Bottom Aqueous Phase Research Articles

Selection of electrode materials for membrane less fuel cells based on immiscible liquids

The possibility of using various materials as electrodes for membraneless fuel cells based on immiscible liquids, both from the standpoint of the thermodynamic possibility of the process and from the point of view of their corrosion resistance, is considered. The corrosion resistance of materials from alloys based on iron, as well as carbon was investigated for use as electrodes in membraneless fuel cells based on immiscible liquids. The possibility of using them instead of electrodes based on ruthenium and platinum in the studied alkaline aqueous ethanol system was shown. It was found that the highest electromotive force in the system occurs when using an activated carbon anode in the top ethanol phase and a carbon steel 10 cathodes in the bottom aqueous phase. The possibility of using activated carbon instead of a ruthenium-coated titanium electrode and platinum-coated titanium electrode, at almost equal exchange currents, will significantly reduce the cost of manufacturing a fuel cell. Thus under certain conditions, this type of fuel cell can compete with membrane fuel cells that have received industrial implementation

Extraction induced by microemulsion breaking as a novel tool for the simultaneous determination of Cd, Mn, Pb and Sb in gasoline samples by ICP-MS and discrete sample introduction

This study reports a simple and efficient method for the simultaneous determination of Cd, Mn, Pb, and Sb at trace levels in gasoline samples by discrete sample introduction in inductively coupled plasma mass spectrometry (ICP-MS), employing the extraction induced by microemulsion breaking as a sample preparation method. In this work, a microemulsion was formed by mixing 0.7 mL of the gasoline sample with 0.28 mL of ethanol and 0.02 mL of 7 mol L−1 HNO3 solution. Afterwards, 0.1 mL of ultrapure water was added to induce microemulsion breaking. This lead to the formation of two different phases: (i) a top organic phase and (ii) a bottom aqueous phase that contained acid, ethanol and the extracted analytes. After that, 20 μL of the bottom phase (extract) was collected, and the analyte concentrations were determined by discrete sample introduction in ICP-MS. Calibration curves with 20 μg L−1 of Rh as an internal standard were set up to each analyte in the range from 1 up to 10 μg L−1, wherein the standard solutions were prepared in the matrix-matched extract (70:25:5, ethanol: deionized water: 7 mol L−1 HNO3 solution). The optimization of the EIMB conditions was carried out by analyzing the effects of the parameters that could affect the extraction efficiency, such as the relation between the nature of the alcohol and the proportion of the volumes of the microemulsion constituents (sample, HNO3 and alcohol), acid concentration, and the water volume used for the microemulsion breaking. The following limits of detection relative to the amount of sample were obtained: 0.03 (Cd), 0.49 (Mn), 0.07 (Pb) and 0.02 (Sb), all of them in μg L−1. The accuracy of the method was evaluated by the analysis of spiked samples, because no certified gasoline reference material is available. The average recoveries achieved for every analyte ranged from 96% to 114%. The developed methodology was successfully applied to the determination of these metals in five commercial gasoline samples.

Offshore Natural Gas Conditioning and Recovery of Methanol as Hydrate Inhibitor with Supersonic Separators: Increasing Energy Efficiency with Lower CO<sub>2</sub> Emissions

The oil and gas industry represents an important contributor to CO2 emissions as offshore platforms are power intensive for producing, processing and transporting hydrocarbons. In offshore rigs CO2 emissions mainly come from on-site gas-fired power generation for heat and electricity production. The accumulation of atmospheric CO2 is one of the main causes of the planetary greenhouse effect, thus CO2 emissions should be minimized. To achieve that, more energy efficient processes for natural gas (NG) conditioning are needed in order to minimize platform power consumption and thus lowering the associated generation of CO2. In addition, in offshore scenarios gas-hydrate obstructions are a major concern in flow assurance strategies, since thermodynamic conditions favoring hydrate formation are present, such as high pressure, low external temperature and gas contact with free water. To avoid hydrate issues, hydrate inhibition is carried out by the injection of a thermodynamic hydrate inhibitor (THI) in well-heads such that it flows along with production fluids, thus removing the thermodynamic conditions for hydrate formation and ensuring unimpeded flow. Therefore, the three-phase high-pressure separator (HPS) is fed with production fluids, where the HPS splits the feed into: (i) an upper gas phase, (ii) hydrocarbon condensate, and (iii) a bottom aqueous phase. The gas phase goes to NG conditioning for hydrocarbon dew point adjustment (HCDPA) and water dew point adjustment (WDPA) so as to make NG exportable. The hydrocarbon condensate (if present) is collected for stabilization and the bottom aqueous phase consisting of water, salts and THI is sent to a THI recovery unit (THI-RU) for THI re-concentration and reinjection. In conventional plants, WDPA and HCDPA are done by glycol absorption and Joule-Thomson expansion respectively. Moreover, the HPS gas carries some THI such as methanol that is lost in the processing. This work analyses a new process – SS-THI-Recovery – where HPS gas feeds a supersonic separator (SS) with injected water and compares it to the conventional processing. As a result, SS ejects a cold two-phase condensate with almost all water, THI and C3+ hydrocarbons, discharging exportable NG with enough HCDPA and WDPA grades, while the condensate gives aqueous THI returned to the THI-RU and LPG with high commercial value. Thus, SS-THI-Recovery not only avoids THI losses as well as exports NG and LPG. Both conventional gas plant and SS-THI-Recovery alternative coupled to THI-RU were simulated in HYSYS 8.8 for a given NG field and targeting the same product specifications. SS-THI-Recovery presented lower power consumption and thus less associated CO2 emissions, while potentially increasing the gas plant profitability, as THI losses are significantly reduced and higher flow rate of LPG with higher commercial value is produced in comparison with the conventional alternative. Hence, the higher efficiency of SS-THI-recovery makes it not only more environmentally friendly with lower CO2 emissions, but also a potential alternative for improving process economics and thus providing an economic leverage that could justify investments in carbon capture technologies, contributing to avoid CO2 emissions even more with cleaner NG and LPG production.

Three-liquid-phase extraction and separation of V(V) and Cr(VI) from acidic leach solutions of high-chromium vanadium–titanium magnetite

Abstract A new method by liquid–liquid–liquid three phase system, consisting of acidified primary amine N1923 (abbreviated as A-N1923), poly(ethylene glycol) (PEG) and (NH4)2SO4 aqueous solution, was suggested for the separation and simultaneous extraction of V(V) and Cr(VI) from the acidic leach solutions of high-chromium vanadium–titanium magnetite. Experimental results indicated that V(V) and Cr(VI) could be selectively enriched into the A-N1923 organic top phase and PEG-rich middle phase, respectively, while Al(III) and other co-existing impurity ions, such as Si(IV), Fe(III), Ti(IV), Mg(II) and Ca(II) in acidic leach solutions, could be enriched in the (NH4)2SO4 bottom aqueous phase. During the process for extraction and separation of V(V) and Cr(VI), almost all of impurity ions could be removed. The separation factors between V(V) and Cr(VI) could reach 630 and 908, respectively in the organic top phase and PEG middle phase, and yields of recovered V(V) and Cr(VI) in the top phase and middle phase respectively were all above 90%. Various effects including aqueous pH, A-N1923 concentration, PEG added amount and (NH4)2SO4 concentration on three-phase partitioning of V(V) and Cr(VI) were discussed. It was found that the partition of Cr(VI) into the PEG-rich middle phase was driven by hydrophobic interaction, while extraction of V(V) by A-N1923 resulted of anion exchange between NO3− and H2V10O284 −. Stripping of V(V) and Cr(VI) from the top organic phase and the middle PEG-rich phase were achieved by mixing respectively with NaNO3 aqueous solutions and NaOH-(NH4)2SO4 solutions. The present work highlights a new approach for the extraction and purification of V and Cr from the complex multi-metal co-existing acidic leach solutions of high-chromium vanadium–titanium magnetite.

Enhanced extraction of oleoresin from ginger (Zingiber officinale) rhizome powder using enzyme-assisted three phase partitioning

Ginger (Zingiber officinale R.) is a popular spice used worldwide. The oleoresin consists of gingerols, shogaols and other non-volatiles as chief bioactive constituents. Three phase partitioning (TPP), a bioseparation technique, based on partitioning of polar constituents, proteins, and hydrophobic constituents in three phases comprising of water, ammonium sulphate and t-butanol, was explored for extraction of oleoresin and gingerols from dry powder. Parameters optimized for maximum recovery of gingerols and [6]-shogaol were ammonium sulphate concentration, ratio of t-butanol to slurry, solid loading and pH. Ultrasound and enzymatic pretreatments increased the yield of oleoresin and its phytoconstituents. Ultrasound pretreatment showed separation of starch in the bottom aqueous phase but is an additional step in extraction. Enzymatic pretreatment using accellerase increased the yield of [6]-, [8]-, [10]-gingerols and [6]-shogaol by 64.10, 87.8, 62.78 and 32.0% within 4h and is recommended. The efficacy of the enzymatic pretreatment was confirmed by SEM and FTIR.

One-Step Separation of Platinum, Palladium, and Rhodium: A Three-Liquid-Phase Extraction Approach

Three-liquid-phase extraction and one-step separation of platinum, palladium, and rhodium in the system composed of diisoamyl sulphide (S201), polyethylene oxide-polypropylene oxide random block copolymer (EOPO), Na2SO4, and H2O were investigated. Experimental results indicated that phase-forming salt type, salt concentrations, coexisting H+ and Cl– concentrations in equilibrious Na2SO4 aqueous solutions have significant influences on the three-liquid-phase partitioning behaviors of Pt(IV), Pd(II), and Rh(III). Under the optimized operation parameters, over 99 wt % of Pd(II), about 90 wt % of Pt(IV), and 85 wt % of Rh(III) in initial feed solutions were respectively concentrated into S201 top phase, EOPO middle phase, and Na2SO4 bottom aqueous phase. The present work explores a possibility to develop a three-liquid-phase extraction approach for one-step separation of platinum metal ions in highly concentrated acidic chloride media obtained by hydrometallurgical processes.

Primary recovery of lipase derived from Burkholderia sp. ST8 with aqueous micellar two-phase system

The partitioning and recovery of lipase derived from Burkholderia sp. ST8 strain was explored using temperature-induced aqueous micellar two-phase system (AMTPS) composed of single nonionic surfactant. Nonionic surfactant Triton X-114 and Pluronic series (triblock copolymer) were evaluated in terms of their clouding phenomenon (cloud-point temperature) and the performance of the lipase partitioning in these AMTPSs. Pluronic L81 showed the most optimum partition efficiency for the recovery of lipase to the micellar phase of the AMTPS. Based on the AMTPS which consisted of 24% (w/w) Pluronic L81 and 0.5% (w/w) potassium chloride (KCl), the selectivity of lipase partitioned to bottom phase has been enhanced to 0.035 and the lipase was purified 7.2 fold. Furthermore, the lipase from the micellar phase was consecutively extracted to a new aqueous solution, with an aim of removing the surfactant from the purified lipase. It was attained by replacing the aqueous top phase from the primary recovery of AMTPS with a new potassium thiocyanate (KSCN) solution. The lipase was then recovered in the newly formed bottom aqueous phase which culminated in the yield of 89% and partition coefficients of 0.34 and 4.50 for lipase and surfactant, respectively. AMTPS offers a convenient and efficient method for the primary recovery of lipase with low cost, large loading capacity and the potential of linear scale up.

Novel Bitumen Froth Cleaning Device and Rag Layer Characterization

A primary bitumen froth product, from a bitumen extraction process, contains approximately 30% water, 10% solids, and 60% bitumen. In bitumen froth treatment vessels, “rag layer” between the top organic phase and the bottom aqueous phase builds up from time to time. The presence of a thick layer of rag renders a two-phase separation into a three-phase separation, causing a significant reduction in oil/water/solids separation efficiency. A novel setup was built in our laboratory, which allows for a two-step water washing of naphtha-diluted bitumen froth (NDBF) and buildup of rag layer to be collected efficiently for further investigation of rag formation mechanisms. In the first step of bitumen froth cleaning, 1–5 mm diameter NDBF drops were introduced into an aqueous phase to allow the NDBF drops to rise to the top as the organic phase. In the second step, the top organic phase was then washed using the bottom aqueous phase by circulating the top organic phase back to the aqueous phase. The bitumen froth ...

Nanofibers of polyaniline synthesized by interfacial polymerization

The average diameter of polyaniline nanofibers obtained by interfacial polymerization using a solution of aniline in toluene as the top organic phase and acidic ammonium peroxydisulfate as the bottom aqueous phase can be controlled by using surface active dopants and/or surfactants in the aqueous phase. The average diameter of polyaniline nanofibers doped with camphorsulfonic acid (CSA) synthesized by interfacial polymerization decreases when twin-tailed anionic surfactants, based on the cis-1,2-alkylethene sulfonate structure (alkyl=C 5H 11 or C 7H 13), are used. For example, the average diameter of polyaniline. CSA nanofibers decreases in the order 48 nm ( no surfactant )>35 nm (C 5H 11-twin-tailed)>28 nm (C 7H 13-twin-tailed). This effect is reversed in polyaniline nanofibers synthesized using 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) as the dopant, e.g., the average fiber diameter of polyaniline. AMPSA increases in the order 23 nm ( no surfactant )<35 nm (C 5H 11-twin-tailed)<55 nm (C 7H 13-twin-tailed). The doping percentage is reduced when surfactants are used although there is no significant change in the pressed-pellet room temperature 4-probe DC conductivity compared to conventional (single-phase) polyaniline·HCl ( σ∼1–5 S/cm). Polyaniline nanofibers also show increased capacitance consistent with their high surface area, e.g., a capacitance value of 277 F/g was observed in nanofibers of polyaniline·AMPSA (23 nm average diameter) compared to 11 F/g in non-fibrillar polyaniline·AMPSA powder. Further optimization and surfactant structure–function evaluation is needed to uncover the mechanism associated with this phenomenon.