Liquid Recovery Research Articles

Research on Mechanism & Applicability of Vortex Tool Process in Gas Well

At present, drainage gas recovery technology is usually used to solve gas well drainage problems in the development of lard gas fields at home and abroad. A large amount of the produced water discharged from the bottom hole effusion is discharged to the ground. In the process of lifting, processing and injection consumes a lot of energy and greatly increased the capital investment and gas production costs, more serious is greatly shortened the economic life of gas wells, while the water produced by the environment also caused serious pollution. In order to achieve high efficiency of gas well production, it is necessary to further study and develop new technology suitable for gas field development, which can improve water drive energy and lifting rate, reduce energy consumption and reduce pollution. For better application of eddy current drainage gas recovery tools, better play to its performance, it is necessary to determine the eddy current drainage gas recovery tools use after the change of the flow pattern, the research on the mechanism both liquid eddy current drainage gas recovery tool, to analyze its influence factors, and carry on the optimization of structure, thus improve the efficiency of gas drainage and production efficiency.

Optimal process selection for natural gas liquids recovery: Energy, exergy, economic, and environmental perspectives

In contrast with extant studies on industrial natural gas liquids (NGL) recovery processes, this study focuses on the most significant configurations, including the industry-standard single-stage (ISS) process, gas subcooled (GSP) process, cold residue gas-recycle (CRR) process, recycle split-vapor (RSV) process, enhanced NGL recovery process (IPSI-1), and internal refrigeration for enhanced NGL recovery process (IPSI-2). Furthermore, this study in-depth analyses the energy, exergy, economics, and environmental factors to determine the optimal configuration based on specific scenarios and priorities. ASPEN HYSYS® V11 is used to simulate six NGL process configurations, each with a processing capacity of 5000 kmol/h. The study identifies critical design variables concerning energy consumption. The energy analysis reveals that the RSV process exhibits the highest energy consumption, totaling 38.00 MW. Additionally, the RSV configuration demonstrates the highest values for exergy destruction, capital cost, CO2 emissions, and purity compared to the other configurations. In contrast, the IPSI-1 process exhibits significantly higher energy efficiency than the RSV process, with 46 % lower energy consumption and the lowest specific CO2 emissions (0.048 kg CO2/kg feed). However, the analytical values for the lowest or middle rankings differ depending on the perspectives considered. Thus, this study provides valuable methods for selecting a conventional technology based on investment, input resources, and sustainable output requirements.

The experimental study on the air oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with Co–Mn–Br system

Abstract 2,5-Furandicarboxylic acid (FDCA), an eco-friendly biomass resource capable of replacing petroleum-based fuels, is gaining increasing popularity. In this article, 2,5-FDCA was prepared by liquid-phase oxidation of the sustainable precursor 5-hydroxymethylfurfural using the Co–Mn–Br catalyst system. The effects of catalyst concentration, catalyst ratio, reaction temperature, reaction time, reaction pressure, and solvent ratio on the reaction of FDCA were investigated. The products are subjected to qualitative and quantitative analyses using high-performance liquid chromatography, infrared spectroscopy, and hydrogen nuclear magnetic spectroscopy. Moreover, considering the loss of catalytic liquid, the suitable reaction conditions were determined as follows: n(Co)/n(Mn)/n(Br) = 1/0.04/0.5, n(HMF)/n(HAC) = 0.05, reaction temperature of 170°C, reaction pressure of 2 MPa, reaction time 40 min, and airflow rate 1.0 L·min−1. Under these conditions, the yield of the product is 86.01%, the purity is 97.53%, and the loss of the catalytic liquid is about 5.63%, which is at an ideal level and provides a good basis for the recovery of the subsequent catalytic liquid and multiple cycle reactions. Through the optimization of the existing process, the use of noble metal catalysts has been reduced, and the recycling of catalytic liquid has also reduced the consumption of catalysts. This advancement marks a significant stride toward sustainable development in the green chemical industry.

Recovery of Chlorosilane Residual Liquid to Prepare Nano-Silica via the Reverse Micro-Emulsion Process.

In this paper, nano-silica particles were prepared from chlorosilane residue liquid using an inverse micro-emulsions system formed from octylphenyl polyoxyethylene ether (TX-100)/n-hexanol/cyclohexane/ammonia. The influence of different reaction conditions on the morphology, particle size, and dispersion of nano-silica particles was investigated via single-factor analysis. When the concentration of chlorosilane residue liquid (0.08 mol/L), hydrophile-lipophilic-balance (HLB) values (10.50), and the concentration of ammonia (0.58 mol/L) were under suitable conditions, the nano-silica particles had a more uniform morphology, smaller particle size, and better dispersion, while the size of the nano-silica particles gradually increased with the increase in the molar ratio of water to surfactant (ω). The prepared nano-silica was characterized through XRD, FT-IR, N2 adsorption/desorption experiments, and TG-DSC analysis. The results showed that the prepared nano-silica was amorphous mesoporous silica, and that the BET specific surface area was 850.5 m2/g. It also had good thermal stability. When the temperature exceeded 1140 °C, the nano-silica underwent a phase transition from an amorphous form to crystalline. This method not only promoted the sustainable development of the polysilicon industry, it also provided new ideas for the protection of the ecological environment, the preparation of environmental functional materials, and the recycling of resources and energy.

Co-pyrolysis of paper-laminated phenolic printed circuit boards and calcium-based additives in fixed and fluidized bed reactors

This study compares the impact of the calcium-based additives and the pyrolyzer on the recovery and the halide content of the oil produced from the pyrolysis of paper-laminated phenolic resin printed circuit boards (FR2-PCB). The preliminary experiments showed that the maximum liquid recovery (40.6%) was achieved in a fluidized bed pyrolyzer containing a 50:50 mixture of CaO and Ca(OH)2 operating at T = 620 °C and PCB-to-additive ratio (FR2/A) = 5.4 g/g for 22 min. Extra tests were then carried out under these conditions in fixed and fluidized bed pyrolyzers to separately explore the impact of CaO, Ca(OH)2, and CaO + Ca(OH)2 on the liquid recovery (LR) and the halogen content of the non-solid products. In the fluidized bed, LR in the presence of CaO, Ca(OH)2, and CaO + Ca(OH)2 was 34.5%, 41.2%, and 38.9 wt%, respectively. The fraction of phenolic compounds in the pyrolysis oil ranged from 86% to 93%, about 1–3% higher than the corresponding values in the fixed bed. Using additives led to lower halide content in the pyrolysis oil of the fluidized bed than that of the fixed bed. However, the opposite trend was observed in the absence of additives. Regardless of the type of pyrolyzer, Ca(OH)2 was more successful than CaO in increasing LR, whereas CaO was more effective than Ca(OH)2 in pyrolysis oil dechlorination. Co-pyrolysis of FR2-PCB and CaO + Ca(OH)2 in a fluidized bed reactor was identified as a practical approach to enhance the recovery of pyrolysis oil comprising only 5% of the original halogen content of the feedstock.

Recovery of superbase ionic liquid using aqueous two-phase systems

Aqueous two-phase systems (ATPS) have been widely used for the purification and separation of biomolecules. However, recent studies have shown that ATPS can also be effective in the purification and recovery of other compounds, such as ionic liquids (IL). Here, we investigated the liquid-liquid phase equilibria of ATPS consisting of 5-methyl-1,5,7-triaza-bicyclo[4.3.0]non-6-enium acetate ([mTBNH][OAc]) and potassium salts (K2CO3 and K3PO4) at 293.2 K and 323.2 K. Our results indicate that both systems exhibited a high IL partition coefficient (k), exceeding 9.5, and achieved a 99.5% recovery of ionic liquid. Moreover, we found that the presence of potassium salt in the ionic liquid-rich phase had a negative impact on the IL cellulose dissolution capability. Therefore, we investigated the removal of potassium salt from the IL and successfully achieved it by using a nanoporous sodium zirconium cyclosilicate (ZS-9 or AV-13). Overall, our study suggests that ATPS can be a promising technique for the purification and recovery of ionic liquids, with potential applications in various industries.

Liquid hydrogen cold energy recovery to enhance sustainability: Optimal design of dual-stage power generation cycles

Liquid hydrogen (LH2) is a promising hydrogen carrier because of its high density. However, liquefying hydrogen requires considerable energy and expenses. To enhance the sustainability, this study focuses on recovering cold energy from LH2 to mitigate costs and carbon emissions in LH2 supply chain. Three power generation configurations are proposed, combining the Brayton and Rankine cycles to efficiently recover cold energy across a wide temperature range of LH2. These configurations are the series Brayton and Rankine (SBR), the parallel Brayton and Rankine (PBR), and the integrated Brayton and Rankine (IBR) processes. In the SBR process, the Brayton cycle recovers cold energy from LH2 in the cryogenic temperature, followed by the Rankine cycle in the low temperature. The PBR process involves the Rankine cycle recovering LH2 cold energy indirectly from the Brayton cycle. In the IBR process, the Rankine cycle recovers cold energy not only from LH2 in the low temperature but also from the Brayton cycle. This results in the highest cold energy recovery performance and net power output, leading to a 6.19% reduction in carbon emissions within the LH2 supply chain. Furthermore, despite its high initial investment, the IBR process demonstrates economic feasibility due to its superior energy performance.

Liquid Natural Gas Cold Energy Recovery for Integration of Sustainable District Cooling Systems: A Thermal Performance Analysis

This paper investigates the heat transfer properties of liquefied natural gas (LNG) in a corrugated plate heat exchanger and explores its application in cold energy recovery for enhanced energy efficiency. The study aims to integrate this technology into a 500 MW gas-fired power plant and a district cooling system to contribute to sustainable city development. Using computational fluid dynamics simulations and experimental validation, the heat transfer behaviour of LNG in the corrugated plate heat exchanger is examined, emphasising the significance of the gas film on the channel wall for efficient heat transfer between LNG and water/ethylene glycol. The study analyses heat exchange characteristics below and above the critical point of LNG. Below the critical point, the LNG behaves as an incompressible fluid, whereas above the critical point, the compressible supercritical state enables a substantial energy recovery and temperature rise at the outlet, highlighting the potential for cold energy recovery. The results demonstrate the effectiveness of cold energy recovery above the critical point, leading to significant energy savings and improved efficiency compared to conventional systems. Optimal operational parameters, such as the number of channels and flow rate ratios, are identified for successful cold energy recovery. This research provides valuable insights for sustainable city planning and the transition towards low-carbon energy systems, contributing to the overall goal of creating environmentally friendly and resilient urban environments.

Investigation of low water recovery based on gas-water two-phase low-velocity Non-Darcy flow model for hydraulically fractured horizontal wells in shale

Various mechanisms are employed to interpret the low water recovery during the shale-gas production period, such as extra-trapped water in the fracture network, water imbibition due to osmotic pressure and capillary pressure. These lead to the difficulty of water flow, which could be described by low-velocity non-Darcy's law known as threshold pressure gradient (TPG). In this paper we firstly employ the low-velocity non-Darcy's law to describe the water flow and use Darcy flow accounting for slip flow and free molecular flow mechanisms to model gas flow in the shale formation. The sensitive study using numerical simulation shows that the proposed flow model could model the low fracturing liquid recovery and that large pseudo TPG leads to lower fracturing liquid recovery. Thus, the proposed model would give new insight to model the low water recovery in shale formations.

STUDY OF THE PERFORMANCE OF THE DYNAMIC LEVEL STABILIZATION SYSTEM OPERATION IN THE WELLBORE EQUIPPED WITH AN ELECTRICAL SUBMERSIBLE PUMP UNIT

Link for citation: Totanov A.S., Molchanova V.A., Urazakov K.R. Study of the performance of the dynamic level stabilization system operation in the wellbore equipped with an electrical submersible pump unit. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 210-219. In Rus. The relevance of the study is related to the widespread use of electrical submersible pump units in the production of low-viscosity oils and water-gas-oil emulsions at this stage of development of mechanized production. However, the current production conditions associated with changing reservoir parameters bring to the fore a number of technical problems that need to be solved. One of these challenges is the phenomenon in which the dynamic level of the well decreases due to changes in reservoir parameters (reservoir pressure, productivity factor, etc.). Decrease of dynamic liquid level in the well leads to complications during operation of electrical submersible pump units. As a consequence, the increased cavitation in impellers is possible due to pressure reduction on the pump intake, and also full pump supply failure is not excluded at significant reduction of the dynamic level of the borehole fluid. In this relation, a technical solution, consisting in installation of bypass device (electrical valve) above the place of suspension of electrical submersible pump plant to maintain stable dynamic liquid level in the well and avoid complications during pump operation, was suggested. To confirm the feasibility of the dynamic level stabilization system, a mathematical model was developed to evaluate the effectiveness of complication prevention with the help of the proposed technical solution during the operation of the electric centrifugal pump unit. The main aim of the research is to develop a calculation method for studying the dynamics of the dynamic level stabilization system. Objects: an electrical submersible pump unit in conjunction with a system for stabilizing the dynamic level of the well. The influence of the diameter and length of the electrical valve on the efficiency of the dynamic level recovery was studied, taking into account hydraulic losses during the system operation. Methods. The research method is reduced to numerical solution of differential, linear and non-linear equations describing flow and pressure at electrical submersible pump unit outlet in steady-state mode, fluid flow through the electrical valve taking into account hydraulic resistances, flow of hydrodynamic processes in annular space during stabilization system operation, that is change of fluid level above the pump depending on borehole conditions and design parameters of electric valve. Results. Effect of parameters of the bypass valve – the diameter of flow section and length on dynamics of change of a liquid level above the pump, as well as the impact of liquid properties, namely its viscosity on intensity of restoration of a liquid level above the pump was studied. It was found that when the diameter of the electrical valve is increased, more intensive restoration of the liquid level above the pump is observed due to the reduction of hydraulic resistance in the valve cavity. Similarly, it was found that with increase of electrical valve length, as well as with increase of viscosity of liquid, coefficient of flow and intensity of liquid level recovery above the pump decreases respectively.

Study on Extraction and Purification of Acanthopanax senticosus Polyphenols by an Ionic Liquid-Assisted Aqueous Two-Phase System.

This study aimed to extract and purify polyphenols from Acanthopanax senticosus. A new green method was developed, in which ionic liquids (ILs) were used as aqueous two-phase (ATP) adjuvants to extract the polyphenols from A. senticosus. An ionic liquid-assisted aqueous two-phase system (IL-ATPS) was established. The purification of the polyphenols from the extraction fluid by AB-8 macroporous resin was conducted, and the kinetic mechanisms were studied. The reuse of ionic liquids was executed. The results showed that an [OMIM]Br-assisted ethanol/NaH2PO4 system (IL-ATPS) was the best extraction solvent. In this study, the following optimal extraction conditions were determined: 32 wt.% ethanol, 25 wt.% NaH2PO4, 9 wt.% additional ionic liquid, a solid-liquid ratio of 1:40 g/mL, an extraction temperature of 50 °C, a pH of 4.0, an extraction time of 50 min, and an extraction rate of the polyphenols at 15.90 mg/g. The optimum adsorption parameters of the macroporous resin AB-8 were as follows: a flow rate of 3.5 BV·h-1, a sample volume of 40 mL, an elution flow rate of 3.5 BV·h-1, an eluent volume of 80 mL, and an eluant that was constituted by an 85% volume fraction of ethanol. The decolorization effect of 4% activated carbon was better than the other amounts; in addition, a decolorization rate of 76.81% and an ionic liquid recovery rate of 81.12% were found to be the most optimal. Compared with the traditional extraction methods, IL-ATPS has the advantages of requiring simple operation, saving time, and high efficiency. In addition, it can be used for the extraction of the polyphenolic compounds.

Viscous liquid recovery by injection of Newtonian and viscoelastic materials in a sand porous media

Viscous liquid recovery by injection of Newtonian and viscoelastic materials in a sand porous media

A novel hybrid process design for efficient recovery of hydrophilic ionic liquids from dilute aqueous solutions

AbstractIonic liquids (ILs) have received much attention in both academia and industries due to their superior performance in many applications. Efficient recovery/recycling of ILs from their dilute aqueous solutions is essential for the acceptance and implementation of many IL‐based technologies by industry. In this work, a practical and cost‐effective hybrid process design method that combines aqueous two‐phase extraction, membrane separation, and distillation operating at their highest efficiencies is proposed for the recovery of hydrophilic ILs from dilute aqueous solutions. The application of this hybrid process design method is illustrated through case studies of recovering two hydrophilic ILs, n‐butylpyridinium trifluoromethanesulfonate ([C4Py][TfO]) (CAS number: 390423‐43‐5) and 1‐butyl‐3‐methylimidazolium chloride ([C4mIm][Cl]) (CAS number: 79917‐90‐1), from their dilute aqueous solutions. For the recovery of 10 wt.% [C4Py][TfO] from aqueous solution, the hybrid process using (NH4)2SO4 as the salting‐out agent could reduce the total annual cost (TAC) and energy consumption by 57% and 91%, respectively, compared with the pure distillation processes. In the case of recovering 10 wt.% [C4mIm][Cl] from aqueous solution, the reduction in TAC and energy savings of the hybrid process with salting‐out agent (NH4)2SO3 could reach 49% and 87%, respectively, compared with the pure distillation process. Furthermore, uncertainty analysis through Monte Carlo simulations show that the proposed hybrid process design is more robust to uncertainties in energy prices and other material (e.g., equipment and solvent) costs.

An MINLP formulation to identify thermodynamically-efficient distillation configurations

Designing configurations for separation of multicomponent mixtures by distillation is challenging because of (i) combinatorial explosion of the choice set, and (ii) nonconvex nature of the governing equations. This work proposes a novel Mixed Integer Nonlinear Program (MINLP) that is formulated to identify configurations that minimize the total exergy loss/maximize thermodynamic efficiency of the separation process. The formulation in its default form has several nonlinear nonconvex equations. We propose a model reformulation via a simple variable elimination technique to reduce the system of nonlinear equations to a single equation, which we refer to as the exergy constraint. We describe the properties of exergy constraints and exploit them in deriving additional valid cuts for the problem. Finally, we use the model for a case study concerning the recovery of Natural Gas Liquids (NGLs) from shale gas.

A review of the energy recovery and energy pressure of liquid

AbstractDue to the rapid development of today's industry, it not only greatly accelerates the consumption of energy, but also causes serious pollution to the environment. Therefore, reducing energy waste and recovering energy has become an important research direction today. This paper introduces the future development trend of renewable energy, discusses the progress of recovery of nonpolluting energy such as marine, bioenergy and thermal energy, and analyzes the efficiency and social benefits of various types of energy recovery. Energy recovery methods for natural gas pipelines are briefly analyzed, and current research advances in energy pressure recovery devices are provided, leading to a summary of methods to improve the efficiency of fluid energy recovery. Finally, it is concluded that although the current energy sources are diversified, the most valued energy sources at present and in the future should be solar energy and ocean, which are infinitely recyclable. This paper will benefit researchers to further understand and study the various aspects of energy recovery.

Prospects for commercial microalgal biorefineries: Integrated pilot demonstrations and process simulations based techno-economic assessment of single and multi-product value chains

Pilot-scale demonstrations and techno-economic simulations are proposed for overcoming uncertainties surrounding technology scale-up impacts and economics of microalgae (MA) biorefineries. Therefore, to contribute to knowledge on promising value chains regarding near-term commercialization, this study investigated the techno-economic performances of alternate commercial (1–10 t MA/d) spirulina MA biorefinery scenarios via integrated pilot demonstrations and Aspen Plus® process simulations. The scenarios include spirulina cultivation and processing into: (I) dried spirulina food product (DSFP), (II) phycocyanin (PCN), (III) PCN + biostimulant for plants (BFP), (IV) 50:50 % MA feedstock split for DSFP and PCN + BFP, and (V) similar to IV but integrated with cattle-dung biogas heat system (CDBHS) allowing for additional liquid biofertilizer recovery. DSFP prices of 13.2–17.3 €/kg (4-fold to 5-fold lower vs market average) were sufficient for profitability of I. Conversely, II and III were unprofitable per the relatively high PCN prices projected for viable operations (283–544 €/kg PCN vs market prices at 170–280 €/kg PCN). Integration of DSFP into the PCN + BFP (IV) plus CDBHS (V) resulted in economically viable biorefineries. Thus, for near-term commercial applications, the integration of the DSFP into the spirulina biorefineries could be strategic for advancing viable productions of the emerging PCN and BFP products. Optimization opportunities for the MA cultivation (e.g. achieved productivity of 8.6 g/m2.d vs reports of 14 g/m2.d) and the downstream processing (e.g. attained PCN yield of 6 % vs theoretical 11 %) could be explored to improve the biorefinery cost and revenues [e.g. 11 % PCN yield corresponds to comparable PCN prices vs the market, i.e. 250–296 €/kg (II) and 154–193 €/kg (III)]. Hence, although the multi-product biorefinery schemes (III-V) could improve the bioresource utilization efficiency, their near-term economic viability will depend largely on the values of the products and technology efficiencies rather than the number of products recovered.

Dairy manure nutrient recovery reduces greenhouse gas emissions and transportation cost in a modeling study

Technologies that separate manure or digestate into fractions with different solids and nutrient contents present interesting options to mitigate manure storage emissions (by reducing the quantity of carbon stored anaerobically) and to improve nutrient distribution (by reducing the quantity of water transported with nutrients). In this study, the dairy farm model, DairyCrop-Syst, was used to simulate storage emissions of methane (CH4), nitrous oxide (N2O), and ammonia (NH3), and to simulate nutrient distribution for a case-study farm in Canada. The farm used several types of manure processing, including: anaerobic digestion (AD), solid-liquid separation (SLS), and nutrient recovery (NR). Simulations were done with combinations of the above technologies, i.e., a baseline with only AD that produced a single (unseparated) effluent, compared to AD+SLS, and AD+SLS+NR that produced two separate fractions. With AD+SLS+NR, the processing system isolated a solid fraction with a high concentration of N and P, and a liquid fraction containing less nutrients. Compared to the baseline system, the addition of solid liquid separation and nutrient recovery (i.e. SLS+NR) reduced CH4 emissions from outdoor liquid digestate storage by 87%, with only a small offset from higher N2O and NH3 emissions from storing the solid fraction. The solid fraction was simulated to be transported to fields at least 30 km away from the dairy barns, while the liquid fraction was transported by dragline to fields adjacent to the barn. The advanced nutrient separation system resulted in much lower transport costs for manure nutrients and the ability to transport N and P to greater distances.

Understanding multiple factors that impact unconventional production: Guidelines to evaluate liquid-rich unconventional resource plays

As the petroleum industry builds long-term production histories in major liquid-rich unconventional resource (UCR) plays, development geologists and engineers have realized that the production gas oil ratio, petroleum type, and ultimate recoveries do not always match the predictive petroleum system models. Early studies suggested that the UCR petroleum systems require neither traditional petroleum traps nor major migration systems but an organic-rich source within optimal maturity window. Possible explanations for these production discrepancies that were not fully characterized in the initial models include uncertainties in source rock characteristics, primary migration fractionation, fractionation related to storage, and production fractionation. Long-term empirical observations suggest that off-structure migration contribution, trapping mechanisms, and reservoir phase (single versus two) play an important role in the liquid-rich UCR production. If the liquid-rich UCR petroleum system is a well-behaved predominantly local charge system, then the generation product can be estimated with an understanding of the local organic matter type and in situ level of maturity. However, if the UCR play is hybrid with significant migrated down-dip charge contribution, then a more complicated work program will be required to estimate well rates and volumes. The liquid-rich UCR play evaluation should reflect these additional factors, which can greatly impact surface production rate and liquid recovery.

Repeated Microphase Separation and Heating-free Distillation-like Behavior of Miscible Binary Liquid Mixtures Using Nanoconfined Grafted Polymer Layers.

Nanoconfinement is known to drive phase separation (often denoted as microphase separation) of two highly miscible liquids by subjecting the two liquids to disparate influences. Here, we propose a paradigm shift to this problem: we introduce the idea of "repeatability" in nanoconfinement-driven microphase separation. A drop consisting of two highly miscible liquids (A and B) is made to pass through a nanochannel grafted with a collapsed layer of polymer that is philic to A but phobic to B. Subsequently, a significant number of molecules of liquid A get imbibed into the polymer layer and the polymer layer partially swells, while the molecules of liquid B mostly remain out of the polymeric layer and are carried away, emerging as a drop on the other side of the polymer bilayer. This passage of drop (of liquids A and B) is continued, and each time liquids A and B get separated with liquid A imbibing into the polymer layer and liquid B being carried away with the drop. This scenario, therefore, points to the repeated occurrence of the microphase separation of miscible binary liquid mixtures, enabling the processing of a much larger volume of liquid, given the fact that the presence of a grafted polymer layer continues to provide a dynamically increasing space where liquid A can get localized after being separated from liquid B. We quantify such repeated microphase separation by noting the extent of separation (of liquid A) and extent of recovery (of liquid B) as functions of nanochannel height and number of passes. Interestingly, we establish that this process also leads to a distillation-like behavior (without any heat addition), where the concentration of liquid B (equivalent to the "less volatile" liquid in a standard distillation process) progressively increases inside the drop after its passage through the nanochannel.

Recovery of ionic liquids from aqueous solutions using membrane technology

Ionic liquids (ILs) have great potential as solvents and catalysts in the most diverse areas of the chemical industry. However, the need for a process that allows the recycling and purification of ILs in an efficient and economically viable manner is restricting the practical application of these solvents. The recycling processes most used to recover ILs are distillation and evaporation, followed by extraction and crystallization. However, most of these processes demand high energy consumption, or temperatures that may compromise the structural and chemical stability of the ILs. This work focuses on understanding the separation of ionic liquid from aqueous solution using membranes, a technique widely used in industry. The separation of eleven ILs (([C4mim][AOc], [C4mim][SCN], [C4mim][CF3SO3], [C4mim][CF3CO2], [C4mim][Cl], [C8mim][Cl], [P4444][Cl], [N4444][Cl], [C4mpip][Cl], [C4mpyr][Cl] and [C4-2-mpy][Cl]) was studied using a nanofiltration (NF270) and a reverse osmosis (BW30LE) membrane. The influence of cation and anion, pressure, IL concentration, and temperature, on the separation of ILs, was evaluated. The Donnan exclusion mechanism was found to be the limiting factor for the reverse osmosis, while the combination of concentration polarization and sieving mechanism was the limiting factor for nanofiltration membrane. The increase of temperature and pressure leads to an increase in the volumetric flux at the cost of a decrease of the IL retention. On the other hand, the increase in the concentration of the IL solution resulted in an increase in the osmotic pressure and, consequently, a decrease in the volumetric flow and a decrease in the rejection of the IL.