Vacuum Distillation Procedure Research Articles

Chemically recyclable polyurethanes based on bio-renewable γ-butyrolactone: From thermoplastics to elastomers

The large-scale production and disposal of petroleum-derived commercial polyurethane materials have caused severe enviroment problem. Although the bio-based or biodegradable polyols have attracted considerable attention to prepare sustainable polyurethanes, the chemical recycling of polyurethanes via controlled bond scission reactions to recover monomer or value-added building blocks still remains as a big challenge. In this contribution, we address this challenge by preparation of biodegradable and chemically recyclable polyurethanes using bio-based telechelic hydroxyl terminated poly(γ-butyrolactone) (PγBL) diols as precursors. The obtained polyurethanes exhibited thermoplastic or elatomeric properties depending on the molar mass of used PγBL diol precursors. The thermal, mechanical and hydrolytic properties of PγBL based polyurethanes are systematically investigated. Remarkably, the polyurethanes are capable of chemical recycling to recover γBL with high purity in an almost quantitative yield by a simple vacuum distillation procedure.

A selective volatilization and condensation process for extracting precious metals from noble lead

Noble lead, which is produced by the reduction smelting of lead anode slime, contains copious rare and precious metals. The vacuum distillation procedure for processing noble lead exhibits the advantages of efficiency and simplicity, and has been industrialized in most of China’s lead, copper and precious metal smelting enterprises. However, the condensation behaviors of volatile components in noble lead remain unknown, making effective Pb and Sb removal difficult; thus, the corresponding system equipment fails to meet the production requirements of separating alloys and enriching precious metals. In this paper, the condensation area of volatile components in noble lead is predicted by the molecular mean free path. Then, preliminary verification and experimental research were carried out on the condensation rules of each component to verify and revise the theory. The experimental results indicate that the dominant condensation zones of Pb and Sb are 24–44 mm and 44–59 mm, respectively. Further experimental studies show that Pb and Bi are removed to below 0.8%, and the direct yields of Pb, Bi and Ag reached 91%, 95% and 94%, respectively, with temperature of 1250 °C, holding time for 3 h and pressure of 5 Pa. This research solves the problem of difficult Pb and Sb removal in the conventional vacuum distillation process of noble lead and realizes the efficient recovery of metals, which has practical guiding significance for the technological conditions in the industrial application of this process and the equipment design. This work meets modern cleanliness, efficiency, and simple metallurgical requirements.

Internal standards: A source of analytical bias for volatile organic analyte determinations

The use of internal standards in the determination of volatile organic compounds as described in SW-846 Method 8260C introduces a potential for bias in results once the internal standards (ISTDs) are added to a sample for analysis. The bias is relative to the dissimilarity between the analyte and internal standard physical properties that influence how easily analytes are separated from a matrix and concentrated during analysis.Method 5032 is a vacuum distillation procedure for extracting analytes from a sample for use with Method 8260C. Vacuum distillation is also incorporated within another GC/MS analytical procedure, Method 8261A. Method 8260C/5032 and Method 8261A are experimentally identical, however, Method 8261A uses internal standards differently by relating the recovery of each compound to its boiling point and relative volatility. By processing each analysis (water, soil, and biota) using both Method 8260C and Method 8261A, the two approaches are compared on the basis of analyte bias and the failure rate of the quality controls.Analytes were grouped by how similar their boiling points and natural log of their relative volatilities (lnRVs) were to their Method 8260C recommended ISTDs. For the most similar analytes, the Method 8260C determinations yielded an average bias less than 10% and a failure to meet calibration criteria less than 7%. However, as the difference between analyte and ISTD became greater the bias increased to over 40% (matrix dependent) and its calibration failure rate approached 70%. In comparison, when the Method 8260C data were reprocessed as Method 8261A determinations, this trend for groupings was minimized with biases increasing from 6% to only 20% and the calibration failure rate went from 0% to 15%.

ETHANOL FERMENTATION WITH SHOCHU DISTILLERY WASTE AND AROMATIC RED RICE BRAN

Shochu distillery waste which had been exhausted by a vacuum-distillation procedure at low temperature (35–40°C) was used for secondary ethanol fermentation with the bran of aromatic red rice (Oryza sativa var. Indica, Tapol). The filtrate of the fermented mash made from kome shochu distillery waste and aromatic red rice bran had a characteristic wine-like red color, contained about 12% ethanol (v/v), and possessed a fine aroma that was fortified with the aromas of higher alcohols and volatile esters during secondary ethanol fermentation. A novel red alcoholic beverage was produced from the industrial by-product of shochu-making, kome shochu distillery waste and a by-product of Sekihan-cooking, aromatic red rice bran. The filtrate of the fermented mash had a characteristic absorbance at 530 nm. As the amounts of aromatic red rice bran in the mash were increased, the absorbance at 530 nm increased. Thus, a novel system utilizing shochu distillery waste, which is conventionally treated as wastewater, and aromatic red rice bran was established economically using a simple vacuum-distillation and secondary ethanol-fermentation procedure without the need for any complicated or expensive processes.

TEST OF ORGANIC SBS LIQUIDS IN THE IR AND UV

Several organic liquids were tested for their SBS reflectivity in the IR and the UV. Especially, the influence of impurities was investigated for both spectral ranges. Chemically specified impurities may decrease the SBS efficiency, particularly in the UV region. In addition undissolved particles spoil the SBS-reflectivity. These particles are detected by light scattering and can be removed using a vacuum distillation procedure. Thus, the reflectivity of e.g. acetone could be increased by a factor of two.

SEMICONTINUOUS ETHANOL FERMENTATION WITHSHOCHUDISTILLERY WASTE*

An effective utilization system using distillery waste discharged from Japanese traditional shochu factory was developed. Mugi (barley) shochu distillery waste discharged from a novel vacuum distillation procedure (35–40°C) contained a large number of viable yeast (7 × 106 cells/ml), glucoamylase activity (19.7 units/ml), acid protease activity (940 units/ml), and neutral protease activity (420 units/ml). Ethanol fermentation was achieved with a mash composed of glucose as the sola carbon source and mugi shochu distillery waste. After ethanol fermentation was completed the fermented broth was again distilled at 35–40°C in vacuo and the non volatile residue used in the next ethanol fermentation. In this way, semicontinuous ethanol fermentation system of more than 10 cycles was developed. Even in the distillate of the mash of the 8th fermentation cycle, 7.9% of ethanol, 33.0 ppm of ethyl acetate, 28.5 ppm of isobutyl alcohol, and other aromatic compounds were present. A semicontinuous ethanol fermentation system has been developed for shochu distillery waste which conventionally is treated as wastewater.

Solid-Phase Extraction Method for Volatile N-Nitrosamines in Hams Processed with Elastic Rubber Netting

Abstract A method was developed for the determination of volatile N-nitrosamines in hams processed In elastic rubber nettings. The method was based on a modification of a solid-phase extraction (SPE) procedure used in the past to determine selected nitrosamines in different types of cured meat products. The nitrosamines detected in ham most likely originate from the amine precursors in rubber and from the nitrite commonly used in the meat curing process. The method was compared with 2 established procedures for N-nitrosodibutylamine (NDBA) analysis in cured meat products: the mineral oil distillation procedure (MOD) and the low temperature vacuum distillation procedure (LTVD). All 3 methods used the same gas chromatographic/chemlluminescent detection conditions and system. No significant difference was found between the MOD and LTVD methods. These methods were found to yield significantly higher NDBA levels than the SPE procedure. When 2,6-dimethylmorpholine was added to the sample before analysis in the MOD and LTVD procedures, artifactual nitrosamines were formed. No artifactual formation was noted in the SPE method. We propose that the new SPE method replace the current methods being used for analysis of netted, cured meat products.

Reflectivity enhancement of stimulated Brillouin scattering liquids by purification

The efficiency of stimulated Brillouin scattering (SBS) in liquids depends on the purity of the applied materials. Besides the certificated chemical impurities little indissolvable dust particles may disturb the SBS process. We demonstrate a vacuum distillation procedure for purification of the commercially available liquids. The reflectivities determined for broadband Q-switched Nd: YAG laser pulses could be enhanced up to factor of two for the distilled liquids.

Batchwise ethanol fermentation with shochu distillery waste

A novel vacuum distillation procedure at low temperature (35–40°C) was applied to shochu distillation to produce a shochu with a mild aroma. The resulting kome (rice) shochu distillery waste contained a large amount of viable yeast (7 × 10 6 cells/ml), glucoamylase activity (70 U/ml), acid protease activity (720 U/ml), and neutral protease activity (420 U/ml). Secondary ethanol fermentation of the mash composed only of glucose as a carbon source and kome or mugi (barley) shochu distillery waste was properly effected. About 10% of ethanol (v/v) was produced in the fermented mash at 30°C within 3 d. In contrast, distillery waste discharged by conventional distillation at high temperature (55–60°C) could not be used for secondary ethanol fermentation at all. The filtrate of secondarily-fermented distillery waste, containing ethanol and possessing a fine aroma fortified with higher alcohols and volatile esters during ethanol fermentation, could be useful for the production of a mirin-like liquor for cooking, Akazake, a characteristic red-colored, sweet alcoholic beverage produced in Kumamoto prefecture only, and a bath additive containing ethanol, a fine aroma, and enzymes. The solid cake of the fermented mash could be used in the same way as conventional sake-kasu, sake-cake. Here, a novel system of utilizing shochu distillery waste, conventionally treated as wastewater, was established economically using a simple vacuum distillation procedure without a need of any complicated process.

Analysis of volatile fatty acids by ion-exclusion chromatography, with special reference to marine pore water

A method for measuring volatile fatty acids using ion-exclusion chromatography is presented. The system was found to be applicable to samples with high salt concentrations (e.g. seawater and marine pore water) when coupled with a vacuum distillation procedure. The method is straightforward, with no sample preconcentration and no introduction of external contamination. Calibration was found to be linear, with good reproducibility (coefficient of variation normally less than 5%) and the system was sufficiently sensitive to operate at the sub-ppm level (minimum detection limit for acetate and propionate was approximately 0.02 and 0.05 ppm, respectively). This technique was used to investigate the distribution of volatile fatty acids with sediment depth at Station E70 in Loch Eil, Scotland (sample was collected in March, 1983) and the results were in good agreement with recent publications. Although the system, at present, is limited in marine pore water to acetate and propionate, it has certain advantages over alternative systems and these are described.

Volatile fatty acids in human peripheral and portal blood: Quantitative determination by vacuum distillation and gas chromatography

In order to determine volatile fatty acids (VFA) in human blood, gas chromatographic analyses were performed after blood samples had been pre-treated by a vacuum distillation procedure with subsequent evaporation. Results of the reproducibility study, investigated by pre-treating five aliquots of one human serum sample showed C.V. values ranging from 7.4 to 18.2. Normal serum VFA values were determined in individual serum samples collected from healthy subjects and compared to those present in serum from patients undergoing gallbladder surgery. The serum VFA values were comparable in the two groups. In the surgical patients, blood was also collected from the portal circulation. All portal serum VFA values, except that of iso-butyric acid, were higher than those found in the samples collected from the peripheral arm vein. VFA values were also determined in serum specimens obtained from blood collected from the arm vein of patients with extensive cirrhosis of the liver. The VFA values showed marked individual variations and were higher than those found in peripheral samples from healthy subjects and patients undergoing gall-bladder surgery, but were lower than those found in samples from the portal circulation from the surgical patients.

Pretreatment methods prior to gaschromatographic analysis of volatile fatty acids from faecal samples

Vacuum distillation and steam distillation have been compared as pretreatment methods prior to the GC analysis of volatile fatty acids (VFA) in faecal material. Vacuum distillation resulted in a recovery range of 90–110% for all VFA in standard solutions. This was superior to the recovery ranges found after pretreatment by steam distillation. Coefficients of variance for steam distilled samples were higher than for vacuum distilled samples. Using a faecal homogenate, the vacuum distillation method was found to be highly reproducible. Spiking experiments substantiated the quantitative recovery of VFA from vacuum distilled samples. Modifications of the standard vacuum distillation procedure showed that care must be taken to ensure adequate cooling of the receiver tube.

Gas-Liquid Chromatographic Method for Determination of Fat-Soluble Vitamins. III. Evaluation of a Vacuum Distillation Procedure for Vitamin E Isolation, Using C-14 Labelled Alpha-Tocopheryl Acetate

Abstract Alpha-tocopheryl acetate, carbon-14 labelled in the methyl group at the two position, was used to determine the stability and recovery of the vitamin during vacuum distillation (140–160°C, and 0.020 mm Hg pressure, 60 minutes). Evaluation was based on measurements of radioactivity with a liquid scintillation spectrometer and a lowbackground Geiger counter. Recoveries of 20 mg of the pure compound were nearly quantitative (97%). Recoveries of the tocopheryl ester added to lard, “stripped” of vitamin E, at 0.5 mg/g or less and to butter at 0.1 mg/g were 98 and 82%, respectively. Results of the differential counting technique suggest that the ester is increasingly unstable at temperatures exceeding 160° and that a molecular rearrangement probably takes place.

Carbonyls in oxidizing fat. VII. A comparison of methods of isolating monocarbonyl compounds

AbstractComparison of quantitative methods for the isolation of aldehydes from lard oxidized at 23C showed an extreme sensitivity of precursors to isolation conditions. Differences existed in the quantity and class compositions of the monocarbonyl compounds isolated. Acid conditions caused considerable breakdown of alkanal and alk‐2‐enal precursors. Steam distillation (100C) released alkanals, alk‐2‐enals, and alk‐2,4‐dienals. The mild Girard T method apparently produced a small amt of alk‐2‐enals from precursors, but except in the initial stages isolated the lowest amounts of aldehydes. Complete evaluation of the method for isolation of free aldehydes was not possible because alkanals were released from precursors during the vacuum distillation procedure (50C). The Schwartz (dilute phosphoric acid), Girard T, and vacuum distillation methods isolated similar amounts of alk‐2,4‐dienals. Curious changes in relationships, possibly indicative of oxidation stages, were observed as autoxidation progressed.

Simple vacuum distillation procedure for determination of the volatile carbonyl content of autoxidising edible fats

AbstractA vacuum distillation procedure is described which, when applied to 10 g. of fat, will recover quantitatively added aliphatic aldehydes ranging in volatility from propanal to dodecanal at a concentration of 0.1 μmole/g. With autoxidising fats the method estimates, more directly than chemical tests for rancidity in present use, the class of substances responsible for rancid and reverted off‐flavours.