Di(2-ethylhexyl)phosphoric Acid Concentration Research Articles

Characterisation of micro polymer inclusion beads by thermogravimetric analysis

In this study micro polymer inclusion beads (μPIBs), containing di-(2-ethylhexyl)phosphoric acid (D2EHPA) as the extractant and poly(vinyl chloride) (PVC) or poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) as the base polymer, were characterised by thermogravimetric analysis (TGA) for the first time and their extraction performance for La3+ was assessed. μPIBs are a novel polymer-based extracting material fabricated via a recently developed phase inversion microfluidic method. However, since the μPIBs are formed under aqueous conditions and D2EHPA can be slightly water soluble at pH values higher than its pKa of 2.8, the final composition could differ from the theoretical one because of D2EHPA leaching during fabrication. Hence, a TGA method was developed to determine the exact composition of μPIBs, using polymer inclusion membranes (PIMs) of known composition as reference materials. For μPIBs and PIMs containing PVDF-HFP as the base polymer, a linear temperature ramp of 10 °C min−1 was applied and the mass loss of D2EHPA and PVDF-HFP was observed at temperatures up to 270 and 400 °C, respectively. PVDF-HFP-based μPIBs fabricated to theoretically incorporate 40, 50 and 60 wt% D2EHPA were found to contain 40.2, 48.9, and 59.6% of D2EHPA, respectively. In the case of PVC-based μPIBs and PIMs, an isothermal step at 220 °C held for 35 min was required to separate the degradation features of D2EHPA and PVC. PVC-based μPIBs with intended D2EHPA concentrations of 40, 50 and 60 wt% were determined to contain 41.4, 49.6, and 60.8% D2EHPA, respectively. Thus, the TGA degradation profiles indicated that PVC- or PVDF-HFP-based μPIBs underwent negligible D2EHPA leaching during fabrication. TGA studies involving the PVC-based μPIBs revealed that Na+, extracted by D2EHPA during the fabrication process, slowed the thermal degradation of D2EHPA at 220 °C and this affected the accuracy of the composition assessment. Moreover, the presence of Na+ in both PVC- and PVDF-HFP-based μPIBs was found to have a negative impact on the extraction of La3+ which could be overcome by washing the μPIBs with 1 M sulfuric acid after fabrication to remove the Na+.

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.

Improvement of Advanced Sample Preparation Systems for the Determination of Trace Ni in Seawater by Electro-Membranes.

Due to its important environmental role, the analysis of trace metals in natural waters is attracting increasing attention; consequently, faster and more accurate analytical methods are now needed to reach even lower limits of detection. In this work, we propose the use of electro-membrane extraction (EME) to improve analytical methods based on hollow fiber liquid phase micro-extraction (HFLPME). Specifically, an EME-based method for the determination of trace Ni in seawater has been developed, using an HFLPME system with di-2-ethylhexyl phosphoric acid (DEHPA) in kerosene as a chemical carrier, followed by instrumental determination by graphite furnace atomic absorption spectroscopy (GFAAS). Under optimum conditions, Ni was pre-concentrated 180 ± 17 times after 15 min, using sample pH = 5.5, the concentration of DEHPA 0.9 M in the liquid membranes, and 1.9 M HNO3 in the acceptor solution, as well as an electric potential of 25 V with the sample being stirred at 500 rpm. When compared with other HFLPME systems for pre-concentration of trace Ni in seawater in the absence of electric potential, the enrichment factor was improved 2.2 times, while the time of extraction was reduced an 89%. The limit of detection of the new method was 23.3 ng L-1, and both its applicability and accuracy were successfully evaluated by analyzing Ni concentration in a seawater-certified reference material (BCR-403), showing the reliability of EME for sample preparation in the determination of trace metals in marine water samples.

Deep fluoride removal from the sulfate leaching solution of spent LIBs by complexation extraction with Al3+ loaded solvent

Fluoride contained in the leaching solution of spent lithium-ion batteries (LIBs) not only decreased product quality, but also led to severe equipment corrosion and potential environmental hazards. Therefore, a coordination extraction system using di-(2-ethylhexyl) phosphoric acid (D2EHPA) loaded with aluminum ions (Al3+) as extractant was designed to deeply remove fluoride from the sulfate leaching solution of spent LIBs that combined the excellent binding affinity of Al3+ to fluoride and the perfect chemical efficiency of solvent extraction. The effects of D2EHPA concentration, loaded Al3+ concentration, equilibrium pH and shaking time on the extraction efficiency of fluoride were investigated. Experimental results indicated that over 99 % of fluoride was selectively extracted and the fluoride concentration in the leaching solution of spent LIBs was reduced from 210 mg/L to 2 mg/L by single-stage extraction, meeting the requirement of fluoride content in the battery grade Ni/Co/Mn sulfate solution and the wastewater discharge standards. The loaded organic phase was scrubbed and stripped by diluted H2SO4, and fluoride could be fully stripped into the stripping solution. Further characterization studies revealed that Al3+ and D2EHPA may mainly coordinate in the form of AlL3·HL in the Al-loaded organic phase (HL denotes D2EHPA). After the Al-loaded organic phase was contacted with solution containing fluoride, a structure of AlFL2·HL coordinated with F- was formed. This study provides a novel technical approach to improve product quality and reduce fluoride wastewater pollution for the recycling process of spent LIBs.

Chromium (III) Ions Were Extracted from Wastewater Effluent Using a Synergistic Green Membrane with a BinaryCombination of D2EHPA and Kerosene

This study used a supported liquid membrane system (SLM) using Celgard 2400 polypropylene as the support, di(2-ethylhexyl) phosphoric acid (D2EHPA) as the carrier, and kerosene as the diluent. To obtain the best carrier concentration, D2EHPA concentrations between 0.04 and 0.6 M were used. The Cr (III) solutions used in the feed phase had various ionic strengths and were adjusted with NaCl at concentrations ranging from 0.25 to 1.75 M. To maintain a constant pH (4) in the feed phase, a 0.2 M acetic acid–sodium acetate buffer was utilized. Because the rate of Cr (III)-carrier complex formation at the interface of the feed solution and membrane increased up to 20 × 10−4 mol/L, it was discovered that transport of Cr (III) rose with an increase in chromium content in the feeding phase. For the optimization of the various stripping agents, HCl concentration was employed, from 0.25 M to 1.75 M. It was observed that Cr (III) transport increased with the increase in HCl concentration because the transport was at a pH gradient, which was the main driving force. Because of the fact that at the feed phase-membrane contact, D2EHPA combined with chromium ions to form the Cr (III)-carrier complex and released H+ protons, in the feed phase, the Cr (III)-carrier complex was diffused into a stripping phase, wherein Cr (III) ions were stripped and the carrier was reversibly protonated again.

Deep eutectic solvent-based three-liquid-phase-extraction system for one-step separation of Cu, Mg and Zn in water samples

A novel and environmentally friendly three-liquid-phase extraction (TLPE) approach was developed for simultaneous separation of copper (Cu), magnesium (Mg) and zinc (Zn) from water samples. The proposed organic/two aqueous phase system consists of di(2-ethylhexyl)phosphoric acid (D2EHPA), Choline Chloride:urea (deep eutectic solvent (DES)), and salt (K2HPO4). The effects of various factors including amount of DES and K2HPO4, pH, D2EHPA concentration, phase-mixing time, and diluent on the preconcentration/separation of Cu, Mg and Zn were evaluated. The results showed that 96.6% of Zn was concentrated in the D2EHPA-rich top phase, whereas 97.8% of Cu and 98.1% of Mg were quantitatively extracted into the DES-rich middle phase and salt-rich bottom phase, respectively. Excellent recovery (>97%) of Cu, Mg and Zn was obtained by using 20% (v/v) D2EHPA in hexane, and 1.72 g DES and 3.12 g K2HPO4 in two lower aqueous phases at pH= 4. The limits of detection were 1.58, 1.55 and 2.37 mg/L for Cu, Mg and Zn, respectively. Relative standard deviations (RSDs) for 0.5 mg/L and 1.0 mg/L of Cu, Mg and Zn in water samples were < 6%. The accuracy of the procedure was confirmed by analyzing a certified reference material of water and tea (NIST SRM 1640a, GBW 07605). Under optimized conditions, excellent agreement was observed between the TLPE-flame atomic absorption spectrometry (FAAS) results and certified values using the student’s t-test (P = 0.05). TLPE procedure was successfully applied for the determination of Cu, Mg and Zn in water samples.

Development of micro polymer inclusion beads (µPIBs) for the extraction of lanthanum

Separation based on polymer inclusion membranes (PIMs) offers an attractive green alternative to conventional solvent extraction by reducing the amounts of extractants used and practically eliminating the use of diluents. Micro polymer inclusion beads (µPIBs) are similar or even identical in composition to PIMs but they are characterised by significantly higher specific surface area which leads to faster extraction and back-extraction.µPIBs composed of di-(2-ethylhexyl)phosphoric acid (D2EHPA) (30 – 80 wt%) as the extractant and poly(vinyl chloride) (PVC) or poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) (70 – 20 wt%) as the base polymer were fabricated via a novel phase inversion microfluidic method and applied to the extraction of La3+ for the first time. The highest D2EHPA concentration, which produced stable, homogeneous and spherical µPIBs, was found to be 60 wt% D2EHPA. La3+ could be efficiently extracted into these µPIBs from aqueous feed solutions at pH 2.5 and subsequently quantitatively back-extracted in a 0.3 M sulfuric acid receiving solution.µPIBs of a composition (45 wt% D2EHPA and 55 wt% PVC) identical to that of a PIM previously studied for the selective extraction of La3+ and having the same mass exhibited 6 times higher surface area and 4.4 times higher initial mass transfer rate in the extraction of La3+. These results clearly demonstrate the suitability of the newly developed µPIBs for the separation of La3+.

Equilibrium studies on reactive extraction of glycine with di(2‐ethylhexyl)phosphoric acid dissolved in n‐octanol, butyl acetate and solvent oil

AbstractBACKGROUNDReactive extraction is an efficient and highly selective technique for the separation of polar organic compounds. In this work, we used three kinds of extractants, namely acidic di(2‐ethylhexyl)phosphoric acid (D2EHPA), neutral tributyl phosphate (TBP) and basic trioctyltertiaryamine (7301) dissolved in three diluents with different polarity (strong‐polar n‐octanol, weak‐polar butyl acetate and non‐polar solvent oil) for optimization of a reactive extraction system. Based on the result, the reactive extraction kinetics of glycine by D2EHPA and the factors that affect the distribution ratio (D) were discussed in detail. Finally, the reactive extraction mechanism was analyzed, and an extraction model was proposed.RESULTSD2EHPA + n‐octanol is the best system for the reactive extraction of glycine. The apparent equilibrium constant K was calculated to be 1.71 L mol−1 and the physical extraction distribution constant (m) was 0.10. The reactive extraction equilibrium of glycine by D2EHPA can be reached in 1 h and room temperature is suitable for the extraction. D2EHPA reacted with glycine to form a 1:1 type ion‐pair complex, and the structure of the complex is less affected by aqueous pH. Chemical extraction is dominant in the extraction process. The distribution ratio D increases with the increase of D2EHPA concentration. pH and polarity of the diluent also have an influence on extraction efficiency.CONCLUSIONThe results provide preliminary practical information and a theoretical basis for the separation of glycine, which would be beneficial for the purification of glycine and the treatment of wastewater containing glycine. © 2021 Society of Chemical Industry (SCI).

Experimental verification on stability analysis of supported-liquid-membrane separation of metal ions by in-situ electrical impedance spectroscopy

BackgroundSupported liquid membrane (SLM) is a very promising method for the recovery and separation of valuable or toxic species from aqueous streams; however, stability is always a critical issue in practice. It is highly desired to develop a non-destructive technique to real-time monitor or detect the stability of an SLM process. MethodsThe stability of an SLM processes was real-time analyzed by electrical impedance spectroscopy (EIS). The separation of equimolar Zn(II) and Cu(II) from sulfate solution through an SLM containing di(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene was selected as the model system owing to the established knowledge of extraction chemistry. Experiments were performed with two types of membrane supports (polycarbonate and poly(vinylidene) fluoride), different D2EHPA concentrations in the organic phase (0.001–0.1 mol/L), pH values of the feed (3.0–5.0) and strip (1.0–3.0) phases, and stirring speeds (0–200 rpm). Correlations between the membrane impedances analyzed according to a proposed equivalent circuit diagram and the separation factors of Zn2+ over Cu2+ measured by SLMs were done to verify the progress of the loss of membrane liquid. Significant findingsUnder the conditions studied, the variations of membrane impedances and separation factors with time using both types of membrane support followed similar trends in most cases. A stability factor of a SLM process based on membrane impedance data was defined, which enables us to predict its relative stability. The present results also demonstrated that all parameters including membrane type, carrier concentration, aqueous pH values, and stirring speed influenced the transport and separation of Zn2+ over Cu2+ and SLM stability.

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%.

Y-019. Immunomodulatory effect of vitamin D on the activators of transcription and transcription factors of CD4+ T cell subsets in pregnant women with preeclampsia

Supported liquid membrane (SLM) is a very promising method for the recovery and separation of valuable or toxic species from aqueous streams; however, stability is always a critical issue in practice. It is highly desired to develop a non-destructive technique to real-time monitor or detect the stability of an SLM process.The stability of an SLM processes was real-time analyzed by electrical impedance spectroscopy (EIS). The separation of equimolar Zn(II) and Cu(II) from sulfate solution through an SLM containing di(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene was selected as the model system owing to the established knowledge of extraction chemistry. Experiments were performed with two types of membrane supports (polycarbonate and poly(vinylidene) fluoride), different D2EHPA concentrations in the organic phase (0.001–0.1 mol/L), pH values of the feed (3.0–5.0) and strip (1.0–3.0) phases, and stirring speeds (0–200 rpm). Correlations between the membrane impedances analyzed according to a proposed equivalent circuit diagram and the separation factors of Zn2+ over Cu2+ measured by SLMs were done to verify the progress of the loss of membrane liquid.Under the conditions studied, the variations of membrane impedances and separation factors with time using both types of membrane support followed similar trends in most cases. A stability factor of a SLM process based on membrane impedance data was defined, which enables us to predict its relative stability. The present results also demonstrated that all parameters including membrane type, carrier concentration, aqueous pH values, and stirring speed influenced the transport and separation of Zn2+ over Cu2+ and SLM stability.

Enhancing the Vanadium Extraction Performance Using Synergistic Mixtures of D2EHPA and TBP in RDC Column with the Perforated Structure; Case Study: Evaluation Probability Density Functions

The reactive extraction behavior on the mean drop size and distribution for synergistic extraction of vanadium from sulfate medium with di-(2-ethylhexyl) phosphoric acid (D2EHPA) and its mixture with tributyl phosphate (TBP) in kerosene has been interpreted in the modified rotating disc contactor column. In batch experiments, the maximum extraction efficiency was obtained in the single extraction system with 0.29 molar D2EHPA at an equilibrium pH of 2, whereas the extraction percentage was significantly increased by adding 0.3 molar TBP into the same D2EHPA concentration due to the synergistic effect. The solvent extraction process has been optimized by applying the central composition design approach in the column experiments. The influence of operational variables such as agitation rate and both phase flow rates as well as the type of used systems have been investigated on drop behavior. A unified model was provided for modified rotating disc columns. It was found from Monte Carlo simulation for uncertainty analysis that the agitation speed and type of utilized systems, namely reactive or physical systems have more profound impacts on the mean drop size. The optimum conditions were obtained at the agitation rate of 400 rpm, and phase flow rates equal to 26 L/h.

Pb-Zn recovery from a malic leach solution of a carbonate type ore flotation tailing by precipitation and solvent extraction

The recovery of zinc and lead from a malic leach solution of a carbonate type ore flotation tailing by precipitation with sulfuric acid followed by solvent extraction using di(2-ethylhexyl)phosphoric acid (D2EHPA) as extractant was investigated. The separation of lead via precipitation was essentially complete from the malic acid leach solution by adding sulphuric acid to reach a pH of 0.25 at 25 °C. The precipitate product was identified by XRD as anglesite (PbSO4). The pregnant leach solution after lead precipitation was then subjected to solvent extraction using D2EHPA. The optimum solvent extraction conditions were determined as 10% D2EHPA concentration, 25 °C temperature, 10 min contact time and phase ratio of unity. Under these conditions, 99.3% of zinc was extracted into the organic phase at a pH of 4.2 in a single contact alongside a substantial amount of Ca (76.6%), and minor amounts of Fe (19.2%) and Mg (18%). Complete stripping of zinc and calcium from the loaded organic solution along with 47.8% of Mg was achieved at a pH 0.5 under room temperature. No iron stripping was observed from the loaded organic. The zinc content in the loaded strip solution could be enriched and then sent to the electrowinning (EW) stage. It is noted that the calcium and magnesium impurities in the loaded strip solution had no adverse effect on the zinc EW process. Based on the experimental results, a flowsheet was proposed for the recovery of Pb and Zn from the malic acid leach solution. With the proposed precipitation and solvent extraction process, two different material streams are produced.

Removal of zinc by emulsion liquid membrane using lecithin as biosurfactant

The present investigation deals with zinc extraction using emulsion liquid membrane (ELM) method with the help of lecithin as biosurfactant. The emulsion liquid membrane system consists of paraffin as organic phase, lecithin as biosurfactant, Di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractant, and sulfuric acid as stripping agent. In this study, five parameters affecting the extraction performance, i.e., lecithin concentration, pH of feed solution, treatment ratio, internal phase to organic phase volume ratio, and D2EHPA concentration were investigated. The stability of emulsion was determined by specifying breakage and swelling of the emulsion. The experiments were performed under ambient conditions to extract zinc with the initial concentration of 250 mg/L. The extraction step was completed after 10 minutes by stirring at 500 rpm. Optimal conditions were obtained at the biosurfactant concentration of 3% (v/v), pH 3, treatment ratio 0.3, internal phase to organic phase volume ratio 0.1, and D2EHPA concentration 6% (v/v). Under optimal conditions, zinc extraction was 98.38%. In these conditions, the breakage and swelling of the emulsion were 6.29% and 8.56%, respectively.

Production of high-purity ThO2 from monazite ores for thorium fuel-based reactor

The present study aims to investigate the optimum parameter in producing high-purity thorium dioxide (ThO2) using Di-2-ethylhexyl phosphoric acid (D2EHPA) and Aliquat-336 as solvent materials. The extraction and purification process was performed using [Th-RE](OH)4 compound which was selectively precipitated from the monazite leach solution. Several parameters such as types of acid (HCl, HNO3 and H2(SO4)), acid molarity (1M–6M), and solvent ratio (10%–30%) were investigated. The findings indicate that different solvents require a distinctive aqueous medium to extract thorium. The optimum concentrations of D2EHPA and Aliquat-336 in extracting thorium were identified to be at 1M H2(SO4) and 4M HNO3 with 30% and 20% ratio, respectively. The multi-stage extraction process was successfully extracted and purified thorium at a purity of 96.8% (D2EHPA) and 98.0% (Aliquat-336). Subsequent conversion to ThO2 yielded a high-purity thorium dioxide at 99.1%. In general, the study elucidates that both solvents have the potential to be utilized as thorium extracting agents in preference to the conventional tri-butyl phosphate (TBP).

Removal of paraquat from aqueous media via HFSLM and mathematical modeling

The removal and recovery of paraquat from an aqueous solution using a hollow fiber supported liquid membrane (HFSLM) was performed. The extractant was Di-(2-ethylhexyl) phosphoric acid (D2EHPA) which was dissolved in kerosene, whereas the recovery solution was a hydrochloric acid solution. It was found that the pH concentration of D2EHPA, concentration of hydrochloric acid at 8, 4% (v/v), and 1.0 M, respectively, were the optimum conditions. In the one-through mode, 70% and 68% of extraction and recovery, respectively, were achieved, while 99% extraction and recovery were obtained in the circulated mode. In addition, the mathematical model can predict the concentration of paraquat in raffinate solution with different paraquat concentrations and flow rates of feed solution with the R2 of 0.923 and 0.843, respectively.

Solvent Extraction of Zinc from a Bioleaching Solution by Modification of D2EHPA: Optimization and Thermodynamic Studies

In this work, zinc extraction from an industrial leach solution was investigated by saponified di(2-ethylhexyl)phosphoric acid (D2EHPA). The solution obtained was from a bioleaching process of a low-grade lead-zinc sulfide ore that contained 50 g/L of zinc and 6.3 g/L of iron. The selective and high Zn(II) extraction yield were obtained by modification of D2EHPA in a proposed two-step process. Firstly, a significant amount of iron (87%) was removed as sodium-jarosite via precipitation from the pregnant leaching solution (PLS) prior to zinc extraction, and secondly, the effective parameters involved in zinc extraction including the contact time, saponification degree, type of saponifier, stirring speed, pH, temperature, D2EHPA concentration, and phase ratio (A:O) were investigated. The results obtained showed that 98.4% of zinc could be extracted under the optimum conditions, i.e. 20% D2EHPA, 15% saponification degree, 650 rpm, pH 2, and an A:O ratio of 1:1 at the ambient temperature (25 ± 2 °C) during 90 s; it was 25% higher than using non-saponified D2EHPA under the same conditions. Moreover, while one theoretical step was required for the complete extraction of zinc by saponified D2EHPA, the required number of steps using D2EHPA was about three. Therefore, the advantages of the process would be two-fold: reducing the number of extraction stages and no need for neutralizing the raffinate in every extraction stage.

Extraction of Zinc in Presence of Cobalt through Hollow Fibre Supported Liquid Membrane from Simulated Industrial Wastewater

Many industrial wastewaters contain toxic metals such as zinc, chromium, cobalt in the form of fluorides and nitrates as anions. Transport of Zn 2+ from simulated industrial wastewater was studied using di-2-ethylhexyl phosphoric acid (D2EHPA) diluted in kerosene as the organic phase. The hollow fibre supported liquid membrane was operated in continuous recycle mode. Effect of feed phase pH, carrier concentration, sulphuric acid concentration in the strip phase, and flow rate on Zn 2+ transport was examined. The feed phase pH was varied in the range of 1.5–2.5. The organic phase concentration was varied in the range of 10-30 %. At the feed phase pH of 2, the extraction rates were found to be high. About 12% rise in mass transfer flux of Zn 2+ ions was observed with an increase in D2EHPA concentration from 10% to 20%. The mass transfer flux of Zn 2+ ions was found to be increased by 28% with an increase in sulphuric acid concentration from 0.5 M to 1 M. The flow rate variation study suggests that mass transfer resistance is mainly contributed by diffusion mechanism through the membrane.

Toward an efficient multi-step separation protocol to recover metallic components from waste leachates

This work presents a study of the separation and recovery of metal elements, through a multi-step protocol based on solvent extraction, stripping and chemical precipitation processes. The waste leachate was produced during the treatment of the mixed solid waste from the decommissioning of a coal-fired power plant. The organophosphorus acid, di-(2-ethylhexyl) phosphoric acid (DEHPA) was investigated as organic extracting agent during the solvent extraction (Step 1). A factorial design with three levels for the organic phase/aqueous phase ratio (O/W), DEHPA concentration and contact time were carried out and a prediction model obtained using a neural-fuzzy approach. Optimized extraction values for Ti (93.4 %), (V) 94.6 % and (Zn) 89.8 % were obtained using 60min of contact time, a DEHPA concentration of 0.5M and O/W ratio of 4. Stripping tests were performed using HCl, H2SO4, NaOH and KOH as stripping agents. The stripping step (step 2) showed optimum results (82 % of Zn and 31 % of V) using 1M H2SO4 solution as stripping agent. A selective precipitation step (step 3) allowed the final separation of metals in aqueous solutions produced in Step 1 and 2. The results showed that an effective separation of Mn and Ni could be carried out at pH 9, while the best separation results for the solution obtained during the stripping step, which contains V and Ti, was obtained at pH 12.

Extraction of Yttrium from Nd Hydroxide concentrate by using D2EHPA

Extraction of yttrium from Nd hydroxide concentrate by using Di-(2-ethylhexyl) phosphoric acid (D2EHPA) has been performed. Nd hidroxide concentrate (Nd(OH)3) is a product of rare earth hydroxide (REOH) pilot plant in the Center for Accelerator Science and Technology, BATAN Yogyakarta, which still contains other rare earth metal elements, such as yttrium (Y). In the extraction process, the aquatic phase is Nd(OH)3 concentrate containing yttrium in HNO3 and as extractant or organic phase is D2EHPA in kerosene. The parameters studied were the concentration of HNO3, the concentration of D2EHPA in kerosene, and stirring time. The result of the optimization process from the research get the following conclusions: the optimum concentration of HNO3 is 1 M, the concentration of D2EHPA in kerosene is 30%, and the optimum stirring time is 25 minutes. In this condition the Kd of Y = 0.979; extraction efficiency of Y = 93.28%; SF Y-Pr, Y-Nd, and Y-Sm are infinite with SF Y-Gd = 6.080 and SF Y-Dy = 1.395. The results of this study are expected to be used as feed on ion exchange columns to separation and purification of other LTJ elements.