Distillation Time Research Articles

Method for attaining rosemary essential oil with differential composition from dried or fresh material.

Rosemary (Rosemarinus officinalis L.) is a well-known medicinal and essential oil plant, utilized by humankind since ancient times. The objective was to determine the effect of steam distillation time (DT) and material (dry or fresh biomass) on essential oil yield, composition, and bioactivity; and to develop regression models that can predict oil yield and composition at specific DT. The oil yield (content) from dry biomass was higher (0.43%) than that from fresh biomass (0.35%) and ranged from 0.18% in the 1.25 min DT to 0.51% in the 40 min DT. There was no yield advantage in extending the DT beyond 40 min, which is much shorter than the DT used by industry. In this study, the antioxidant capacity of the rosemary oil using the ORACoil method was 4,108 μmolVE/L. Rosemary oil did not exhibit significant antileishmanial, antimalarial, or antimicrobial activity. In general, the low-boiling constituents eluted earlier than the higher boiling constituents of the essential oil, resulting in a great variation of essential oil composition obtained at different DT. The most important constituents are α-pinene, eucalyptol, and camphor. The highest α-pinene concentration in the oil (30.4%) was obtained from dry biomass at 2.5 min DT; eucalyptol (23.3% of the total oil) from fresh biomass at 2.5 min DT; and camphor (15.9% of the total oil) from fresh biomass at 160 min DT. The DT could be used as an inexpensive tool to alter essential oil composition of the essential oil from fresh or dried rosemary biomass, and to produce rosemary oils with elevated or lowered concentration of specific targeted oil constituents to meet specific market demands.

Effect of alcoholic fermentation on the quality of grape brandies

Grape brandy is a product obtained by fermentation and distillation of crushed grapes of cultivated grapevine Vitis vinifera. Grape brandy quality depends on many factors such as: grapevine varieties, climate, soil, time and method of distillation, storage methods and other distillates. The grapevine variety 'Neoplanta' grown in the experimental field of the PD 'Center for Viticulture and Enology' in Nis was used in the experiment. Tests were performed in the laboratory of the Centre. Healthy grapes of harvest maturity were squashed by a stalk-removing electric crusher. Fermentation was performed in plastic containers in the presence of the indigenous microflora of wine yeasts. This paper presents the influence of pH and inorganic nitrogen added to the fermentation medium on the content of volatile components and concentrations of higher alcohols.

Composition of rugosa rose (Rosa rugosa thunb.) hydrolate according to the time of distillation

Rugosa rose (Rosa rugosa Thunb.) is one of the most common rose species in Poland. It has mild soil and climate requirements and is resistant to low temperatures. Rugosa rose hips are a valuable raw material used in food and pharmaceutical industries, while flowers and petals may be a source of fragrant products, such as essential oil and hydrolate. The main aim of this study was to verify usefulness of dried R. rugosa petals for essential oil and hydrolate production. We also assessed the use of rugosa rose petals remaining after oil distillation for hydrolate production.The R. rugosa dried petals immersed in water were subjected to simple distillation and five fractions of primary rose hydrolate were obtained. In parallel, essential oil from the second sample of petals was obtained by hydrodistillation in Clevenger-type apparatus. The distillation residue was used for obtaining four fractions of secondary hydrolate. The volatiles from hydrolate fractions were isolated by liquid–liquid extraction with diethyl ether. The essential oil and hydrolate volatiles were analyzed by GC–FID–MS.Hydrolate fractions contained similar amounts of volatiles (20–30mg/L) with the exception of the first fraction of primary hydrolate (60mg/L). β-Phenylethanol, citronellol, geraniol, and nerol were the main volatile constituents of primary hydrolate. β-Phenylethanol, citronellic acid, and geranic acid were the main volatile constituents of secondary hydrolate. The content of alcohols decreased, while the content of monoterpene esters (citronellyl, neryl, and geranyl acetate) as well as monoterpene acids (citronellic, neric, and geranic acid) increased in successive fractions of both hydrolates.The scent and composition of essential oil and hydrolate obtained from R. rugosa petals were similar to those of rose oil and rose water produced from damask rose (Rosa damascena Mill.). This proves, that rugosa rose distillation products may become an alternative to fragrant damask rose products.

PEMURNIAN ETANOL HASIL FERMENTASI KULIT UMBI SINGKONG (Manihot Utilissima Pohl) DARI LIMBAH INDUSTRI KERUPUK SANJAI DI KOTA BUKITTINGGI BERDASARKAN SUHU DAN WAKTU DESTILASI

Bukittinggi city with approximately 132 industry crackers Sanjai spend 300-500 kg of cassava per day for each industry. Solid waste production process results Sanjai crackers this one is skin cassava. Cassava’s peel produces 15-20% carbohydrate content of 68-85% of the weight of the bulb, so it has great potential to be converted into bioethanol. Carbohydrates in the tuber peel can be processed into ethanol by fermentation and for separating ethanol from it’s mixture used method of distillation. Distillation temperature and time used affects the quality and quantity of bioethanol produced. This study aims to determine the best time and temperature distillation to produce bioethanol at the highest levels. Ethanol content analysis was conducted using the specific gravity using line arregression equation and Table gravity of Indonesian Pharmacopoeia. The results showed that the highest levels of ethanol distillate obtained in the distillation temperature of 71o C for 5 hours is 16.60% using regression methods and 14.1% according to Table Pharmacopoeia with yield ranging between 2.30%- 5.80% and the efficiency of distillation 28, 94% -57.50%. Time and temperature distillation have a real impact on the levels of ethanol produced atthe level of 5%.

Hydrosols evaluation in pest control: insecticidal and settling inhibition potential against Myzus persicae (Sulzer)

AbstractThe hydrosols are by‐products derived during the extraction of essential oils. Although essential oils have been widely evaluated for their insecticidal activities, the possible use of hydrosols in pest control has been almost unknown. The effects of the hydrosols of Origanum majorana (marjoram), Mentha pulegium (pennyroyal), and Melissa officinalis (lemon balm) on the survival and settling behaviour of the aphid pest Myzus persicae were investigated. The hydrosols were isolated using Clevenger hydrodistillation (i) with conventional heating (HD) and (ii) assisted by microwaves (MWHD). GC‐MS analysis showed that the volatiles occurring in the hydrosols were similar between the two techniques. Hydrosols were assayed for possible settling inhibitory effects on M. persicae in Petri dishes (15 cm diameter). In each dish, a sprayed together with an unsprayed eggplant leaf piece was placed. An adult aphid <24 h old was released on the treated leaf and its path length was recorded during the initial 10 min. Then, its position (on the treated or untreated leaf) was recorded 10, 20, 30, 60 min and 24 h after spraying. M. officinalis HD hydrosol resulted in fourfold increase of the path length compared with the control (deionized water). The last observation (24 h) revealed that M. officinalis and M. pulegium HD hydrosols had the strongest inhibitory effect. Additionally, O. majorana hydrosols caused 10–15% aphid mortality after 24 h. In this study, the wider use of the MWHD technique is further supported as in addition to its well‐known advantages (i.e. shorter distillation time, less energy consumption), the effects of the hydrosols produced are comparable to those obtained by HD. Most importantly, the results clearly showed that the potential of hydrosols in pest control ought not to be ignored and should attract the interest of future studies.

Three-step vacuum separation for treating arsenic sulphide residue

Up to now, most of arsenic sulphide residue can't be properly disposed. The traditional processes for treating arsenic sulphide residue have some widespread drawbacks such as the complex process, the high cost in operation, and the less than satisfactory removal effect and environmental protection. In view of this, a process of three-step vacuum separation was proposed for treating arsenic sulphide residue in this work. During vacuum separation, elemental sulphide and arsenic trioxide could be recovered effectively in primary distillation at temperature of 180 °C, distillation time of 2.0 h, corresponding to the residual gas pressure of 15 Pa. In secondary distillation, arsenic sulfide was obtained under the condition of 450 °C for 30 min, with a residual gas pressure of 15 Pa. When the temperature increased to 1000 °C for 2 h, lead sulfide was evaporated out in third distillation. Through the three-step vacuum separation, calcium fluoride was left behind in the third distilland, in which the content of arsenic was 5.65 × 10−4 wt.%. Correspondingly, the removal rate of arsenic was almost 100%. The vacuum process is expected to be effectively employed for recycling valuable components from arsenic sulphide residue, and meanwhile eliminating its pollution.

Separation of elemental sulfur from zinc concentrate direct leaching residue by vacuum distillation

Properly disposal and reutilization of direct leaching residue (DLR) from metal production industries can reduce environmental pollution as well as better conserve resources. In this study, recovery of elemental sulfur from zinc concentrate DLR using vacuum distillation was thoroughly investigated. The results show that elemental sulfur recovery using vacuum distillation was over 98% with a high purity under optimized conditions. The low temperature requirement (200–300°C) of vacuum distillation may reduce the energy consumption comparing to traditional distillation under ambient pressure. Effects of parameters (distillation time, vacuum, temperature, particle size and distillation area) on sulfur recovery rate were presented. High sulfur recovery rate was observed with relative pressure lower than −0.09 megapascal (MPa). Sulfur recovery rate increased sharply with temperature in the range of 140–220°C, while temperature above 220°C only slightly promoted sulfur recovery. Smaller DLR particle size and larger distillation area facilitated mass and heat transportation, and resulted in higher sulfur recovery rates. The vacuum distillation separation technology reveals an alternative method to efficiently and economically separate elemental sulfur from zinc concentrate DLR. The impacts of operation parameters on the sulfur recovery rate were well documented in this study, and they are important for further optimizing the process and strategically applying the technology in a larger scale scenario.

Biological Activity of Abies Sibirica Essential Oil and its Major Constituents for Several Enzymes In Vitro

The composition of essential oil isolated from Abies sibirica needles was determined. Furthermore, the compositions of various fractions obtained by distillation of the essential oil were investigated. Bornylacetate (34.21%), camphene (17.47%), and α-terpene (6.72%) were the major constituents of 31 detected in the essential oil. The contents of the constituents in various fractions changed during production of the essential oil depending on the distillation time. Various fractions of the essential oil were tested for biological activity that was assayed using in vitro enzymatic test systems. It was found that the biological activity of A. sibirica essential oil depended largely on the contents of the major constituents such as bornylacetate and camphene.

Responses of Myzus persicae (Sulzer) to three Lamiaceae essential oils obtained by microwave-assisted and conventional hydrodistillation

The essential oils derived from three plants within the Lamiaceae family, Origanum majorana L. (marjoram), Mentha pulegium L. (pennyroyal), and Melissa officinalis L. (lemon balm), using two techniques for their isolation, were evaluated for their effects on longevity and fecundity of the aphid Myzus persicae (Sulzer). The two techniques employed were Clevenger hydrodistillation (i) using conventional heating (HD) and (ii) assisted by microwaves (MWHD). Analysis of the essential oils by GC-MS showed an increase in the oxygenated fraction determined in MWHD oils. The effects of essential oils were screened with two concentrations, 250 and 500μl/l, on aphid adults <24h old enclosed individually in clip-cages on eggplants (Solanum melongena L.). All the essential oils significantly reduced aphid longevity and fecundity, compared with the controls. M. pulegium oils exhibited the most significant activity at 500μl/l, with longevity shortened by 8 days (87% reduction) and fecundity reduced more than 40-fold. Carvacrol and piperitone were the main constituents of the O. majorana and M. pulegium essential oils, respectively. Their toxic action was shown to be similar to that of the respective essential oils. Mixtures of commercially purchased pure compounds (citral, β-caryophyllene, caryophyllene oxide) associated with M. officinalis essential oils were also proved effective. These results indicate a high potential of O. majorana, M. pulegium, and M. officinalis essential oils but also of their major constituents as alternatives in the management of M. persicae. However, further studies should follow to test the bioefficacy of these oils in larger scale experiments. The comparison of the efficacy of essential oils produced with the traditional HD and the MWHD technique showed no significant difference. Thus, the use of MWHD for the extraction of essential oils for pest control is suggested, considering also its well-known advantages such as shorter distillation time and less energy consumption.

Dual extraction of essential oil and podophyllotoxin from creeping juniper (Juniperus horizontalis).

Juniperus horizontalis Moench (Family Cupressaceae), commonly called creeping juniper, is a widely distributed species in the United States and much of Canada. It is potentially a source for two important chemical products, the anticancer drug synthetic precursor, podophyllotoxin and essential oils. The objectives of this study were to ascertain the likelihood of utilizing J. horizontalis needles for the simultaneous production of both (−)-podophyllotoxin and essential oil components and to determine the optimum distillation time (DT) needed for the production of essential oil containing a specific ratio of constituents. Eleven different distillation times were tested in this study: 20, 40, 80, 160, 180, 240, 480, 600, 720, 840, and 960 min. Total essential oil content increased with increasing distillation time from a minimum of 0.023% at 20 min to a maximum of 1.098% at 960 min. The major constituents present in the oil were alpha-pinene, sabinene, and limonene. The percent concentration of sabinene in the essential oil varied from a high of 46.6% at 80 min to a low of 30.2% at 960 min, that of limonene changed very little as a result of distillation time and remained near 30% for all distillation times, whereas the concentration of alpha-pinene was 9.6% at 20 min DT and decreased to 4.2% at 960 min. Post distillation analysis of needles revealed elevated amounts of (−)-podophyllotoxin remaining in the tissue varied in the amount of podophyllotoxin present, from a low of 0.281% to a high of 0.364% as compared to undistilled needles which gave 0.217% podophyllotoxin. As a result of this study, specific essential oil components can now be targeted in J. horizontalis by varying the distillation time. Furthermore, needles can be successfully utilized as a source of both essential oil and podophyllotoxin, consecutively.

Влияние эфирного масла пихты сибирской (&lt;i&gt;Abies sibirica&lt;/i&gt;) и его отдельных компонентов на активность некоторых ферментов &lt;i&gt;in vitro&lt;/i&gt;

Определен состав эфирного масла, выделенного из древесной зелени пихты сибирской (Abies sibirica). Кроме того, исследован состав различных фракций, получаемых в процессе отгонки эфирного масла пихты сибирской. Из 31 компонента, обнаруженного в эфирном масле, наибольшее количество приходится на борнилацетат — 34, 21 %, камфен — 17,47 %, α-терпинен — 6,72 %. В процессе получения эфирного масла содержание компонентов в различных фракциях меняется в зависимости от времени отгонки. Проведено тестирование различных фракций эфирного масла на биологическую активность, которую оценивали с помощью тест-систем in vitro. Установлено, что биологическая активность эфирного масла пихты сибирской в значительной степени зависит от содержания в нем основных компонентов, таких как борнилацетат и камфен.

Method for obtaining three products with different properties from fennel (Foeniculum vulgare) seed

The objectives of this study were to determine the effects of distillation time (DT; 15–1080min) on yield, composition, and antioxidant capacity of fennel (Foeniculum vulgare) seed essential oil (EO) as well as on the yield, composition, and properties of lipids extracted from steam-distilled fennel seeds (15–600min). EO yield increased with increasing DT to a maximum of 1.375% at 1080min. The principal constituent was estragole, comprising 82–91% of the overall content. Other species included limonene, fenchone, and anethole. Antioxidant capacity of the EO was essentially unaffected by DT, with capacities ranging from 11.2 to 20.6μmolTrolox/g. The yield of lipids extracted from steam distilled fennel seeds was unaffected by DT and ranged from 21.7 to 22.8mass%. The fatty acid composition was also unaffected by DT, and the major constituents were petroselenic (67.0–71.3%) and oleic (12.0–16.4%) acids. The concentrations of tocopherols, tocotrienols, and phytosterols were unaffected by DT whereas unsaponifiables and EO content in lipids decreased with increasing DT. Acid value, kinematic viscosity, peroxide value, and pour point increased with increasing DT, whereas density decreased. Induction period, heteroatom content, and Gardner color were unaffected by DT. As DT increased, in vitro degradability of defatted, steam-distilled fennel seeds decreased. In summary, longer DT negatively impacted feed quality of steam-distilled, defatted seed meal and lipid quality but did not significantly affect EO composition and antioxidant capacity.

Essential Oil Yield and Composition of Garden Sage as a Function of Different Steam Distillation Times

Garden sage (Salvia officinalis L.) is a medicinal, culinary, ornamental, and essential oil plant with a wide range of ecological adaptation. Garden sage essential oil traditionally is extracted by steam distillation from the above-ground biomass and has widespread applications as an aromatic agent in the food and pharmaceutical industries as well as in perfumery and cosmetics. The hypothesis of this study was that the steam distillation time (DT) may significantly affect essential oil yield and composition of garden sage and, therefore, DT could be used as a tool to obtain oil with different composition. Therefore, the objective was to evaluate the effect of various steam DTs (1.25, 2.5, 5, 10, 20, 40, 80, and 160 minutes) on garden sage oil yield and composition. Most of the oil in the garden sage dry herbage was extracted in 10-minute DT; extending DT up to 160 minutes did not significantly increase oil yields. Overall, 39 oil constituents were identified in the garden sage essential oil. Fourteen oil constituents with the highest concentration in the oil were selected for statistical analyses. Monoterpenes represented the major percentage (58.2% to 84.1%) of oil composition followed by sesquiterpenes (4.0% to 16.1%) and diterpenes (0.3% to 7.6%). Overall, the monoterpene hydrocarbons (α-pinene, camphene, β-pinene, myrcene, and limonene) were eluted early in the steam distillation process, which resulted in their high concentration in the oil at 5- to 10-minute DT and relatively low concentrations in the oil obtained at 160-minute DT. In general, the concentration of sesquiterpenes (β-caryophyllene, α-humulene, and verdifloral) increased with increasing duration of the DT and reached their respective maximum concentrations in the oil at 160-minute DT. The relative concentrations of major constituents, camphor and cis-thujone, in the oil obtained at 2.5-minute DT were higher than in the oils obtained at longer DT. Therefore, if oil with high concentrations of camphor and cis-thujone is desirable, garden sage dried biomass ought to be steam distilled for 2.5 to 5 minutes and the oil collected. If oil with a high concentration of monoterpene hydrocarbons and a high concentration of oxygenated monoterpenes is desirable, then garden sage should be distilled for 20 minutes. If oil with a high concentration of the diterpene manool is desirable, then garden sage should be steam-distilled for 80 minutes. If oil with a high concentration of sesquiterpenes is desirable, then garden sage should be steam-distilled for 160 minutes. The duration of steam distillation can be used as an economical method to obtain garden sage oil with a different chemical composition. The regression models developed in this study can be used to predict garden sage oil yield and composition distilled for various amounts of time and to compare literature reports in which different durations of DT were used.

Facile recovery of acetic acid from waste acids of electronic industry via a partial neutralization pretreatment (PNP) – Distillation strategy

In recent years, attention on treatment of industrial waste acids has been increasing considerably due to enforcement of the environmental regulations as well as economical considerations about the waste acids. In this paper, a novel approach for recovery of acetic acid (HAc) from electronic industrial waste acids, containing about 58wt.% of HAc, 39wt.% of nitric acid (HNO3), 3wt.% of phosphoric acid (H3PO4), and small amount of hydrochloride acid (HCl) and hydrofluoride acid (HF), was developed using partial neutralization pretreatment (PNP)-distillation strategy. The effects of distillation time, types of alkali for neutralization and oil bath temperature on recovery of HAc were systematically studied. It was found that HAc can be efficiently recovered from the waste acids with a yield of 94.3% (purity 99.4%) under optimal conditions. The treatment scheme for HAc recovery from waste acids is featured by feasibility, reproducibility and massive productivity.

Steam distillation extraction kinetics regression models to predict essential oil yield, composition, and bioactivity of chamomile oil

Chamomile (Matricaria chamomilla L.) is one of the most widely spread and used medicinal and essential oil crops in the world. Chamomile essential oil is extracted via steam distillation of the inflorescences (flowers). In this study, distillation time (DT) was found to be a crucial determinant of yield and composition of chamomile essential oil, but not of the antioxidant capacity. Essential oil obtained at 30, 60, 90, 120, 180, 240, 360, 480, 600, and 720min showed significant increase in oil yield with increasing DT, reaching a maximum of 3.1g oil per 1000g of flowers at 720min. The major compounds that were identified and quantified were anethole, β-farnesene, spathulenol, α-bisabolol oxide B, α-bisabolone oxide A, chamazulene, α-bisabolol oxide A, and spiroether. β-farnesene showed a decrease in content with increasing DT, whereas α-bisabolol oxide A, spiroether, and chamazulene rapidly increased up to 240min, after which it started to plateau showing negligible change. Anethole content showed a steady decrease over time from approximately 2.4% at 30min to 0.54% at 720min. Yields of spathulenol, α-bisabolol oxide B, α-bisabolol oxide A, α-bisabolone oxide A, chamazulene, and spiroether essential oil constituents expressed as g/100g of dried chamomile inflorescences showed a steady increase that was described well by the Michaelis-Menton model. If higher concentrations of α-bisabolol oxide A and chamazulene, and higher oil yields are desired, chamomile flowers must be steam distilled for 480min. However, if oil with high β-farnesene concentration is desirable, then chamomile flowers should be distilled for 30min. Distillation time can be used as a modifier of chamomile essential oil yield and composition. The kinetics regression models developed in this study can be utilized to predict essential oil yield, and composition of chamomile oil.

Influence of drying, storage and distillation times on essential oil yield and composition of anise hyssop [Agastache foeniculum (Pursh.) Kuntze

In the present study, the effects of two different drying methods, with different storage and distillation periods, on the essential oil content and composition of Agastache foeniculum (Pursh.) Kuntze were studied. The results showed a reduction of the oil content due to the drying treatments and the storage period. The plant material dried at room temperature (25°C) showed the highest essential oil content (2.2%), whereas these dried by oven (40°C) were lower (1.6%). The oil content of anise hyssop was also affected by storage time. The distillation time did not have a significant effect on the essential oil content of anise hyssop. The oil composition was then determined by gas chromatographic (GC) methods. Accurate quantitative analysis has been carried out through the measurement of correction factor of the most abundant oil constituent, methyl chavicol, and for this compound analytical data have been expressed as g/100 g of the oil. Methyl chavicol was quantified as 97.2–98.1 g/100 g, while the second most abundant compound, limonene, was determined as 0.8–1.4% of the total oil. The yield of those two compounds seemed to be roughly unaffected either by the two drying methods or by storage and distillation times.

Bark Essential Oil of Cedrelopsis grevei from Madagascar: Investigation of Steam‐Distillation Conditions

The effect of the distillation time on the yield and chemical composition of the bark essential oil of Cedrelopsis grevei Baill. was investigated. Distillation kinetics were determined for three batches of bark sampled from two sites, i.e., Itampolo (batches IT1 and IT2) and Salary (SAL), located in a region in the south of Madagascar with characteristically large populations of C. grevei. The bark samples were subjected to steam distillation, and the essential oil was collected at 3-h intervals. The total yield (calculated after 14 h of distillation) varied from 0.9 to 1.7%, according to the batch tested. Moreover, the essential oils obtained were characterized by GC-FID and GC/MS analyses. During the course of the distillation, the relative percentages of the most volatile components (monoterpenes and sesquiterpene hydrocarbons) diminished progressively, whereas the least volatile ones (oxygenated derivatives) increased at a consistent rate. Principal component analysis (PCA) and agglomerative hierarchical clustering analysis (AHC) of the results, performed on 13 principal components, allowed distinguishing three chemical groups, corresponding to the three batches, irrespective of the distillation time. This indicated that the chemical variability currently observed with commercial samples is not mainly linked to the experimental conditions of the extraction process, as the distillation time did not significantly alter the chemical composition of the essential oils.

Hydrodistillation extraction time effect on essential oil yield, composition, and bioactivity of coriander oil.

Coriander (Coriandrum sativum L.) is a major essential oil crop grown throughout the world. Coriander essential oil is extracted from coriander fruits via hydrodistillation, with the industry using 180-240 min of distillation time (DT), but the optimum DT for maximizing essential oil yield, composition of constituents, and antioxidant activities are not known. This research was conducted to determine the effect of DT on coriander oil yield, composition, and bioactivity. The results show that essential oil yield at the shorter DT was low and generally increased with increasing DT with the maximum yields achieved at DT between 40 and 160 min. The concentrations of the low-boiling point essential oil constituents: α-pinene, camphene, β-pinene, myrcene, para-cymene, limonene, and γ-terpinene were higher at shorter DT (< 2.5 min) and decreased with increasing DT; but the trend reversed for the high-boiling point constituents: geraniol and geranyl-acetate. The concentration of the major essential oil constituent, linalool, was 51% at DT 1.15 min, and increased steadily to 68% with increasing DT. In conclusion, 40 min DT is sufficient to maximize yield of essential oil; and different DT can be used to obtain essential oil with differential composition. Its antioxidant capacity was affected by the DT, with 20 and 240 min DT showing higher antioxidant activity. Comparisons of coriander essential oil composition must consider the length of the DT.

A Lantern Retort for Small-Scale Gold Extraction

Two major retorts used in small-scale gold mining operations to reduce mercury emissions, during amalgam distillation are the steel and thermex retorts. Steel retorts are not very popular due to the reported darkening of gold after retorting. In addition, its opaque nature prevents miners from observing the process directly. The Thermex glass retort introduced by the United Nations Industrial Development Organisation (UNIDO) is also not patronised due to the extended heating periods resulting from the low thermal conductivity of glass. This paper describes a new retort, the Lantern retort, a combination of highly conductive steel with transparent glass, and therefore, a potential solution to the above concerns. The Lantern retort has a shorter warm-up and amalgam distillation time, and the rate of heating is 1.81oC/s while that of the Thermex is 1.49oC/s. For an amalgam of mass 20 g, 900 s was required to carry out complete distillation in the Lantern retort as against 2100 s in the Thermex. The height of the distillation column of the Lantern retort required to reduce mercury loss to below 1%, as it is with the Thermex retort, is 2.5 cm. Other advantages of the Lantern retort are that, it is less expensive and can withstand the harsh terrain of small-scale gold mining.

Essential Oil Composition and Yield of Anise from Different Distillation Times

Anise (Pimpinella anisum L.) is a spice, an essential oil crop, and a medicinal plant with a long history of use. Anise seed oil is extracted from anise seed through steam distillation. There is no experimentally established optimal time for distillation of anise seed. We hypothesized that the distillation time (DT) can be customized for optimum yield and composition of anise essential oil. In this study, we determined the effect of nine steam DTs (5, 15, 30, 60, 120, 180, 240, 360, and 480 minutes) on essential oil yield and essential oil composition of anise seed. We developed regression models to predict essential oil yield, the concentration of individual constituents, and the yield of these constituents as a function of DT. Highest essential oil yield (2.0 g/100 g seed, 2%) was obtained at 360-minute DT. The concentration of transanethole, the major anise oil constituent, varied from 93.5% to 96.2% (as a percent of the total oil) and generally was high at 15- to 60-minute DT and low at 240- to 480-minute DT. However, the yield of transanethole (calculated from the essential oil yield and the concentration of transanethole in the oil) increased with increasing DT to reach maximum at 360-minute DT. The concentration of the other oil constituents varied significantly depending on the DT, and some of them were higher at the shorter DT than at the longer DT. However, the yields of these constituents were highest at longer DT (either 360 or 480 minutes). DT can be used to obtain anise essential oil with different composition that would benefit the essential oil industry. This study demonstrated the need for providing DT in reports where anise seed essential oil yield and composition are discussed. This article can also be used as a reference point for comparing studies in which different DTs were used to extract essential oil from anise seed.