Cleaning Efficiency of Amino‐Acid Surfactants with Polyoxyethylene Ether and Isopropanol in Liquid Carbon Dioxide

Although anionic surfactants have a distinct positive influence on the removal of particulate soil, the removal of particulate soils is insufficient in CO₂ compared to perchloroethylene. A series of amino‐acid surfactants was selected as main surfactants to study the influence of polyoxyethylene ether and cosolvent on the cleaning effect. Glu‐C12 and C16(3) gave the best cleaning results, which increased from a detergency value of 4.6 when no surfactants were used to 8.32 when surfactants were used. In all experiments, charged anionic surfactant particles were formed, which are responsible for the removal of particulate soil from fabric by electrostatic repulsion. The use of a cosolvent (Isopropanol [IPA]) had a positive effect on the removal of particulate soil when using Glu‐C12 and TX‐45. However, for other compounding combinations, the addition of IPA had a negative effect on particulate soil removal. Of the cosolvents investigated, IPA was the most suitable. With the polarity of the system increasing after adding IPA, the ethylene oxide groups of TX‐45 were partially extended to CO₂. Through the steric effects of branched methyl groups, the cleaning effect was improved.     

Pervaporation of Organic Liquids from Binary Aqueous Mixtures using Poly(trifluoropropylmethylsiloxane) and Poly(dimethylsiloxane) Dense Membranes

In this work we have compared and contrasted the pervaporation behaviour (separation factor and flux) of fluorosilicone dense membranes based on poly(trifluoropropylmethylsiloxane) (PTFPMS) with poly(dimethylsiloxane) (PDMS) dense membranes. In particular, pervaporation experiments were carried out at 298 K using lab-made PTFPMS, lab-made PDMS and commercial PDMS membranes in order to remove three different organic liquids pyridine (PY), isopropanol (IPA) and methylethylketone (MEK) from dilute (<10 wt.%) binary aqueous mixtures. All of the silicone membranes studied were found to be successful for the desired separations. The permeation flux of pyridine–water liquid mixtures for the PTFPMS membranes was found to increase with the pyridine concentration in the feed mixtures. The separation factor for PDMS membranes for the removal of pyridine, IPA and MEK from aqueous binary mixtures (1 wt.%) was found to be higher than that of PTFPMS membranes while the normalized flux was higher for PTFPMS membranes under identical test conditions. The effect of crosslink density of the PTFPMS membranes on the separation of pyridine–water mixtures was also studied. For a 1 wt.% feed solution the total flux increased with the molar mass between crosslinks, whereas the separation factor for pyridine–water was highest for a molar mass between crosslinks of 15,320 g mol⁻¹.     

Phase Separation of Lactan Gum from Fermentation Broths by Addition of Water-Miscible Organic Solvents

Abstract

A microbial polysaccharide (lactan gum) produced by bacterium ATCC 55046 was precipitated from fermentation broths by the addition of ethanol, acetone, isopropanol, or tert-butanol. Compositions of the precipitate and supernatant phases were determined as a function of organic solvent concentration and used to construct binodal solubility curves. Lactan did not precipitate at bulk-mixture organic solvent concentrations below 35% (wt) ethanol, 35% acetone, 33% isopropanol, or 25% tert-butanol. At organic solvent concentrations just exceeding the solubility transition point, the precipitates were soft, moist, and sponge-like in texture, with low lactan concentrations. At higher organic solvent concentrations the precipitates were compact and dense. The maximum lactan concentration in the precipitate was 25–37%, depending on the organic solvent type and concentration. Increasing the organic solvent concentration beyond 50% for ethanol, or 70% for acetone, decreased the lactan concentration in the precipitate. No such decrease occurred for isopropanol and tert-butanol. Thus, organic solvent usage, from greatest to least, was in the order ethanol, acetone, isopropanol, and tert-butanol, but the maximum lactan concentration in the precipitate, from greatest to least, was in the order acetone, isopropanol, ethanol, and tert-butanol.     

Comparison of Lipid Extraction from Microalgae and Soybeans with Aqueous Isopropanol

The extraction efficiency of microalgae lipids with aqueous isopropanol (IPA) was investigated and compared with the extraction of oil from full-fat soy flour. The effects of the type of microalgae (Scenedesmus sp. and Schizochytrium limacinum), cell rupture, and IPA concentration on the yield of oil and non-lipid biomass were determined. The oil yield from intact cells of Scenedesmus was 86–93 % with 70, 88, or 95 % (by wt) IPA. Ultrasonic cell rupture prior to oil extraction decreased the oil yield of Scenedesmus to 74 % when extracting with 70 % IPA. The oil yield from intact cells of S. limacinum was <23 % regardless of the IPA concentration, but ruptured cells gave a 94–96 % oil yield with 88 or 95 % IPA. The different response of the two microalgae to extraction with IPA is possibly caused by differences in the cell wall structure and type and amount of polar lipids. The oil yield from soy flour with 88 and 95 % IPA was 93–95 %, which was significantly greater than yields with 50 and 70 % IPA. Cell rupture had no effect on soy flour extraction. In general, the oil yield from the ruptured cells of both microalgae and soy flour increased with increasing IPA concentration.     

Ni2P as an electron donor stabilizing Pt for highly efficient isopropanol fuel cell

A key challenge for isopropanol fuel cell is to find efficient catalyst for the catalytic ability improvement of isopropanol electro-oxidation reaction. Here, we anchor Pt nanoparticles on the Ni₂P/resin carbon (RC) to form a Pt–Ni₂P/RC assembly. Strong interactions at Ni₂P–Pt interface induce the Ni₂P to donate electrons to stabilize Pt, thus effectively decreasing the adsorbed energy of isopropanol. As a result, Pt–Ni₂P/RC exhibits much higher mass activity and better stability than those of Pt/RC and Pt/C. When assembled into a direct isopropanol fuel cell, Pt–Ni₂P/RC shows a peak power density of 0.095 W cm⁻², which is 31.9% greater than that of Pt/C catalyst. Our results offer a new strategy to stabilize Pt by an electron donor for developing affordable direct isopropanol fuel cells.     

Design,Calibration, and Test of a New Dissolution Isoperibol Microcalorimeter

Abstract

A new cell type batch isoperibol microcalorimetric for the determination of dissolution enthalpies of small amounts of easily or slightly soluble solids was developed at the Universities of the Andes and the National University of Colombia.

An innovative mixing system for avoiding error due to the common brittle point breakage effect has been designed in this new cell. This cell has a capacity of 40 mL and the sample holder can contain solid samples between 10.0 and 30.0 mg. The high stability of the baseline allows solution experiments to be extended over several hours. All measurements reported were conducted at 298.15 K using water as the solvent. The microcalorimeter was electrically calibrated in order to establish a calibration constant and thermal leakage. On the other hand, the device was chemically calibrated by potassium chloride dissolution. The performance of the instrument was further tested by measuring the dissolution enthalpies for acetanilide and adenine (18.25±0.56 and 31.78±0.64 kJ mol^?1, respectively). No concentration dependence was found. The results agreed with previous reports.     

Thermal and chemical inactivation of lactococcal bacteriophages

Ten lactococcal bacteriophages in M17 broth were treated by heat (72 °C, 15 min and 90 °C, 5 min), ethanol and isopropanol at concentrations of 10%, 50%, 75% and 100% (v/v). The heat treatments were not sufficient to inactivate all the bacteriophages studied whereas ethanol, which was also more efficient biocide than isopropanol, at a concentration of 75% could inactivate all the phages in 1 min. The 50% and 75% of ethanol were more effective than 100%, which was also observed for isopropanol. Survival curves’ deviations from linearity as sigmoidal shapes could be described via an empirical model with four parameters. The parameters of the model could be reduced from four to two with a slight loss of goodness-of-fit. The reduced model also provided good fit to describe the isopropanol inactivation kinetics of the phages at concentrations of 50% and 75%. This demonstration may also be a useful tool for further inactivation studies in which ethanol or other biocides are used with sufficient survival data points at selected time intervals. Although more studies should be carried out with different phages, this study confirmed the lethal effect of ethanol, commonly used to disinfect utensils and laboratory equipment, on lactoccocal bacteriophages.     

气相色谱法测定火药中异丙醇、乙酸乙酯和苯的含量

用气相色谱法对火药中异丙醇、乙酸乙酯和苯的含量进行测定。样品用甲醇提取,采用氢火焰检测器检测,检测器温度200℃,柱箱温度145℃,气化室温度190℃,载气为氮气,流速50 m L/min,外标法定量。该方法对异丙醇、乙酸乙酯和苯的最低检测浓度为0.5,0.3,0.6μg/m L;在5~100μg/m L浓度范围内均呈良好的线性关系,线性系数r0.990;方法回收率在94.8%~96.5%之间,相对标准偏差(n=6)在2.5%~3.6%之间。符合火药质量检测的要求,方法可用于火药中异丙醇、乙酸乙酯和苯含量的检测。     

白花菜籽油的制备及脂肪酸组成分析

采用溶剂浸提法提取白花菜籽油,对其提取工艺条件进行了研究,并用气相色谱法对其脂肪酸的种类和相对含量进行了测定。结果显示,以异丙醇为浸提溶剂,料液比(质量体积比)为1∶7,浸提时间为60 min,浸提温度为60℃时,白花菜籽油的提取率最高为28.4%。利用气相色谱鉴定出14种脂肪酸,主要有亚油酸(62.65%)、油酸(20.66%)、棕榈酸(10.98%)、硬脂酸(4.18%),饱和脂肪酸质量分数为15.68%,不饱和脂肪酸质量分数为84.32%,其中单不饱和脂肪酸质量分数为21.01%,二不饱和脂肪酸质量分数为62.65%,三不饱和脂肪酸质量分数为0.67%。     

从异丙醇副产叠合油中提取高纯度异丙醚

在对异丙醚的生产方法和作用进行简介的同时,着重对从异丙醇副产叠合油中提取高纯度异丙醚的方法进行了论述,并对所得到的工艺流程进行了交代。