Distillation Step Research Articles

Measurement of geologic nitrogen using mass spectrometry, colorimetry, and a newly adapted fluorometry technique

Abstract. Long viewed as a mostly noble, atmospheric species, recent work demonstrates that nitrogen in fact cycles throughout the Earth system, including the atmosphere, biosphere, oceans, and solid Earth. Despite this new-found behaviour, more thorough investigation of N in geologic materials is limited due to its low concentration (one to tens of parts per million) and difficulty in analysis. In addition, N can exist in multiple species (NO3−, NH4+, N2, organic N), and determining which species is actually quantified can be difficult. In rocks and minerals, NH4+ is the most stable form of N over geologic timescales. As such, techniques designed to measure NH4+ can be particularly useful.We measured a number of geochemical rock standards using three different techniques: elemental analyzer (EA) mass spectrometry, colorimetry, and fluorometry. The fluorometry approach is a novel adaptation of a technique commonly used in biologic science, applied herein to geologic NH4+. Briefly, NH4+ can be quantified by HF dissolution, neutralization, addition of a fluorescing reagent, and analysis on a standard fluorometer. We reproduce published values for several rock standards (BCR-2, BHVO-2, and G-2), especially if an additional distillation step is performed. While it is difficult to assess the quality of each method, due to lack of international geologic N standards, fluorometry appears better suited to analyzing mineral-bound NH4+ than EA mass spectrometry and is a simpler, quicker alternative to colorimetry.To demonstrate a potential application of fluorometry, we calculated a continental crust N budget based on new measurements. We used glacial tills as a proxy for upper crust and analyzed several poorly constrained rock types (volcanics, mid-crustal xenoliths) to determine that the continental crust contains ∼ 2 × 1018 kg N. This estimate is consistent with recent budget estimates and shows that fluorometry is appropriate for large-scale questions where high sample throughput is helpful.Lastly, we report the first δ15N values of six rock standards: BCR-2 (1. 05 ± 0. 4 ‰), BHVO-2 (−0. 3 ± 0. 2 ‰), G-2 (1. 23 ± 1. 32 ‰), LKSD-4 (3. 59 ± 0. 1 ‰), Till-4 (6. 33 ± 0. 1 ‰), and SY-4 (2. 13 ± 0. 5 ‰). The need for international geologic N standards is crucial for further investigation of the Earth system N cycle, and we suggest that existing rock standards may be suited to this need.

Design of a continuous gas-phase process for the production of hexafluoropropene oxide

The partial oxidation of hexafluoropropene (HFP) yields 2,2,3-trifluoro-3-trifluoromethyl oxirane (commonly known as hexafluoropropene oxide, HFPO), a highly reactive and versatile fluorochemical intermediate that is used in the manufacture of various high-performance organofluorine products. Most industrial methods of HFPO preparation involve the high-pressure liquid-phase oxidation of HFP in the presence of chemical oxidizers and solvents. Processes that employ molecular oxygen as the oxidizing agent generally have a lower environmental impact. In this study, the design and analysis of a 500tpa continuous gas-phase process for the epoxidation of HFP with molecular oxygen was carried out. A modular coil-type reactor fabricated from drawn copper tubing is proposed to attain residence times up to 120s which are required for acceptable levels of HFP conversion (70%) and HFPO yield (40%). The HFPO product is separated from the residual HFP through a novel sequence of CO2 gas stripping and conventional distillation steps. A final product having a purity of 99.8mol% is obtained. The recovered HFP, which has a purity of 99.2mol%, is subsequently recycled. The process unit operates at a HFP recycle ratio of 0.39.

Optimization of Hydrothermal and Diluted Acid Pretreatments of Tunisian Luffa cylindrica (L.) Fibers for 2G Bioethanol Production through the Cubic Central Composite Experimental Design CCD: Response Surface Methodology.

This paper opens up a new issue dealing with Luffa cylindrica (LC) lignocellulosic biomass recovery in order to produce 2G bioethanol. LC fibers are composed of three principal fractions, namely, α-cellulose (45.80% ± 1.3), hemicelluloses (20.76% ± 0.3), and lignins (13.15% ± 0.6). The optimization of LC fibers hydrothermal and diluted acid pretreatments duration and temperature were achieved through the cubic central composite experimental design CCD. The pretreatments optimization was monitored via the determination of reducing sugars. Then, the 2G bioethanol process feasibility was tested by means of three successive steps, namely, LC fibers hydrothermal pretreatment performed at 96°C during 54 minutes, enzymatic saccharification carried out by means of a commercial enzyme AP2, and the alcoholic fermentation fulfilled with Saccharomyces cerevisiae. LC fibers hydrothermal pretreatment liberated 33.55 g/kg of reducing sugars. Enzymatic hydrolysis allowed achieving 59.4 g/kg of reducing sugars. The conversion yield of reducing sugar to ethanol was 88.66%. After the distillation step, concentration of ethanol was 1.58% with a volumetric yield about 70%.

A Solvent-Free Base Liberation of a Tertiary Aminoalkyl Halide by Flow Chemistry

A flow setup for base liberation of 3-(N,N-dimethylamino)propyl chloride hydrochloride and solvent-free separation of the resulting free base has been developed. Production in flow profits from an on-demand approach, useful for labile aminoalkyl halides. The requirement for obtaining a dry product has been fulfilled by the simple use of a saturated NaOH solution, followed by isolation of the liquid phases by gravimetric separation. The flow setup has an E factor reduction of nearly 50%, and a distillation step has been avoided. The method exemplifies how flow chemistry can be exploited to simplify, improve, and optimize manufacturing processes.

Scientific Opinion related to a notification from DuPont Nutrition Biosciences Aps on behenic acid from mustard seeds to be used in the manufacturing of certain emulsifiers pursuant to Article 21(2) of Regulation (EU) No 1169/2011 – for permanent exemption from labelling

Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver a scientific opinion related to a notification from DuPont Nutrition Biosciences Aps on behenic acid from mustard seeds to be used in the manufacturing of certain emulsifiers pursuant to Article 21(2) of Regulation (EU) No 1169/2011 – for permanent exemption from labelling. Behenic acid is produced from rapeseed–mustard seed variants prevalent in India, namely Brassica juncea (L.) Czern. (oriental mustard), Brassica rapa (L.) (brown/yellow Sarson or Toria), Brassica napus (L.) (rapeseed) and Brassica nigra (L.) W.D.J.Koch (black mustard). No human or animal allergenicity data were provided by the applicant for either behenic acid or the emulsifiers manufactured from behenic acid. Based on enzyme-linked immunosorbent assay (ELISA) data, the Panel considers that proteins and peptides may not be carried over into behenic acid after the two distillation steps reported in the manufacturing process in amounts beyond 1 mg/kg. The Panel notes that the maximum amount of mustard protein that could be consumed from emulsifiers manufactured from behenic acid (E 470a, E 471 and E 477) on a single occasion by an adult under the proposed conditions of use would be around 0.00119 mg, which is about 1,000 times lower than the protein doses reported to trigger allergic reactions in mustard-allergic individuals (around 1 mg). On the basis of the data presented, the Panel concludes that oral consumption of emulsifiers manufactured using behenic acid from mustard seeds (E 470a, E 471 and E 477) are unlikely to trigger an allergic reaction in susceptible individuals (i.e. mustard-allergic individuals) under the proposed conditions of use.

Evaluation of a Raman spectroscopic method for the determination of alcohol content in Greek spirit Tsipouro

A Raman spectroscopic method and the conventional distillation method for the determination of alcohol content % (v/v) in Greek spirit Tsipouro used. A univariate calibration model was constructed employing the band area at 880 cm-1 of standard ethanol solutions. The concentrations of 46 samples were then measured using the calibration model and the results were compared with those obtained using the conventional analysis employing a distillation step. Alcohol content in Greek spirit Tsipouro measured with the conventional method ranged from 35.1 to 71.2 % (v/v). The determination coefficient (R2) value was 0.9997 while the corresponding values of the relative errors ranged between – 13.1 -1.0 %. According to the proposed method the alcohol concentration in Greek spirit Tsipouro ranged from 27.7 to 68.2 % (v/v). The proposed method is simple, rapid, economical and does not require any sample pre-treatment steps. It could be a starting point for the design of more specific models according to the requirements of the spirit industry.

Multiple effect concentration of ethanol by ohmic-assisted hydrodistillation

Our previous work on ethanol distillation by ohmic-assisted hydrodistillation (OAHD) successfully concentrated ethanol from 10 to 50% (v/v). In this work, two additional concentration steps were conducted using the 50% (v/v) product obtained from the first concentration stage at a constant wattage of 168W using the same OAHD device. The second distillation step resulted in a product with ethanol concentration of 76% (v/v) and the third step yielded ethanol concentration of 84% (v/v). Results were compared to conventional hydrodistillation (HD), and were indicative that OAHD reduces one third of energy cost in ethanol distillation process. Not only was OAHD superior to HD in terms of time and energy consumption, but also resulted in higher ethanol concentrations than HD after the third step of distillation: 84.3±0.3% vs. 82.5±0.5%, respectively. OAHD also showed better process control and was able to stop the distillation process faster than HD. In both second and third distillation steps, the time required to stop the process with OAHD (1min) was shorter than for HD process (10min). The findings of this study further confirm our previous work, and reveal that this emerging distillation technique has the potential of yielding high concentrations of ethanol from dilute alcoholic solutions in a more economical and environmental friendly way.

Protein Nitrogen Determination by Kjeldahl Digestion and Ion Chromatography

We report development and validation of a simple, rapid, and accurate method for the quantitation of protein nitrogen, which combines Kjeldahl digestion and ion chromatography with suppressed conductivity detection and requires nanomolar amount of nitrogen in samples (≥10 μg protein). The mechanism of suppressed conductivity detection does not permit analysis of samples containing copper (present in Kjeldahl digestion solution) and aluminum (present in many vaccines as adjuvants) due to precipitation of their hydroxides within the suppressor. We overcame this problem by including 10 μM oxalic acid in Kjeldahl digests and in the eluent (30 mM methanesulfonic acid). The chromatography is performed using an IonPac CS-16 cation exchange column by isocratic elution. The method reduces the digestion time to less than 1 h and eliminates the distillation and titration steps of the Kjeldahl method, thereby reducing the analysis time significantly and improving precision and accuracy. To determine protein nitrogen in samples containing non-protein nitrogen, proteins are precipitated by a mixture of deoxycholate and trichloroacetic acid and the precipitates are analyzed after dissolving in KOH. The method is particularly useful for biological samples that are limited and can also be applied to food, environmental, and other materials.

Power consumption evaluation of different fed-batch strategies for enzymatic hydrolysis of sugarcane bagasse.

The minimization of costs in the distillation step of lignocellulosic ethanol production requires the use of a high solids loading during the enzymatic hydrolysis to obtain a more concentrated glucose liquor. However, this increase in biomass can lead to problems including increased mass and heat transfer resistance, decreased cellulose conversion, and increased apparent viscosity with the associated increase in power consumption. The use of fed-batch operation offers a promising way to circumvent these problems. In this study, one batch and four fed-batch strategies for solids and/or enzyme feeding during the enzymatic hydrolysis of sugarcane bagasse were evaluated. Determinations of glucose concentration, power consumption, and apparent viscosity were made throughout the experiments, and the different strategies were compared in terms of energy efficiency (mass of glucose produced according to the energy consumed). The best energy efficiency was obtained for the strategy in which substrate and enzyme were added simultaneously (0.35 kg(glucose) kWh⁻¹). This value was 52% higher than obtained in batch operation.

New Processes to Extract Pure Betacarotenes Molecules Using Acetic Acid Solvent

Betacarotenes molecules extractions using acetic acid (99% of purity) as solvent followed by distillated water neutralization or hexane solvent to get back betacarotenes. To obtain pure betacarotenes molecules, distillation step is necessary for the second process which use hexane solvent; however for the first process which use distillated water neutralization, decantation step is enough. The first process is energetically profitable. Unrefined palm oil which contains betacarotenes molecules with triglycerides and grease acids is used as model product for betacarotenes extraction. Both of the two processes have extraction rate more than 27% which increases proportionally with the weight of unrefined palm oil used for extraction.

Determining the Effect of Chemical and Physical Pretreatments on the Yield and Energy Output of Cellulosic Ethanol from Panicum Virgatum

The world needs an energy source that can replace nonrenewable fossil fuels, which release greenhouse gases into the atmosphere. We explored the production of ethanol from switchgrass, a North American grass that is suitable for biofuel production because it contains large amounts of cellulose, a chemical energy that can be used as fuel. Our experiments evaluated whether key factors would increase the efficiency of ethanol production from switchgrass — in other words, which factors produced the highest percentage of ethanol in the final step of distillation. There are four steps to producing ethanol: pretreatment, enzymatic hydrolysis, fermentation, and distillation. We tested two variables: the concentration of potassium hydroxide (KOH) added to the switchgrass during pretreatment and using ground versus unground grass. After adding the KOH to the grass and letting it sit for a week, we balanced the pH and added 5 grams of cellulase to each sample to convert the cellulose to glucose. After 48 hours, we added 10 grams of yeast to turn the glucose into ethanol. In the final step, we distilled all of the samples and measured the percentage of alcohol. Most large-scale production companies use a 30% KOH concentration during their pretreatment procedure, leading us to speculate that a 30% KOH concentration would yield the greatest amount of ethanol. Contrary to this expectation, we found that the sample with 15% KOH content produced the greatest ethanol yield.

Investigating the Variation of Volatile Compound Composition in Maotai-Flavoured Liquor During Its Multiple Fermentation Steps Using Statistical Methods.

The use of multiple fermentations is one of the most specific characteristics of Maotai--flavoured liquor production. In this research, the variation of volatile composition of Maotai-flavoured liquor during its multiple fermentations is investigated using statistical approaches. Cluster analysis shows that the obtained samples are grouped mainly according to the fermentation steps rather than the distillery they originate from, and the samples from the first two fermentation steps show the greatest difference, suggesting that multiple fermentation and distillation steps result in the end in similar volatile composition of the liquor. Back-propagation neural network (BNN) models were developed that satisfactorily predict the number of fermentation steps and the organoleptic evaluation scores of liquor samples from their volatile compositions. Mean impact value (MIV) analysis shows that ethyl lactate, furfural and some high-boiling-point acids play important roles, while pyrazine contributes much less to the improvement of the flavour and taste of Maotai-flavoured liquor during its production. This study contributes to further understanding of the mechanisms of Maotai-flavoured liquor production.

Improved automatic steam distillation combined with oscillation-type densimetry for determining alcoholic strength in spirits and liqueurs.

The determination of the alcoholic strength in spirits and liqueurs is required to control the labelling of alcoholic beverages. The reference methodology prescribes a distillation step followed by densimetric measurement. The classic distillation using a Vigreux rectifying column and a West condenser is time consuming and error-prone, especially for liqueurs that may have problems with entrainment and charring. For this reason, this methodology suggests the use of an automated steam distillation device as alternative. The novel instrument comprises an increased steam power, a redesigned geometry of the condenser and a larger cooling coil with controllable flow, compared to previously available devices. Method optimization applying D-optimal and central composite designs showed significant influence of sample volume, distillation time and coolant flow, while other investigated parameters such as steam power, receiver volume, or the use of pipettes or flasks for sample measurement did not significantly influence the results. The method validation was conducted using the following settings: steam power 70 %, sample volume 25 mL transferred using pipettes, receiver volume 50 mL, coolant flow 7 L/min, and distillation time as long as possible just below the calibration mark. For four different liqueurs covering the typical range of these products between 15 and 35 % vol, the method showed an adequate precision, with relative standard deviations below 0.4 % (intraday) and below 0.6 % (interday). The absolute standard deviations were between 0.06 % vol and 0.08 % vol (intraday) and between 0.07 % vol and 0.10 % vol (interday). The improved automatic steam distillation devices offer an excellent alternative for sample cleanup of volatiles from complex matrices. A major advantage are the low costs for consumables per analysis (only distilled water is needed). For alcoholic strength determination, the method has become more rugged than before, and there are only few influences that would lead to incomplete distillation. Our validation parameters have shown that the performance of the method corresponds to the data presented for the reference method and we believe that automated steam distillation, can be used for the purpose of labelling control of alcoholic beverages.

Purification of biodiesel using a membrane contactor: Liquid–liquid extraction

The use of biodiesel in engines requires a high purity (99.65wt.%), which is to be obtained by the removal of a large water amount and a large number of distillation steps. Membrane extraction was studied as a more efficient and environmentally friendly process to purify a synthetic biodiesel stream composed of methyl esters from rapeseed oil, methanol and glycerol. The potential of several flat sheet membranes to remove impurities was evaluated. All hydrophobic membranes showed breakthrough pressure values higher than 0.5bar. A PTFE membrane from Sterlitech was selected due to its high chemical resistance against biodiesel. The effect of the concentration of solutes and of the flow rate on the flux was investigated. The overall mass transfer coefficient was calculated and compared with experimentally observed values, which are in the range of 3.5–7 E-03 (cm/min) for methanol. Thus, this membrane technique allows purifying biodiesel, suggesting its potential in industrial applications.

Biocatalytic synthesis of biodiesel utilizing deep eutectic solvents: A two-step-one-pot approach with free lipases suitable for acidic and used oil processing

The synthesis of biodiesel with free lipases starting from refined rapeseed oil and low quality cooking oils was evaluated. A two-enzyme-one-pot system was developed, which gave ethyl ester yields of 96% with less than 1% of residual fatty acids before purification. In the first reaction step Thermomyces lanuginosus lipase was employed, which exhibited high activity of 600nmol/s/mg on triglycerides. Triglyceride turnover was nearly 100% and ethyl ester–glyceride mixtures with 3–4% of fatty acids accumulated. In the second reaction step, Pseudozyma antarctica lipase B dissolved in deep eutectic solvents was applied successfully for residual glyceride transesterification and fatty acid esterification. After phase separation, biodiesel was purified in a one-step refinement to yield a product with 97.6% ethyl ester content. Glycerol of high quality was obtained in a single distillation step from the hydrophilic deep eutectic solvent phase. Comparative trials with several used cooking oils revealed, that the first transesterification step worked equally well, while reaction velocity of the second step was lower than with refined oils. More than 80% ethyl ester yield were obtained with all used cooking oils tested.

Tequila vinasses acidogenesis in a UASB reactor with Clostridium predominance

Tequila vinasses represent an acidic, highly concentrated pollutant effluent generated during the distillation step of Tequila production. Although acidogenesis of Tequila vinasses has been reported for some reactor configurations, a characterization of the bacteria present during this metabolic process is lacking in the literature. Hydraulic retention times (HRT) between 36 and 6 h and organic loading rates (OLR) from 5 to 30 g COD L−1 d−1 were assessed in a UASB reactor fed with Tequila vinasses. Results showed that OLR excerted a stronger effect (p ≤ 0.0001) on parameters such as gas production rate, pH, and acidity than HRT. While it was clear that shorter HRT were related to higher volatile fatty acid production levels. Figures above 2 Lgas Lreactor−1 d−1 (where “gas” could be a mixture of methane and hydrogen) were attained only with an OLR as high as 30 g COD L−1 d−1. Bacterial identification of a sludge sample at the end of the experiment revealed that acid-tolerant microorganisms that remained in the reactor were exclusively affiliated to the Clostridium genera, being the first report of organisms identification for Tequila vinasses acidogenesis. These findings are relevant to the field of biotechnology since acidogenesis of Tequila vinasses using identified and studied microorganism abilities (i.e. Clostridium strains) presents the opportunity of optimizing processes intended for different metabolites production (butanol, volatile fatty acids, hydrogen, solvents).

Toward the zero-emission coal-to-liquids plant

A novel near-zero-emission process for obtaining clean middle-distillate fuels, primarily from coal and with some algal input, has been developed. This process involves the solvent extraction of coal, followed by two stages of hydrotreating and hydrogenation, and finally distillation, to produce fuels of very low sulfur and low aromatics content. Prototype fuels have been shown to provide performance comparable to petroleum-derived jet and diesel fuels in gas turbine and small diesel engines, as well as in the solid oxide fuel cell. Approaches for reducing plant emissions nearly to zero would begin with obtaining the hydrogen needed for hydrotreating the primary coal liquid extract by water electrolysis with non-carbon electricity. The process heat necessary for the extraction, hydrotreating and distillation steps could be obtained from concentrated solar power or non-carbon electricity. Hydrotreating of the primary coal extract will produce hydrogen sulfide. Use of solar splitting of hydrogen sulfide would prevent any emissions of this pollutant, and at the same time provide the opportunity to recycle hydrogen back into the process and obtain an additional revenue stream from the sale of by-product sulfur. Some carbon dioxide production is likely, and would be inevitable if natural-gas-fired process heaters were used. Carbon dioxide capture in algal photobioreactors is proposed; oils recovered from the algae could be blended with the coal-derived liquids, and spent algae could be gasified to produce additional hydrogen for hydrotreating and hydrogenation.

Deoxygenation of waste cooking oil and non-edible oil for the production of liquid hydrocarbon biofuels

Deoxygenation of waste cooking vegetable oil and Jatropha curcas oil under nitrogen atmosphere was performed in batch and semi-batch experiments using CaO and treated hydrotalcite (MG70) as catalysts at 400°C. In batch conditions a single liquid fraction (with yields greater than 80wt.%) was produced containing a high proportion of hydrocarbons (83%). In semi-batch conditions two liquid fractions (separated by a distillation step) were obtained: a light fraction and an intermediate fraction containing amounts of hydrocarbons between 72–80% and 85–88% respectively. In order to assess the possible use of the liquid products as alternative fuels a complete chemical characterization and measurement of their properties were carried out.

Synthesis of high molecular weight sulfonated poly(arylene ether sulfone) copolymer without azeotropic reaction

Currently, most sulfonated poly(arylene ether sulfone) (s-PAES) polymers are synthesized using a solvent mixture consisting of toluene and dimethylacetamide (DMAc) by two successive reactions, namely azeotropic water removal, followed by nucleophilic substitution. In this study, a novel method for the synthesis of s-PAES polymers has been developed, where alcohols such as methanol, ethanol, or 2-propanol are used along with DMAc as the co-solvent in the place of toluene that is used in the conventional synthesis of s-PAES. Moreover, the synthesis method used in this study involves only one step, namely the polymerization at 160°C and does not require the azeotropic water distillation step at 140°C. The new synthesis method was found to yield s-PAES polymers with a higher molecular weight in a shorter reaction time compared to the conventional polymerization method. Further, membrane electrode assemblies (MEA) were fabricated using the synthesized s-PAES polymer membranes, in order to evaluate the performance of the membranes in polymer electrolyte membrane fuel cells (PEMFCs). The results indicate that the s-PAES membranes synthesized using the method proposed in this study have a great potential for use as PEMFC membranes.

Evaluation of permeation of macauba oil and n-hexane mixtures through polymeric commercial membranes subjected to different pre-treatments

Macauba is a Brazilian palm tree with high edible oil productivity and of great interest to many applications. In the oil extraction process, solvent recovery is one point of major concern, due to its high energy consumption and oil quality losses. Those drawbacks can be partially overcome by integration of membrane technology to the usual solvent distillation step. The present work tested four ultrafiltration (UF) and one nanofiltration (NF) membrane (Microdyn-Nadir) on the solvent recovery of synthetic mixtures of macauba oil and n-hexane. Membranes were pre-treated before use with different solvents in specific time lengths, according to preliminary studies. The membrane performance was evaluated by permeate flux and oil retention. Macauba (pulp and kernel) oil was evaluated by determinations of acidity, peroxide value and fatty acid profile. Membranes showed usual flux behaviour, compatible with other studies concerning oil/solvent mixtures permeation, although its values were quite above the expected. Best results for retention (>30%) are related to the membranes with lower molar mass cut-off (MMCO), and the best balance between permeate flux and oil retention was found for the NF membrane (12.4gm−2h−1, 34.7%).