Temperature-regulation liquid gating membrane with controllable gas/liquid separation

Membrane separation technology with the ability to regulate gas/liquid transport and separation is critical for environmental fields, such as sewerage treatment, multiphase separation, and desalination. Although numerous membranes can dynamically control liquid-phase fluids transport via external stimuli, the transport and separation of gas-phase fluids remains a challenge. Here, we show a temperature-regulation liquid gating membrane that allows in-situ dynamically controllable gas/liquid transfer and multiphase separation by integrating a thermo-wettability responsive porous membrane with functional gating liquid. Experiments and theoretical analysis have demonstrated the temperature-regulation mechanism of this liquid gating system, which is based on thermo-responsive changes of porous membrane surface polarity, leading to changes in affinity between the porous membrane and the gating liquid. In addition, the sandwich configuration with dense Au-coated surfaces and heterogeneous internal components by a bistable interface design enables the liquid gating system to enhance response sensitivity and maintain working stability. This temperature-regulation gas/liquid transfer strategy expands the application range of liquid gating membranes,which are promising in environmental governance, water treatment and multiphase separation.

Rapid hydrate formation and efficient gas separation based on aqueous solid carrier

The long hydrate induction time and limited gas-liquid contact area leads to slow hydrate formation rate and low water-hydrate conversion rate.Porous media are often used to promote hydrate formation because of their large specific surface area.Consequently,we used 3A molecular sieve as a water-carrying solid in this work,and investigated the dynamic renewal of the gas-liquid interface and its effect on hydrate formation.The formation kinetics of ethane hydrate was first measured in an aqueous molecular sieve system.Then the separation of(H_(2)+CH_(4)+C_(2)H_(6)+C_(3)H_(8))gas mixture was conducted via hydrate formation.The results show that the formation rate and gas storage capacity of ethane hydrate can be greatly improved by using aqueous molecular sieve.Compared with a pure water system under the same temperature and pressure,aqueous molecular sieve has obvious advantages in separation effect and energy consumption for separating gas mixtures.

Rapid and real-time analysis of multi-component dissolved gas in seawater by Raman spectroscopy combined with continuous gas-liquid separator

Rapid and sensitive detection of dissolved gases in seawater is quite essential for the investigation of the global carbon cycle.Large quantities of in situ optical detection techniques showed restricted measurement efficiency,owing to the single gas sensor without the identification ability of multiple gases.In this work,a novel gas-liquid Raman detection method of monitoring the multi-component dissolved gases was proposed based on a continuous gas-liquid separator under a large difference of partial pressure.The limit of detection(LOD)of the gas Raman spectrometer could arrive at about 14 μl·L^(-1)for N_(2)gas.Moreover,based on the continuous gas-liquid separation process,the detection time of the dissolved gases could be largely decreased to about 200 s compared with that of the traditional detection method(30 min).Effect of equilibrium time on gas-liquid separation process indicated that the extracted efficiency and decay time of these dissolved gases was CO_(2)>O_(2)>N_(2).In addition,the analysis of the relationship between equilibrium time and flow speed indicated that the decay time decreased with the increase of the flow speed.The validation and application of the developed system presented its great potential for studying the components and spatiotemporal distribution of dissolved gases in seawater.

Performance assessment of an inline horizontal swirl tube cyclone for gas-liquid separation at high pressure

The application of swirl tube cyclone for gas-liquid separation is attractive due to its small size and weight. However, very scarce information on the performance of the swirl tube cyclone especially at high operating pressure emulating actual field condition was published in journals. Performance assessment was usually done at a low operating pressure using either air-water, air-fine particle mixtures or dense gas such as SF6 . This paper fills the existing gaps and reports the initial findings on the performance assessment of a horizontal swirl tube cyclone for gas-liquid separation operating at a flow rate of 5 MMSCFD at 40-60 bar operating pressure.

Evaluation of gas-liquid separation performance of natural gas filters

Fibrous filters are often used to remove contaminants including both dusts and liquid droplets from natural gas. This paper aims to evaluate the gas-liquid separation performance of three types of cartridge filters used in the West-East natural gas transmission project. The comparison of the original pressure drop of clean filters and the evolution of pressure drop as liquid droplets deposited in the filter media are described. The original pressure drops of these filters were similar but the pressure drops at a steady state were different. Fractional efficiency was used to study the separation performance of cartridge filters. Droplets at the outlet of the filters had small diameters, no more than 3 μm, but were very numerous. The effect of filtration velocity on gas-liquid separation performance was analyzed. Higher filtration velocity indicated better gas-liquid separation performance. Finally the quality factor related to pressure drop and filtration efficiency was applied to evaluate the gas-liquid separation performance.

New high permeable polysulfone/ionic liquid membrane for gas separation

In this study,the effects of 1-Ethyl-3-methylimidazolium tetrafluoroborate ionic liquid on CO2/CH4 separation performance of symmetric polysulfone membranes are investigated.Pure polysulfone membrane and ionic liquid-containing membranes are characterized.Field emission scanning electron microscopy(FE-SEM)is used to analyze surface morphology and thickness of the fabricated membranes.Energy dispersive spectroscopy(EDS)and elemental mapping,Fourier transform infrared(FTIR),thermal gravimetric(TGA),X-ray diffraction(XRD)and Tensile strength analyses are also conducted to characterize the prepared membrane s.CO2/CH4 separation performance of the membranes are measured twice at 0.3 MPa and room temperature(250 C).Permeability measurements confirm that increasing ionic liquid content in polymer-ionic liquid membranes leads to a growth in CO2 permeation and CO2/CH4 selectivity due to high affinity of the ionic liquid to carbon dioxide.CO2 permeation significantly increases from 4,3 Barrer(1 Barrer=10^-10 cm^3(STP)·cm·m^-2·s^-1·cmHg^-1,1 cmHg=1.333 kPa)for the pure polymer membrane to 601.9 Barrer for the 30 wt%ionic liquid membrane.Also,selectivity of this membrane is improved from 8.2 to 25.8.mixed gas te sts are implemented to investigate gases interaction.The results showed,the disruptive effect of CH4 molecules for CO2 permeation lead to selectivity decrement compare to pure gas te st.The fabricated membranes with high ionic liquid content in this study are promising materials for industrial CO2/CH4 separation membranes.

Machine learning-based ionic liquids design and process simulation for CO_(2) separation from flue gas

Rational design of ionic liquids(ILs),which is highly dependent on the accuracy of the model used,has always been crucial for CO_(2)separation from flue gas.In this study,a support vector machine(SVM)model which is a machine learning approach is established,so as to improve the prediction accuracy and range of IL melting points.Based on IL melting points data with 600 training data and 168 testing data,the estimated average absolute relative deviations(AARD)and squared correlation coefficients(R^(2))are 3.11%,0.8820 and 5.12%,0.8542 for the training set and testing set of the SVM model,respectively.Then,through the melting points model and other rational design processes including conductor-like screening model for real solvents(COSMO-RS)calculation and physical property constraints,cyano-based ILs are obtained,in which tetracyanoborate[TCB]-is often ruled out due to incorrect estimation of melting points model in the literature.Subsequently,by means of process simulation using Aspen Plus,optimal IL are compared with excellent IL reported in the literature.Finally,1-ethyl-3-methylimidazolium tricyanomethanide[EMIM][TCM]is selected as a most suitable solvent for CO_(2)separation from flue gas,the process of which leads to 12.9%savings on total annualized cost compared to that of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide[EMIM][Tf_(2)N].

Performance of Inner-core Supersonic Gas Separation Device with Droplet Enlargement Method

To improve the separation performance of a supersonic gas separation device for the treatment of gas mixture with a single heavy component, a novel structure with shorter settlement distance was constructed and a method of droplet enlargement was applied. A series of experiments were carried out in the improved separation device under various conditions, using air-ethanol vapor as the medium and micro water droplets as nucleation cen- ters. The effects of the inlet pressure, temperature and relative humidity, the swirling intensity, and mass flow rate of water on the separation performance were investigated. The separation was improved by increasing the inlet pressure and relative humidity. With the decrease of swirling intensity and mass flow rate of water, the separation efficiency increased first and then decreased. The inlet temperature had a slight effect on the separation. The results showed that the separation performance was effectively improved using the proposed structure and method, and the best separation in this study was obtained with the ethanol removal rate about 55% and dew point depression 27 K. The addition of water had little pollution to the air-ethanol vapor system since the water carry-over rate was within the range of -2 %-0 in most cases.

Separation Properties of a New Polysiloxane-Anchored β-Cyclodextrin Derivative as Gas Chromatography Stationary Phase

A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It exhibited separation abilities to disubstituted benzene isomers and some chiral solutes. It was also found that the polarity of CD derivatives can be lowered both by chemically bonding it to polysiloxane and by diluting it in polysiloxane. The separation abilities of the polysiloxane anchored CDs (SP CD) are higher than that of the unbonded CDs (S CD) and the diluted S CD at lower column temperature. Hydrosilylation reaction is one of the best methods to lower the operating temperature of CDs.

Separation and Characterization of Nitrogen-Rich Components in Coker Gas Oils from Athabasca Bitumen

It is well known that gas oils from oilsands bitumen are difficult to hydrotreat. In order to develop the most appropriate flow sheet and operating conditions, a thorough knowledge of the molecular structure and behaviour of bitumen and its gas oil products is needed. In this work, the gas oil samples are fractionated in an attempt to isolate and identify the problematic molecular species for hydrotreating. It is found that the major nitrogen sources in coker gas oils are associated with relatively small pentane insoluble species and an even smaller, highly polar, hexane insoluble species. Structural information obtained for these fractions indicates that they are formed during the cracking of resin molecules. Nitrogen speciation shows that the pyrroles are the primary nitrogen type, with pyridines also being an important species. Both nitrogen species are undesirable in the hydrotreating process. Pyrroles in particular are subject to polymerisation, producing gums and sediments that foul filters and other equipment while pyridines can directly deactivate the hydrotreating catalyst.

Numerical Simulation and Experimental Study on the Performance of Gas/liquid Spiral Separator

The gas/liquid spiral separator, a key component in the compressed air system, was used to remove liquid and oil from gas stream by centrifugal and gravitational forces. To optimize the design of the separator,the relationship between the performance and structural parameters of separators is studied. Computational fluid dynamics (CFD) method is employed to simulate the flow fields and calculate the pressure drop and separation efficiency of air-liquid spiral separators with different structural parameters. The RSM (Reynolds stress model)turbulence model is used to analyze the highly swirling flow fields while the stochastic trajectory model is used to simulate the traces of liquid droplets in the flow field. A simplified calculation formula of pressure drop in spiral structures is obtained by modifying Darcy's equation and verified by experiment.

Separation of m-cresol from aromatic hydrocarbon and alkane using ionic liquids via hydrogen bond interaction

Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes;the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids(ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents(COSMO-RS)model and the liquid–liquid phase equilibrium(LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and nheptane, 1-ethyl-3-methylimidazolium acetate(emim CH3 COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emim CH3 COO: model oils mass ratio of 0.5 and 298.15 K,emim CH3 COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.

The combination of 1-octyl-3-methylimidazolium tetrafluorborate with TBAB or THF on CO2 hydrate formation and CH4 separation from biogas

[C_8min] BF_4 was used in this work to combine with TBAB or THF for the investigation about thermodynamic and kinetic additives on CO_2 and CH_4/CO_2 hydrates. The results show that [C_8min] BF_4 has the inhibition effect on the equilibrium of hydrate formation. About the kinetic study, [C_8 min] BF_4 could improve the rate of CO_2 hydrate formation and increase the gas uptake in hydrate phase. At the same time, the combination of TBAB and [C8 min] BF_4 could increase the mole friction of CH_4 in residual gas comparing with the data in THF solution. CH_4 separation efficiency was strongly enhanced. Since that the size of CO_2 and CH_4 molecules are similar, CH_4 and CO_2 could form the similar hydrate, so the recovery of CH_4 from biogas decreases lightly. The CH_4 content in biogas can purified from 67 mol% to 77 mol% after one-stage hydrate formation. In addition, the combination of THF and[C_8 min] BF_4 do not have obvious promoting effect on CH_4 separation comparing with the gas separation results in pure THF solution.

Separation of ionic liquids from dilute aqueous solutions using the method based on CO_2 hydrates

Ionic liquids （ILs） have been regarded as the potential novel solvents for improved analytical- and process-scale separation methods.The development of methods for the recovery of ILs from aqueous solutions to escape contamination and recycle samples will ultimately govern the viability of ILs in the future industrial applications. Therefore, in this paper a new method for separation of ILs from their dilute aqueous solutions and simultaneously purification of water was proposed on the basis of the CO2 hydrate formation. For illustration, the dilute aqueous solutions with concentrations of ILs ranging from 2× 10^-3 mol% to 2×10^-1 mol% were concentrated. The results show that the separation efficiency is very impressive and that the new method is applicable to aqueous solutions of both hydrophobic and hydrophilic ILs. Compared to the literature separation method based on the supercritical CO2, the new method is applicable to lower concentrations, and more importantly, its operation condition is mild.

PREPARATION OF MICROPOROUS ULTRA HIGH MOLECULAR WEIGHT POLYETHYLENE (UHMWPE) BY THERMALLY INDUCED PHASE SEPARATION OF A UHMWPE/LIQUID PARAFFIN MIXTURE

Ultra-high molecular weight polyethylene (UHMWPE) with a microporous structure was prepared via thermally induced phase separation (TIPS).Liquid paraffin (LP) was used as a diluent in the preparation of microporous UHMWPE. Small angle laser light scattering (SALLS) and differential scanning calorimetry (DSC) were used to determine the phase separation temperatures,i.e.the cloud points and the dynamic crystallization temperatures,respectively.It was found that the cloudI points were coincident with the cryst...

Applications of metal–organic frameworks for green energy and environment: New advances in adsorptive gas separation, storage and removal

The separation of gas molecules with similar physicochemical properties is of high importance but practically entails a substantial energy penalty in chemical industry. Meanwhile, clean energy gases such as H_2 and CH_4 are considered as promising candidates for the replacement of traditional fossil fuels. However, the technologies for the storage of these gases are still immature. In addition, the release of anthropogenic toxic gases into the atmosphere is a worldwide threat of growing concern. Both in academia and industry, considerable research efforts have been devoted to developing advanced porous materials for the effective and energy-efficient separation, storage, or capture of the related gases. In contrast to conventional inorganic porous materials such as zeolites and activated carbons, metal–organic frameworks(MOFs) are considered as a type of promising materials for gas separation and storage. In this contribution, we review the recent research advance of MOFs in some relevant applications, including CO_2 capture, O_2 purification, separation of light hydrocarbons, separation of noble gases, storage of gases(CH_4,H_2, and C_2 H_2) for energy, and removal of some gaseous air pollutants(NH_3, NO_2, and SO_2). Finally, an outlook regarding the challenges of the future research of MOFs in these directions is given.

Economic Comparison of Three Gas Separation Technologies for CO2 Capture from Power Plant Flue Gas

Three gas separation technologies,chemical absorption,membrane separation and pressure swing adsorption,are usually applied for CO2 capture from flue gas in coal-fired power plants.In this work,the costs of the three technologies are analyzed and compared.The cost for chemical absorption is mainly from $30 to $60 per ton(based on CO2 avoided),while the minimum value is $10 per ton(based on CO2 avoided).As for membrane separation and pressure swing adsorption,the costs are $50 to $78 and $40 to $63 per ton(based on CO2 avoided),respectively.Measures are proposed to reduce the cost of the three technologies.For CO2 capture and storage process,the CO2 recovery and purity should be greater than 90%.Based on the cost,recovery,and purity,it seems that chemical absorption is currently the most cost-effective technology for CO2 capture from flue gas from power plants.However,membrane gas separation is the most promising alternative approach in the future,provided that membrane performance is further improved.

Effect of montmorillonite on hydrate-based methane separation from mine gas

Three types of mine gas samples were used in the solutions of tetrahydrofuran(THF),sodium dodecyl sulfate(SDS)and THF-SDS with/without MMT respectively to investigate the effect of montmorillonite(MMT)on separation characteristics of methane recovered from mine gas based on hydrate method.The partition coefficient,separation factor and recovery rate were used to evaluate the effects of MMT,and the selection factor was primarily proposed to define the selectivity of mine gas hydrate in the relative target gases.The experimental results indicate that MMT could improve the following factors including hydration separation factor,the selection factor,the partition coefficient,and the recovery rate.Furthermore,the effect of SDS on the function of MMT is analyzed in the process of hydration separation.Finally,due to the results of the experiment,it is concluded that MMT hydration mechanism explores the effect of MMT enrichment methane from mine gas.

Solvent extraction and separation of copper from base metals using bifunctional ionic liquid from sulfate medium

A novel solvent extraction process for extraction and separation of copper from other base metal ions using a bifunctional ionic liquid (IL) (trioctylmethylammonium/2,4,4-trimethylpentyl phosphinate, [A336/Cy272]) in kerosene was reported. This IL was found to extract copper more efficiently than the individual extractants Aliquat 336 or Cyanex 272. Formation of an octahedral copper-IL complex was characterized by UV-Visible spectra and metal ligand interaction was confirmed by FTIR spectra. The loading capacity of 0.1 mol/L [A336/Cy272] was found to be 1.71 g/L. Stripping studies reported that 0.298 g/L copper ions were efficiently stripped using 0.1 mol/L sulfuric acid from 0.05 mol/L loaded IL. The selectivity of copper against nickel, cadmium and iron was investigated from their equimolar binary mixtures using 0.05 mol/L [A336/Cy272] in kerosene. The highest separation factorβCu/Cd=8.41 was obtained at pH 3.56. Copper can be effectively separated from nickel over the pH range studied. The IL extracts preferentially iron over copper and the highest separation factorβFe/Cuwas 3246 at pH 2.4. The extraction rate of metal ions from a synthetic solution containing copper with other metal impurities was in the order of Fe>Zn>Cu>Cd>Co>Ni.

Separation of Red (Y_2O_3:Eu^(3+)), Blue (BaMgAl_(10)O_(17):Eu^(2+)) and Green (CeMgAl_(10)O_(17):Tb^3) Rare Earth Phosphors by Liquid/Liquid Extraction

A novel process for separation of red （Y2O3：Eu^3＋）, blue（BaMgAl10O17：Eu^2＋） and green （CeMgAl10O17：Tb^3） rare earth fluorescent powders was proposed. At first, the blue powder can be extracted selectively from an aqueous solution using a chelating collector 2-thenoyltrifluoroacetone （TTA） dissolved in heptane at alkaline pH condition, then, chloroform was used for extracting the green powder into organic phase. The red phosphor remains in aqueous phase with potassium sodium tartrate depressant （PST）. Therefore, three phosphors can be separated successfully from their artificial mixtures by liquid/liquid extraction, and grades and recovery of separated products reach respectively as follows： red is 96.9% and 95.2%, blue is 82.7% and 98.8%, green is 94.6% and 82.6%.