Concentration Of Salting-out Agent Research Articles

Kinetic enhanced separation of praseodymium and neodymium induced by specific ion effect

The precise and controllable separation of Pr/Nd is the key to restricting the recovery of rare earths from neodymium magnets. However, it is difficult to realize the efficient separation by difference in thermodynamic properties of Pr3+ and Nd3+. In present work, the enhanced separation was achieved by a kinetic extraction strategy in systems with different salting-out agents. The comprehensive effect of multiple ions including salt anions and cations on enhanced separation of Pr3+/Nd3+ were investigated. Experimental results revealed that the separation coefficient can be higher than 8. The enhancing effect on separation of Pr3+/Nd3+ from different salting-out agents followed the order of NaCl < NaNO3 < NaSCN < LiNO3. It had a relationship with the salting-out effect, which could be influenced by the type and concentration of salting-out agents. In details, the salting-out effect was closely related with hydration of salt anions and cations. There are differences in the binding ability of rare earth ions to the above anions. The behaviors of rare earth ions arriving at the interface were different under specific ion effect of Li+ and Na+. By molecular dynamics simulations, it verified that the separation behaviors were related with diffusion mass transfer rate to the interface and the adsorption behaviors of rare earth ions at the interface. At the end, the recycling and recovery of lithium was suggested. This work provides a basis for developing a new method for efficient and green separation of adjacent rare earths.

Selective extraction of Nd(III) by novel carboxylic acid based ionic liquids without diluent from waste NdFeB magnets

The development of an environmentally friendly extractant for selective recovery of rare earth elements is critical but still faces significant challenges. Two low viscosity carboxylic acid based ionic liquids [A336][BTA] and [A336][OTA] were synthesized for selective extraction of Nd(III) from waste NdFeB magnets. First, the extraction behaviors of two kinds of ionic liquids were compared under different conditions, such as time, pH value of aqueous phase, dosage of ionic liquids, and concentration of salting-out agent. The optimal extraction condition of [A336][OTA] was optimized by response surface methodology, and the extraction efficiency reached 99.1%. The extraction mechanism was proposed as ion association by UV–Vis spectrum, IR spectrum and 1H NMR, and was supported from that perspective of quantum chemical calculation. The extraction thermodynamics, kinetics and isothermal model were studied in detail. [A336][OTA] maintained an extraction efficiency of 95.6% even after seven cycles. The extractant shows good selective separation performance in waste NdFeB magnets, and is an extractant with good application prospect. This work has provided an environmentally friendly extractant for the recovery of Nd(III) from waste NdFeB magnets.

Recovery of rare earths in different media with novel dicarboxylate based ionic liquid and application to recycle SmCo magnets

Recovery and separation of rare earth elements was highly crucial but difficult. In this study, a well-designed new ionic liquid named as benzyltributylammonium decanedioate ([N444Bn]2[SA]) was developed to extract rare earths and separate Sm(III) from the spent SmCo magnets in acetate medium for the first time. To exhibit the superiority of acetate medium, the extraction of Nd(III) and La(III) in three different media were comparatively investigated under different conditions, including equilibrium time, initial pH of aqueous solution, rare earth concentration, extractant concentration, salting-out agent concentration and extraction temperature. The results revealed that the better extractabilities of La(III) were observed in acetate medium rather than those in chloride medium (i.e., 97.6% versus 78.6%), which may be attributed to the low-hydrated nature of acetate ions. Importantly, the back-extraction experiments indicated that 91.4% Nd(III) can be stripped from [N444Bn]2[SA] by using 1.5 mol/L HOAc, revealing the outstanding reusability of ionic liquid in the industrial separation-stripping cycles. Furthermore, the ion association mechanism was proposed to describe the extraction behavior and confirmed by the slope analysis and FT-IR characterizations in three media. In terms of the SmCoCu mixture separation, the maximal separation factor of Sm(III)/Co(II) was calculated as 3078 in simulated solution. Impressively, the recovery of Sm(III) from the actual SmCo magnets by our dicarboxylate-type ionic liquid was also successfully achieved with a recycling rate of 96.8% and a Sm(III)/Co(II) selectivity of 148, which exhibited the potential application in the separation of Sm(III) from the spent SmCo magnets.

DISTRIBUTION OF THORIUM (IV) IONS IN AQUEOUS EXFOLIATING SYSTEM CONTAINING ANTIPYRINE AND SULFOSALICYLIC ACID

The possibilities of an aqueous delaminating system containing antipyrine (AP) and sulfosalicylic acid (SSA) for extracting macro - and microamounts of thorium (IV) were studied. The proposed extraction system eliminates the use of toxic organic solvents. The dependences of the distribution of metal from nitrate solutions between phases on the concentration of reagents, acidity of the medium, the amount of inorganic salting-out agent (NaNO3, NH4NO3, Na2SO4) and the volume of the aqueous phase are determined, and optimal conditions for extraction are found. It is shown that in the organic phase with a volume of 1.6 ml at room temperature, macro-and microamounts of thorium (IV) are extracted by 88 and 90%, respectively. The maximum extraction of the cation is achieved at the ratio of AP: SSA = 2.0 : 1.0 and their concentration, mol/l: 0.6: 0.3, while the acidity of the medium created by nitric acid should be equal to 0.015 mol/l (pHequ. = 1.8-1.9). The extraction of thorium (IV) becomes quantitative if inorganic salts (sodium sulfate, sodium nitrate) are introduced into the AP – SSA – 0,015 mol/l HNO3 – H2O system, which, by reducing the activity of water, increase the concentration of reagents in the aqueous phase. The concentration of salting-out agents should correspond to 1.0 and 2.5 mol/l. A mechanism for the distribution of a mixed thorium (IV) complex containing AP, SSA, nitrate ions, solvated with a salt of antipyrinium sulfosalicylate is proposed. The extract is mixed in any relationship with distilled water, providing the use of various instrumental methods of analysis. A method for extraction-photometric determination of thorium (IV) with a toron indicator has been developed. The limit for the fulfillment of the Bouguer-Lambert-Beer law is established. The apparent coefficient of light absorption is calculated (ε = 1.7∙104).

Boosting the extraction of rare earth elements from chloride medium by novel carboxylic acid based ionic liquids

Two novel carboxylic acid based ionic liquids (ILs), benzyltributylammonium myristic acetate ([N444Bn][MA]) and benzyltributylammonium dodecanedioic acetate ([N444Bn]2[DDA]), have been rationally designed and successfully synthesized for the extraction of yttrium (denoted as Y(III)) from a chloride aqueous solution and for the separation of mixed rare earth elements (REEs). Comparison studies of the extraction performances of [N444Bn][MA] and [N444Bn]2[DDA] were carefully investigated under different conditions (e.g., equilibrium time, solution acidity, salting-out agent concentration, and REEs concentration). The results indicated that the extraction efficiency of Y(III) reached 87.18% after 2 min using [N444Bn]2[DDA], whereas it required 10 min to reach an extraction efficiency of 47.37% using [N444Bn][MA], mainly due to the larger electronegativity of the incorporated dicarboxylates in the anions of [N444Bn]2[DDA], which enhanced its coordination with Y(III) compared to [N444Bn][MA]. However, [N444Bn][MA] illustrated better selective separation behavior than [N444Bn]2[DDA] in mixed REEs solutions (including La, Nd, Eu, Ho, Yb and Y), and the selective factors of Yb and La were 16.21 and 3.30, respectively. Furthermore, the ion association mechanism, evolved from the slope analysis and FT-IR results, contributed to avoiding the saponification procedures and resultant saponification wastewater during the extraction process. In addition, the back-extraction experiments indicated that ~97% Y(III) can be stripped from [N444Bn]2[DDA] and [N444Bn][MA] using 1.0 M and 0.4 M HCl, respectively, demonstrating that these ILs can be further used in large-scale applications for the separation and recovery of REEs.

A recovery strategy of Sm, Co for waste SmCo magnets by fatty acid based ionic liquids

Cleaner and lower-cost recovery and separation of samarium(III) and cobalt(II) from waste SmCo magnets can effectively alleviate supply risks of the strategic metals. Based on this goal, a family of renewable, low-cost, biocompatible, non-toxic fatty acid-based ionic liquids (FAILs), including [N1888][DA], [N1888][LA] and [N1888][PA] were synthesized and developed for the separation of Sm(III)/Co(II) from samarium-cobalt simulated solution. The effect factors, i.e. equilibrium time, FAIL molar concentration, salting-out agent concentration and initial pH of aqueous solution were investigated. The extraction mechanism was proposed to be ion association by slope analysis and FT-IR. Under the optimized extraction conditions, a higher purity CoCl2 (99.5%) product was obtained by a simple extraction-stripping-washing process with the consumption of Na2C2O4 and NH3·H2O. The produced salty wastewater with lower concentration from the process could be recycled. Sm2O3 with a purity of 99% were obtained by roasting the Sm2(C2O4)3 at 800 °C for two hours. The whole process was simple and sustainable, illustrating its potential for industrial applications.

DETERMINATION OF POLYCYCLIC AROMATIC HYDROCARBONS IN SOIL SAMPLES USING ULTRASONIC PROBE AND SALT-ASSISTED LIQUID-LIQUID EXTRACTION COUPLED WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Background : Polycyclic aromatic hydrocarbons (PAHs) are a class of chemicals which have 2 to 7 fused aromatic rings. It is demonstrated that even trace amounts of PAHs are carcinogens, mutagens, and teratogens which can lead to serious risk to the health of humans. According to these facts, determination of PAHs in environmental samples is essential. Methods : In this study, ultrasonic in combination with salt-assisted liquid-liquid extraction was used efficiently for the extraction of PAHs from soil and water samples. In order to evaluate the performance of the proposed method three PAHs, naphthalene, anthracene and pyrene were selected as model analytes. Influential parameters on the extraction efficiency of analytes such as extraction solvent and its volume, salting-out agent and its concentration, ultrasonic time, ultrasonic amplitude and pulse were investigated and optimized. Results : The optimum conditions were as follow; extracting solvent; tetrahydofuran, extracting solvent volume; 3 mL, salting-out agent; sodium acetate, salting-out agent concentration; 20 %w/v, ultrasonic time; 10 s, ultrasonic amplitude; 60% and ultrasonic pulse; 0.5 s. The limits of quantitation for pyrene, naphthalene and anthracene were 1.0, 1.0 and 0.7 ng g-1, respectively. Under the optimum conditions, obtained recoveries in different matrices were in the range of 80.0 to 100.0% with a relative standard deviation better than 7.5%. Conclusions : In the proposed method, after the UAE, sample was exposed to SALLE without need of solid residue removal from the sample. Therefore, extraction steps such as filtration and centrifuge were removed which lead to time saving.

Recovery of fluorine utilizing complex properties of cerium(IV) to obtain high purity CeF3 by solvent extraction

Abstract Utilizing complex properties of cerium(IV) with fluorine(I), this paper investigated the recovery of fluorine from nitrate solutions in the form of CeF 3 by solvent extraction. The extraction mechanism was studied firstly, and then CeF 3 was obtained from the extracted organic phase by reductive stripping. The effects of the main parameters such as HNO 3 concentration, extractant concentration, F(I) concentration, salting-out agent concentration and the temperature were examined and discussed. Showing that HNO 3 concentration, salting-out agent concentration and the temperature did not affect the extraction of Ce(IV). The presence of F(I) can decrease the extraction of Ce(IV). The extraction of HNO 3 , Ce(IV) and Ce(IV)-F have been studied respectively, and the extracted complexes are considered to be HNO 3 ·Cyanex923, Ce(NO 3 ) 4 ·2Cyanex923 and Ce(HF)(NO 3 ) 4 ·Cyanex923 individually. The extraction mechanisms were concluded according to slope analysis, and the loading capacities of Ce(IV) had been obtained. The Infrared Spectra of extracted complexes was determined, showing that the NO 3 − ion is a bidentate ligand. High purity CeF 3 nanoparticle was obtained and the size distribution, SEM and TEM images of the nanoparticle were given, CeF 3 nanoparticle was acquired also in H 2 SO 4 system and the difference between the two CeF 3 were compared.

Extraction mechanism of rare earths from chloride acidic solution with ammonium-bifunctionalized ionic liquid extractants

A series of ammonium-bifunctionalized ionic liquid extractants (ammonium-Bif-ILEs) combined with a number of anions, including carboxylic acids and 1,3-diketonates, have been prepared and studied in this report. Their extraction behavior and properties toward rare earth ions (REs(III)) are systematically investigated in chloride media as a function of important parameters such as aqueous phase pH, salting-out agent concentrations, and extraction temperature. The separation performance of ammonium-Bif-ILEs toward REs(III) are systematically discussed. The results demonstrate that ammonium-Bif-ILEs have a synergistic effect between the cation and anions in separation of REs(III). The influences of different anions on separation factor (β) values are further studied. By comparison, ammonium-Bif-ILEs containing 1,3-diketonates have more potential applications in La(III)/RE(III) separation than those containing carboxylic acids.

Solvent Extraction of Neodymium(III) by Functionalized Ionic Liquid Trioctylmethylammonium Dioctyl Diglycolamate in Fluorine-free Ionic Liquid Diluent

The extraction behavior of neodymium and other rare earths from nitric acid media by the functionalized ionic liquid trioctylmethylammonium dioctyl diglycolamate, [A336][DGA], was investigated. The nonfluorinated ionic liquid trioctylmethylammonium nitrate, [A336][NO3], was used as diluent. The extraction behavior of neodymium(III) in this ionic liquid solution was carried out as a function of various parameters such as the pH, concentration of the extractant, type of acidic media, temperature, concentration of salting-out agent, and concentration of the aqueous feed. The extraction behavior of [A336][DGA] in [A336][NO3] was compared with that of [A336][DGA] in the chloride-containing ionic liquid diluent [A336][Cl] (Aliquat 336). The distribution ratios obtained in [A336][DGA] were compared with those observed in molecular extractant N,N-dioctyl diglycol amic acid (HDGA), from which the anion of the ionic liquid extractant was prepared. The distribution ratio for extraction of neodymium(III) by [A336][DGA] in [A336][NO3] was higher than that for extraction by HDGA in [A336][NO3], at pH values >2. The effects of thermodynamic parameters, the stripping of neodymium(III) from the ionic liquid, and the reusability of the functionalized ionic liquid were studied in detail. The general applicability of the extraction system was illustrated by the extraction of lanthanide(III) ions other than neodymium(III).

Extraction mechanism of cerium(IV) in H2SO4/H3PO4 system using bifunctional ionic liquid extractants

The extraction of Ce(IV) in H2SO4/H3PO4 system was investigated systematically using bifunctional ionic liquid extractants (Bif-ILES) [A336][P507], [A336][P204] and [A336][C272] in n-heptane. The effects of H2SO4 concentration, extractant concentration and salting-out agent concentration were observed in detail. The extraction mechanism of Ce(IV) in H2SO4/H3PO4 system was obtained. The comparison with other extractants such as Cyanex923, TBP was also studied. Thermodynamic functions of the extraction reaction were calculated, showing that the extraction was an exothermic process. The separation of Ce(IV) from RE(III) and Th(IV) was also investigated. The result indicated that Ce(IV) could be selectively extracted in this system. CePO4 nanoparticles were obtained in the process of stripping using H2O2 in H2SO4/H3PO4 system. X-ray diffraction (XRD), scanning electron microscopy (SEM) and spectroscopy were adopted for the characterization of the sample.

Extraction and recovery of cerium(IV) and fluorine(I) from sulfuric solutions using bifunctional ionic liquid extractants

The extraction of cerium(IV) (Ce(IV)), fluorin (F −) and Ce(IV)–F mixture solution from sulfuric acid medium using bifunctional ionic liquid extractants (Bif-ILEs) [trialkylmethylammonium][di-(2-ethylhexyl)orthophosphinate] ([A336][P507]), [trialkylmethylammonium][di-2-ethylhexylphosphinate] ([A336][P204]) and [trialkylmethylammonium][bis 2,4,4-trimethylpentylphosphinate] ([A336][C272]) in n-heptane have been investigated in this report. The effect of H 2SO 4 concentration, extractant concentration and salting-out agent concentration has been investigated. The thermodynamic parameters have been determined, showing that the extraction was exothermic. The extraction mechanism has been obtained. The comparison for the extraction of Ce(IV), Ce(IV) in Ce(IV)–F mixture solution, cerium(III) (Ce(III)) and thorium(IV) (Th(IV)) has been investigated and the extraction efficiency order followed as: Ce(IV) > Th(IV) > Ce(III). Ce(IV) in Ce(IV)–F mixture solution was extracted in the form of CeF 3+. The highest separation factor ( β) values of Ce(IV)/Ce(III) and CeF 3+/Ce(III) were 3.32 × 10 3 and 2.58 × 10 3 in the [A336][P507] extraction system, 7.27 × 10 2 and 6.94 × 10 2 in the [A336][P204] extraction system, and 1.84 × 10 2 and 2.75 × 10 2 in the [A336][C272] extraction system, respectively, which indicated that Ce(IV) and Ce(IV) in Ce(IV)–F mixture solution could be separated from Ce(III) effectively.

Effect of the nature and concentration of salting-out agents on the extraction of cobalt(II) from chloride solutions with trialkylamine

The effect of chlorides of Ca2+, Ni2+, Mg2+, Al3+, Li+, Fe2+, Cr3+, Na+, NH4+, La3+, Nd3+ on the extraction recovery of cobalt from chloride solutions with mixtures based on trialkylamine was studied. The series of the salting-out activity of differently charged cations and the degree of their coextraction were determined.

Solvent extraction of thorium (IV) and europium (III) ions by diphenyl-N,N-dimethylcarbamoylmethylphosphine oxide from aqueous nitrate media

The extractive properties of a CMPO-type extractant, diphenyl- N , N -dimethylcarbamoylmethylphosphine oxide (DΦDMCMPO) in dichloromethane, have been investigated towards thorium (IV) and europium (III) ions in nitrate media at 20 °C. The conventional log–log plot analysis of the extraction equilibrium data reveals that the thorium and europium ions are extracted as complexes characterized by a metal/ligand ratio of 1:3 and 1:2, respectively. The effects of solvent, type and concentration of salting-out agent on the extraction abilities of the ligand were studied. The comparative extraction experiments in nitric acid medium showed that DΦDMCMPO exhibits higher efficiencies than tri- n -octylphosphine oxide (TOPO). The influence of temperature on the extraction of the studied ions from 1 M sodium nitrate medium into 1,2-dichloroethane by DΦDMCMPO was tested as a function of temperature in the range 20–40 °C. The distribution ratios of europium ions decrease when raising the temperature, while with thorium ions the opposite phenomenon was observed. From the distribution measurements, thermodynamic parameters such as the free energy (Δ G °), enthalpy (Δ H °) and entropy (Δ S °) changes associated with the extraction processes could be evaluated.

Solvent extraction of lanthanides with triisoamylphosphate and di-(2-ethylhexyl)phosphoric acid from trichloroacetic acid and nitric acid solutions

The study on solvent extraction of some rare earth elements with triisoamyl phosphate (TiAP) and a mixture of TiAP and di-(2-ethylhexyl)phosphoric acid (D2EHPA) from trichloroacetic acid and nitric acid solutions has been carried out. It was found that Y has been more effectively extracted with TiAP from the trichloroacetic acid solution than from the mono and dichloroacetic acid solutions. The influence of various factors such as acid, RE and salting-out agent concentrations on the distribution ratio has been studied. The synergistic extraction effects were observed for low trichloroacetic acid and high nitric acid concentrations. The influence of the TiAP–D2EHPA ratio and the total concentration of two extractants, as well as acid concentration on the synergistic extraction ratio has been investigated. RE extraction isotherms by TiAP and D2EHPA alone and by a mixture of these extractants in the above extraction systems were established.

Synergistic extraction of uranium(VI) from nitric acid solution by a mixture of n-octyldecylsulfoxide (ODSO) and petroleum sulfoxides (PSO) in carbon tetrachloride

The synergistic extraction of uranium(VI) from nitric acid aqueous solution with a mixture of n-octyldecylsulfoxide (ODSO) and petroleum sulfoxides (PSO) in carbon tetrachloride was studied. It has been found that the maximum synergistic extraction effect occurs where the molar ratio of PSO to ODSO is three to five. The composition of the complex of synergistic extraction is UO2(NO3)2· ODSO · PSO. The formation constant of the complex KOP = 57.6±5.19. The effect of extractant concentration, nitric acid concentration, salting-out agent concentration, complex anion concentration and temperature on the extraction equilibrium of uranium(VI) was also studied.

The Synergic Extraction of Uranium(VI) with Bis(octylsulfinyl)ethane (BOSE) and Petroleum Sulfoxides (PSO)

The synergic extraction of uranium(VI) from nitric acid solution with a mixture of bis(octylsulfinyl)ethane (BOSE) and petroleum sulfoxides (PSO) in 1,1,2,2- tetrachloroethane has been studied. The composition of the complex of the synergic extraction is UO2(NO3)2·BOSE·PSO. The formation constant of the complex is KPT = 4.44±0.23. The effect of extractant concentration, nitric acid concentration, salting-out agent concentration and temperature on the extraction equilibrium of uranium(VI) is also studied and the enthalpy of the extraction reaction is calculated. It has been found that the maximum synergic extraction effect occurs if the molar ratio of PSO to BOSE is one to one.

The Extraction of Uranium(VI) with n-Octyldecylsulfoxides (ODSO)-Toluene

The liquid-liquid extraction of uranium(VI) from aqueous nitric acid with n-octyldecylsulfoxide (ODSO) in toluene has been studied over a wide range of conditions. The extracted species appears to be UO2(NO3)2·2ODSO. The extraction increased with increasing nitric acid concentration up to 2.0 mol/l and then decreased. Extraction also increased with increasing extractant concentration. The influence of temperature, salting-out agent concentration and complex anion concentration on the extraction equilibrium were also investigated, and the enthalpy of the extraction reaction was calculated.

Liquid-liquid extraction of uranium(VI) from nitric acid solutions with bis(octylsulfinyl)ethane (BOSE)

The liquid-liquid extraction behavior of uranium(VI) from aqueous nitric acid with bis(octylsulfinyl)ethane (BOSE) in 1,1,2,2-tetrachloroethane has been studied over a wide range of conditions. The extracted species appears to be UO2(NO3)(2). 2BOSE. It was found that the extraction increases with increasing nitric acid concentration up to 7 mol/l and then decreased. Extraction also increases with increasing extractant concentration. The influence of temperature and salting-out agent concentration on the extraction equilibrium and stripping of uranium(VI) was also investigated and the enthalpy of the extraction reaction was obtained.

Study on the synergic extraction of uranium(VI) with petroleum sulfoxides (PSO) and tri-n-butyl phosphate (TBP) mixture

The synergic extraction of uranium(VI) from nitric acid solution with petroleum sulfoxides (PSO) and tri-n-butyl phosphate (TBP) mixture has been studied. It has been found that maximum synergic extraction effect occurs if the molar ratio of PSO to TBP is two to three. The composition of the complex of synergic extraction is UO2(NO3)(2). TBP . PSO. The formation constant of the complex is K-PT = 8.19. The effect of extractant concentration, nitric acid concentration, salting-out agent concentration and temperature on the extraction equilibrium of uranium(VI) was also studied.