Diluent System Research Articles

Extraction Equilibria in the Samarium Nitrate–Nitric Acid–Water–Di(2-ethylhexyl)phosphoric Acid–Organic Diluent System

Extraction Equilibria in the Samarium Nitrate–Nitric Acid–Water–Di(2-ethylhexyl)phosphoric Acid–Organic Diluent System

Lowering spinning temperature for polyketone (PK) hollow fiber membrane fabrication with low-toxic diluent system via thermally induced phase separation

Due to the excellent solvent resistance properties of polyketone (PK), the traditional non-solvent induced phase separation (NIPS) preparation process is both highly toxic and complex. In this work, we successfully and efficiently prepared PK hollow fiber membranes using the thermally induced phase separation (TIPS) method, capitalizing on a low-toxicity diluent system of polyethylene glycol 300 (PEG300) and triethylene glycol (TEG). Moreover, by simply adding TEG to the diluent, we achieved a reduction in the spinning temperature, resulting in membranes that display an interconnected structure formed through the liquid-liquid phase separation process. We systematically investigated the impact of the TEG ratio in the diluent, PK concentration, and propylene carbonate (PC) ratio in the bore liquid on the phase diagram, membrane morphology, and characteristics of PK membranes. Increasing the PC ratio in the bore liquid significantly improves the inner surface porosity due to PC penetration into the dope solution, leading to high water permeability. Additionally, the resulting PK membrane exhibits exceptional resistance to organic solvents. This work introduces a novel approach to lower the spinning temperature for PK membrane preparation in the TIPS process while preserving the membrane structure and properties.

Experimental and theoretical studies (DFT) on technetium extraction as HTcO4 using dicyclohexano-18-crown-6 in a blend of isodecyl alcohol and n-dodecane from acidic medium

Fundamental studies on technetium extraction from acid medium using a versatile supramolecule, dicyclohexano-18-crown-6 (DCH18C6) in isodecyl alcohol-n-DD diluent system from acidic nuclear waste have been reported here. It was observed that the maximum extraction (DTc ∼ 2.03) and ∼99% recovery of technetium can be achieved when an organic phase of 0.4 M DCH18C6 in 50% isodecyl alcohol + n-dodecane was used to extract technetium from 4.0 M HNO3 solution followed by three successive stripping contact with water. Two types of mechanisms are found to be operative depending on the acidity of feed solution, an extraction mechanism like, H+aq. + TcO4−aq. + DCH18C6org = HTcO4.DCH18C6org up to 4.0 M feed acidity and HTcO4.DCH18C6org + H +aq. + NO3−aq = DCH18C6org.HNO3 + TcO4−aq.+ H +aq. for feed acidity beyond 4.0 M HNO3. Almost identical interaction energies of adducts DCH18C6-HTcO4 & DCH18C6–HNO3 obtained in the DFT calculations. The extraction is driven by low hydration energy of pertechnate compared to nitrate up to 4.0 M HNO3 and beyond 4.0 M HNO3 concentration of nitrate dominates the hydration energy effect causing decrease in the technetium extraction irrespective of the equal interaction energies.

Structuring of a Liquid in a Water–Lanthanide (or Nickel) Salt–D2EHPA–Diluent System

Structuring of a Liquid in a Water–Lanthanide (or Nickel) Salt–D2EHPA–Diluent System

A criterion of diluent selection for the polymeric membrane formation via thermally induced phase separation process based on Hansen solubility parameter theory

The Hansen solubility parameter (HSP) theory, which includes the Hansen dispersion (D), polar (P), and hydrogen (H) components and a derivative ‘solubility parameter distance, Ra’ parameter, was adopted to evaluate the interaction between different polymers and their various diluents, so as to obtain a valuable and feasible criterion for the diluent selection of the thermally induced phase separation (TIPS) process for the preparation of polymeric membranes. Firstly, a full-scale database of the four HSP parameters of typical polymer-diluent systems was obtained based on a complete literature review about the phase separation process of all the polymer/diluents systems that have been applied to prepare polymeric membranes via TIPS and our additional exploratory experiments for membrane formation mechanism, in which two different phase separation processes including solid to liquid and liquid to liquid were distinguished. Relationships between the Ra parameter and the phase separation behavior were figured out to get a criterion for selecting the single diluent for the typical polymers. Moreover, the diluent selection was extended by adding a second diluent, and a schematic three-dimensional phase diagram was drawn to provide a feasible understanding of the TIPS process of the polymer-binary diluent system. Taking polypropylene (PP) as the representative example, plenty of exploratory experiments for the membrane formation mechanism based on a literature review were conducted to propose a guide based on the Hansen polar and hydrogen solubility component parameters to help select a proper binary diluent system.

Evaluation of diagnostic accuracy of developed rapid SARS-COV-2 IgG antibody test kit using novel diluent system.

Immunochromatographic assay kits are used in primary diagnostics which is based on the principle of antigen and antibody interaction. These kits play pivotal role in rapid surveillance of infectious diseases at early stages as well as for the surveillance of the contagious diseases. The immunochromatographic test kits lacks sensitivity and specificity with certain diseases. In this study, our intention was to develop a rapid test kit for SARS-COV-2 with a novel diluent system to enhance the efficacy of antigen–antibody binding and thereby the improvement in the sensitivity outlined. Finally, IgG antibodies against SARS-COV-2 virus peptides were analyzed using 25 positive and 25 negative confirmed clinical samples. The sensitivity of the clinical studies showed 91% sensitivity and 100% specificity. Therefore, the authors propose that this assay will be a potential tool for efficient community or sentinel surveillance of SARS-COV-2 infection and additionally, for effective monitoring of convalescent sera therapy.

Reactive Extraction of Valeric Acid with a Tributyl Phosphate + Diluent System

The production of carboxylic acids from renewable resources using fermentation technology is still restricted because of the limitations in the recovery of the product from fermentation broth. In t...

Inductively coupled plasma with mass-spectrometry method development and validation for gadolinium in gadolinium-based contrast agents of pharmaceutical formulations

Gadolinium-based contrast agent interacts with the human body temporarily and improves the pictures of inside of the body produced by magnetic resonance imaging, computed tomography, X-rays and ultrasound and it also helps to distinguish the normal from abnormal conditions. In this study, the authors developed a simple, rapid, reliable and robust inductively coupled plasma mass-spectrometry method for estimation of gadolinium in gadolinium-based contrast agents to check the drug quality and ensure the patient safety. The samples were digested at 160°C using the microwave digestion system and the gadolinium was extracted in 0.4% (w/w) nitric acid. Interference of deposited gadolinium on sample cone and skimmer cone were investigated and evaluated. The developed method was validated as per ICH Q2 (R1) guideline and USP<730>. The precision was evaluated with six independent assays of gadolinium in each gadolinium-based contrast agent. The test method was found linear (r2 > 0.999) with five different levels covered from 25~200%, and accurate, mean recoveries were 92.5~107.5% at three different levels covered from 50~150%. The robustness was performed by changing the nitric acid concentration (0.4±0.04%, w/w) in diluent system. This method is suitable to quantitatively determine the amount of gadolinium in gadolinium-based contrast agent of drug products in presence of excipients used in formulation and also in drug substance.

Modeling of the Competition between Uranyl Nitrate and Nitric Acid upon Extraction with Tri-n-butyl Phosphate.

Uranium is a strategic element and plays an important role in energy resources. A H2O–HNO3–UO2(NO3)2–TBP (tri-n-butyl phosphate)–diluent system is commonly used for uranium separation and purification in liquid–liquid extraction. Uranyl nitrate is promoted by the existence of nitrate at low HNO3 concentrations but is inhibited at high HNO3 concentrations. Considering the competitive extraction between HNO3 and UO2(NO3)2, a generic extraction model is developed. The activities of components in the aqueous phase were estimated using Pitzer models. The thermodynamic equilibrium constants and Pitzer parameters were regressed by experimental data. The resulting model was able to successfully predict uranyl nitrate, nitric acid, and water extraction over a large range of conditions (U, 0–1.8 mol/L; HNO3, 0–10 mol/L; TBP, 5–100 vol %) within average absolute relative deviations of 11.2, 15.7, and 23.8%, respectively. The predicted results show that water and nitric acid were extracted as di-solvates HNO3·(TBP)2·H2O and (TBP)2·2H2O at low nitric acid concentrations, with the formation of mono-solvates HNO3·TBP and HNO3·TBP·H2O as the acid concentration increased. Uranyl nitrate was shown to be rejected from the organic phase as the formation of HNO3·TBP and HNO3·TBP·H2O in acid was extracted at high acid concentrations.

Preparation and Research of Solvent-Free Epoxy Coating for Drinking Water Tank

By compounding E42 and E51 epoxy resin, blending modified polyamide curing agent and modified fatty amine curing agent, optimizing glycidyl ether reactive diluent system, using safe non-toxic pigment filler and grading wear resistance filling and optimization auxiliaries system, the developed coating sanitary index meets the requirements of “Sanitary Standard for Drinking Water”, and the wear resistance (cs17, 1000g/1000r, mg) is 64.4mg. The coatings passed 6J impact resistance test and is resistant to bending 1.5° without cracks. The coatings also have excellent resistance to medium corrosion and salt spray.

Effect of ionic liquid on the extraction of uranium with pillar[5]arene-based phosphine oxide from nitric acid solutions

Abstract The extraction of U(VI) from aqueous nitric acid solutions with pillar[5]arene-based phosphine oxide (L) and [C8mim][NTf2] ionic liquid dissolved in 1,2-dichloroethane was explored. A great positive impact in this system was observed. The effect of IL concentration in the organic phase and HNO3 concentration in the aqueous phase is considered. The distribution ratios of U(VI) were significantly enhanced upon adding a small amount of ionic liquid as compared with organic diluent. The extraction system was also examined for its ability towards extraction of lanthanides and Th4+. The results revealed higher separation factors towards UO2 2+ over Th4+ in the presence of ionic liquid compared with organic diluent. Other factors such as C8mim+ and NTf2 − have also been considered. This extraction system has shorter equilibrium time as compared with in IL diluent. Stripping experiments showed almost quantitative back extraction of UO2 2+ within two stages. With high selectivity towards UO2 2+ and efficient back extraction, this new POP5A-ionic liquid-organic diluent system shows promise for future application of uranium recovery.

FTIR Spectra of N,N,N',N'-Tetraoctyl Diglycolamide Complex in Room Temperature Ionic Liquids

The interaction of an octyl derivative of diglycolamide extractant complex in three different types of room temperature ionic liquids (RTILs) was studied by ATR-FTIR spectroscopic method. The shift in stretching vibrational frequencies for the functional groups (C=O and C-O) in the nitrate ion-extractant complexes and metal ion-extractant complexes in room temperature ionic liquids namely, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2], 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([C4mpyr][NTf2]) and 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide ([C4mpip][NTf2]) was compared. These results were also compared with that obtained for molecular diluent system, n-dodecane.

Separation of strontium-90 from a highly saline high level liquid waste solution using 4,4′(5′)-[di-tert-butyldicyclohexano]-18-crown-6 + isodecyl alcohol/n-dodecane solvent

Selective and efficient separation of 90Sr from high level waste solution of high salt content will pave the way to manage a problematic waste and also for utilization of recovered 90Sr for societal purpose. In the present work, a process for selective separation of 90Sr is described using 4,4′(5′)-[di-tert-butyldicyclohexano]-18-crown-6 (DtBuCH18C6) dissolved in an industrial diluent system: isodecyl alcohol + n-dodecane. The process solvent is optimized as 0.1 M DtBuCH18C6 + 50% isodecyl alcohol/n-dodecane for satisfactory extraction of strontium at higher nitric acid concentrations (D4-8 M HNO3 = 5–14). Stoichiometry determination by slope analysis method showed 1:1:1 M ratio for Sr2+, DtBuCH18C6 and HNO3 in the extracted complex. Among the inert and active constituents of the waste, extraction of plutonium (IV) (DPu = 0.3) and barium (DBa = 0.7) was observed to some extent, extraction of calcium was almost negligible (DCa = 0.01) while no extraction of americium, cesium, ruthenium, niobium, zirconium and lanthanides was observed. Stripping of the loaded organic was achieved by deionized water, three consecutive contacts each with fresh deionized water results in complete stripping of strontium.

CO2 aided H2 recovery from water splitting processes

Solar energy can be utilized to produce H2 via photocatalytic water splitting. One major drawback of the one-step approach is the co-production of H2 and O2 in the same reactor environment creating a potentially hazardous scenario. This obstacle can be avoided by utilizing CO2 as a flammability suppressant which is proven to be more effective than N2. In this case study, several membrane cascade designs were implemented to recover the H2 while maintaining compositions outside the flammability range. The optimizations are based on the use of commercially available composite polymer membranes from Membrane Technology and Research, Inc. (MTR) in the spiral wound architecture. Both the H2-selective membrane (Proteus™) and CO2-selective membrane (Polaris™) were explored in three layouts. The process optimization is solved by nonlinear programming. The aim of the study was to minimize the present value of all outgoing cash flow (no income) for the separation process and achieving 99% product (H2) purity. Optimization results showed that utilizing three membrane units of Proteus™ material with one recycle stream is the optimum layout over a wide range of recovery values. Incorporating the CO2-selective membrane (Polaris™) leads to more expensive process due to higher recycle flow rates to compensate for the low selectivity of this material. Overall, the best economic results for this process were obtained at 85% recovery rate with 99% product purity at a cost of 6.40 $/kg. Comparing to our previous study using a N2 diluent, higher purity product with lower specific cost can be achieved with CO2 diluent system but with slight decrease in recovery rate. As a final element to this study, comparative simulations were executed to demonstrate the potentially added value of using hollow fiber membranes versus spiral wound for this separation process.

HPLC method for simultaneous analysis of ticagrelor and its organic impurities and identification of two major photodegradation products

A simple, fast and sensitive analytical method by high-performance liquid chromatography (HPLC) was developed and validated for the simultaneous determination of ticagrelor and two synthesis impurities. The HPLC method was established using an Agilent 1200 Series equipment coupled to photodiode array detector (PDA) at 270nm with a Zorbax Plus C8 column (150×4.6mm, 5.0μm), injection volume of 20μL, and a constant temperature of 25°C. The mobile phase consisted of acetonitrile: ammonium acetate 50mM (57:43, v/v) and pH adjusted to 8.2 with ammonium hydroxide 6M, at a flow rate of 0.7mL/min. No interference peaks from excipients and diluent system indicated the specificity of the method. The calibration curves showed determination coefficients (r2)>0.99, calculated by linear regression. The limit of quantitation (LOQ) for impurities 1 and 2 were 2.0 and 0.2μg/mL, respectively. Intra and interday relative standard deviations (RSDs) were <2% for ticagrelor and <6% for the impurities, proving the precision of the method. Besides, two mayor degradation products formed when sample solutions of ticagrelor were exposed to UVC radiation were elucidated and the mechanisms involved in the photolytic degradation of ticagrelor were proposed.

Modelling of a Uranium Reprocessing Extraction System

Modeling of the H2O–HNO3–UO2(NO3)2–TBP–diluent system has been considered herein. Mole fractions, volume fractions and rational activity coefficients are used in order to create the system of equations on the basis of the mass action law. The method of calculating activity coefficients is provided. Water distribution was taken into account due to the significant importance of free water. Solvate parameters were determined in three subsystems. Application of activity coefficients of nitric acid and uranyl nitrate in mixed solutions was considered during the calculation of the H2O–HNO3–UO2(NO3)2–TBP–diluent system.

Calculation of the activity of uranyl nitrate and nitric acid in the H2O–HNO3–UO2(NO3)2–TBP–diluent system using Zdanovskii’s rule

The description of the H2O–HNO3–UO2(NO3)2–TBP–diluent system required calculation of the activity coefficients of uranyl nitrate and nitric acid in mixed solutions. Three methods for determining the activity coefficients were considered: from the experimental data, using Pitzer’s equation, and using Zdanovskii’s rule with Mikulin’s equations. All the three methods lead to similar results. The relative root-mean-square deviation is 7–10%, but it depends on correct evaluation of the error. The third method will allow calculation of the activity coefficients in multicomponent solutions.

Dissipative particle dynamics study and experimental verification on the pore morphologies and diffusivity of the poly (4-methyl-1-pentene)-diluent system via thermally induced phase separation: The effect of diluent and polymer concentration

Dissipative particle dynamics (DPD) simulation was performed to construct the mesophase membrane morphologies of poly(4-methyl-1-pentene) (PMP) during thermally induced phase separation (TIPS). The PMP morphologies and their fluid diffusivities relationship was established using a mesoscale 3-D tetragonal-like structure construction. The effects of PMP concentration and the use of a single diluent (dioctyl phthalate, diphenyl ether, and dibutyl phthalate) or a mixed diluent on the pore morphology were compared. The diffusivity resistance was evaluated by comparing the mean square displacement of a hypothetical fluid bead through tetragonal-like morphologies in three normal directions. The 3-D morphology and density profile results revealed that larger pores were produced after TIPS when the PMP-diluent interaction was weaker. Radial distribution function analysis showed that poor diluent and high PMP concentration could form a coarsened structure with less interconnectivity, indicating more diffusion resistance. To verify DPD simulation results, PMP hollow fibre membranes (HFMs) were fabricated via TIPS, and HFM cross-sectional morphologies proved that the pore structures agreed with the DPD-simulation 3-D evolution diagram. The structure-fluid diffusivity resistance relationship was also confirmed by porosity measurements and gas permeation testing. The DPD simulation method is promising for the fabrication and design of gas-diffusive membranes, especially in terms of the rational selection of diluent and polymer concentration.

Solvent extraction of plutonium(IV) in monoamide – ammonium ionic liquid mixture

Abstract The extraction behavior of plutonium(IV) was studied in the room temperature ionic liquid, trioctylmethylammonium bis(trifluoromethanesulfonyl)imide ([N 1888 ][NTf 2 ]) containing a monoamide, N,N- dihexyloctanamide (DHOA). The unusual extraction of Pu(IV) observed in this ionic liquid system was reported in this paper. The extraction behavior of plutonium(IV) was investigated as a function of various parameters, such as feed acid concentration, extractant and ionic liquid concentration, type of the extractants, equilibration time and temperature. Changing the extractant from DHOA to tri- n -butyl phosphate reduced the distribution ratio of Pu(IV). The extraction trend of Pu(IV) in neat [N 1888 ][NTf 2 ] was compared with those observed in other ionic liquids such as 1-alkyl-3-methylimidazolium bistriflimide ([C n mim][NTf 2 ]). Pu(IV) extraction in [N 1888 ][NTf 2 ] was found to follow a combination of anion exchange mechanism and neutral solvation pathway at feed acidities above 2 M HNO 3 . The extraction of Pu(IV) in DHOA/[N 1888 ][NTf 2 ] was also compared with those observed in a molecular diluent system, DHOA/ n -DD. All thermodynamic parameters governing the extraction of plutonium(IV) in [N 1888 ][NTf 2 ] was determined and discussed in detail. Stripping of Pu(IV) from the loaded ionic liquid phase was performed using dilute nitric acid.

Reactive Extraction of Picolinic Acid Using Tri-n-octylamine Dissolved in Different Diluents: Effect of Solvent Polarity

Picolinic acid is a useful intermediate for the synthesis of different pharmaceuticals, herbicides, and metal salts which is applied in the food supplements. Due to the rapid rise in the costs of fossil resources, efforts are made to synthesize this carboxylic acid from the renewable feedstock like biomass. The recovery of picolinic acid can be achieved by reactive extraction which is catching the attention of the researchers. For higher selectivity and efficient recovery of acid with high distribution, a proper combination and selection of extractant–diluent system is required. Therefore, the current study is focused on the reactive extraction of picolinic acid [(0.01 to 0.10) mol·kg–1] from aqueous solution by using tri-n-octylamine [TOA, (0.115 to 0.459) mol·kg–1] as extractant dissolved in five different diluents (cyclohexane, chlorobenzene, dichloromethane, 4-methylpentan-2-one, and octan-1-ol). The extraction results are interpreted and analyzed defining three terms like distribution coefficient (KD...