Solvent Recovery Step Research Articles

Carotenoids from wastewater-grown microalgae biomass: Life cycle assessment and techno-economical analysis

Microalgae stand out as a valuable source of carotenoids, with potential applications in various industrial sectors. Cultivating microalgae in wastewater emerges as an alternative to mitigate the high costs associated with the synthetic production of these compounds while contributing to sanitation resource recovery. Previous studies demonstrated the potential for obtaining lutein and betacarotene from biomass cultivated in domestic sewage and agro-industrial effluent. This study conducted comprehensive economic and life cycle analyses to evaluate cultivation reactors (high-rate pond and hybrid system) and extraction methods (ethyl acetate solvent and supercritical fluid) to acquire 1 kg of carotenoids efficiently. For all evaluated scenarios, higher environmental impacts were observed in the Human carcinogenic toxicity category and human health environmental damage associated with ethyl acetate and electricity consumption. Ethyl acetate also stood out with higher costs. The high-rate pond and hybrid system showed similar environmental impacts in scenarios with ethyl acetate extraction; however, when supercritical fluid was used, cultivation in the first reactor resulted in 2.2–6.2 times lower environmental impacts in Midpoint categories. Regarding the extraction method, the use of supercritical fluid demonstrated superior economic and environmental performance despite registering a 53% higher energy consumption than solvent extraction. Thus, for the viability of obtaining carotenoids from microalgae biomass, we recommend that two-stage cultivation approaches, incorporating solvent recovery steps and biomass valorization in a cascade manner within a biorefinery context, be considered in future studies.

Industrial demonstration of indirect mineral carbonation in the cement and concrete sector

This paper reports on the successful construction, commissioning and operation of a mobile indirect mineral carbonation (IMC) pilot plant in the concrete sector. This work confirms the technical feasibility of IMC at large scale, while producing precipitated calcium carbonate (PCC) and leached recycled concrete aggregate (RCA) as useful products. The plant is capable of handling industrial flue gas or pure CO2 as carbon feedstock, while processing around 80 kg/h of RCA as calcium feedstock, and storing around 0.9 kg/hr of CO2. Good recyclability of the aqueous ammonium nitrate mother liquor is suggested, although small changes occurred over time, with only small effects on the operation. Importantly, some CaCO3 precipitates in the dissolution reactor, especially at high CO2 feed rates; this does not decrease the CO2 storage rate, but it reduces the PCC production rate. The plant may be operated at a variety of operating conditions and it responds to them as expected from thermodynamic considerations. Similarly, the trade-offs in terms of performance parameters also change as expected. The observed calcium extraction efficiency is rather low due to the thermodynamic nature of the batch dissolution step. Also, the ammonium nitrate losses are rather high due to the plant not having a solvent recovery step integrated. Potentially alternative reactor concepts for the dissolution section can improve the calcium extraction efficiency while including a washing step, thus alleviating the main limitation. Material tests with the products of the process suggest that leached RCA is as good as, or even better than fresh RCA for use as aggregate in concrete; ground PCC performs similar as ground limestone in cement, however it is not the most attractive use of fine PCC, as higher value applications exist. Although improvements to the plant design are necessary to make the process economically and environmentally viable, this work represents an important steppingstone towards industrial implementation of IMC, and confirms its technical feasibility in the concrete sector.

Physio‐Electrochemically Durable Dry‐Processed Solid‐State Electrolyte Films for All‐Solid‐State Batteries

AbstractThe dry process is a promising fabrication method for all‐solid‐state batteries (ASSBs) to eliminate energy‐intense drying and solvent recovery steps and to prevent degradation of solid‐state electrolytes (SSEs) in the wet process. While previous studies have utilized the dry process to enable thin SSE films, systematic studies on their fabrication, physical and electrochemical properties, and electrochemical performance are unprecedented. Here, different fabrication parameters are studied to understand polytetrafluoroethylene (PTFE) binder fibrillation and its impact on the physio‐electrochemical properties of SSE films, as well as the cycling stability of ASSBs resulting from such SSEs. A counter‐balancing relation between the physio‐electrochemical properties and cycling stability is observed, which is due to the propagating behavior of PTFE reduction (both chemically and electrochemically) through the fibrillation network, resulting in cell failure from current leakage and ion blockage. By controlling PTFE fibrillation, a bilayer configuration of SSE film to enable physio‐electrochemically durable SSE film for both good cycling stability and charge storage capability of ASSBs is demonstrated.

Techno-economic optimization of novel energy-efficient solvent deasphalting process using CO2 as a stripping agent

The solvent deasphalting (SDA) process is specifically designed to selectively remove asphaltene from heavy oil feedstocks. However, high energy consumption resulting from the separation processes used to recover the extraction solvent from the mixture of oil products and solvent is a challenge in the SDA process. In this study, a novel SDA process in which the solvent recovery steps were modified by employing carbon dioxide instead of steam as the stripping agent was developed. In addition, the operating and heat integration parameters of the novel CO2-assisted SDA process were optimized using bilevel optimization to minimize the total annualized cost. A genetic algorithm was applied to optimize the process operating variables in the upper-level problem, including the temperature and pressure of solvent recovery units. In the lower-level problem, heat integration parameters—the minimum temperature difference (ΔTmin) and the heat load distribution of hot and cold utilities—were optimized. The optimization results demonstrated that the novel SDA process is more energy-efficient and economical than the conventional SDA process.

Separation of microbial oil produced by Mortierella isabellina using polymeric membranes.

The objective of this work was to concentrate, through a membrane separation process, the fatty acids from oil/solvent mixture. The oil was obtained by ultrasound-assisted extraction from freeze-dried cells of Mortierella isabellina. The concentration of the fatty acids was investigated using flat-sheet polymer membranes of ultrafiltration and nanofiltration. The effects of temperature and pressure were evaluated by the retention of the fatty acids. Oil retentions between 45.23 and 58.20% to ultrafiltration membrane and 43.50 and 56.00% to nanofiltration membrane were observed. The best condition for the ultrafiltration membrane was 4bar and 40°C and for nanofiltration membrane was 12bar and 50°C. The oil contains a high concentration of oleic acid and palmitic acid that is a desirable property for the biodiesel production. The results showed the applicability of this technology in the solvent recovery step whereas the oil recovered contains a high concentration of fatty acids.

A Systematic Molecular Design Framework with the Consideration of Competing Solvent Recovery Processes

This Article presents a Computer Aided Molecular Design (CAMD) framework that considers both the solute extraction and the solvent recovery steps simultaneously during the solvent design. The choice of a solvent has a significant role not only on the effectiveness of the process, but also on the safety, health, and environmental impact. In addition, the energy required for solvent regeneration is dependent on both the chosen solvent and its recovery techniques. Therefore, we have incorporated physicochemical property targets, safety, health, and environmental (SHE) aspects and utilities cost needed to recover the solvent during the design stage. Fuzzy Analytic Hierarchy Process (FAHP) weighting approach is applied to assign consistent weights to the multiple objective functions. Through this approach, the designed solvents with favorable functionalities can be recovered through an economically efficient and environment friendly process. The developed methodology is used to design a solvent to be used in palm oil industry for residual oil extraction from palm pressed fiber.

Enhanced Lipid Recovery from Marine Chlorella Sp. by Ultrasonication with an Integrated Process Approach for Wet and Dry Biomass

Lipid extraction from microalgal biomass faces some challenges such as the selection of a suitable biomass type and its quality, lipid yield (LY), and process energy consumption. This study aimed to develop optimized processing conditions using response surface methodology, for the ultrasonic extraction (UE) of lipids from wet and dried marine Chlorella sp. Integrated process approaches with different extraction and solvent recovery steps were developed for the evaluation of the lipid recovery and process energy consumption. The effects of other processing factors, such as the biomass-to-solvent ratio, solvent type, and solvent-to-solvent ratio were investigated. The biomass and lipids extracted were characterized by scanning electron microscopy-energy-dispersive X-ray (SEM-EDX) and gas chromatography-flame ionization detection (GC-FID) analysis, respectively. With a single extraction and single-solvent recovery (1-1 cycle) process, the LYs from fresh and stored paste were 11.7% and 6%, respectively, while freeze-dried biomass produced an 18.5% LY. The energy consumption was 6000 MJ/kg lipid for the wet route and 8200 MJ/kg lipid for the dry route in the 1-1-cycle process. Dried biomass was selected for further investigation due to its longer storage-period capability and higher LY. The LY of the 2-1-cycle process using methanol/hexane (2/1 v/v) with a biomass-to-solvent ratio of 1/20 g/mL was 31% and was considered as a base case scenario of this study, which is 40.3% and 9.7% greater than those of the 1-1 cycle and 2-2 cycle, respectively. The lipids obtained from the 2-1 cycle at the optimum condition were mainly saturated fatty acids which are suitable for a biodiesel feedstock.

Benefits of Water-Based Binder Electrodes for Li-Ion Batteries

Leclanché implements the innovative water-based production process; applied to all cell electrodes, it results in cost effective large format 30Ah LTO- and 43 Ah graphite-based cells, while minimizing environmental impact of manufacturing and ensuring very high cell performances and lifetime stability. Some of the benefits of water-based binder electrodes are: No more usage of organic (toxic) solvents in the mixing and coating processes. Reduced manufacturing cost of aqueous vs. solvent processing. Elimination of expensive solvent recovery steps, reduction of capital cost for coating equipment and elimination of expensive inactive components. Simplification of machinery (no EX requirements). Machinery size reduction (water extraction is faster than NMP one, therefore the drying section for coating line is reduced). Fast drying speed and low drying temperature require less electric power and yield to higher production rate. No dry room required for cell assembly, only humidity control is required during electrolyte filling, etc. The innovative high-quality manufactured electrodes lead to very high mechanical and electrochemical stability during cycling, e.g. Leclanché large-capacity LTO lithium-ion batteries allow for tenths of thousands full-DoD cycles to be reached, even in highly demanding conditions (see Fig.1). The lifetime estimation exceeds 20.000 cycles and is little affected by C-rate. Fig. 1: Lifetime characteristics at RT (21°C); influence of C-rate and lifetime estimation of 16 Ah cell Figure 1

Extraction of Bitumen from Oil Sands Using Deep Eutectic Ionic Liquid Analogues

It is demonstrated that bitumen can be separated from “water-wet” Alberta oil sands and “oil-wet” Utah oil sands using a so-called analogue ionic liquid (IL) based on deep eutectic mixtures of choline chloride and urea (ChCl/U) together with a diluent such as naphtha. Unlike conventional ILs, these eutectics are relatively cheap and environmentally friendly. The process is straightforward and involves simply mixing the components at ambient temperatures followed by standard solid/liquid and liquid/liquid separation steps. The ChCl/U mixture appears to reduce the adhesion of bitumen to sand, facilitating separation. It is also immiscible with hydrocarbons such as bitumen or oil. Coupled with a large density difference, this results in a sharp phase separation of hydrocarbons from the ChCl/U mixture. The ChCl/U deep eutectic essentially acts as a separating fluid, keeping the naphtha-diluted bitumen and extracted sand apart, facilitating subsequent separations and solvent recovery steps. However, ChCl/U mix...

Desolventizing organic solvent-soybean oil miscella using ultrafiltration ceramic membranes

This work reports the use of ceramic membranes with different cut-offs (5, 10 and 20kDa) for the separation of synthetic mixtures simulating soybean oil industrial miscellas in organic solvents (n-hexane, ethanol and isopropanol). The mass ratios oil/solvent investigated in this work were 1:4, 1:3 and 1:1 (w/w) for the feed pressures of 0.5–4bar depending on the miscella. It is shown that n-butanol was the best solvent for the proper conditioning of 20kDa membrane, since it increased permeate flux of n-hexane, up to 314L/m2h at 1bar of transmembrane pressure. The desolventizing of oil/solvent mixtures was strongly affected by solvent nature, and on the solute–solvent–membrane affinity. The highest retentions were observed for oil/ethanol mixtures, with values usually close to 100%, as a consequence of polarity as well as low solvation power. Crude oil mixture with n-hexane (industrial mixture) yielded greater retention and lower flux than those obtained with refined oil, due to the polarized layer formed by gums and phospholipids. Results reported in this work indicate the potential applicability of this technology in vegetable oil processing and biodiesel industries in the solvent recovery step.

Separation of soybean oil/n-hexane and soybean oil/n-butane mixtures using ceramic membranes

This study aimed to investigate the separations of mixtures of refined soybean oil/n-hexane, crude soybean oil/n-hexane (industrial miscella) and refined soybean oil/pressurized n-butane using membrane technology. Commercial ceramic membranes with molecular weight cut-offs between 5 and 10kDa were employed, varying the mass ratios of the oil/solvent, from 1:1 to 1:3 (w/w). Oil rejections up to 100%, total permeate fluxes (oil+solvent) up to 42.97kg/m2h with oil permeate fluxes up to 1.4kg/m2h were obtained. The industrial miscella showed the same behavior observed for the synthetic mixtures presenting an increase in the oil rejection with a decrease in total permeate flux. In the separation of the oil/n-butane mixtures, higher oil rejections were obtained when compared to the system oil/n-hexane. The results presented in this work indicate the potential applicability of membrane technology in vegetable oil processing and biodiesel industries in the solvent recovery step.

Increasing the sustainability of membrane processes through cascade approach and solvent recovery—pharmaceutical purification case study

Membrane processes suffer limitations such as low product yield and high solvent consumption, hindering their widespread application in the pharmaceutical and fine chemicals industries. In the present work, the authors propose an efficient purification methodology employing a two-stage cascade configuration coupled to an adsorptive solvent recovery unit, which addresses the two limitations. The process has been validated on purification of active pharmaceutical ingredient (API) from genotoxic impurity (GTI) using organic solvent nanofiltration (OSN). The model system selected for study comprises roxithromycin macrolide antibiotic (Roxi) with 4-dimethylaminopyridine (DMAP) and ethyl tosylate (EtTS) as API and GTIs, respectively. By implementing a two-stage cascade configuration for membrane diafiltration, the process yield was increased from 58% to 95% while maintaining less than 5 ppm GTI in the final solution. Through this yield enhancement, the membrane process has been “revamped” from an unfeasible process to a highly competitive unit operation when compared to other traditional processes. The advantage of size exclusion membranes over other separation techniques has been illustrated by the simultaneous removal of two GTIs from different chemical classes. In addition, a solvent recovery step has been assessed using charcoal as a non-selective adsorbent, and it has been shown that pure solvent can be recovered from the permeate. Considering the costs of solvent, charcoal, and waste disposal, it was concluded that 70% solvent recovery is the cost-optimum point. Conventional single-stage diafiltration (SSD) and two-stage diafiltration (TSD) configurations were compared in terms of green metrics such as cost, mass and solvent intensity, and energy consumption. It was calculated that implementation of TSD, depending on the batch scale, can achieve up to 92% cost saving while reducing the mass and solvent intensity up to 73%. In addition, the advantage of adsorptive solvent recovery has been assessed revealing up to 96% energy reduction compared to distillation and a 70% reduction of CO2 footprint.

Non‐Evaporative Solvent Recovery Step in Deacidification of Used Frying Oil as Biodiesel Feedstock by Methanol Extraction

AbstractAn alternative deacidification process combining a liquid–liquid extraction with a non‐evaporative solvent recovery step was proposed for preparing used frying oil (UFO) as biodiesel feedstock. The liquid–liquid extraction step using methanol was simulated for obtaining refined UFO with a final residual free fatty acids (FFA) content ≤ 1%. Solvent recovery step of the process, which is based on the precipitation of FFA with Ca(OH)2 as insoluble calcium soaps, was investigated experimentally. With the aim of maximizing the FFA removal from the methanol extract, the influence of process variables such as FFA concentration in the extract phase, Ca(OH)2 amount, stirring rate and temperature were investigated by using model extract phases. Complete removal of FFA was achieved in 30, 20, and 15 min, from the extract phases containing 3.86, 7.78, and 11.58 wt% FFA, respectively, when the precipitation was carried out at a temperature of 65 °C, stirring rate of 250 rpm and by using 18 times the stoichiometric Ca(OH)2 amount. The precipitate quickly settled down due to the agglomeration, thereby provided an efficient and easy separation of the methanol from the solids. Provided the final residual content of FFA in methanol was too low, recovered methanol can be recycled for more FFA extraction. Although the suggested process offers a feasible method for preparing UFO as biodiesel feedstock, the effect of other decomposition products in UFO must be investigated in depth for using such a process on an industrial scale.

Improvement of Process for Reducing the Benzene Content in Motor Gasoline Using an Emulsion Liquid Membrane and Distillation.

The process for removing toxic benzene from reformate based on an emulsion liquid membrane and distillation was improved and the calculation results of the new and old processes were compared. In the new process, benzene and non-aromatic hydrocarbons with boiling points close to that of benzene are removed from the reformate by two ordinary distillators to yield low-benzene reformate. The benzene and non-aromatic hydrocarbons are separated by the liquid membrane. The process calculation was carried out based on the previous empirical correlation of the mass transfer coefficient in the packed column permeator. Low-benzene reformate of the same flow rate and benzene content as in the previous process could be obtained by distillators with practical numbers of stages and operating conditions. The total aromatics content in the low-benzene reformate was higher than that of the original reformate, in contrast to the previous process. The octane number of the low-benzene reformate is thus higher than that of the original reformate. The yield of benzene was almost the same and the mass fraction of benzene in the product considerably increased. The flow rate of the stream to the permeator, consisting of the benzene and non-aromatics removed from the reformate, was naturally smaller than that in the previous process, where the original reformate was fed directly to the permeator. Therefore, the new process can treat larger amounts of the reformate than the previous process with the equivalent size of permeator. In the solvent recovery step, both the number of distillation stages and the heat energy required could be reduced. Solvent recovery absorbed the major part of the energy for the whole process. The energy requirement for the whole process was therefore lowered.