Vacuum Distillation Method Research Articles

Deep Tellurium Purification for the Production of Electronic and Photonic Materials

carry out the process of obtaining high-purity tellurium by the vacuum distillation method, a reactor design consisting of high-purity quartz glass and graphite is proposed. During the process, the tellurium melt evaporates; and the vapor is transferred from the hot part of the system to the colder one and condenses in the form of a solid phase (distillate) without the formation of a liquid. Regularities in the redistribution of impurities between the distillate and the cube stillage residue, as well as the spatial distribution of impurities in the distillate during the purification of metallic tellurium, are studied. It is established that some impurities, for example, s-metals, Zn, Ni, and V, and rare metals, are distributed uniformly along the length (20 cm) of the distillate. At the same time, Se tends to concentrate in the far (from the still) part of the distillate with a difference of more than one order of magnitude than in the near part.

Application of vacuum distillation in refining crude lead

This paper introduces a new process for refining crude lead by vacuum distillation. The saturated vapor pressures of lead and impurity elements were calculated, and the removal effect of impurity elements was quantitatively predicted using the vapor-liquid equilibrium diagram. In addition, the low temperature followed by high temperature vacuum distillation method and the high temperature followed by low temperature method were adopted to adjust the order of impurity removal. The refining effect was experimentally studied using these two methods, and the best parameters were determined. The predictions are in close agreement with the experimental results. Based on theoretical and experimental analyses, a new, clean and efficient process for refining crude lead was developed. First, the crude lead was distilled by vacuum distillation at 10 Pa and 1673 K for 30 min, and then, the volatiles and residues were collected. Second, the volatiles were vacuum distilled at 10 Pa and 1273 K for 30 min. The removal rates of Cu, Sn, Ag, Zn, Sb and Bi were 99.73%, 99.72%, 96.23%, 90.78%, 74.80% and 8.82% respectively, and the purity of Pb reached 99.03%.

Recovery of Mercury from Dental Amalgam Scrap-Indian Perspective.

Aim:The aim is to recycle mercury from dental amalgam scrap using the vacuum distillation method.Materials and Methods:A total of 150 g of dental amalgam scrap was taken in a round bottom flask and was subjected to vacuum distillation at 398°C. The vapor of mercury was collected in another round bottom flask.Observation:The procedure is carried out for mercury recovery using vacuum distillation apparatus, and mercury vapor are collected in a round bottom flask, and the silver is recovered using sucrose as reducing agent. Using 150 g of dental amalgam scrap 50%–80% of silver are recovered, and silver has a purity of 70%–80%. However, the total time required in the reduction process ranged between 303 and 600 min.Conclusion:Mercury could be recycled from dental amalgam scrap through vacuum distillation method at 398°C and its implication of dental amalgam scrap in an Indian perspective.

Ammonia nitrogen separation performance and kinetics from biogas slurry using vacuum distillation method

Ammonia nitrogen separation performance and kinetics from biogas slurry using vacuum distillation method

S75 Application of Vacuum Distillation to Treat Wastewater Coming from Hot Rolling Process

Based upon the concepts of vacuum distillation and utilization of waste heat to treat wastewater, a vacuum distillation method has been put forward to be used for treatment of wastewater coming from hot rolling process. Experiments were conducted to study the dependence of pH, electrical conductivity (EC), chemical oxygen demand (COD) and suspended solids (SS) of treated water on operating pressure and evaporation rate. Based upon the analysis of the results, optimum values for the operating pressure and evaporation rate were determined. The results showed that treated water can meet the requirements set for the recycled water in iron and steel industries.

Mg–Al–Ca系合金を真空蒸留した高純度マグネシウムの製造とその押出材の耐食性と引張特性

In order to improve the property of high purity magnesium produced from Mg–Al–Ca alloy, vacuum distillation and extrusion method has been employed. The vacuum distillation with the raw material temperature of 600°C, condenser temperature of 310–350°C, and purification time at 8 h is able to control the amount of impurity such as Fe, Ni and Cu less than 0.0003%. The efficiency of purification and condenser condensate of alloy is achieved nearly 90%. The corrosion rate of high purity magnesium after extruded at 300–375°C and extrusion ratio of 100 is about 0.4 mm/y, which is better than that of purity 99.99% magnesium. Further, the tensile strength of extruded specimen is about 200 MPa, and the elongation is about 15%.

Research on the removal of impurity elements during ultra-high purification process of terbium

Ultra-high purification of terbium (Tb) by vacuum distillation and external getter was investigated. More than 20 kinds of impurity elements were analyzed by glow discharge mass spectrometry (GDMS) and inert gas analysis (IGA). The analysis results show that total impurities decrease from 1114 ppm to 63 ppm. High volatile metallic impurities such as Mg, Ca, Mn, Zn, and Tm can be reduced effectively after distillation. The oxygen (O) concentration can be decreased to 1.8 ppm after deoxidation process, which currently is one of the best results in the contemporary studies. The chemical driving force for deoxidation has been calculated in this paper. The different deoxidation results of Tb metal with various purity have been discussed in detail using the secondary ion mass spectroscopy (SIMS). Finally, a ultra-high purity Tb with low concentration of O can be obtained through vacuum distillation and external getter method.

Using stable isotopes to determine dew formation from atmospheric water vapor in soils in semiarid regions

Moisture sources for dew formation in soils can be classified into soil water and atmospheric water vapor. Discriminating respective contribution of the two moisture sources is important for knowledge of water balance valuation. Stable 2H and 18O of atmospheric water vapor are temporal variation; thus, they may be different to that in soil water, which makes it feasible to discriminate moisture sources between soil water and atmospheric water vapor. In this paper, we took soil samples in the semiarid northern Chinese Loess Plateau and extracted the soil water using the high-temperature vacuum distillation method. Stable isotope profiles and δD-δ18O slopes of the soil water showed that the dew condensed from atmospheric water vapor occurred mainly in the upper 20 cm of the soil layer. The atmospheric water vapor hardly influenced the soil water at 30-cm depth and the deeper soil layer. The significantly low deuterium excess of the soil water at the depth of 10 and 20 cm indicated that the dew in the soil underwent intensive evaporation after the dew formation.

In Vitro Impact of Treatment With Aqueous Extract of Cassia Fistula on Red Blood Cell Sickling in Individuals With Sickle Cell Trait

Background: Sickle cell anemia is an autosomal recessive genetic blood disorder caused by a replacement of an amino acid in the hemoglobin structure, followed by disturbance in its electrical charge. In this disorder, the solubility of hemoglobin is reduced, in hypoxic condition, and formation of crystals occurs, leading to sickling the shape of red blood cells (RBC). The Cassia Fistula (C. fistula) (Flous Plant), as a flowering plant in the fabaceae family, is used as a traditional medicine in the treatment of sickle cell anemia. Objectives: The aim of this study was to evaluate the impact of aqueous extract of C. fistula (the ripped fruit) on red cells in sickle cell anemia. Materials and Methods: The aqueous extract of C. fistula fruit was obtained by vacuum distillation method, using different dilutions of 1:2, 1:4, 1:8, 1:16, 1:50, 1:100, 1:200. The RBC from individuals presenting the hemoglobin S (HbS) trait were washed and treated with different dilutions. After 24 hours incubation, they were evaluated by sickling test (sodium metabisulfite test). The Wilcoxon signed ranks test was used for data analysis. Results: Sickle cells were observed among 20% of subjects with the dilution of 1:50 and 70% of subjects with the dilution of 1:100. Mean percentage of sickle red cells with dilutions of 1:50, 1:100 and 1:200 were 3.75%, 25.75% and 43.0%, respectively. Conclusions: It is suggested that C. fistula may protect RBC against sickling, in hypoxic conditions, in individuals with HbS gene defect.

APPLICATIONS OF MOLECULAR DISTILLATION TECHNIQUE IN FOOD PRODUCTS

There are several separation techniques -including conventional distillation- for extracting heat sensitive compounds from food products. However, some compounds may have high boiling points at which other compounds might be adversely affected. Vacuum application is also needed for such kinds of foods. Molecular distillation is an advanced vacuum distillation method performed by short-path evaporators. Distance between evaporator and condenser is extremely reduced which results in minimized pressure drop. Heat sensitive material meets heat for a shorttime under high vacuum, thus low or no decomposition occurs. This review aims to discuss the basics and uses of molecular distillation in foods.

Impact of Extraction Methods on Antioxidant and Antimicrobial Activities of Citrus Essential Oils

In this study, impact of extraction methods, cold-pressing and vacuum-distillation methods, on yield, chemical composition, antioxidant and antimicrobial activities of citrus essential oils were investigated. The antioxidant activities of citrus essential oils were determined by DPPH scavenging and Ferric thiocyanate assays, while the antimicrobial activities were determined by growth inhibition zone diameter and broth dilution assays against several important foodborne pathogens. The yields of essential oils of Dao lime, PhuTho orange and DoanHung pomelo, extracted by the vacuum-distillation method, were 0.16 %, 0.59 % and 0.04 %, respectively, significantly higher than those extracted by the cold-pressing methods (0.03 %, 0.25 % and 0.03 %, respectively). Total relative concentrations of nine major components of the essential oils extracted by the cold-pressing and vacuum-distillation methods were not significantly different. However, concentration of individual component in the essential oils was changed when using the vacuum-distillation method. Although the essential oils extracted by both cold-pressing and vacuum-distillation methods showed strong antioxidant and inhibition capacities, the antioxidant and antimicrobial activities of citrus essential oils extracted by the vacuum-distillation method were lower than those extracted by the cold-pressing method. As a result, the vacuum-distillation is considered to be the promising innovation theme for producing natural fragrance and essential oil with high production efficiency.

Tracing stable isotopes (δ²H and δ¹⁸O) from meteoric water to groundwater in the Densu River basin of Ghana.

This study represents the first attempt to study soil water δ(18)O profiles in Ghana using a mechanical auger. In this paper, the characteristics of δ(18)O and δ(2)H in rain water, surface water, soil water and groundwater have been used to understand the transformation mechanism of rain water to groundwater. Rain waters were sampled in Koforidua and Accra. Surface water and groundwater were sampled from the Densu River and selected boreholes in the basin, respectively. Soil waters were taken from three typical sites, namely, Potroase (POT), Teacher Mante (TM) and Ayikai Doblo (AD) in the northern, middle and southern zone from 0.00- to 6-m depth. The soil water was extracted using vacuum distillation method. The distribution of the stable isotopes of rain water is influenced by rainfall amount with minimal temperature effect. In general, the soil water is of meteoric origin undergoing fractionation-controlled evaporation. In the middle zone, the soil water shows some evidence of recharge from enriched source. The three profiles show similar trend of enriched values in the upper depths with gradual depletions of δ(18)O with depth. The POT profile showed relatively more depleted values suggesting a fast infiltration. In all the three profiles, soil waters below 3m were found to contribute to groundwater recharge with piston flow as the dominant mechanism. The study also revealed that there is a significant contribution of enrich source to the groundwater system leading to the dilution of the infiltrating water by the large aquifer.

Quantitative Vacuum Distillation of Crude Oils to Give Residues Amenable to the Asphaltene Determinator Coupled with Saturates, Aromatics, and Resins Separation Characterization

The automated Asphaltene Determinator coupled with saturates, aromatics, and resins (SAR–AD) separation is a powerful characterization tool initially designed for the rapid and repeatable analysis of asphalt bitumen and petroleum residua. By virtue of the evaporative light scattering detector (ELSD) and the fact that saturates and a portion of aromatics do not contain chromophores, making them undetectable in the 500 or 700 nm detectors, the complete quantification of petroleum fractions by this method is somewhat restricted to samples that do not contain a significant amount of volatiles. Crude oils can contain more than 70% of volatile material, which is not detected by the ELSD. To overcome the SAR–AD volatile limitation, a quantitative vacuum distillation method was developed to capture the volatiles and produce unaltered residua that does not lose volatiles in the ELSD. To complete the characterization, the volatiles are analyzed for their saturate, aromatic, and reactive olefin contents by proton nu...

Concrete Corrosion in Tunnels: A Stable O and H Isotope Study of TSA Mechanism

Degradation of concrete caused by the formation of secondary hydrous sulfate minerals (e.g. thaumasite, ettringite and gypsum) can cause serious problems concerning the durability of building structures. To provide a better understanding of the formation conditions of these sulfate minerals we have investigated thaumasite (Ca3Si(OH)6(CO3)(SO4)•12H2O), ettringite (Ca6Al2(SO4)3(OH)12•26H2O) and gypsum (CaSO4•2H2O) with the aim of extracting crystal (i.e. structural) water and analysing its stable O and H isotopes. The crystal water was released and collected using a heating and vacuum distillation method followed by δ2H and δ18O analyses on a liquid water isotope analyser. Results indicated that this setup is highly promising to trace the isotopic composition of water involved in the precipitation of the various hydrous sulfate mineral. Based on our data we calculated O and H isotope fractionation factors for thaumasite and ettringite between crystal and aqueous H2O. The results agree with previous findings that the sulfate mineral formation, responsible for concrete damage, is occurring in highly concentrated solutions (5000 up to 30000mg L-1 SO4) due to evaporation.

Nickel powders recycled from invar scrap by magnesiothermic reduction.

A study on the recovery of nickel from Fe-Ni alloy scrap was conducted using molten magnesium by dissolving only Ni component and then removing Mg using vacuum distillation method. The recovering faction of nickel higher than 99% was achieved at temperatures above 1,073 K and 99.5% of purity level of nickel was successfully obtained under vacuum degree of 10(-5) torr at temperatures above 1,273 K. The purity, phase, and recovery rate of nickel were examined by scanning electron microscopy, elemental analyser, and X-ray diffraction.

Improved synthesis of [18F]FLETT via a fully automated vacuum distillation method for [18F]2-fluoroethyl azide purification

The synthesis of [18F]2-fluoroethyl azide and its subsequent click reaction with 5-ethynyl-2′-deoxyuridine (EDU) to form [18F]FLETT was performed using an iPhase FlexLab module. The implementation of a vacuum distillation method afforded [18F]2-fluoroethyl azide in 87±5.3% radiochemical yield. The use of Cu(CH3CN)4PF6 and TBTA as catalyst enabled us to fully automate the [18F]FLETT synthesis without the need for the operator to enter the radiation field. [18F]FLETT was produced in higher overall yield (41.3±6.5%) and shorter synthesis time (67min) than with our previously reported manual method (32.5±2.5% in 130min).

물질흐름분석을 통한 폐윤활유 재활용 공정의 정제유 생산량 산정

This paper presents the estimation of actual recyclable amounts and the evaluation of waste oil recycling processes at recycling facilities using material flow analysis (MFA). The estimation of actual recycling rates through the processes of waste lubricating oils is a very important subject not only in the point of view oil recycling efficiency by energy conversion processes but also in the perspective of the recycling technology level. In this study, the recycling processes and recycling rates of waste lubricating oil recycling facilities were evaluated by using a MFA approach, a total of 10 site visits and a total of 30 site questionnaires in Korea. The MFA methodology based on mass balance approach applied to identify the inputs and outputs of waste oils during the recycling processes at waste oil recycling facilities. It is necessary to determine the composition and flows of the input materials to be recycled and foreign substances in a waste recycling facility. A complete understanding of the waste flows in the processes along with the site visit and data surveys for the recycling facilities was required to develop a material flow for the processes and determine the process yield by different treatment methods (chemical distillation, vacuum distillation and high temperature pyrolysis). The results show that on average the process yields for chemical distillation, vacuum distillation, and high temperature pyrolysis were 89.9 ± 7.7%, 77.9 ± 16.1%, and 57.9 ± 9.3%, respectively. During the chemical distillation method, water in waste oils was a major fraction (> 50%), while the vacuum distillation method resulted oil large amounts of oil sludge produced during the recycling process. The process yields for different treatment methods depended upon several factors including the quality of incoming waste oils, the type and operating conditions of recycling processes that are applied to. Based on the material flow analysis in this study, the actual recycled amount of waste oil was estimated to be approximately 260,809 ton in 2011.

Validation and application of a cryogenic vacuum extraction system for soil and plant water extraction for isotope analysis

Abstract. Stable isotopic analysis of water in plant, soil, and hydrological studies often requires the extraction of water from plant or soil samples. Cryogenic vacuum extraction is one of the most widely used and accurate extraction methods to obtain such water samples. Here, we present a new design of a cryogenic vacuum extraction system with 18 extraction slots and an innovative mechanism to aerate the vacuum system after extraction. This mobile and extendable multi-port extraction system overcomes the bottleneck of time required for capturing unfractionated extracted water samples by providing the possibility to extract a larger number of samples per day simultaneously. The aeration system prevents the loss or mixture of water vapor during defrosting by purging every sample with high-purity nitrogen gas. A set of system functionality tests revealed that the extraction device guarantees stable extraction conditions with no changes in the isotopic composition of the extracted water samples. Surprisingly, extractions of dried and rehydrated soils showed significant differences of the isotopic composition of the added water and the extracts. This observation challenges the assumption that cryogenic extraction systems to fully extract soil water. Furthermore, in a plant water uptake study different results for hydrogen and oxygen isotope data were obtained, raising problems in the definition from which depths plants really take up water. Results query whether the well-established and widely used cryogenic vacuum distillation method can be used in a standard unified method of fixed extraction times as it is often done.

Highly efficient click labeling using 2-[18F]fluoroethyl azide and synthesis of an 18FN-hydroxysuccinimide ester as conjugation agent

Click labeling using 2-[¹⁸F]fluoroethyl azide has been proven to be promising methods of radiolabeling small molecules and peptides, some of which are undergoing clinical evaluations. However, the previously reported method afforded low yield, poor purities and under desirable reproducibility. A vacuum distillation method was used to isolate 2-[¹⁸F]fluoroethyl azide, and the solvent effect of acetonitrile and dimethylformamide (DMF) on the click labeling using Cu(I) from copper sulfate/sodium ascorbate was studied. The labeling conditions were optimized to radiosynthesize a hydroxysuccinimide ester (N-hydroxysuccinimide, or NHS). 2-[¹⁸F]fluoroethyl azide was isolated by the vacuum distillation method with >80% yield within 10min in a "pure" and click-ready form. It was found that the amount of DMF was critical for maintaining high levels of Cu(I) from copper sulfate/sodium ascorbate in order to rapidly complete the click labeling reaction. The addition of bathophenanthrolinedisulfonic acid disodium salt to the mixture of copper sulfate/sodium ascorbate also greatly improved the click labeling efficiency. Through exploiting these optimizations, a base-labile NHS ester was rapidly radiosynthesized in 90% isolated yield with good chemical and radiochemical purities. We have developed a general method to click-label small molecules efficiently using [¹⁸F]2 for research and clinical use. This NHS ester can be used for conjugation chemistry to label antibodies, peptides and small molecules as positron emission tomography tracers.

An effective method for thallium bromide purification and research on crystal properties

Thallium bromide (TlBr) is a promising candidate for room-temperature X- and gamma-ray detectors in view of its excellent intrinsic features. However, material purity and crystal quality concerns still limit the use of TlBr crystals as detectors. In this work, a combination of hydrothermal recrystallization (HR) and vacuum distillation (VD) methods were applied to purify TlBr salts prior to crystal growth. Trace impurities at the ppb/ppm level were determined by inductively coupled plasma mass spectroscopy (ICP-MS). The results showed that the impurity concentrations of the TlBr salt decreased significantly after HR and VD purification, and high performance of the resultant TlBr crystal in areas such as electrical and optical properties was achieved. The combination of HR and VD methods could fabricate purer material, with an order of magnitude higher resistivity and better optical quality, than HR or VD method used separately. The possible technological considerations affecting the parameters of the crystals are investigated.