclusion compound-based free fatty acid fractionation

The effect of cooling rate on the degree of removal of saturated acyl groups from FFA derived from canola oil and the isolation of di- and polyunsaturated acyl groups from FFA derived from vegetable and fish oil, respectively, during urea inclusion compound (UIC)-based fractionation was investigated. Traditionally, slow cooling has been used (ca.−1°C min⁻¹). A more rapid cooling rate (−47°C min⁻¹) produced UIC crystals of similar morphology and thermodynamic properties, but of a size an order of magnitude smaller than the UIC formed during slow cooling. Fractionations used only renewable materials (urea, FFA, and 95% ethanol as solvent) and benign operating conditions (ambient pressure, 25–75°C, and neutral pH). When the recovery of FFA (in the solvent-rich phase) was relatively high (>60%), the selectivity of UIC-based fractionation toward the inclusion of saturated FFA and against polyunsaturated FFA was not affected by the cooling rate. In contrast, when the FFA recovery was low, representing cases in which an increase of the PUFA purity is a more important economic goal, a slower cooling rate resulted in a significantly greater discrimination against PUFA groups, hence to a FFA product with a measurably greater purity. This paper was presented at the 96th AOCS Anual Meeting and Expo, Salt Lake City, Utah, on May 4, 2005.     

Effect of stream segregation on ozonation for the removal of significant COD fractions from textile wastewater

Ozonation was tested on selected streams of cotton finishing textile plant wastewater for optimizing chemical oxygen demand (COD) removal. For this purpose, significant COD fractions in the wastewater were experimentally identified and the effect of ozone on these fractions was investigated. Ozonation experiments were performed with a 1 dm³ sample volume. Ozone treatment of batches of raw wastewater provided, at a rate of 62 mg min^?1 and a gas feeding time of 15 min, achieved complete colour removal but only 21% COD reduction. Increasing the feeding time to 30 min slightly increased the COD removal to 32%. At this feeding time, removal of the readily biodegradable COD was 60%, but soluble inert COD reduction remained at 16%, indicating selective preference of ozone for simpler compounds. At low concentrations, ozone was mainly influential on soluble COD compounds. Longer feeding times also affected particulate compounds, resulting in the solubilization of the COD fractions. Pre‐ozonation of the dye‐house wastewater, as a segregated stream, proved much more effective in the breakdown of refractory organic compounds, rendering the overall plant effluent more amenable to biological treatment. © 2002 Society of Chemical Industry     

RFCC分馏和吸收稳定系统的腐蚀与防护

文章对重油催化裂化装置分馏和吸收稳定系统郎腐蚀产物和腐蚀机理进行了分析和评估,同时结合实际情况提出了一些切实可行的防护措施。     

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.     

Molecular fractionation in melt-crystallized polyethylene: 3. Microscopy of solvent-treated samples

Microscopy of melt-crystallized polyethylenes treated with hot p-xylene has revealed information concerning the morphology of the systems, in particular the distribution of the segregated low molecular weight material in the structure. It seems that this material, in accordance with earlier reports, is concentrated in the spherulite boundaries and between main lamellae within the spherulites. The effect of thermal treatment and the structure of the material on this morphological aspect is reported.     

低分子量聚丙烯的制备及平衡熔点的测定

采用不同温度下溶剂抽提和熔融态下温度梯度萃取两种方法对聚丙烯进行了分级。后一种分级方法可获得相同等规度，分子量分布窄的聚丙烯级份。测得低分子量聚丙烯（Ｍｎ＝２４００，Ｍｗ／Ｍｎ＝２．０）的平衡熔点为３９８．７Ｋ。分析该关品的熔融行为，发现晶体内的晶片厚度有一分布，其随结晶温度的升高而变窄。按照Ｈｏｆｆｍａｎ－Ｇｉｂｂｓ方程，计算出片晶的平均厚度为３．５ｍｍ。     

Scheme for density separation and identification of compound forms in size-fractionated fly ash

A scheme has been developed for the separation of compounds in size-fractionated fly ash by linear density gradients. Minor crystalline components such as calcium ferrite, haematite, magnetite, MgO, barite, anhydrite, rutile and mica were identified in addition to the major compounds mullite, quartz and CaO in a fly ash of pulverized subbituminous coal from western USA. The utility of the scheme in identifying minor crystalline components in fly ash has been demonstrated.     

Antifeedants against <Emphasis Type="Italic">Hylobius abietis</Emphasis> Pine Weevils: An Active Compound In Extract of Bark of <Emphasis Type="Italic">Tilia cordata</Emphasis> Linden

Linden (Tilia cordata) bark was shown to contain an antifeedant effective against the large pine weevil, Hylobius abietis. Soxhlet extraction of inner and outer bark resulted in an extract that showed antifeedant activity in a microfeeding assay. The extract was fractionated by chromatography on silica gel using gradient elution with solvents of increasing polarity. The content of the fractions obtained was monitored by thin layer- and gas chromatography. Fractions of similar chemical composition were merged. Two of the 17 fractions showed antifeedant activity in the microfeeding assay. Nonanoic acid was identified in both of these fractions. Subsequent testing in the microfeeding assay showed that nonanoic acid possessed strong antifeedant activity against H. abietis adults.