Solvent Recovery Process Research Articles

Spiral-wound organic solvent membrane modules for dewaxing solvent recovery

The petrochemical industry is typically energy-intensive, involving frequent and intricate separation processes. SINOPEC is a globally recognized lubricant manufacturer and distributor, with a substantial production capacity exceeding 1.7 million tonnes in 2022. The dewaxing solvent recovery process in lubricant production necessitates a multi-stage flash and distillation treatment, resulting in substantial energy consumption and high costs. Utilizing organic solvent nanofiltration (OSN) membranes offers a feasible alternative approach to address this issue. A series of thin film composite OSN membranes with varying molecule weight cut-offs were prepared through precise adjustment of the chemical composition and proportion of the organic co-monomers. The application potential of the optimized membranes in the lubricant dewaxing solvent recovery was evaluated using lubricant base oil derived from the actual production line, specifically light deasphalted oil and vacuum cut2. The membrane exhibited a rejection of 99.3 % for light deasphalted oil and 95.6 % for vacuum cut2, with corresponding fluxes of 16.8 and 13.4 LMH under 2 MPa, respectively. Based on this, spiral-wound membrane modules (1.8″ × 12″) were fabricated and their suitability for dewaxing solvent recovery was further validated. The fabrication of spiral-wound membrane modules (8″ × 40″) is in progress, with intentions to conduct a pilot plant trial on the lubricant oil manufacturing line.

Process design and techno-economic analysis for the lignin oil solvent recovery and purification process

A technology to extract lignin oil from pretreated biomass has been developed for a cosmetic additive application (i.e., UV protection) through isopropyl alcohol without any catalyst. It was used for co-product lignin oil with XOS from a biorefinery process in this study. One of the key factors impacting economic feasibility is extraction solvent recovery, and it is important to design the process details based on techno-economic analysis. Therefore, this study has integrated lab experiments, process designs with Aspen Plus process simulations, and Excel-based techno-economic analysis to investigate the effect of solvent recovery on overall economics. Three options for solvent recovery (e.g., distillation, salting-out, and molecular sieve) have been explored. The salting-out method showed the best economic performance with an IRR of 33.6%, while the distillation method was 21.7% and the molecular sieve method was 16.7%. Key parameters are also identified by sensitivity analyses, which indicate the improvement potential for each case. This study has laid a foundation for lignin oil production studies, but its concept and approach can be applied to any solvent recycling in a biorefinery process, which is often neglected in lab-scale biorefinery studies.

An integrated process by ultrasonic enhancement in the deep eutectic solvents system for extraction and separation of chlorogenic acid from Eucommia ulmoides leaves

This study established an integrated process for the extraction and enrichment of chlorogenic acid(CGA)from Eucommia ulmoides leaves in a deep eutectic solvent system via ultrasonic wave-enhanced adsorption and desorption practices utilizing macroporous resins. Although deep eutectic solvents (DESs) have the advantages of chemical stability, good dissolving capacity, and nonvolatilization, routine solvent recovery operations are not suitable for subsequent separation in this solvent system. Based on the above characteristics, this study integrated the extraction and enrichment processes, in which DESs extracts directly loaded onto the macroporous adsorption resin, avoiding the loss of target components in solvent recovery and redissolution processes. The screening results of solvents and resin types further showed that choline chloride-malic acid (1:1) was the optimal DES, and the NKA-II resin had high adsorption and elution performance for CGA. The viscosities of the DESs were much higher than those of water and conventional organic solvents; thus, the mass transfer resistance was large, which could also affect the adsorption behaviour of the macroporous resin. The thermal and mechanical effects of ultrasound could effectively enhance the efficiency of the mass transfer, adsorption, and desorption in the DES systems. When compared to no sonication treatment, the CGA adsorption at various ultrasonic powers (120–600 W) was examined. At optimal ethanol concentration (60%), the effect of the ultrasonic treatment on the recovery of the DESs (water eluting process) and the desorption capability of CGA were confirmed. The use of three volumes of water elution could recover the DESs without loss of CGA. The adsorption process significantly differed depending on the ultrasonic settings, and the absorption balance time and experimental adsorption capacity at equilibrium were enhanced. Additionally, the adsorption procedure of the NKA-II macroporous resin for CGA under ultrasonic treatment could be clarified by the pseudo second order kinetic equation and the Freundlich isotherm model. Thermodynamic and dynamic parameters indicated that physical adsorption was the main process of the entire procedure, and it was a spontaneous, exothermic, and entropy-reducing physical adsorption process. This study potentially indicates that the use of ultrasonication, as a high-efficiency, environmentally friendly method, can enhance the features of the macroporous resin to better purify target chemicals from a DES extract.

MATHEMATICAL MODEL OF MEMBRANE MODULE FOR SOLVENT RECOVERY FROM SOYBEAN OIL MISCELLA

A mathematical model was developed to predict the performance of solvent recovery process in the extraction of vegetable oils. The model is oriented to mathematical programming and to be used in the optimization of a biorefinery superstructure. Experimental data published were recompiled for the PVDF-10SI membrane. For the case study, the mathematical model gives much more conservative design results than if the design was made only with punctual experimental data. To concentrate miscella from 25% wt to 38% wt of oil, the required membrane area is 275.22 m2 for the mathematical model, while the design through punctual experimental data gives a membrane area of 224.23 m2. Besides, the mathematical model allows evaluating the separation performance of each of the intervening compounds through their permeabilities. This is an important contribution, since the results obtained using punctual experimental data are not accurate enough for membrane process design in the oils desolventizing.

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

Synergizing machine learning, molecular simulation and experiment to develop polymer membranes for solvent recovery

Organic solvent nanofiltration (OSN) is a robust membrane technology for solvent recovery and molecular separation in harsh conditions. However, the current OSN membranes are largely produced through trial-and-error methods. In this study, machine learning (ML), molecular simulation (MS) and experiment are synergized for the development of OSN membranes. Using three different learning strategies, ML models are first constructed to identify critical gross properties (i.e., solvent viscosity, membrane thickness and water contact angle) and establish a phenomenological relationship for permeability prediction. Subsequently, ML models based on molecular representation via concatenated fragments are developed to predict methanol permeabilities in three polymer of intrinsic microporosity (PIM) membranes (PIM-A1, CX-PIM-A1 and PIM-8). The methanol permeability predicted in PIM-A1 is the highest among the three and also higher than that in archetypal PIM-1. Next, MS is conducted to provide microscopic insights into swelling behavior and methanol permeation in the three PIM membranes. Finally, the PIM-A1 membrane is experimentally fabricated and found to exhibit nearly complete solute rejection and methanol permeability of 2.33 × 10−6 L·m/m2·h·bar, which validates the ML prediction. This study demonstrates that the synergy of ML, MS and experiment can fundamentally elucidate and quantitatively predict solvent permeation in polymer membranes, and the holistic approach may advance the development of new membranes for solvent recovery and other important separation processes.

Development of an Interactive Software Tool for Designing Solvent Recovery Processes.

Solvents are used in chemical and pharmaceutical industries as a reaction medium, selective dissolution and extraction media, and dilution agents. Thus, a sizable amount of solvent waste is generated due to process inefficiencies. Most common ways of handling solvent waste are on-site, off-site disposal, and incineration, which have a considerable negative environmental impact. Solvent recovery is typically not used because of potential difficulties in achieving required purity guidelines, as well as additional infrastructure and investments that are needed. To this end, this problem must be studied carefully by involving aspects from capital needs, environmental benefits, and comparison with traditional disposal methods, while achieving the required purity. Thus, we have developed a user-friendly software tool that allows engineers to easily access solvent recovery options and predict an economical and environmentally favorable strategy, given a solvent-containing waste stream. This consists of a maximal process flow diagram that encompasses multiple stages of separations and technologies within those stages. This process flow diagram develops the superstructure that provides multiple technology pathway options for any solvent waste stream. Separation technologies are placed in different stages; depending on the component, they can separate in terms of their physical and chemical properties. A comprehensive chemical database is created to store all relevant chemical and physical properties. The pathway prediction is modeled as an economic optimization problem in General Algebraic Modeling Systems (GAMS). With GAMS code as the backend, a Graphical User Interface (GUI) is created in Matlab App Designer to provide a user-friendly tool to the chemical industry. This tool can act as a guidance system to assist professional engineers and provide an easy comparative estimate in the early stages of process design.

Systematic Design of Solvent Recovery Pathways: Integrating Economics and Environmental Metrics

The increasing trend of solvent usage by chemical industries has caused an upsurge in hazardous waste solvents and, consequently, increased their toxicity potential within the environment. The increase in overall carbon and ecological footprints due to conventional waste handling techniques such as incineration and onsite and offsite disposal can hardly be overstated. Even though solvent recovery methods present a better alternative to these techniques, analysis is generally centered on economics. This paper presents a framework that evaluates the economic and sustainability metrics of solvent recovery processes. In the first approach, standalone software (SimaPro) was used to evaluate the impact of the recovery process. The framework was extended by incorporating the economics, Sustainable Process Index (SPI), and Emergy metrics. Thus, solvent recovery challenges have been transformed into a multiobjective optimization problem that is solved through superstructure and mixed-integer nonlinear programming techniques. The applicability of the framework is illustrated by two comprehensive case studies with varying complexities, and the results are compared with conventional methods. The results indicate that about 76–85% of the ecological and energy burden can be prevented if solvent recovery is the preferred option to incineration.

Conversion of Enantiomers during the Separation of Acetoin from Fermentation Broth

Acetoin (AC) is an important platform compound with two enantiomers (R)-AC and (S)-AC. Due to its unique spatial structure, optically pure AC has particularly high application in asymmetric synthesis. Highly optically pure AC could be produced from glucose using biofermentation technology. In this paper, we have observed that the recovered AC product from the fermentation broth containing (R)-AC was a racemic mixture. The changes of the enantiomeric excess (e.e.) of (R)-AC enantiomers in the feed solution during the recovery process were then investigated, confirming that the racemization occurs during solvent distillation. Further studies showed that high temperature is the main factor affecting the conversion of the two enantiomers, while low temperature significantly prevents this conversion reaction. Therefore, we optimized the solvent recovery process and used vacuum distillation to reduce the distillation process temperature, which effectively prevented the racemization: obtains AC products with more than 98% purity and successfully maintained the proportion of (R)-AC above 96%. To our knowledge, this is the first report on the factors affecting the enantiomeric purity in the downstream extraction process of AC production by fermentation.

Potential trade-off between water consumption and water quality: life cycle assessment of nonaqueous solvent dyeing

Fashion industry consumes over 60% of global fibers and attracts increasing attentions due to its environmentally polluting supply chain. In addition to natural fibers cultivation, wet processes of textile manufacturing are also important contributors to water-related impacts due to their large freshwater consumption and the production of chemicals containing wastewater. Despite of efforts made in improving efficiency of water use and wastewater treatment in textile industry, innovative ‘water-free’ technologies, such as nonaqueous dyeing technology using organic solvent, have been developed and demonstrated to reduce water consumption significantly. However, the potential impact on water quality by organic solvents induced in supply chain of this emerging technology remains unassessed, posing an unknown risk of its promotion. Hence, in the present study, a comprehensive life cycle assessment is applied to evaluate its full environmental impacts, including those on ecosystem and human health caused by decamethylcyclopentasiloxane (D5) as the solvent used. Further, the nonaqueous dyeing system is compared with traditional aqueous dyeing technology from both environmental and economic perspectives. Results indicate that nonaqueous dyeing system is advanced in most of environment categories except for abiotic depletion potential (ADP) and Ecotoxicity. However, scenarios analysis reveal that these findings are influenced by the loss fraction of D5 during the solvent recovery process. It is suggested that the loss fraction should be controlled below 2% o.w.f. for the nonaqueous dyeing technology to be advanced throughout all environmental categories. Nonaqueous D5 dyeing could reduce water consumption by 61.30%-79.95% and greenhouse gas emissions by 43.70% compared to the traditional system, delivering a promising contribution to China's 2060 carbon neutrality ambition. Sensitivity and uncertainty analyses are also conducted to investigate the effects of the key parameters (incl. inventory data and USEtox model inputs) and demonstrate the robustness of our assessment.

Amine-Ionic Liquid Blends in CO2 Capture Process for Sustainable Energy and Environment

In the present work, an experiment for CO2 capture process were performed by absorption using various aqueous solvent blends of amine and ionic liquids. The solvent blends were prepared for various compositions by mixing TetraButylAmmonium Acetate [TBA][OAC] and TetraButylAmmonium Bromide [TBA][Br] ionic liquids with Monoethanolamine (MEA). The obtained results were compared with baseline MEA. It was observed that capture efficiency of CO2, absorption rate of CO2 and CO2 diffusion coefficient of MEA-[TBA][OAC] and MEA-[TBA][Br] solvent blends were comparatively higher than baseline 30%MEA. Moreover, the parameters such as density, viscosity, pH, carbon loading and surface tension of all the solvent blends were measured for before and after absorption process. The carbon loading of solvent blends MEA-[TBA][Br] (0.405 mole of CO2/mole of solvent) and MEA-[TBA][OAC](0.459 mole of CO2/mole of solvent) was slightly lower than baseline MEA (0.494 mole of CO2/mole of solvent). However, the viscosity of MEA-[TBA][Br] blends were remarkably lower than MEA-[TBA][OAC] blend and baseline MEA. This might be an important key factor in solvent recovery process with lesser energy demand for sustainable energy and environment.

A hybrid ultrafiltration/nanofiltration/pervaporation membrane process for intensifying the refining of crude canola oil and solvent recovery

Conventional edible oil processing methods with all their drawbacks have not changed over the past decades. Therefore, the main novelty of this study is to develop a three-stage hybrid membrane process to remove phospholipids, pigments, and solvent from the crude canola oil miscella by combining ultrafiltration, nanofiltration, and pervaporation processes. For the first and second stages, ultrafiltration and nanofiltration membranes were prepared by phase inversion method using polyethersulfone as polymer, and triethylene glycol and polyethylene glycol as additives. Pervaporation for the first time was conducted for solvent recovery, using commercial polydimethylsiloxane composite membranes with different active layer thicknesses. Almost full rejection of phospholipids (>99.9%) was obtained by addition of both additives, and approximately remained constant by changing the additive concentration. A 91.49% reduction in the color of crude oil with a flux of 1.17 L/m2.h was obtained at the end of the bleaching stage. The solvent recovery by the pervaporation process with the polydimethylsiloxane composite membranes showed the 100% oil rejection with acceptable flux. The proposed hybrid ultrafiltration/nanofiltration/pervaporation membrane process showed an excellent performance in terms of permeation flux, phospholipids rejection, and color reduction for refining crude canola oil and solvent recovery processes and meets the criteria of process intensification.

A Review on Mixed Matrix Membranes for Solvent Dehydration and Recovery Process.

Solvent separation and dehydration are important operations for industries and laboratories. Processes such as distillation and extraction are not always effective and are energy-consuming. An alternate approach is offered by pervaporation, based on the solution-diffusion transport mechanism. Polymer-based membranes such as those made of Polydimethylsiloxane (PDMS) have offered good pervaporation performance. Attempts have been made to improve their performance by incorporating inorganic fillers into the PDMS matrix, in which metal-organic frameworks (MOFs) have proven to be the most efficient. Among the MOFs, Zeolitic imidazolate framework (ZIF) based membranes have shown an excellent performance, with high values for flux and separation factors. Various studies have been conducted, employing ZIF-PDMS membranes for pervaporation separation of mixtures such as aqueous-alcoholic solutions. This paper presents an extensive review of the pervaporation performance of ZIF-based mixed matrix membranes (MMMs), novel synthesis methods, filler modifications, factors affecting membrane performance as well as studies based on polymers other than PDMS for the membrane matrix. Some suggestions for future studies have also been provided, such as the use of biopolymers and self-healing membranes.

Simulation and Techno-economic Analysis of a CO2 Capture Scheme for Combustion Processes

Literature search has revealed that most post-combustion CO2 capture processes available to power plants are hinged on sorption technologies (chemical absorption and desorption) which are cost and energy-intensive. The colossal cost of solvents used for the absorption of CO2, the high energy requirements for the absorption & solvent recovery processes, plant design & control related complications, and environmental concerns about the solvents are some of the challenges associated with this option of post-combustion CO2 capture approach which is widely being adopted to mitigate CO2 emissions from power plants. In this study, the capture of CO2 from flue gas by exploring the concept of change of state of matter, which is essentially a physical approach to CO2capture, is presented as an alternative to the typical methods in the industry.

Optimal design framework and techno-economic-environmental assessment for efficient solvent recovery separation of ethyl acetate and methanol

Pharmaceutical solvent recovery processes cause tremendous fossil energy consumption and pollutant emission. In order to search highly efficient separating processes, a novel optimization framework is developed for the solvent recovery industry. Take an important solvent recovery process of the ethyl acetate and methanol separation as case study, dimethyl sulfoxide and glycerol are firstly screened as optimal extractants for two different sequences. Through multi-parameters coordinated optimization, the total annual cost, energy consumption, and CO2 emission of the first case are 282.0 k$/y, 642.6 kW, and 1956 t/y, 37.2%, 35.9%, and 50.0% lower than that of the second case. A response surface methodology is then used to further optimize the operating parameters of the first case with minimum total annual cost as objective function. Through integrating multi-parameter coordinated optimization and response surface methodology, the optimal total annual cost is found to be only 264.6 k$/y with product purities above 99.8 wt%, and the optimal operating factors are number of stages of 50 and 12, reflux ratios of 1.236 and 0.401, extractant/feedstock ratio of 3.6 for the extractive tower and recovery tower, respectively. The corresponding energy consumption and CO2 emission of the first case are further decreased to 574.0 kW and 1749 t/y, 10.7% and 10.6% lower than that of preliminary optimization results. It is concluded that the proposed strategy will have application prospect for improving the techno-economic-environmental performance of the relevant processes.

Quantification of N-methylmorpholine-N-oxide and its main degradation products by nuclear magnetic resonance spectroscopy

An important part of Lyocell fibers production is solvent recycling. Determining the content of the degradation products in the solvent will be helpful to select a reasonable solvent recovery process. However, a suitable method to simultaneously measure N-methylmorpholine-N-oxide and its main degradation products N-methylmorpholine and morpholine has not yet been reported, hence in this paper, a nuclear magnetic resonance spectroscopy method for quantitative analysis of N-methylmorpholine-N-oxide and its major degradation products was established. The feasibility of this nuclear magnetic resonance method was verified by using it to determine the contents of N-methyl morpholine-N-oxide, N-methylmorpholine, and morpholine in analytical samples and actual sample.

Applications of de-oiling and reactivation of spent clay

The environment impact of de-oiling and re-activation process of spent clay from oil industry was evaluated. The process includes many technical steps; de-oiling the entrained spent clay using solvent extraction techniques; solvent recovery process; re-activation process wherein the oil-free spent clay is treated with acid; and thermal polishing step at high temperature to increase the activity. Many solvents were used for de-oiling steps. The performance of solvent for oil recovery can be categorize as follow: Tri-chloromethane > di-chloromethane > MEK > stabilized condensate > 1-butanol > ethyl acetate > LPG condensate > toluene > hexane > 2-propanol The reactivated spent clay was applied for one step reclamation process of waste lubricating oil. It is adsorption–extraction process with solvent and additive. The activity of reactivated spent clay was compared with virgin clay during reclamation process. The reclaimed lubricating oil was analyzed for different physical properties. It was found that the reactivation process of spent clay from acid treatment followed by thermal treatment gave the best results.

Progress on Silica Pervaporation Membranes in Solvent Dehydration and Solvent Recovery Processes.

Separation processes aimed at recovering the solvent from effluent streams offer a means for establishing a circular economy. Conventional technologies such as distillation are energy-intensive, inefficient and suffer from high operating and maintenance costs. Pervaporation based membrane separation overcomes these challenges and in conjunction with the utilization of inorganic membranes derived from non-toxic, sufficiently abundant and hence expendable, silica, allows for high operating temperatures and enhanced chemical and structural integrity. Membrane-based separation is predicted to dominate the industry in the coming decades, as the process is being understood at a deeper level, leading to the fabrication of tailored membranes for niche applications. The current review aims to compile and present the extensive and often dispersive scientific investigations to the reader and highlight the current scenario as well as the limitations suffered by this mature field. In addition, viable alternative to the conventional methodologies, as well as other rival materials in existence to achieve membrane-based pervaporation are highlighted.

Polymethylaminosiloxane Grafted Transition Metal Catalyst DICAT‐V for Chemoselective Aerobic Oxidation of 5‐HMF into 2,5‐Diformyl Furan

AbstractIn the present study polymethylaminosiloxane (PMAS) grafted transition metal catalysts DICAT−M were explored for the chemoselective oxidation 5‐HMF (5‐hydroxymethyl furfural) into DFF (2,5‐diformyl furan). A series of DICAT−M; DICAT−Fe, DICAT−Co, DICAT−Mn, and DICAT−V were synthesized by grafting Fe, Co, Mn, and V, respectively and tested for the oxidation of 5‐HMF. All the synthesized catalysts selectively oxidize 5‐HMF in presence of air without the addition of any base, activator or co‐catalyst. Of the tested catalysts, the vanadium grafted catalyst (DICAT−V) showed an excellent performance with >88 % yield of DFF and >92 % conversion of 5‐HMF in low boiling organic solvent ACN at 110 °C and 20Kg/cm3. The use of ACN facilitated both solvent recovery and product separation process. The structural and surface morphological properties of DICAT−V were studied by using ATR‐FITR, SEM/EDX, XRF, XRD, and BET surface area analysis. Exploration of PMAS provides an excellent backbone architecture with bidentate amine anchors to hold transition metal and resulted in stable, robust, and recyclable catalysts. The plausible reaction mechanism was proposed for DICAT−V assisted chemoselecive aerobic oxidation. Moreover, DICAT−V showed the consistent performance to obtain >88 % yield and >90 % conversion for five consecutive recycle runs. Thus the employment of DICAT−V for 5‐HMF oxidation contributes to the development of the green and sustainable process by integrating recyclable catalyst, additive‐free protocol, LBP solvent, air as the oxidant, and high process throughputs.

Evaluation of CO2-induced azole-based switchable ionic liquid with hydrophobic/hydrophilic reversible transition as single solvent system for coupling lipid extraction and separation from wet microalgae

The utilization of microalgae as bioenergy source was limited by the excessive cost and energy consumption during the process of lipid extraction and separation. CO2-induced switchable ionic liquids (S-ILs) with reversible hydrophobic-hydrophilic conversion were synthesized and applied for lipid extraction and separation. The reversible transition mechanism of switchable IL is due to the formation of carbamate. The novel approach based on S-ILs was developed for lipid extraction from wet microalgae, which coupled microalgae cell disruption, lipid extraction, separation, and solvent recovery process without additional solvents. The highest lipid extraction efficiencies from wet microalgae were obtained by C6DIPA-Im, and the lipids were recovered from the extraction phase by simply bubbling CO2. Furthermore, C6DIPA-Im maintained more than 83.6 ± 3.6% of its initial lipid extraction efficiency after recycling five times. The S-IL based extraction and separation method provides a new strategy for sustainable bioenergy production.