Continuous Solvent Extraction Research Articles

Recovery of Rhodium by Solvent Extraction using N, N, N′, N′, N″, N″-Hexahexyl-nitrilotriacetamide and Electrodeposition

The development of solvent extraction and direct electrodeposition processes is crucial for reducing the volume of secondary waste. In this study, the extraction behavior of Rh(III) using N, N, N, N′, N′, N′-hexahexyl nitrilotriacetamide (NTAamide(C6)) was investigated with three different diluents that have relatively high dielectric constants. Slope analysis revealed that the extraction mechanism of Rh(III) is based on ion-pair extraction. The electrochemical behavior of the extracted Rh(III) complexes in each diluent was investigated using cyclic voltammetry. Rh(III) was reduced to Rh(0) through a three-electron transfer in the NTAamide(C6)/acetophenone, 1,2-dichloroethane, and 1-octanol systems. Moreover, the diffusion coefficient of the extracted Rh(III) complex was evaluated using semi-differential analysis. The electrodeposits were recovered through continuous solvent extraction and direct electrodeposition. The electrodeposits were identified as Rh metals by X-ray photoelectron spectroscopy and X-ray diffraction analyses.

Solvent extraction of La, Nd, and Eu using a newly designed solutions spray system

This research covers a new continuous solvent extraction “solutions spray system” technique to extract lanthanum (La), neodymium (Nd), and europium (Eu) from chloride solution using DEHPA. This setup enhanced the extraction kinetics and mass transfer compared to the conventional mixer-settler by generating micro-sized droplets of the feed streams in the mixing chamber, causing speedy and better mass transfer, and the special design of the settling column boosted the separation process with improved quality products. Variables like pH, DEHPA concentration, ionic strength, and aqueous/organic phase ratio were studied to determine the performance of this setup. At the optimum values of these variables (2.0 pH, 0.303 M DEHPA, and 1.54 mol/L ionic strength), the percent extraction of La, Nd, and Eu was 95.03 %, 99.36 %, and 99.98 %, and the distribution ratio was 19.14, 155.25 and 4165 respectively, which showed the extraction in a single stage. Furthermore, the values of separation factors, SFEu/La = 6.69, SFEu/Nd = 5.33, and SFNd/La = 1.26 at 0.50 pH, showed the selectivity of these elements. Later on, McCabe Thiele diagrams were plotted for extraction and stripping sections to see the minimum number of theoretical stages for the complete recovery of REEs and their selective separation from each other.

MTT Assay on Anticancer properties of the different extracts of roots of Lantana camara Linn.

Lantana camara, considered a weed is an evergreen plant found throughout the world. Traditionally it has been used in the treatment of various ailments and has been supported by scientific investigation. Phytoconstituents present in almost all parts of this plant have been reported in various literature. This study has been done on the root part of Lantana camara, the dried and powdered root was subjected to continuous solvent extraction with Hexane followed by Ethyl Acetate and Methanol. Ethyl Acetate and Methanol extracts were evaluated for anticancer activity by MTT assay, MCF7 cell line was used with Cisplatin a known anti-cancer drug as a standard reference, and the measurements were carried out at wavelengths 570 and 630nm. The percentage of growth inhibition was calculated. The concentration of test extract needed to inhibit cell growth by 50% (IC50) value generated from the dose-response curve. IC50 values of Ethyl Acetate extract were greater than 500µg/ml and Methanol extract 450.05µg/ml.

Liquid–liquid extraction for in situ carboxylic acid recovery via continuous membrane-based emulsion separations

A membrane-based emulsion separator can enable continuous solvent extraction in bioprocessing separations with substantially improved demulsification and mass transfer rates, including where emulsion formation is a challenge.

A Continuous Extraction Protocol for the Characterisation of a Sustainably Produced Natural Indigo Pigment.

The sustainable industrial production of indigo necessitates a unique extraction process to separate the plant-derived compounds. Calcium compounds are added to encourage hydrolysis of these precursors and to facilitate the isolation of the final form, resulting in an organic-inorganic composite pigment with unspecified characteristics. In this study, we devised a continuous solvent extraction procedure to fractionate the organic indigoid phase within the composite pigment. Overcoming challenges posed by limited solubility in the common organic solvents, this method allows for the analysis of individual fractions, significantly enhancing resolution. Comprehensive characterisation using spectroscopic analysis, thermogravimetry, and UHPLC-MS/MS revealed the potential for quantifying primary components of the natural pigment and distinct differentiation from the synthetic dye. This approach also holds promise for establishing robust manufacturing practices in the industrial production of natural indigo.

Refining of Palladium, Platinum, and Rhodium from a Pregnant Leach Solution of Spent Automotive Catalysts by Continuous Counter-Current Solvent Extraction with Ionic Liquids in Mixer-Settlers

Refining of Palladium, Platinum, and Rhodium from a Pregnant Leach Solution of Spent Automotive Catalysts by Continuous Counter-Current Solvent Extraction with Ionic Liquids in Mixer-Settlers

Selective recovery of thorium and uranium from leach solutions of rare earth concentrates in continuous solvent extraction mode with primary amine N1923

A continuous counter-current extraction for the selective recovery of thorium (Th) and uranium (U) from the Yen Phu (Vietnam) rare earth concentrate leach solutions was systematically studied. The primary amine N1923 was used as an extractant which was prepared in the isoparaffin IP-2028 diluent. Thorium and uranium were selectively recovered in a hydrometallurgical circuit established by continuous mixer-settler extraction, scrubbing, and back-extraction at the laboratory scale. The desired purity of Th and U can be achieved by managing the volume ratio of organic to aqueous phase (O/A ratio) in the corresponding steps. Highly pure Th and U were recovered from the pregnant back-extraction liquor and the raffinate, respectively, which have satisfactory properties for further processing of the subsequent nuclear materials.

Separation of heavy rare-earth elements by non-aqueous solvent extraction: Flowsheet development and mixer-settler tests

The separation of rare-earth elements (REEs) is considered one of the most challenging processes in solvent extraction. In recent years, non-aqueous solvent extraction, a unit operation within solvometallurgy, has stepped into the limelight as one of the promising techniques for efficient REEs separation. In this paper, a rare-earth hydroxide concentrate, originating from mining waste and containing mainly heavy rare-earth elements (HREEs), was redissolved in ethylene glycol + 10 vol% water, 0.43 mol L−1 HCl and 0.8 mol L−1 NaCl. Based on batch experiments, a conceptual flowsheet was proposed for the separation of the HREEs into 2 groups: a thulium group (Tm, Yb and Lu) and a dysprosium group (Dy, Ho, Er and Y). Continuous solvent extraction tests in lab-scale mixer-settlers were performed to confirm the technical feasibility of the developed system, as well as to identify and resolve possible bottleneck points. Eventually, using only 16 stages of lab-scale mixer-settlers, the purity of the thulium group and dysprosium group elements, originally 34% and 54%, respectively, reached 99.8% and 98.7%, respectively. Further optimization remains necessary for the separation and purification into highly pure single REEs.

Separation of niobium and tantalum using continuous multistage counter-current solvent extraction with trioctyl amine

Niobium and tantalum are valued for their uses in nuclear, steel, aviation and electronics industries. This paper elucidates the development of a multistage counter-current separation process for obtaining pure niobium and tantalum from the hydrofluoric acid solution of Coumbite-Tantalite ore (leach liquor), with trioctyl amine (TOA) as the extractant solvent. Contrary to the conventionally used multistage process this novel route does not use any other acid in addition to hydrofluoric acid, resulting in the elimination of the generation of mixed fluoride waste. Reaction equilibrium constants for the reactions involving the extraction of hydrofluoric acid, niobium and tantalum have been determined and were used to generate equilibrium distribution curve of niobium and tantalum in the organic and aqueous phase. The number of counter-current stages required for an appropriate organic to aqueous phase volume (O/A) ratio was determined using McCabe-Thiele calculations. Selective extraction of 99% of tantalum from the leach liquor was achieved using 5 v/v% TOA and two counter-current stages for an O/A ratio of four. The tantalum lean raffinate was treated with commercial grade hydrofluoric acid to form the niobium feed solution having 16 M free acidity. Near complete extraction of niobium was achieved using a three stage counter-current process with O/A ratio of two and 10 v/v% TOA as the organic extractant. The calculations for the stage-wise variation of concentrations were validated by batch experimental simulation of counter-current processes.

Study of lanthanum-didymium separation by solvent extraction from a liquor conditioned with lactic acid

Rare earth elements (REE) have increased in importance in the world due to the diverse applications in high-tech industries. The fact that Brazil has the world’s second largest REE reserves makes it a potential producer of these elements. However, for that to occur, it is necessary to have knowledge about the production technologies of rare earths, mainly the technologies used in the refining stages, in which China predominates. Generally, the leached solution contains a mixture of REE and the main challenge is to improve selectivity during their separation and purification. For this reason, techniques to improve the efficiency of the separation of these elements have been widely studied in recent years. In the present study, we seek to define efficient routes for the separation of lanthanum (La) from didymium (Pr and Nd) by the solvent extraction technique (SX), using the organophosphorus extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507) from a liquor conditioned with lactic acid. Isotherms were constructed using the McCabe-Thiele method to estimate the number of theoretical stages and the aqueous/organic ratio (A/O) necessary to achieve efficient separation during the process. In continuous solvent extraction experiments, REE recovery percentages and purity of didymium and lanthanum above 90% were obtained. Didymium with 99.9% purity was obtained in a circuit with nine extraction stages (extraction A/O ratio of 4:1) and seven scrubbing stages (scrubbing A/O ratio of 2:1). The results presented here show that the use of lactic acid can be a promising alternative to boost the efficiency of the solvent extraction process for the separation of these light rare earth elements.

Continuous pressurized extraction versus electric fields-assisted extraction of cyanobacterial pigments

Cyanobacteria pigments, in special carotenoids and phycobiliproteins, are usually used in industry as raw extracts, although there is still no standard methodology for their extraction. For the co-extraction of carotenoids and phycobiliproteins from the marine cyanobacterium Cyanobium sp., a continuous pressurized solvent extraction (CPSE) system and an electric fields-assisted extraction system based in ohmic heating were optimized using Central Composite Designs, with three factors each: time (t), temperature (T) and, flow (f) for CPSE; and time, temperature and frequency (F) for ohmic heating. The content of pigments and the antioxidant capacity of extracts were evaluated. All tested factors seem to influence the extraction of pigments in different ways: a high temperature (70 °C) had a positive impact on the extraction rate in both methods, while the influence of time depended on the extraction principle. Flow and frequency affected directly the extraction efficiency and these methods are indeed suitable for cyanobacterial pigments extraction, achieving good extraction results. Optimal conditions for co-extraction of carotenoids and phycobiliproteins in CPSE were T = 70 °C, t = 20 min and f = 1.5 mL min−1, and for ohmic heating they were T = 70 °C, t = 5 min and F = 20 kHz. Both, CPSE and ohmic heating systems allowed obtaining better extraction yields when compared with a previously optimized extraction method (homogenization), used here as a reference. However, ohmic heating was the best methodology for pigments co-extraction from Cyanobium sp.

In-vitro hypoglycemic activity of lawsonia inermis Linn. Leaf extracts

in-vitro hypoglycemic activity of lawsonia inermis Linn. Leaf extracts

Continuous microfluidic solvent extraction of cobalt from mimicked and real asteroid leaching solutions

This research proposes a pathway for the last step of the asteroid mining process: the purification of the adjacent metals, cobalt and nickel, in the frame of in-situ resource utilization (ISRU) in space. Major technological and economic challenges will need to be overcome, and one main issue to be tackled is the reduction of water usage in this process. Therefore, the leached metal solutions are expected to contain ultra-high metal concentrations, up to 10 mol/l. These solutions will have challenging thermodynamic properties (increased density, viscosity and interfacial tension). As a result, an analysis of dimensionless numbers for fluidics and mass transport was made, showing that some of these are favourable under the constraints of accessible microfluidic operations. Experiments were performed with advanced microfluidic reactors (a coiled-flow inverter (CFI) and an industrial re-entrance flow reactor from Corning®) at high metal concentrations and high nickel to cobalt ratios (3:0.3 mol/l Ni:Co). Using Cyanex 272 as a selective extractant for cobalt, extraction efficiencies of 60% with high separation factors (>1000) were reached in just one extraction stage. The CFI showed high extraction efficiency for low fluid velocities and a residence time of 60 s. For the Corning® reactor, high fluid velocities or the use of many modules (>3) are needed to obtain an emulsion, resulting in high extraction efficiencies at a very short residence time of 13 s. The comparison between the CFI and the Corning® reactor shows that they share the best operation point (at 120 ml/h), but the Corning® reactor performs better at higher flow rates and thus can leverage higher productivity. However, the CFI is easier to operate and has a much lower pressure drop, resulting in low energy input. Finally, an iron meteorite sample was leached and efficiently extracted in both microfluidic reactors.

Continuous-Flow Extraction of Adjacent Metals-A Disruptive Economic Window for In Situ Resource Utilization of Asteroids?

For the in situ resource utilization (ISRU) of asteroids, the cost-mass conundrum needs to be solved, and technologies may need to be conceptualised from first principals. By using this approach, this Review seeks to illustrate how chemical process intensification can help with the development of disruptive technologies and business matters, how this might influence space-industry start-ups, and even industrial transformations on Earth. The disruptive technology considered is continuous microflow solvent extraction and, as another disruptive element therein, the use of ionic liquids. The space business considered is asteroid mining, as it is probably the most challenging resource site, and the focus is on its last step: the purification of adjacent metals (cobalt versus nickel). The key economic barrier is defined as the reduction in the amount of water used in the asteroid mining process. This Review suggests a pathway toward water savings up to the technological limit of the best Earth-based processes and their physical limits.

Continuous solvent extraction operations for the removal of molybdenum from ammonium tungstate solution with quaternary ammonium salt extractant

The continuous solvent extraction operations for the removal of molybdenum from ammonium tungstate solution was conducted using a solvent extraction system consisting of 10% (v/v) N263 as extractant and 30% (v/v) isooctanol as modifier in sulfonated kerosene for 63 h under optimized conditions in mixer-settlers. The concentration of Mo in raffinate was less than 10 mg/L with mass ratio of Mo/WO3 less than 6.0 × 10−5 and the concentration of Mo in strip liquor reached 30 g/L with mass ratio of WO3/Mo less than 1.0 × 10−2, which was consistent with the results of batch tests. The loaded organic solution and the oxidized organic solution were characterized by infrared spectroscopy and the results demonstrated that molybdenum exists in the form of [Mo2O11(H2O)2]2− in oxidized organic solution. The theoretical calculation of temperature change of the organic solution in oxidation process was conducted. The oxidant of 7 wt% H2O2 was recommended to be used during industrial production and a cooling water system has to be installed around the oxidation tank at the same time.The new process exhibited significant advantages of low overall costs, large value increase due to molybdenum producibility of MSA and environmental friendliness without wastewater and residue generation.

Hydrometallurgical separation of zinc and copper from waste brass ashes using solvent extraction with D2EHPA

A blend of brass ashes containing 48.0% of zinc and 16.6% of copper was processed through selective leaching with dilute H2SO4 and solvent extraction, using D2EHPA as the extracting agent in order to separate zinc and copper. Solvent extraction tests performed in bench and pilot scales were designed to evaluate the following operating parameters: time, pH, D2EHPA concentration, A/O ratio in the extraction step, and O/A ratio in the stripping step. Zinc present in the brass ashes was efficiently leached by H2SO4 (recovery of 91.9%), whereas only 8.6% of copper was leached, producing a liquor containing zinc (28.6g/L), copper (1.5g/L), calcium (0.45g/L), iron (0.43g/L), and chloride (0.22g/L), as well as fluoride, lead, nickel and cadmium, at levels below 0.01g/L. Zinc was selectively extracted over copper by solvent extraction with D2EHPA. A continuous solvent extraction run in pilot scale was carried out using 4 extraction stages (pH=2, A/O ratio=1) and 2 stripping stages (O/A ratio=2), where 91.8% of zinc extraction and 96.9% of zinc stripping were achieved. Iron extraction efficiency reached 85.9%, thus illustrating the need for its prior removal if required. The fluorine extraction was 29.9%, as compared to 10.4% for chlorine, whose respective extractions are related to the presence of iron and zinc in the liquor, as evidenced by species speciation analysis. A copper concentrate containing 42.2% was obtained in the leaching step.

Simultaneous determination of eight neonicotinoid insecticides, fipronil and its three transformation products in sediments by continuous solvent extraction coupled with liquid chromatography-tandem mass spectrometry.

Neonicotinoids (NEOs) and fipronil (FIP) are insecticides that are widely used in modern agriculture and have received considerable attention in recent years due to their adverse effects on non-target organisms in the environment. In the present study, a new method to simultaneously detect eight common NEO insecticides and FIP and its three transformation products (FIPs) in sediments was developed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) based on a combined pretreatment of continuous solvent extraction (CSE) and solid phase extraction (SPE). Under optimized conditions, 5.0g of freeze-dried sediment samples were initially extracted with methanol (20mL)-methanol (15mL)-water (20mL) in sequence, and then the extract was cleaned with hydrophilic-lypophilic balance SPE cartridges, and HPLC-MS/MS analysis was conducted. The established method was validated to be sensitive, linear, accurate, and precise. The limits of detection (LOD) and limits of quantification (LOQ) of target compounds were 0.012-0.055μg/kg d.w and 0.031-0.091μg/kg d.w, respectively. Good linearity (R2>0.990) was observed between 4.0×10-2 and 20.0μg/kg d.w. The recovery rates of all target insecticides were between 75.5% and 98.5%, and the relative standard deviations (RSD) were all less than 15.0% at the low, medium, and high spiked levels. Finally, the optimized method was applied to analyze 12 target insecticides in the sediments obtained from Jiaozhou Bay of China and its main inflow rivers. Acetamiprid, thiamethoxam, fipronil sulfide, and fipronil sulfone were detected in the river sediment samples at the concentration from <LOQ to 0.197μg/kg d.w. Thus, the two types of studied insecticides can enter the sedimentary environment. Overall, the proposed method can be used to investigate the contamination status of typical NEOs and FIP insecticides in sediments and provide base data to comprehensively understand their environmental behavior, safety, and fate.

Exergy Analysis of Directional Solvent Extraction Desalination Process.

This paper presents an exergy analysis to evaluate the performance of a continuous directional solvent extraction (DSE) desalination process using octanoic acid. The flow of exergy was calculated for each thermodynamic state and balanced for different components of the system to quantify the inefficiencies in the process. A parametric study was performed to evaluate the impact of three critical design variables on exergy consumption. The parametric study reveals that the total exergy input decreases significantly with an increase in heat exchanger effectiveness. The results also indicate that the heat exchangers account for the highest exergy destruction. The total exergy consumption, however, has a slightly declining trend as the recovery-ratio increases. There is a small variation in the total exergy consumption, within the uncertainty of the calculation, as the highest process temperature increases. When compared to conventional desalination processes, the exergy consumption of the DSE, with heat recovery of 90%, is comparable to those of multi-stage flashing (MSF), but much higher than reverse osmosis (RO). Octanoic acid, which has low product water yield, is identified as the primary factor negatively impacting the exergy consumptions. To exploit the low-grade and low-temperature heat source feature of the DSE process, directional solvents with higher yield should be identified or designed to enable its full implementation.

Continuous solvent extraction operations for the separation of W and Mo in high concentrations from ammonium solutions with acidified N1923

To separate tungsten and molybdenum from the ammonium solution containing 31.2 g/L WO3 and 32.5 g/L Mo, the continuous operations of solvent extraction were carried out using acidified primary amine extractant of N1923 in mixer-settlers. Thermodynamic analysis of the WMoH2O system showed that W(VI) could be selectively extracted over Mo (VI) by primary amine since WO42− was preferentially transformed to polymeric ions as the pH decrease. The results of 58 h continuous operations indicated that the solvent extraction process could be used effectively to separate W(VI) from ammonium molybdate solutions. The raffinate contained only 6.0–7.0 mg/L WO3 with a mass ratio of WO3/Mo less than 3.45–4.99×10−4, which can be used to produce ammonium molybdate with MSA-0 grade of Chinese National Standards. Compared with traditional methods on separation of W and Mo, the new process exhibited obvious advantages of low cost, high separation factor of W/Mo, environmental friendliness, which is expected to make good economic and social benefits.

Continuous Flow Droplet-Based Crystallization Platform for Producing Spherical Drug Microparticles

In this paper, we demonstrate a continuous flow evaporative crystallization platform for producing monodisperse microparticles containing crystalline API with tunable particle sizes and compositions, which are suitable for direct compounding. Monodisperse drug-laden emulsions are first generated via microfluidics and undergo continuous solvent extraction within a tubular crystallizer to emerge as microparticles. We demonstrate this platform on four different types of hydrophobic drug and drug-excipient formulations to show the generality of this method and discuss the solvent extraction performance of the platform using a mathematical model. Our approach combines four conventional manufacturing steps in the conventional secondary drug manufacturing cycle–crystallization, blending, milling, and granulation, into a single step which directly produces monodisperse and spherical microparticles of tailored size and composition. This system paves the way for innovative continuous bottom-up formulation of microp...