Multistage Solvent Research Articles

Enhanced SO2 and CO2 synergistic capture with reduced NH3 emissions using multi-stage solvent circulation process

NH3-based SO2 and CO2 synergistic capture technology shows promise in reducing the costs associated with current flue gas desulfurization and CO2 capture systems. However, it faces challenges such as NH3 slip and high energy consumption. In this study, we proposed an advanced Multi-Stage Solvent Circulation (MSC) process that incorporates a desulfurization-washing solution circulation, which involved partitioned absorption according to different functions of SO2 capture, CO2 capture, and NH3 emission control. The experimental results demonstrated that using desulfurization solution in place of water for washing reduced the NH3 emissions from the absorber and desorber by 10.6 % and 7.9 %, respectively. Additionally, the recovered NH3 enhanced SO2 capture, resulting in a 61.8 % decrease in SO2 emission concentration. A pilot-plant trial model for SO2 and CO2 synergistic capture was further developed using Aspen Plus. The impact of operational time and parameters on capture efficiency and energy consumption were analyzed. Under typical flue gas conditions, the process achieved SO2 capture efficiency of > 99 %, regeneration energy consumption of 2.42 GJ/t CO2, NH3 emissions of < 5 ppm. This study presents a novel approach for designing a SO2 and CO2 synergistic capture system, which has the potential to facilitate the economic and effective implementation of post-combustion flue gas pollutant control management and carbon emission reduction.

Preparative separation of the constituents from Ginkgo biloba L. leaves by a combination of multi-stage solvent extraction and countercurrent chromatography.

In this study, we employed a combination approach for the preparative separation of constituents from Ginkgo biloba L. leaves. It involved multi-stage solvent extractions utilizing two-phase multi-solvent systems and countercurrent chromatography (CCC) separations using three different solvent systems. The n-heptane/ethyl acetate/water (1:1:2, v/v) and n-heptane/ethyl acetate/methanol/water (HepEMWat, 7:3:7:3, v/v) solvent systems were screened out as extraction systems. The polarities of the upper and lower phases in the multi-solvent systems were adjustable, enabling the effectively segmented separation of complex constituents in G. biloba L. The segmented products were subsequently directly utilized as samples and separated using CCC with the solvent systems acetate/n-butanol/water (4:1:5, v/v), HepEMWat (5:5:5:5, v/v), and HepEMWat (9:1:9:1, v/v), respectively. As a result, a total of 11 compounds were successfully isolated and identified from a 2g methanol extract of G. biloba L through two-stage extraction and three CCC separation processes; among them, nine compounds exhibited high-performance liquid chromatography purity exceeding 85%.

Controllable-gradient-porous cooling materials driven by multistage solvent displacement method

Passive radiative cooling holds significant potential for efficiently cooling terrestrial objects by simultaneously reflecting sunlight and radiating heat to the cold outer space. Numerous studies have designed high-performance radiative cooling structures using polymethyl methacrylate (PMMA) due to its inherent extinction coefficient.However, obtaining highly favorable spectral characteristics for reflecting sunlight using PMMA, often done through the fabrication of micro/nanoscale structures, remains a central barrier for widespread application. Herein, we report a facile, economical, and scalable multistage solvent displacement-based method for fabricating hierarchically gradient porous PMMA metafilms with highly efficient daytime and nighttime passive radiative cooling performance. Here, the “ouzo effect” works as the driving force for micro/nanopore formation by solvent displacement, which also controls the size of the pores based on different solution ratios. The PMMA metafilm features an ultrahigh solar reflectance of 0.99 and superior mid-infrared thermal emittance of 0.97, which allows for the average and peak subambient temperature drops of 4.6 °C and 8.2 °C, respectively, along with an average radiative cooling power of 90 W/m2 during a 24-h uninterrupted thermal measurement. The hierarchically gradient micro/nanopore distribution of the PMMA metafilm significantly enhances the solar reflectance and thermal emittance within the atmospheric transparency window. Moreover,the multistage solvent displacement method is highly versatile and promising for fabricating porous structures, further offering a cost-efficient, eco-friendly, and sustainable manufacturing path for high-performance radiative cooling application.

Solvent screening for the extraction of aromatic aldehydes

The aromatic aldehydes vanillin, syringaldehyde, and p-hydroxybenzaldehyde find applicability in a broad field ranging from additives in food, cosmetics, and fragrances to precursors of electrochemically active substances used in organic redox flow batteries. These aldehydes can be obtained by wet oxidation of lignin a macromolecule present in woody biomass followed by the isolation via solvent extraction from the resulting acidic solutions.The present study investigates solvents grouped by esters, ethers, terpenes, and terpenoids, in addition to 1-octanol for their performance in extraction of the aromatic aldehydes vanillin, p-hydroxybenzaldehyde and syringaldehyde from an acidic aqueous solution. Solvent extractions are performed at 25 and 50 °C in double-walled tempered separation funnels. The overall extraction efficiency is determined by back-extractions performing a pH-swing at 25 °C. Aldehyde concentrations are measured by HPLC-UV. Karl-Fischer titration and total organic carbon measurements are used to account for the mutual solubility.The best-performing solvent in the case of aldehyde yields at low mutual solubility is given by the ester butyl acetate with extraction efficiencies of 96.53 % for p-hydroxybenzaldehyde, and > 95 % and > 93 % for vanillin and syringaldehyde, respectively. The highest overall extraction efficiency among all solvents suitable for alkaline back-extraction is achieved by cyclopentyl methyl ether with 94.73 % for p-hydroxybenzaldehyde, 94.04 % for vanillin and 87.91 % for syringaldehyde. The solvents geraniol, 1-octanol, ethyl acetate, and 2-methyl tetrahydrofuran show increased uptake of water with ethyl acetate, and 2-methyl tetrahydrofuran pointing out a high solvent loss with 9.82 vol% and 15.84 vol%, respectively. The terpene p-cymene showed preferable extraction of vanillin and syringaldehyde over p-hydroxybenzaldehyde with mutual solubility below 0.02 vol%, which makes it and interesting candidate for multistage solvent extraction.

Ammonia-based post-combustion CO2 and SO2 integrating capture using multi-stage solvent circulation process

Amidst growing environmental concerns stemming from fossil fuel combustion, which releases a considerable amount of pollutants and greenhouse gas. In an effort to mitigate the costs of existing combustion flue gas desulfurization and CO2 capture systems, a new multi-stage circulation (MSC) process for integrating capture of CO2 and SO2 using ammonia-based absorbents was proposed. Different functional zones were interconnected using ammonia (NH3) and potassium carbonate (K2CO3) blended solution as the absorbent, enabling efficient SO2 capture in the 1st stage, CO2 enrichment in the 2nd stage, CO2 capture enhancement in the 3rd stage and recovery of escaped NH3 in the 4th stage. Experimental results demonstrated the effectiveness of NH3/K2CO3 solution in enhancing CO2 capture efficiency. The overall CO2 capture efficiency varied between 95.4 % and 84.1 % at inlet CO2 concentrations ranging from 5 % to 30 %. Under typical combustion flue gas conditions of 622 ppm SO2 and 15 vol% CO2, the process exhibited a SO2 removal efficiency exceeding 99.5 %, with CO2 capture efficiency surpassing 70 %. Furthermore, the CO2 desorption duty was determined to be 2.48 GJ/t CO2. 13C NMR results confirmed that simultaneous absorption of CO2 and SO2 led to the accumulation of SO2 in the liquid phase, reducing the CO2 loading in rich solvent. To address these challenges, coupled optimization strategies was proposed, ensuring high capture efficiency and low CO2 desorption duty under the complex and variable conditions of flue gas parameters, SO2 concentration, and CO2 concentration.

Multi-stage solvent circulation absorption enhancement: System optimization for energy-saving CO2 capture

One of the major barriers in industrial applications of solvent-based CO2 capture is the significant energy consumption required for absorbent regeneration. In this study, a novel multi-stage circulation (MSC) CO2 absorption process was proposed, which implemented independent regulation of each stage, resulting in enhanced CO2 capture performance and reduction of CO2 regeneration duty. The MSC absorber was designed with four stages from bottom to top, each serving distinct functions, including CO2 enrichment, CO2 main absorption, CO2 capture efficiency enhancement and aerosol capture. Simulation of the MSC process achieved a rich ethanolamine (MEA) solvent CO2 loading of 0.512–0.570 mol CO2/mol amine, which was 8.1 %–9.9 % higher than typical process. The effects of test duration, amine solution flow rates, reaction temperatures and inlet CO2 concentrations on CO2 absorption performance were studied using the MSC experimental platform. The CO2 regeneration duty reduced by over 13.2 % of the MSC process compared to a typical process using 25 wt% MEA solution and by over 22.9 % using piperazine (PZ)/N-methyldiethanolamine (MDEA) solution. Furthermore, the utilization of NH3/K2CO3 solution achieved an energy consumption reduction of over 41.7 %, resulting in a CO2 regeneration duty as low as 2.02 GJ/t CO2 (1.84 GJ/t CO2, subtracting the heat loss). Meanwhile, potential strategies for optimizing parameters of MSC process were proposed to address the complex and volatile conditions.

Design of Multi-Stage Solvent Extraction Process for Separation of Rare Earth Elements

Design of Multi-Stage Solvent Extraction Process for Separation of Rare Earth Elements

Design of a Modular Annular Centrifugal Contactor for Lab-Scale Counter-Current Multistage Solvent Extraction

ABSTRACT Annular centrifugal contactors (ACCs) have appealing properties as counter-current multistage solvent extraction (SX) equipment, allowing high throughput at short residence times, small liquid hold-up, and small footprint. The number of commercial suppliers of laboratory-scale ACCs is limited, and their designs have restricted flexibility. Commercial 25 mm diameter ACCs were customized with transparent PMMA surroundings of the mixing zones, allowing visual process monitoring and identification of operational malfunctions. The separation zone of several rotors was lengthened compared to the factory design, which allows longer average residence times in the modified contactors, while keeping the organic flow rate constant in the bank of interconnected contactors. The Couette gap could be increased or decreased without affecting the mixing performance. A 3D-printed stator allows for more efficient draining of the light and heavy phases, and reduces liquid hold-up and volumes required to efficiently achieve steady-state conditions in the process. The hydrodynamic performance of the modified equipment was demonstrated by a SX process of uranium with TBP. First a literature data set of distribution ratios for uranium in HNO3 and 30% TBP diluted in dodecane was utilized to create an empirical model in SX Process simulation software. A flowsheet was designed to validate the model, and it provides an example of the methodology to progress from batch to multistage process. Online density measurements were used to monitor and control the uranium concentrations, and to achieve the desired high metal loading steady-state conditions. It was demonstrated that ruthenium decontamination from uranium could be improved in modified ACCs with longer residence time in the mixing zones of the scrubbing section.

Separation of Cesium and Rubidium from Solution with High Concentrations of Potassium and Sodium

Solvent extraction with 4-tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP) is an effective method for the separation and purification of rubidium and cesium. A solution containing a high K+ concentration (exceeding 80 g/L), which was ultra-salty, with about 200 g/L alkali metal ions, was used to extract Rb+ and Cs+. The effects of the process parameters on the separation of cesium and rubidium were systematically studied. The optimum conditions were as follows: NaOH concentration of 0.5 mol/L, t-BAMBP concentration of 1 mol/L (in sulfonated kerosene), organic/aqueous volume ratio (O/A ratio) of 3:1, and contact time of 1 min. The extraction rates of cesium and rubidium were 99.81 and 98.09%, respectively, and 19.31% of potassium was co-extracted in the organic phase after five-stage countercurrent extraction. About 99.32% of K+ in the organic phase could be removed after five-stage countercurrent scrubbing with deionized water at an O/A ratio of 2:1 for 2 min. When 0.5 mol/L hydrochloric acid solution was used as detergent, almost all of the cesium and rubidium (&gt;99%) could be recovered by two-stage countercurrent stripping at an O/A ratio of 3:1 for 2 min. A solid compound was found and collected from the organic phase during multi-stage solvent extraction. Its composition and structure were determined by XRD, infrared Fourier-transform, and ICP-MS.

Effect of solvents on the composition of Rosa x damascena concrete oil in multistage solvent extraction

Four different solvents, ethyl acetate, ethanol, petroleum ether, and hexane, were used for the multistage solvent extraction of rose concrete oil from the aromatic plant species of Rosa x damascena. The components present in the concrete oils were analyzed using Gas Chromatography-Mass Spectrometer. After the multistage solvent extraction process, the solvent was removed by using a rotary vacuum evaporator. Methyl alpha d-glucopyranoside, 5-hydroxy methyl furfural, 2,3-butanediol, and ethyl-d glucopyranoside were the major components identified using ethyl acetate ethanol, hexane, and petroleum ether as a solvent, respectively. The phenyl ethyl alcohol and 5-hydroxymethyl furfural were identified as the repeated components in all four solvents. The solvent ethanol showed a different composition when compared to the other three solvents. A high yield was obtained when ethanol was used as a solvent. The type of solvent used significantly impacts the compositions of the concrete oil of Rosa x damascena.

Synthesis of refinery desulfurization solvent network with multi-stage solvent regeneration

Increasing process of sour crude oil and demand of low-sulfur oil products expand the desulfurization units in refineries, which raises the desulfurization solvent circulation as well as the energy cost for solvent regeneration. In this work, synthesis of desulfurization solvent network with multi-stage solvent regeneration is investigated to reduce the energy cost. Firstly, this work presents superstructures for desulfurization solvent network with regeneration considering one-stage structure, two-stage cascaded structure, and two-stage parallel structure, respectively. Next, mathematical models for the three cases are formulated as nonlinear programming problems where the objective function aims to minimize the total energy consumption. Finally, a case study is conducted to illustrate the proposed method. The results show that the two-stage structures reduce more energy costs than the one-stage structure by 7.65% and 8.46%, respectively, which means that two-stage regeneration is more attractive. Besides, the parallel structure is better than the cascaded structure, because the energy requirement for solvent regeneration is more sensitive to the outlet concentration of hydrogen sulfide than the inlet concentration.

Control comparison of extractive distillation configurations for separating ethyl acetate-ethanol-water ternary mixture using ionic liquids as entrainer

The new extractive distillation configurations, which use ionic liquids (ILs) as entrainer to develop green processes, have attracted widespread attention among scholars. Design and comparison of different process control schemes can facilitate the application of new solvents in future continuous production. In this paper, three extractive distillation configurations, including conventional extractive distillation (CED), multistage solvent recovery (MSR), and thermally coupled extractive distillation (TCED), are selected from previous work. The separation system of ethyl acetate-ethanol-water ternary mixture is studied, and 1-butyl-3-methylimidazolium acetate is used as an efficient entrainer. In order to compare the dynamic characteristics, six proportional-integral control schemes are established to evaluate the plant-wide control performance of those arrangements. Then, the improved control schemes, which correspond to the three extractive distillation configurations, are selected to test the dynamic behavior under complex disturbance conditions. Integral absolute error and destroyed exergy are calculated to examine the robustness and energy efficiency of the system. The results show that the plant-wide dynamic responses of MSR process are satisfactory in terms of product purity, and the total destroyed exergy of CED process is relatively small during the operation period. There is an effective trade-off between controllability and energy efficiency, and the optimal control scheme should be determined based on actual conditions.

Recycling process for carbon fiber reinforced plastics with polyamide 6, polyurethane and epoxy matrix by gentle solvent treatment

Due to the complex composition of carbon fiber reinforced plastics (CFRPs), a complete and useful recovery of such composite material is a real challenge. This paper presents studies on potential solvent-based recycling processes for three CFRP samples comprising polyamide 6 (PA6), polyurethane resin (PUR) and epoxy resin (EP) matrix. Different proprietary CreaSolv® Formulations were applied in laboratory scale and under thermodynamically subcritical conditions in order to dissolve the polymeric matrix and separate the inert carbon fibers. By variation of decisive process parameters, the influence of the temperature-time-load during solvent treatment and solvent recovery was observed carefully. A complete removal of the polymer matrix of all samples was achieved by means of multi-stage solvent extraction without reducing both the length and tensile strength of the recovered carbon fibers. The recovered PA6 matrix polymer revealed no significant decline of its initial average molecular weight. For the dissolved and extracted resin matrices, feedstock recycling was identified as suitable reprocessing. All of the solvent formulations tested were recycled successfully, keeping the initial dissolution properties and, thus, being applicable in a closed loop process design.

Pore–Filling and Thermally Cross–Linked Polyethersulfone Membranes with High Ion Exchange Capacity and Thermal Stability for PEFCs

Polymer electrolyte membrane fuel cells (PEFCs) have attracted considerable attention due to their high efficiency and clean electric generating system. Especially, in terms of the catalytic activity and water management, there is a great demand for operation under high temperature and low relative humidity. Under such situation, we recently succeeded in the development of heat–resistant electrolyte membrane (PI-CLSPES) with high ion exchange capacity (IEC) from porous polyimide (PI) substrates and highly sulfonated polyethersulfones (SPES150: IEC = 4.9meq/g) by using both polymer-filling and thermal cross–linking methods. The PI substrate can be prepared by using the viscolastic phase separation phenomenon: multi-stage solvent replacement of polyammic acid (PAA) cast film into N-methyl-2-pyrrolidone (NMP) and methanol, followed by thermal treatment. We found that the changes in viscosity of PAA solution, thickness of PAA cast film and immersion time afford the PI substrates with various pore sizes. On the other hand, the SPES150 membrane with high IEC is obtained by further sulphonation of sulfonated poly(arylene ether sulfone) (SPES50) in concentrated sulfuric acid, and allowed for impregnation into the pores of the porous PI substrate. The SPES150 inside the PI pores can be cross-linked between the sulfonic acid and phenyl groups by appropriate thermal treatment, and consequently, lead to the high thermal stability and suppression of membrane swelling. Moreover, the pore-filling and cross-linked membranes still retain the high IEC, and displayed the superior proton conductivity under high temperature comparable to that of Nafion. The detailed proton conducting behavior of the polymer electrolyte membranes as well as their structural analysis will be presented.

Multistage Solvent Extraction for High Yield Oil and Phorbol Esters Removal from Thai Toxic Jatropha curcas Meal

In this study, we investigate the possibility for the production of high yield oil and phorbol esters removed from Thai toxic Jatropha curcas meal. Optimum oil recovery by hexane extraction to obtain high oil yield was accomplished in 3 stages of batch extraction, following which the de-oiled meal was further determined for the optimum conditions for removal of phorbol esters (PEs) by aqueous ethanol extraction from the first to the third stage of batch extraction with the aim of yielding detoxified de-oiled meal product for use as a raw material in animal feed. The optimum conditions for oil extraction was 3-stage extraction with each stage operated at 1:3 (w/v) of toxic meal to hexane at 40 °C for 30 min. This condition gave 100 % de-oiling efficiency compared with the Soxhlet extraction method. The optimum condition for PEs removal from the de-oiled meal involved 2-stage extraction with each stage operated at 1:3 (w/v) of de-oiled meal to aqueous ethanol at 50 °C for 30 min. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the multiple reaction monitoring mode, was used to confirm the PEs residue in the detoxified de-oiled meal. The confirmation showed that the 2 stages of PEs extraction could remove 100 % of the PEs from the de-oiled meal. The results from our study can provide the basis for the efficient commercial production of both J. curcas oil and detoxified de-oiled meal. doi: 10.14456/WJST.2015.32

Composition and Properties of Some Petroleum Waxes

Structural composition of paraffin waxes and soft wax fraction derived from microcrystalline wax were determined. Waxes were fractionated by multistage solvent crystallization at different temperatures. The n-alkane components of the waxes were separated by urea adduction. The average structural parameters of parent waxes, their fractions, and urea adductables were estimated by 1h and 13C NMR spectroscopy. The thermal parameters viz. phase transition temperature and the associated energy during phase transitions were determined by using DSC and correlated with the penetration temperature behavior of waxes. The carbon number distribution determined by GC for these waxes and their n-alkane components were also correlated with physical properties and thermal parameters.

Supercritical fluid extraction of ethanol from aqueous solutions

The recovery of ethanol from aqueous solutions was studied by using supercritical carbon dioxide. At 333.2 K and 10.0 MPa, vapor–liquid equilibrium data of the mixture CO 2+ethanol+water were determined. No azeotrope was observed. Theoretical calculation of equilibrium stages was performed and compared with countercurrent column experiments. Separation of extract and solvent was optimized by multistage solvent distillation. The height of one theoretical stage was found to depend on the ethanol content of the liquid phase. Moreover, flooding point measurements were carried out with ethanol+water mixtures of different composition.

Application of fast solvent extraction processes to studies of exotic nuclides

Fast solvent extraction is a chemical separation method, which can be applied to study exotic nuclides. Since about 1970 the SISAK technique, which is an on-line method based on multi-stage solvent extraction separations, has been successfully used to investigate the nuclear properties of β-decaying nuclides with half-lives down to about one second. During the last decade it has become possible to produce transactinide elements in high enough yields to investigate their chemical properties on a one-atom-at-a-time scale. For this purpose it was necessary to improve and change the detection part of the SISAK system in order to be capable to detect spontaneously fissioning and α-decaying nuclides in a flowing organic solution. This technique is based on liquid scintillation counting with pulse-shape discrimination and pile-up rejection

Role of the Extraction Equilibrium Constant in the Countercurrent Multistage Solvent Extraction−Stripping Process for Metal Ions

Computer simulation of a steady-state coutercurrent multistage metal solvent extraction−stripping process (ESP) using cation-exchange reagents shows that there is a value of extraction equilibrium constant, K, yielding the maximum metal recovery when the other operational parameters are constant. Qualitatively, this is because the larger K makes stripping more difficult. Steady-state local linearization reveals the symbolic relation behind the numerical results. The coefficient of d(ln K) in the differential equilibrium relation extended to the countercurrent multistage process is the weighted average of the partial derivative, in each stage, of the equilibrium organic-metal molarity with respect to ln K under constant equilibrium aqueous-metal molarity, where the weight is related to the partial derivative of the equilibrium organic-metal molarity with respect to the equilibrium aqueous-metal molarity under constant K. The balance of these coefficient values for the extraction and stripping sections of ESP determines the trend of the recovery with varying K: at the maximum recovery, these values are equal to each other. The stagewise plot of the partial derivative of the equilibrium organic-metal molarity with respect to ln K under constant equilibrium aqueous-metal molarity versus organic-metal loading ratio clarifies the relation between the trend of the recovery with varying K and the organic-metal loading.

Steady-State Local Linearization of the Countercurrent Multistage Extraction Process for Metal Ions

Steady-state local linearization of the countercurrent multistage solvent extraction process for metal ions with cation exchange reagents has been carried out on the basis of the differential forms of (i) the equilibrium relation and (ii) the material balance for the metal ion, in each stage. The result is presented as a normal form total differential equations for the respective stages expressing the relation of the metal ion molarities in the aqueous phase to the operational parameters capable of independent continuous variation. These equations have been validated by comparing their numerical solutions for a model system with those by the conventional simulation method. These equations, thus, provide a new simulation method enabling one to efficiently draw a precise diagram expressing the effect of one operational parameter on the process performance.