Tributyl Phosphate Concentration Research Articles

Development and optimization of high-performance extraction chromatography method for separation of rare earth elements

The effectiveness of commonly used extractants for chromatographic separation of rare earth elements (REEs) was compared. Columns loaded with similar molar concentrations of tributyl phosphate (TBP), di-(2-ethylhexyl) phosphoric acid (HDEHP), and N-Methyl-N, N, N-tri-octyl-ammonium chloride (Aliquat-336), with mineral acid as eluent were evaluated. Retention factors were determined, and separation efficiency was assessed based on the resolution data of the REEs acquired under the same elution conditions for each column. HDEHP demonstrated the best separation efficiency for the entire REE series (mean Rs = 2.76), followed by TBP (mean Rs = 1.52), while Aliquat-336 exhibited the lowest performance (mean Rs = 1.42). The HDEHP-coated column was then used to optimize the extraction chromatographic separation of the REEs. The primary challenge was to completely elute the heavy REEs (Tb – Lu) while maintaining adequate separation of the light REEs (La – Gd) within a reasonably short time. The stepwise gradient elution procedure improved the resolution between adjacent REEs, allowing the complete separation of the entire REE series within 25 minutes. Better separation efficiency for light REEs was achieved at higher column temperatures and a mobile phase flow rate of 1.5 mL/min in the tested domain of 20–60 °C, and 0.5–2.0 mL/min, respectively, resulting in plate heights (H) ranging from 0.011 to 0.027 mm.

Mechanisms for the separation of Li+ and Mg2+ from salt lake brines using TBP and TOP systems

The tributyl phosphate (TBP)/FeCl3 system has been widely used for lithium extraction from high‑magnesium salt lakes. However, at high TBP concentrations, the Li/Mg selectivity is significantly lower. This study revealed that at high TBP concentrations, TBP alone extracted Mg2+ to form MgCl2·6TBP as the main product, thus affecting the extraction efficiency of Li+. On this basis, a neutral phosphate with long carbon chains, trioctyl phosphate (TOP), was used to replace TBP. The separation capacity and extraction mechanism of the TOP/FeCl3 system were studied, and density functional theory (DFT) calculations were employed to model the cationic complexes of the TOP and TBP systems. The results showed that in the presence of FeCl3, the extraction efficiency of Li+ (ELi) reached 91 %, and the Li/Mg separation factor (βLi/Mg) was 5688. In contrast, in the TBP/FeCl3 system with the same concentration, the ELi and βLi/Mg values were much lower at 74 % and 239, respectively. Furthermore, the TOP complex of Li+ had shorter Li − O bond lengths and a more negative binding energy, while that formed with Mg2+ had longer Mg − O bond lengths and the smallest HOMO–LUMO gap, indicating that TOP bonded more stably with Li+ and was less prone to Mg2+ extraction than TBP.

Preparation of new alginate capsules enclosing diatomite and organic extractants to uptake lanthanum

The present study conducted syntheses of Ca-alginate composite beads, which involved trioctyl-amine (TOA), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO) organic extractants, and diatomite for separation of La(III) ions from dilute aqueous solutions. The surface morphology of the capsules was examined under Scanning Electron Microscopy, while their chemical structure was characterized using Fourier Transform Infrared Spectroscopy. Alginate composites were prepared by adding concentrations of TBP (1%–10%), TOPO (0.005 M–0.09 M) and TOA (1%–10%) organic extractants to the Na-alginate-diatomite mixture.The effects of various parameters on adsorption such as solution pH, contact time, metal ion concentration, and temperature, were individually tested using standard solutions of La(III). The maximum uptake capacity of the alginate composite adsorbent, consisting of TOA, diatomite, and alginate for La(III) ions, was examined at 25 °C. Adsorption data were analyzed using Langmuir, Freundlich, Dubinin–Radushkevich (D-R), Temkin, Flory-Huggins and Brunauer, and Emmett and Teller (BET) isotherm models. The biosorption isotherm parameters were estimated by both linear and nonlinear regression analyses. The results indicate that the Langmuir model provides a better fit than the other models for the adsorption equilibrium data.Thermodynamic parameters such as variations of enthalpy, entropy, and Gibbs free energy were calculated. The maximum uptake capacity of the alginate composite adsorbent, including TOA, diatomite, and alginate for La(III) ions from aqueous solutions was found to be 146.4 mg/g. The adsorption efficiency in dilute solutions was determined to be 97.2%.

Organophosphate esters concentrations in human serum and their associations with Sjögren syndrome

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers due to their excellent properties. The interference of OPEs on immune function has been proven, but the epidemiological data on OPEs exposure to related immune function diseases, such as sjögren syndrome (SjS), is limited. In cross-sectional study, 283 serum samples were collected from healthy individuals (n = 145) and patients with SjS (n = 138) in Hangzhou, China. Eight OPEs, triethyl phosphate (TEP), tributyl phosphate (TBP), tris (2-chloroethyl) phosphine (TCEP), triphenyl phosphate (TPHP), tri (1-chloro-2-propyl) phosphate (TCIPP), 2-ethylhexyldi-phenyl phosphate (EHDPP), tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), and tri (2-butoxyethyl) phosphate (TBOEP), were frequently measured in serum samples. In addition, we explored the associations between the serum OPEs concentration and the risk of SjS. Results showed that TEP (mean controls 2.17 and cases 3.63 ng/mL) was the most abundant OPEs in the serum samples of the control and case groups, followed by TCIPP (mean controls 0.54 and cases 0.78 ng/mL). Serum TEP, TPHP, and EHDPP concentrations were positively correlated with SjS [odds ratio (OR): 1.97, 1.96, and 2.42, respectively; 95% confidence interval (CI):1.34–2.89, 1.34–2.87, and 1.34–2.87, respectively] in the adjusted model, and a negative correlation of TBP concentrations with SjS in the adjusted model (OR: 0.35, 95% CI: 0.17–0.70) was observed. Compared with the lowest quartile concentrations, the ORs of SjS at the highest quartile concentrations of TEP (OR: 4.93, 95% CI: 2.24–10.82) and TPHP (OR: 4.75, 95% CI:1.89–11.94) were significantly higher. This study suggests that human exposure to OPEs may increase the risk of SjS.

Solvent extraction of gold from a chloride-hypochlorite leached solution of waste printed circuit boards

ABSTRACT This study reveals the reclamation process of gold from a brine-leached solution of waste printed circuit boards (WPCBs) after the maximum leaching of base metals in a nitric acid medium. The brine leaching performed in the presence of hypochlorite yielded leach liquor of 152 ppm Au, 86 ppm, Cu, and 62 ppm Ni that underwent solvent extraction with tri-butyl phosphate (TBP) in Exxol D80. The gold extraction process was observed to be selective over base metal impurities, while the effect of TBP concentration, equilibrium pH, temperature, and organic-to-aqueous phase ratio was optimized. Experimental results showed the formation of complex into the extraction phase with the negative enthalpy change value of −98.7 kJ/mol. Thiosulphate mobilized stripping of gold from the loaded-TBP could give about 99% recovery efficiency of the solvent extraction process along with a good regeneration of the organic extractant to be re-used.

Экстракционное извлечение рутения из растворов аффинажного производства с использованием трибутилфосфата

The extraction of ruthenium from the nitrite solution at different concentrations of tributyl phosphate (TBP) was investigated. It has been established that undiluted TBP is an effective extractant for extracting the element from solution. The possibility of deep purification of the ruthenium extract from impurity platinum metals by washing the saturated organic phase with a solution of sodium nitrite was showed. It was revealed that a high degree of ruthenium stripping is achieved using an alkali solution.

Intensified reactive extraction of 4-hydroxypyridine with di(2-ethylhexyl) phosphoric acid in 1-octanol by using tributyl phosphate

Tributyl phosphate (TBP) exhibit significant intensification effect toward the extraction of 4-hydroxypyridine by di(2-ethylhexyl) phosphoric acid in 1-octanol via a more tendency to form (1:1) type complexes. The efficient separation of amphoteric organic compounds from dilute solutions is of great importance in the industrial field. In the present work, the reactive extractions of 4-hydroxypyridine (4-HP) with tributyl phosphate (TBP), di(2-ethylhexyl) phosphoric acid (D2EHPA) and TBP + D2EHPA dissolved in 1-octanol were investigated, respectively. The influences of the initial concentrations of TBP, D2EHPA and TBP + D2EHPA on distribution ratio ( D ) were discussed, as well as the reactive extraction mechanism were proposed. The obvious intensification effect was observed when the mixture of TBP and D2EHPA was used as extractant. The best extraction conditions were found to be of the molar ratio of D2EHPA and TBP at 2:1 and the equilibrium aqueous pH at 3.50–4.50. D values increased with the increase of the total concentration of TBP and D2EHPA in 1-octanol. Especially, the analysis on the extraction mechanisms clearly indicate (i) TBP in 1-octanol shows negligible reactive extraction toward 4-HP, (ii) D2EHPA in 1-octanol exhibits moderate extraction effect by forming 4-HP:D2EHPA (1:1) and 4-HP:2D2EHPA (1:2) type complexes, while (iii) D2EHPA in TBP/1-octanol demonstrates the maximum distribution ratio with the 4-HP:D2EHPA (1:1) type complex domination. The discussion provides new insights on the mechanism and opens a new way for the intensified extraction of amphoteric organic compounds by using the mixture of multiple extractants in the diluent.

Removal of propionic acid from aqueous solutions by tributyl phosphate in a room‐temperature ionic liquid using Box-Behnken design

In this study, propionic acid removal from aqueous solutions by tributyl phosphate (TBP) in a room‐temperature ionic liquid was investigated. A room-temperature ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide [HMIM][Tf2N], was used as a diluent. TBP was utilized as a reactant. The relationship between the extraction efficiency and various process parameters like initial propionic acid concentration, initial TBP concentration in [HMIM][Tf2N], and water/organic phase ratio were analysed by using Box-Behnken design which is one of the response surface methodology (RSM). The optimum extraction conditions for the reactive extraction of propionic acid with [HMIM][Tf2N] were detected as initial propionic acid concentration of 5.429 % (w/w), TBP concentration in [HMIM][Tf2N] of 2.854 mol.L-1 and phase ratio of 0.558.

Toxic responses of freshwater microalgae Chlorella sorokiniana due to exposure of flame retardants

Flame retardants, such as Tetrabromobisphenol A (TBBPA), Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tributyl phosphate (TBP), are frequently detected in surface water. However, the effects of FRs exposure on aquatic organisms especially freshwater microalgae are still unclear. In this study, the toxicities of TBBPA, TDCPP and TBP to microalgae Chlorella sorokiniana, in terms of growth inhibition, photosynthetic activity inhibition and oxidative damage, were investigated, and according ecological risks were assessed. The results showed that TBBPA, TDCPP and TBP had inhibitory effects on C. sorokiniana, with 96 h EC50 (concentration for 50% of maximal effect) values of 7.606, 41.794 and 49.996 mg/L, respectively. Fv/Fm decreased as the increase of exposure time under 15 mg/L TBBPA. Under 50 mg/L TDCPP and 80 mg/L TBP exposure, Fv/Fm decreased significantly after 24 h. However, Fv/Fm rose after 96 h, indicating that the damaged photosynthetic activity was reversible. The content of chlorophyll a decreased, as the increase of TBBPA concentration from 3 to 15 mg/L. However, chlorophyll a increased first and then decreased, as the increase of TDCPP and TBP concentrations from 0 to 50 mg/L and 0–80 mg/L, respectively. Results indicated that C. sorokiniana could use the phosphorus of TDCPP and TBP to ensure the production of chlorophyll a. The risen content of reactive oxygen species, malondialdehyde as well as superoxide dismutase activity indicated that exposure to FRs induced oxidative stress. Additionally, the risk quotients showed that tested FRs had ecological risks in natural waters or wastewaters. This study provides insights into the toxicological mechanisms of different FRs toward freshwater microalgae for better understanding of according environmental risks.

Efficient removal of dissolved tributyl phosphate from nitric acid solution by a membrane dispersion micro extractor

Since the evaporator accident on the Savannah River Site, ‘red oil’ has been considered an important safety issue in every nuclear reprocessing plant. The removal of dissolved tributyl phosphate (TBP) from nitric acid solution can directly avoid the formation of ‘red oil’ during the reprocessing of spent nuclear fuel. The present work proposed a novel extractor, membrane dispersion micro extractor (MDME) for the TBP removal. The effects of the continuous to dispersed phase flowrate, residence time and initial concentration of nitric acid in the aqueous phase on the removal efficiency and overall volumetric mass transfer coefficient were investigated. The dispersion performance of the studied system was also carried out. The results indicate that the concentration of TBP in the aqueous phase could be reduced below 20 mg/L within a short residence time of 75 s at the flowrate ratio of 10 for the inlet stream of TBP-0.3 mol/L HNO3-kerosene, which mimicked the real industrial system. The increase in the nitric acid concentration would lead to the higher removal efficiency. The overall volumetric mass transfer coefficient could reach 0.135 s−1–0.179 s−1, which is two or three orders of magnitude higher than that of the traditional solvent extraction equipment.

Kinetics and mechanism of Eu(III) transfer in tributyl phosphate microdroplet/HNO3 aqueous solution system revealed by fluorescence microspectroscopy.

In this study, we reveal an Eu(III) extraction mechanism at the interface between HNO3 and tributyl phosphate (TBP) solutions using fluorescence microspectroscopy. The mass transfer rate constant at the interface is obtained from the analysis of fluorescence intensity changes during the forward and backward extractions at various HNO3 and TBP concentrations to investigate the reaction mechanism. This result indicates that one nitrate ion reacts with Eu(III) at the interface, whereas TBP molecules are not involved in the interfacial reaction, which is different from the results obtained using the NaNO3 solution in our previous study. We demonstrate that the chemical species of Eu(III) complex with nitrate ion and TBP in the aqueous solution play an important role for the extraction mechanism. The rate constants of the interfacial reactions in the forward and backward extractions are (4.0-5.0) × 10-7mM-1s-1 and (3.2-3.3) × 10-6ms-1, respectively. We expect that our revealed mechanism provides useful and fundamental knowledge for actual solvent extraction.

Kinetically revealed transfer mechanism of europium (III) in tributyl phosphate microdroplet/NaNO3 aqueous solution system by fluorescence microspectroscopy

In the present study, we investigate the mechanism of the extraction of Eu(III) with a tributyl phosphate (TBP) microdroplet using fluorescence microspectroscopy. The TBP microdroplet is immobilized in a microcavity, and an interface between TBP and an NaNO3 aqueous solution is formed by immersion of the droplet-immobilizing device. The fluorescence intensity change in the TBP microdroplet during Eu(III) extraction is monitored in real time. As a result, we demonstrate that the rate-determining process is the interfacial reaction of Eu(III) in the TBP/aqueous solution system. To elucidate the reaction mechanism of Eu(III) at the interface, the dependences of the mass-transfer rate constants on the NO3− and TBP concentrations are investigated. Consequently, the mechanism of Eu(III) extraction, in which two nitrate ions and one TBP molecule are involved in the interfacial reaction, is quantitatively revealed. The interfacial reaction rate constant is determined to be (1.3–1.9) × 10−6 m M−3 s−1 for the forward reaction and (3.0–3.6) × 10−6 m s−1 for the backward reaction. The present approach allows us to analyze the extraction kinetics in a manner that is not possible in a bulk solution and will provide an effective strategy for developing solvent extraction.

Kinetic study on extraction of metal-cyanide complex ions by the N263-TBP system

In this study, the extraction of metal-cyanide complex ions in gold-leaching, cyanide-containing wastewater by a trioctylmethylammonium chloride (N263)-tributyl phosphate (TBP)-n-octanol-sulfonated kerosene system was investigated. The effects of N263 and TBP concentrations, the aqueous phase pH, and phase ratio (O/A) on the extraction were investigated by adopting the response surface methodology, and the operating parameters were optimized. The optimal solution was obtained by solving the model optimally. A Cu ion concentration of 3,000 mg/L, an N263 concentration of 0.459 mol/L, a TBP concentration of 0.214 mol/L, an initial pH of the aqueous phase of 10.064, and O/A of 0.900 were determined to be optimal for realizing an extraction yield of 99%. The effects of column height, oil droplet volume, metal ion concentration, N263 and TBP concentrations, and temperature on the mass transfer rate were investigated using the single droplet method. Kinetic studies showed that the kinetic equation for the extraction system was Rf (Mass transfer rate) = 1.57 × 10-4·CCu·CTBP·CN263. The apparent activation energy of Cu(I) was 15.186 kJ/mol. The extraction process was controlled by the diffusion process. Furthermore, the chemical reaction occurred at the two-phase interface, where the copper cyanide complex ions preferentially bound to TBP at the interface between the two phases, and the bound anion cluster then reacted with the N263 cation to form the extractive complex, which then entered the organic phase from the interface.

Silver extraction using emulsion liquid membrane system containing D2EHPA-TBP as synergistic carrier: optimization through response surface methodology

ABSTRACT The present investigation deals with silver extraction using an emulsion liquid membrane. The emulsion liquid membrane system consists of paraffin as organic phase, Span 80 as surfactant, Di-(2-ethylhexyl) phosphoric acid (D2EHPA) and Tributyl Phosphate (TBP) as carrier, and hydrochloric acid as stripping agent. Experiments were designed and modeled by response surface methodology using Design Expert 11 software, which determines the extraction rate as a function of Span 80 concentration, D2EHPA concentration, TBP concentration, HCl concentration, and treatment ratio. The ANOVA results indicate that the model is statistically significant because of the high R 2 (0.9828) and the low p-value of <0.0001. The results showed that the silver extraction increases by increasing all affecting parameters up to their optimal values and after that extraction rate decreases with increasing of them. The process was optimized to obtain maximum extraction rate, minimum D2EHPA concentration, and minimum treatment ratio. The optimal conditions were obtained at a surfactant concentration 3.26% (V/V), D2EHPA concentration 0.0045 mol/L, TBP concentration 5% (V/V), HCl concentration 0.56 mol/L, and treatment ratio 0.5. Under these conditions, the silver extraction rate was 99.87%.

Dissolution of Palladium Metal in Solvent Leaching System with the Presence of Oxidizing Agent

Platinum group metals (PGMs) are important for the manufacture of advanced materials in the field of catalysts and electronic devices. Since the chemical properties of PGMs are very similar to each other, hydrometallurgical processes should be employed to recover PGMs with high purity from either ores or secondary resources. In hydrometallurgical processes for PGMs, the first step is the dissolution of PGMs. For this purpose, inorganic acid solutions with oxidizing agents are generally employed. In this work, nonaqueous solvent leaching systems with a relatively cheap price were employed to investigate the dissolution of pure palladium (Pd) metal. The solvent leaching systems consisted of concentrated hydrochloric acid solution and commercial extractants such as tributyl phosphate (TBP), 7-hydroxydodecan-6-one oxime (LIX 63), and di-n-octyl sulfide (DOS) in the presence of H2O2 as an oxidizing agent. Among the three systems, TBP showed the best efficiency for the dissolution of Pd. The effect of several parameters like TBP concentration, temperature, time, stirring speed and the weight ratio of Pd to TBP/HCl/H2O2 was explored. The dissolution percentage of Pd by the HCl–H2O2–TBP system was higher than by the HCl–H2O–H2O2 system at the same concentration of HCl and H2O2. The role of TBP in enhancing the dissolution of Pd was discussed on the basis of the interaction between HCl and TBP. Compared to aqueous systems, mass transfer is important in the dissolution of Pd metal by the solvent leaching system. Optimum conditions for the complete dissolution of Pd were obtained.

La(III) Ion Selective Electrode with PTFE Membrane Containing Tributyl Phosphate Ionophore

Methods for the quantitative determination of lanthanum that have been developed are generally spectroscopic methods such as inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES), and X-ray fluorescence spectrometry, which has relatively high operational costs. The feasibility of the potentiometric method using ion selective electrode (ISE) as an alternative method for lanthanum (III) determination needs to be studied because it is simple, easy to use, and has high sensitivity and selectivity. In this study, we developed ion selective electrode using PTFE membrane impregnated with tributyl phosphate (TBP) as ionophore. TBP is commonly used as a complexing agent for rare-earth ions in supported liquid membrane (SLM) separation process. We found that the compound can be used as an ionophore for ISE. This study aims to make a lanthanum ion selective electrode (III) (La-ISE) which has a Nernstian response. The parameters studied in the construction of this electrode were the effects of PTFE membrane immersion ionophore solution, ionic strength adjuster (ISA), and the inner solution composition. The performance parameters studied for the La-ISE were linear range, response time, detection limit, selectivity, and the lifetime of the electrode. Construction of the electrode begins with the preparation of the PTFE membrane as the main component. PTFE membrane was impregnated for 12 hours in the TBP solution having a concentration of 0.25 M or 0.50 M in kerosene. After it was dried, the membrane was attached to the end of the electrode tube with adhesive. Then, the electrode was filled with an internal solution containing a mixture of KCl 10-3 M with La (III) 10-3 M. The internal reference electrode was Ag/AgCl electrode. Before it was used, the electrode was soaked in a solution of La (III) 10-3 M for 12 hours.The effect of TBP concentration on the electrode performance was studied using two concentrations of TBP: 0.25 M and 0.50 M. The calibration curves obtained using both electrodes have good linearity. Nernst factor obtained from both electrodes is similar, although the Nernst factor obtained with an electrode having 0.50 M TBP closer to the theoretical value.ISA used in the measurement was KNO3. The effect of ISA on the performance of the electrode was studied using electrodes containing TBP with the concentration of 0.25 M or 0.50 M. The concentration of KNO3 used in this study was 0.01 M and 0.10 M. The Nernst factors obtained with electrodes containing 0.25 M TBP, in general, higher than those obtained with electrodes containing 0.50 M TBP in the same ISA. Electrode containing 0.50 M TBP resulted in the Nernst factor close to theoretical value when a measurement was conducted in 0.10 M KNO3.

Optimization for Liquid-Liquid Extraction of Cd(II) over Cu(II) Ions from Aqueous Solutions Using Ionic Liquid Aliquat 336 with Tributyl Phosphate.

This study investigates the separation of two heavy metals, Cd(II) and Cu(II), from the mixed synthetic feed using a liquid-liquid extraction. The current study uses tri-octyl methylammonium chloride (Aliquat 336) as the extractant (with tributyl phosphate (TBP) as a phase modifier), diluted in toluene, in order to investigate the selective extraction of Cd(II) over Cu(II) ions. We investigate the use of ethylenediaminetetraacetic acid (EDTA) as a masking agent for Cu(II), when added in aqueous feed, for the selective extraction of Cd(II). Five factors that influence the selective extraction of Cd(II) over Cu(II) (the equilibrium pH (pHeq), Aliquat 336 concentration (Aliquat 336), TBP concentration (TBP), EDTA concentration (EDTA), and organic to aqueous ratio (O:A)) were analyzed. Results from a 25–1 fractional factorial design show that Aliquat 336 significantly influenced Cd(II) extraction, whereas EDTA was statistically significant for the antagonistic effect on the E% of Cu(II) in the same system. Moreover, results from optimization experiment showed that the optimum conditions are Aliquat 336 concentration of 99.64 mM and EDTA concentration of 48.86 mM—where 95.89% of Cd(II) was extracted with the least extracted Cu(II) of 0.59%. A second-order model was fitted for optimization of Cd(II) extraction with a R2 value of 0.998, and ANOVA results revealed that the model adequately fitted the data at a 5% significance level. Interaction between Aliquat 336 and Cd(II) has been proven via FTIR qualitative analysis, whereas the addition of TBP does not affect the extraction mechanism.

Experimental perspective for reactive separation of malonic acid using TBP in natural non-toxic solvents

Recent technological advancement allows the synthesis of malonic acid from the bio-fermentation route by using cost-effective raw material like biomass, which enhances its overall production. The dilute aqueous stream of malonic acid produced from the biological route needs to be recovered. Process intensification with precise operating conditions and low toxicity such as reactive separation is applied for extraction of malonic acid from the dilute aqueous stream by using non-toxic natural solvents like canola oil, sunflower oil, and soybean oil with the tributyl phosphate (TBP) extractant. An in-depth experimental analysis is performed in the present study to evaluate extraction complexation equilibrium constant (KE(MA)), extraction efficiency (E(MA)%), distribution coefficient (KD(MA)), and loading ratio (Z(MA)). The overall loading ratio is less than 0.5 for all solvents, which signifies the formation of 1:1 complexation. KD(MA) and E(MA)% with soybean oil are in range of 0.265–0.832, and 20.683–43.850, for sunflower oil is 0.208–0.763 and 17.227–42.340, for canola oil is 0.301–0.875 and 22.878–45.106. The behavior of TBP-malonic acid complexation equilibrium in the reactive separation process is predicted by comparing relative basicity model values with experimental outputs. The separation process requires a continuous column operation, and the number of transfer stages is evaluated to be 2. Furthermore, the diffusion coefficients (D(MA)) of malonic acid to the natural, non-toxic solvents with variable TBP concentrations are evaluated by employing various empirical correlations. The present study paves the way for future research in continuous in-situ product recovery of malonic acid produced via biological route.

Equilibrium and mechanism studies of gold(I) extraction from alkaline aurocyanide solution by using fluorine-free ionic liquids

Solvent extraction based on ionic liquids is generally considered to be an environmentally benign and effective technology for gold(I) recovery. The aim of this work is to study gold(I) extraction from aurocyanide solution using fluorine-free ionic liquids [A336][SCN], [A336][MTBA] and [A336][Mal]. Various factors that affect gold(I) extraction (including concentration of ionic liquids, equilibrium pH, concentration of the modifier tributyl phosphate (TBP), reaction time and initial concentration of gold in an aqueous solution) were studied and optimized. The results indicate that the three Aliquat 336-based ionic liquids all exhibit excellent behaviors for gold(I) extraction. More than 99.8% of gold(I) can be extracted from the aqueous phase into the ionic liquid phase. The gold-loaded ionic liquids were characterized using infrared spectroscopy and mass spectrometry to study the extraction mechanism of gold(I). The results revealed that extraction of gold(I) into the ionic liquid phase was based on an exchange reaction between the anion Au(CN) 2 − in aqueous solution and the anion SCN− in ionic liquid [A336][SCN]. The logarithmic relationship between distribution coefficient and TBP concentration indicates that two TBP molecules are involved in the formation of the extracted complex. The extracted complex was determined to be A336+·Au(CN) 2 − ·2TBP. In addition, the gold(I)-loaded ionic liquids can be efficiently stripped using NH4SCN, 2-methylthiobenzoic acid and methyl maltol. The results establish that Aliquat 336-based ionic liquids have potential application prospects in gold(I) recovery from cyanide solutions.

The key factors and mechanism study on lithium extraction by TBP-FeCl3 extraction system

The key factors and mechanism of lithium extraction using tributyl phosphate(TBP) as extractant, kerosene as diluent, and FeCl3 as co-extractant were investigated. The theoretical Raman spectra of FeCl3 and FeCl4− were calculated by DFT. The key factors MgCl2, FeCl3 and TBP were studied. The results suggested the increase of MgCl2 concentration was conducive to extraction lithium and the influence of Cl− was greater than Mg2+. Fe3+ and Cl− were the optimal central ions and ligands for the formation of monovalent anions. The concentration of TBP should not too much for improving the separation effect of Li+ and Mg2+.