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Recovery of cobalt from spent lithium ion batteries by using acidic and basic extractants in solvent extraction process
Accepted Manuscript Recovery of cobalt from spent lithium ion batteries by using acidic and basic extractants in solvent extraction process Rezvan Torkaman, Mehdi Asadollahzadeh, Meisam Torab-Mostaedi, Mohammad Ghanadi Maragheh PII: DOI: Reference:
S1383-5866(16)32874-X http://dx.doi.org/10.1016/j.seppur.2017.06.023 SEPPUR 13801
To appear in:
Separation and Purification Technology
Received Date: Revised Date: Accepted Date:
28 December 2016 10 June 2017 11 June 2017
Please cite this article as: R. Torkaman, M. Asadollahzadeh, M. Torab-Mostaedi, M.G. Maragheh, Recovery of cobalt from spent lithium ion batteries by using acidic and basic extractants in solvent extraction process, Separation and Purification Technology (2017), doi: http://dx.doi.org/10.1016/j.seppur.2017.06.023
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Recovery of cobalt from spent lithium ion batteries by using acidic and basic extractants in solvent extraction process Rezvan Torkaman*, Mehdi Asadollahzadeh, Meisam Torab-Mostaedi, Mohammad Ghanadi Maragheh Materials and Nuclear Cycle Research School, Nuclear Science and Technology Research Institute, P.O. Box: 11365-8486, Tehran, Iran Abstract Solvent extraction studies of cobalt from aqueous chloride solution have been focused on using three acidic (Cyanex301, D2EHPA, Cyanex272) and two basic (Alamine336, TOA) extractants. The effects of operating variables, such as time, chloride or sulfate ions, aqueous phase acidity, concentration of the extractant, temperature and various acid solutions in the metal stripping from the loaded organic phase were studied. The values of the stoichiometric coefficients for reactive extraction of cobalt from aqueous chloride solution were calculated by using the relationship between log D and equilibrium concentration of the five extractants. According to the results, Cyanex301 extraction system led to an increase in extraction efficiency of cobalt from aqueous solution in the low concentration range (0.1 M) from the diluted chloride solution (pH=6-7), while, TOA extractant was an appropriate extractant for cobalt extraction in chloride acidic aqueous solution (6 M HCl). The results illustrate that the increase in temperature was favorable for the extraction cobalt with the five extractants. In addition, the useful data for recovery of cobalt from the synthetic leach liquor of the spent lithium ion batteries were obtained from the experimental data. Keywords: Solvent Extraction, Lithium Ion Batteries, Amine Extractants, Acidic Organophosphorous Extractants
*
Corresponding author: R. Torkaman ([email protected]) Tel: +982188221117; Fax:+982188221116
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1. Introduction In recent years, the rechargeable batteries have become the electrochemical power sources for portable electronic devices such as notebooks, laptops, cameras and mobile phones [1, 2]. Nowadays, lithium ion batteries (LIBs) with high energy density, high power density, and long life discharge are widely used in portable electronic apparatuses [3, 4]. The mostly used material for cathodes in LIBs is LiCoO2 (60%Co) due to its high capacity. The recovery of used lithium ion batteries, especially LiCoO2 has become a significant issue, because of the potential environmental pressures and the recovery of valuable metals such as aluminum, copper, nickel, lithium, cobalt from a secondary and a cheaper mineral source. Various recycling processes for the spent LIBs have been reported in the literature [5-8]. Compared with the other processes for the recovery of metals, the solvent extraction has been widely used for separation and recovery of valuable metals from the spent lithium ion batteries with the higher rate of recovery and low energy consumption. This method is the best technique for continuous operation with short reaction time and mild reaction conditions [9]. The appropriate selection of the process parameters, such as the type of extractant, the concentration of the extractants, the organic to aqueous phase ratio, the composition of the aqueous and organic phases can be varied to reach the extraction and separation of selective components [10]. Extraction and separation of metals such as Fe(II,III), Mn(II), Co(II), Ni(II), Cu(II), Cd(II), and Zn(II) from various types of wastes such as the remnants of the electronic devices, the used catalysts [11-13], spent batteries [14-16] and other wastes [17] have been investigated by applying precipitation and solvent extraction technique. The extraction and separation of molybdenum and cobalt from the leach liquor of molybdenum–cobalt spent catalyst by using Cyanex272 and Cyanex301 were studied by Padhan and Sarangi [18]. Extraction and separation of cobalt in the presence of the other metals employing various extractants, either discretely [19-21] or synergistically [22-24], have been reported.
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The recovery of cobalt with 95% purity was achieved by the solvent extraction process with D2EHPA and Cyanex272 extractants and sodium was removal by final washing [1]. The extraction and separation of Co(II), Mn (II), Li(I) and Ni(II) from the leach liquor of LIBs using Cyanex272 extractant were investigated by Nayl and co-workers [25]. The high extraction efficiencies (92.5% Mn(II) and 81% Co(II)) were obtained by 10 min shaking time at 25°C with 0.04 M NaCyanex272. The mixture of PC88A and Versatic 10 acid extractants in kerosene was utilized for the separation of Mn from the spent lithium battery leach liquor containing Mn, Co, Li and Ni with 17.7, 11.4, 5.3 and 12.2 g/L concentrations, respectively [26]. The addition of Versatic 10 acid to PC88A extractant decreased the extraction efficiency of Co rather than Mn, therefore, the separation factor value of Mn over Co increased and reached the value equal to 23.67 [26]. The influence of the addition of acetate ions to the aqueous solution was investigated for extraction of cobalt by Voorde and co-workers. They observed that the addition of acetate ions to the aqueous phase could improve the extraction efficiency of cobalt [27]. The effective recycling route for nickel, cobalt, lithium and magnesium recovery from leaching liquor of waste cathode materials was scrutinized by using D2EHPA extractant [28]. Various synergistic extractant systems were investigated in order to recover Co(II), Ni(II) and Cu(II) from sulfuric and chloride leach solutions and the process flow sheet was proposed for the recovery of the three metals from the chloride solutions [29]. The sodium salts of TOPS-99 and Cyanex272 in kerosene were used for extraction and separation of cobalt from nickel laterite bacteria leach liquor. Co(II) was recovered from the leach liquor using Na-Cyanex272, and finally, nickel extraction was removed by Na-TOPS-99 with 99.84% yield [30]. The main objective of the present work is to extract and separate cobalt from the leach liquor of the used lithium ion batteries. In order to extract cobalt from the aqueous phase solution, acidic organophosphorous extractants (D2EHPA, Cyanex272, Cyanex301) and amine extractants (TOA and Alamine336) were used. The effective factors, including the type of extractant, concentration of extractant, initial aqueous pH, temperature, and operating matrix, namely sulfate and chloride were
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investigated under batch experimental conditions. Also, stripping processes were studied to separate the metal ions and to send the aqueous solutions to the electrowinning section for preparation of metals from cobalt and the other valuable ions. 2. Experimental 2.1. Chemicals and reagents The acidic organophosphorous extractants such as di(2-ethylhexyl) phosphoric acid (D2EHPA), bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex301) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272) were purchased from Aldrich. The amine extractants, such as commercial grade Alamine 336 and tri-Octyl amine (TOA) were provided by the NetSun Company of China, and used without any further purification. The physicochemical properties of these extractants are shown in Table 1. Kerosene with main component of saturated aliphatic hydrocarbons, was used as a diluent for organic phases; it was purchased from Tehran Petroleum Refinery. The other materials such as 1-decanol, toluene and carbon tetrachloride were provided by Merck for experiments with various diluents. Industrial grade of cobalt sulfate or chloride was with 80% purity supplied by Azma Sanat Zeynali Company. For experiments with the presence of impurities in the aqueous phase, the lithium, nickel, copper and aluminum chlorides were prepared from Aldrich. 2.2. Preparation of the solutions The synthetic Co(II) solutions without impurities were formed by using certain amounts of Co(II) chloride hexahydrate in distilled water. The initial pH of the solutions for experiments with acidic extractants was adjusted to a desired value by employing dilute HCl and NH4OH solution. For experiments with amine extractants, fuming HCl was added to the aqueous solutions in order to produce solutions at various molarities of acids. The total cobalt ion concentration in each synthetic solution was fixed to 1000 mg/L. The synthetic solution with impurities, simulating leach liquor of the spent lithium ion batteries after iron precipitation and containing 350 mg/L Li, 1000 mg/L Co, 400 mg/L Cu, 100 mg/L Al and
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100 mg/L Ni was provided by dissolving the required amount of analytical grade metal chlorides in distilled water. The aqueous solution of HCl or H2SO4 with the desired concentration was used in the stripping conditions, and the loaded organic phase containing cobalt and other components was utilized as the organic phase. 2.3. Procedure In the extraction and stripping experiments, 10 mL of aqueous phase and 10 mL of organic phase containing an extractant were mixed and shaken in reagent bottles using a thermostatic water shaker adjusted to 25 ºC. All experiments were carried out at a fixed contact time of 30 min, based on the results of the preliminary experiments indicating that 15 min should be sufficient to achieve equilibrium. After reaching equilibrium, the phases were separated by means of a separation funnel. Metal ion concentrations in the aqueous phase before and after extraction were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). 2.4. Distribution coefficient and separation factor The distribution coefficient for cobalt was calculated as follows: (1)
where [Co]initial is the initial cobalt concentration in the aqueous phase before the extraction and [Co]aq is the cobalt concentration in the aqueous phase after the extraction. The extraction efficiency for cobalt or the other metals in the experiments was defined as follows: (2)
The distribution coefficient for other metals is calculated in the same way as that of cobalt (Eq.1).The efficiency of separation of cobalt from lithium, nickel or other metals is defined by the separation factor β: (3)
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where, Dmetal denotes the distribution coefficients for lithium, copper, aluminum and nickel in the experiments. The stripping percent (%S) for the experiments was calculated as follows: (4)
where, [M]aq,a is the equilibrium concentration of metal ion in the stripping acid and [M]org,t is the initial concentration of metal ion in the loaded organic phase, respectively. 3. Results and discussion The experiments for cobalt extraction were carried out in two steps. In the first step, the extraction of Co(II) without impurities by using three acids and two basic extractants was investigated. The effects of various parameters such as aqueous phase acidity, extractant concentration, temperature and stripping conditions on the extraction efficiency were studied. In the second step, the extraction and separation of cobalt from the synthetic leach liquor of the spent lithium ion batteries were investigated and the effect of the type of the extractant on the extraction and stripping was studied. 3.1. Extraction cobalt without impurities 3.1.1. Effect of contacting time The effect of the contacting time on the cobalt extraction from 1 to 30 min is shown in Fig.1. The results show that the optimum equilibrium time equal to 30 min is appropriate to reach equilibrium with various extractants. 3.1.2. Effect of aqueous phase acidity The effect of pH on the extraction of Co(II) ions from chloride aqueous solutions using three acidic extractants is shown in Fig.2a. The reaction is reversible and cobalt can be stripped from the organic phase by the increase in the aqueous phase acidity. Hence, the higher pH leads to the extraction of cobalt with the acidic extractants (Cyanex301, Cyanex272, D2EHPA). Therefore, the optimum value of pH (pH=7.2) is controlled by using one drop of ammonia solution, because the main problem is resolved with the change of pH in the aqueous phase after equilibrium with the organic phase when acidic extractants are used. The pH control problem in the experiments is usually solved by the addition of appropriate quantities of ammonia solution. The higher amount of 6
ammonia (pH>8) leads to the formation of deposits; consequently, it is not suitable for the extraction experiments. In the experiments with TOA and Alamine336, the optimal aqueous phase acidity is determined by varying the HCl concentration of the aqueous phase, the results of which are shown in Fig.2b. Obviously, the extraction efficiency of cobalt increases with increasing HCl concentration to a maximum of 6 M. Then, the decrease in the extraction efficiency of Co(II) at a higher HCl concentration is observed. This behavior is attributed to the extraction of the excess HCl and the form of the hydrogen dichloride ion [HCl2-]. 3.1.3. Effect of extractant concentration In order to compare the concentration of the acidic and basic extractants for cobalt extraction; the results are shown in Fig.3.
Experimental data illustrate that the trioctylamine extractant is a
promising asset for cobalt extraction in chloride acidic aqueous solution (6 M HCl), while the Cynex301 extractant with a lower concentration range (0.1-0.25 M) is appropriate for the diluted aqueous chloride solution (pH=6-7). The results show that the extraction cobalt with Cyanex301 is inferior to the other acidic extractants. The higher extraction efficiency for cobalt could be obtained in aqueous solution when using Cyanex301 as an extractant and, but environmental effects limit the use of it in industrial processes. 3.1.4. Determination of stoichiometric coefficients for extraction equations Acidic extractants (D2EHPA, Cyanex301 and Cyanex272) in kerosene exist in the form of dimer, and are used for the extraction of cobalt as represented by the Eq. (5): (5) (6) where, H2A2 represents the dimer forms of the acidic extractants in the above equations. The relationship between the logarithmic distribution coefficient and equilibrium pH is shown in Fig. 4. The slope is about 2 for the acidic extractants indicating that the two moles of hydrogen ion
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are released when one mole of cobalt is extracted and put into the organic phase by the acidic extractants (D2EHPA, Cyanex301 and Cyanex272). Fig.5 shows the relationship between the logarithmic distribution coefficient and the equilibrium concentration for the acidic extractants. The slope of log–log linear relationship between the equilibrium extractant concentrations with the corresponding distribution ratio is found to be around two for three acidic extractants, illustrating the participation of the two molecules of the acidic extractants in the extracted metals species. Aligned with the obtained results, the extraction reaction is given as follows: (7) Amine extractants (TOA or Alamine336) extract cobalt from chloride aqueous solution by the following reaction: (8) (9) where R3N represents the trioctylamine or Alamine336 extractants (R = alkyl group, N = nitrogen). The relationship between logarithmic distribution coefficient and equilibrium concentration for Alamine336 or TOA is given in Fig. 6a. The value of slopes (equal to 2) in this figure indicates that the participation of the two molecules of Alamine336 or TOA in the extracted metals species. Fig. 6b shows the relationship between log D and log[HCl]; the slope is about 2 for two basic extractants. Therefore, the extraction reaction with the amine extractants could be summarized by Eq. (10): (10)
3.1.5. Effect of temperature The variations in the extraction efficiency of cobalt at temperatures (25–55 °C) were investigated. Evidently, the extraction efficiency increased with increasing temperature from 25 to 55 °C. Results
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in Fig.7 show that the increase in temperature is favorable for the cobalt extraction with these extractants. 3.1.6. Effect of solvent as diluent The effect of the solvent as a diluent on the extraction of Co(II) is reported in Table 2, and the picture of cobalt extraction with 1-decanol solvent is shown in Fig.8. It is observed that the extraction of Co(II) varies with the nature of diluents. The extraction efficiency increases with the decrease in the dielectric constant (ε) and dipole moment of the diluents. This can be explained by the fact that the interactions between the basic and acidic extractants in this research work (D2EHPA, Cyanex301, Cyanex272, Alamine336 and TOA) with diluents having a high dielectric constant are generally stronger than those of low dielectric constant such as kerosene. The strong interaction of diluents and extractants leads to the lower extraction efficiency for cobalt. Therefore, kerosene with high extraction efficiency is appropriate for cobalt extraction. 3.1.7. Effect of sulfate or chloride in aqueous phase The variation in the sulfate or chloride ions in aqueous phase solutions is illustrated in Fig.9. The results show that the type of operating matrix in aqueous solution (chloride or sulfate ions) have almost no effect on the extraction of cobalt from chloride or sulfate solution with acidic extractants (Cyanex301, Cyanex272, D2EHPA), whereas the slight increase in cobalt extraction was observed with basic extractants (TOA and Alamine336), because the reaction rate between the basic extractants and sulfate ion is higher than that of the chloride ions. 3.1.8. Stripping experiments from loaded organic phase The effect of various concentrations of aqueous acid solutions with HCl and H2SO4 on the stripping of cobalt from the loaded organic phase is surveyed, the results of which are shown in Fig.10. According to the experimental results, sulfuric acid can be considered as an acceptable stripping solution with (2 M concentration) as it could reach the fair extraction of cobalt from the loaded organic phase with D2EHPA, Cyanex272 or Cyanex301 extractants. For the basic extractants (TOA
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and Alamine336), sulfuric acid with a lower concentration (1 M) is appropriate to reach the maximum stripping efficiencies. 3.2. Extraction of cobalt with impurities The extraction of cobalt from the aqueous solutions with the presence of impurities (Ni(II), Li(I), Al(III) and Cu(II)) was investigated. The schematic diagram of the solvent extraction process is shown in Fig.11. The extraction efficiency for cobalt and the other metals with three acidic and two basic extractants is shown in Fig.12. The result shows that the extraction efficiency with Cyanex301 is higher than with D2EHPA and Cyanex272 extractants. Also, the extraction of copper and nickel with Cyanex301 is lower than that with the other acidic extractants. The extraction of cobalt with TOA extractant is higher than that with the Alamine336 extractant, but the nickel extraction with amine extractants is higher than that with the acidic extractant. The stripping experiments for the recovery of cobalt from the loaded organic phases with the basic and acidic extractants were carried out; the results are shown in Fig.13, which highlights the point that the recovery of cobalt from the organic phase was obtained with a stripping percentage is higher than 90% for the five extractants. The stripping percent (%S) for lithium ions is very low with these extractant. Therefore, lithium was separated from cobalt in the experimental data with the separation factor (βCo/Li) equal to 611.9, 19.7, 13.6, 76.3 and 36.7 for Cyanex301, D2EHPA, Cyanex272, TOA and Alamine336, respectively. For better separation of cobalt from the other metals, two or three stages are required in the solvent extraction process. The results show that Cyanex301 and TOA extractants are more suitable for the extraction and recovery of cobalt from mixture of metals in the aqueous phase. 4. Conclusion In this research work, the solvent extraction process was used to recover cobalt from the used lithium ion batteries by means of three acid extractants (Cyanex301, D2EHPA, Cyanex272) and two base extractants (Alamine336, TOA). The results indicated that cyanex301 extractant in comparison with other organic acid extractants (D2EHPA, Cyanex272) showed the higher extraction efficiency in the solvent extraction process. The results show that D2EHPA extractant is
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failed to completely separate Co from Ni. The extraction of nickel with this extractant was higher than with the other extractants, therefore, D2EHPA extractant required a large number of extraction stages. In addition, experimental results show that trioctylamine extractant was a promising asset for cobalt extraction in the chloride acidic aqueous solution (6 M HCl) in comparison with Alamine336 extractant. The separation of lithium from cobalt was achieved with the separation factor (βCo/Li) equal to 611.9, 19.7, 13.6, 76.3 and 36.7 for Cyanex301, D2EHPA, Cyanex272, TOA and Alamine336, respectively. The results will be useful in the hydrometallurgical process for the recovery of cobalt from the used lithium ion batteries.
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[22] C.Y. Cheng, M.D. Urbani, M.G. Davies, Y. Pranolo, Z. Zhu, Recovery of nickel and cobalt from leach solutions of nickel laterites using a synergistic system consisting of Versatic 10 and Acorga CLX 50, Miner. Eng., 77 (2015) 17-24. [23] N.A. Grigorieva, I.Y. Fleitlikh, Cobalt extraction from sulfate media with bis(2,4,4trimethylpentyl)dithiophosphinic acid in the presence of electron donor additives, Hydrometallurgy, 138 (2013) 71-78. [24] Z. Zhu, W. Zhang, Y. Pranolo, C.Y. Cheng, Separation and recovery of copper, nickel, cobalt and zinc in chloride solutions by synergistic solvent extraction, Hydrometallurgy, 127-128 (2012) 1-7. [25] A.A.Nayl, M. M.Hamed, S.E.Rizk, Selective extraction and separation of metal values from leach liquor of mixed spent Li-ion batteries, J. Taiwan Inst. Chem. Eng. , 55 (2015) 119-125. [26] S.H. Joo, S.M. Shin, D. Shin, C. Hyun, J.P. Wang, Extractive separation studies of manganese from spent lithium battery leachate using mixture of PC88A and Versatic 10 acid in kerosene, Hydrometallurgy, 156 (2015) 136-141. [27] I.V.d. Voorde, L. Pinoy, E. Courtijn, F. Verpoort, Influence of acetate ions and the role of the diluents on the extraction of copper (II), nickel (II), cobalt (II), magnesium(II) and iron (II, III) with different types of extractants, Hydrometallurgy, 78 (2005) 92-106. [28] X. Chen, T. Zhou, J. Kong, H. Fang, Y. Chen, Separation and recovery of metal values from leach liquor of waste lithium nickel cobalt manganese oxide based cathodes, Sep. Purif. Technol., 141 (2015) 76-83. [29] C.Y. Cheng, K.R. Barnard, W. Zhang, Z. Zhu, Y. Pranolo, Recovery of nickel, cobalt, copper and zinc in sulphate and chloride solutions using synergistic solvent extraction, Chinese J. Chem. Eng., 24 (2016) 237-248. [30] R.K. MISHRA, P.C. ROUT, K. SARANGI, K.C. NATHSARMA, Solvent extraction of zinc, manganese, cobalt and nickel from nickel laterite bacterial leach liquor using sodium salts of TOPS99 and Cyanex 272, Trans. Nonferrous Met. Soc. China, 26 (2016) 306-316.
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Figure Captions Fig.1. Effect of time on the extraction of Co(II) from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants) Fig.2. Effect of aqueous phase acidity on the Co(II) extraction from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; Time=30 min) Fig.3. Effect of extractant concentration on the Co(II) extraction from chloride solution (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants; Time=30 min) Fig.4. Relationship between logarithmic distribution coefficient (log D) and equilibrium pH for acidic extractants (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; Time=30 min) Fig.5. Relationship between logarithmic distribution coefficient (log D) and equilibrium concentration for acidic extractants (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants) Fig.6. Relationship between logarithmic distribution coefficient (log D) and (a) equilibrium concentration; (b) log [HCl] for amine extractants (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L) Fig.7. Effect of temperature on the extraction of Co(II) from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 4 M for basic extractants) Fig.8. Cobalt extraction by using 1-decanol as a diluent in the organic phase
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Fig.9. Effect of chloride and sulfate ions on the cobalt extraction (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants) Fig.10. Stripping behavior of cobalt with different concentrations of mineral acids from loaded organic phase (Conditions: aqueous/organic phase volume ratio =1; T = 298.15 K; Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); [Co(II)]=0.8 g/L in the loaded organic phase) Fig.11. Schematic diagram for extraction and stripping cobalt from synthetic leach lithium batteries by using three acidic and two basic extractants Fig.12. Extraction efficiency for cobalt and the other metals from synthetic leach lithium batteries by using three acidic and two basic extractants Fig.13. Stripping percentage for recovery of cobalt and the other metals from the loaded organic phase
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Table Captions: Table 1. Physicochemical properties of acidic organophosphorous and amine extractants Table 2. Effect of various diluents on the extraction of cobalt from aqueous solution by using organophosphorous and amine extractants
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Table 1. Physicochemical properties of acidic organophosphorous and amine extractants solubility Commercial
density structure
molecular
chemical name
in water pKa
3
name
(Kg/m ) weight (mg/L) bis(2,4,4trimethylpentyl)
Cyanec301
950
322.55
7
2.61
920
290.42
0.38
6.37
965
322.43
0.01
3.24
809
353.67
0.05
-
821
395.75
0.05
-
dithiophosphinic acid bis(2,4,4Cyanex272
trimethylpentyl) phosphinic acid di(2-ethylhexyl)
D2EHPA phosphoric acid TOA
tri-octyl amine mixture of tri
Alamine336
R3N
(octyl-decyl) amine
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Table 2. Effect of various diluents on the extraction of cobalt from aqueous solution by using organophosphorous and amine extractants Dielectric Dipole Diluent
constant
moment
(ε)
(D)
8.1
Extraction Efficiency (%)
Cyanex301 D2EHPA Cyanex272 TOA
Alamine336
1.6
91.46
72.73
62.84
1.60
0.70
Chloroform 4.81
1.04
81.17
76.75
69.69
7.71
4.55
Toluene
2.38
0.36
92.89
79.48
72.42
86.82
79.43
Kerosene
1.8
0
96.65
82.83
86.15
94.45
88.88
1-decanol
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Fig.1. Effect of time on the extraction of Co(II) from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants)
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Fig.2. Effect of aqueous phase acidity on the Co(II) extraction from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; Time=30 min)
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Fig.3. Effect of extractant concentration on the Co(II) extraction from chloride solution (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants; Time=30 min)
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Fig.4. Relationship between logarithmic distribution coefficient (log D) and equilibrium pH for acidic extractants (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; Time=30 min)
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Fig.5. Relationship between logarithmic distribution coefficient (log D) and equilibrium concentration for acidic extractants (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2)
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Fig.6. Relationship between logarithmic distribution coefficient (log D) and (a) equilibrium concentration; (b) log [HCl] for amine extractants (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L)
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Fig.7. Effect of temperature on the extraction of Co(II) from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 4 M for basic extractants)
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Fig.8. Cobalt extraction by using 1-decanol as a diluent in the organic phase
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Fig.9. Effect of chloride and sulfate ions on the cobalt extraction (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants)
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Fig.10. Stripping behavior of cobalt with different concentrations of mineral acids from loaded organic phase (Conditions: aqueous/organic phase volume ratio =1; T = 298.15 K; Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); [Co(II)]=0.8 g/L in the loaded organic phase)
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Fig.11. Schematic diagram for extraction and stripping cobalt from synthetic leach lithium batteries by using three acidic and two basic extractants
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Fig.12. Extraction efficiency for cobalt and the other metals from synthetic leach lithium batteries by using three acidic and two basic extractants
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Fig.13. Stripping percentage for recovery of cobalt and the other metals from the loaded organic phase
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Highlights Cyanex301, D2EHPA, Cyanex272, Alamine336 and TOA extractants were investigated. TOA and Cyanex301 extractants were appropriate extractants for cobalt extraction. Recovery of cobalt from the leach liquor of the spent lithium ion batteries were obtained. The effects of operating variables were studied for recovery and separation of cobalt.
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Graphical abstract
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S1383-5866(16)32874-X http://dx.doi.org/10.1016/j.seppur.2017.06.023 SEPPUR 13801
To appear in:
Separation and Purification Technology
Received Date: Revised Date: Accepted Date:
28 December 2016 10 June 2017 11 June 2017
Please cite this article as: R. Torkaman, M. Asadollahzadeh, M. Torab-Mostaedi, M.G. Maragheh, Recovery of cobalt from spent lithium ion batteries by using acidic and basic extractants in solvent extraction process, Separation and Purification Technology (2017), doi: http://dx.doi.org/10.1016/j.seppur.2017.06.023
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Recovery of cobalt from spent lithium ion batteries by using acidic and basic extractants in solvent extraction process Rezvan Torkaman*, Mehdi Asadollahzadeh, Meisam Torab-Mostaedi, Mohammad Ghanadi Maragheh Materials and Nuclear Cycle Research School, Nuclear Science and Technology Research Institute, P.O. Box: 11365-8486, Tehran, Iran Abstract Solvent extraction studies of cobalt from aqueous chloride solution have been focused on using three acidic (Cyanex301, D2EHPA, Cyanex272) and two basic (Alamine336, TOA) extractants. The effects of operating variables, such as time, chloride or sulfate ions, aqueous phase acidity, concentration of the extractant, temperature and various acid solutions in the metal stripping from the loaded organic phase were studied. The values of the stoichiometric coefficients for reactive extraction of cobalt from aqueous chloride solution were calculated by using the relationship between log D and equilibrium concentration of the five extractants. According to the results, Cyanex301 extraction system led to an increase in extraction efficiency of cobalt from aqueous solution in the low concentration range (0.1 M) from the diluted chloride solution (pH=6-7), while, TOA extractant was an appropriate extractant for cobalt extraction in chloride acidic aqueous solution (6 M HCl). The results illustrate that the increase in temperature was favorable for the extraction cobalt with the five extractants. In addition, the useful data for recovery of cobalt from the synthetic leach liquor of the spent lithium ion batteries were obtained from the experimental data. Keywords: Solvent Extraction, Lithium Ion Batteries, Amine Extractants, Acidic Organophosphorous Extractants
*
Corresponding author: R. Torkaman ([email protected]) Tel: +982188221117; Fax:+982188221116
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1. Introduction In recent years, the rechargeable batteries have become the electrochemical power sources for portable electronic devices such as notebooks, laptops, cameras and mobile phones [1, 2]. Nowadays, lithium ion batteries (LIBs) with high energy density, high power density, and long life discharge are widely used in portable electronic apparatuses [3, 4]. The mostly used material for cathodes in LIBs is LiCoO2 (60%Co) due to its high capacity. The recovery of used lithium ion batteries, especially LiCoO2 has become a significant issue, because of the potential environmental pressures and the recovery of valuable metals such as aluminum, copper, nickel, lithium, cobalt from a secondary and a cheaper mineral source. Various recycling processes for the spent LIBs have been reported in the literature [5-8]. Compared with the other processes for the recovery of metals, the solvent extraction has been widely used for separation and recovery of valuable metals from the spent lithium ion batteries with the higher rate of recovery and low energy consumption. This method is the best technique for continuous operation with short reaction time and mild reaction conditions [9]. The appropriate selection of the process parameters, such as the type of extractant, the concentration of the extractants, the organic to aqueous phase ratio, the composition of the aqueous and organic phases can be varied to reach the extraction and separation of selective components [10]. Extraction and separation of metals such as Fe(II,III), Mn(II), Co(II), Ni(II), Cu(II), Cd(II), and Zn(II) from various types of wastes such as the remnants of the electronic devices, the used catalysts [11-13], spent batteries [14-16] and other wastes [17] have been investigated by applying precipitation and solvent extraction technique. The extraction and separation of molybdenum and cobalt from the leach liquor of molybdenum–cobalt spent catalyst by using Cyanex272 and Cyanex301 were studied by Padhan and Sarangi [18]. Extraction and separation of cobalt in the presence of the other metals employing various extractants, either discretely [19-21] or synergistically [22-24], have been reported.
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The recovery of cobalt with 95% purity was achieved by the solvent extraction process with D2EHPA and Cyanex272 extractants and sodium was removal by final washing [1]. The extraction and separation of Co(II), Mn (II), Li(I) and Ni(II) from the leach liquor of LIBs using Cyanex272 extractant were investigated by Nayl and co-workers [25]. The high extraction efficiencies (92.5% Mn(II) and 81% Co(II)) were obtained by 10 min shaking time at 25°C with 0.04 M NaCyanex272. The mixture of PC88A and Versatic 10 acid extractants in kerosene was utilized for the separation of Mn from the spent lithium battery leach liquor containing Mn, Co, Li and Ni with 17.7, 11.4, 5.3 and 12.2 g/L concentrations, respectively [26]. The addition of Versatic 10 acid to PC88A extractant decreased the extraction efficiency of Co rather than Mn, therefore, the separation factor value of Mn over Co increased and reached the value equal to 23.67 [26]. The influence of the addition of acetate ions to the aqueous solution was investigated for extraction of cobalt by Voorde and co-workers. They observed that the addition of acetate ions to the aqueous phase could improve the extraction efficiency of cobalt [27]. The effective recycling route for nickel, cobalt, lithium and magnesium recovery from leaching liquor of waste cathode materials was scrutinized by using D2EHPA extractant [28]. Various synergistic extractant systems were investigated in order to recover Co(II), Ni(II) and Cu(II) from sulfuric and chloride leach solutions and the process flow sheet was proposed for the recovery of the three metals from the chloride solutions [29]. The sodium salts of TOPS-99 and Cyanex272 in kerosene were used for extraction and separation of cobalt from nickel laterite bacteria leach liquor. Co(II) was recovered from the leach liquor using Na-Cyanex272, and finally, nickel extraction was removed by Na-TOPS-99 with 99.84% yield [30]. The main objective of the present work is to extract and separate cobalt from the leach liquor of the used lithium ion batteries. In order to extract cobalt from the aqueous phase solution, acidic organophosphorous extractants (D2EHPA, Cyanex272, Cyanex301) and amine extractants (TOA and Alamine336) were used. The effective factors, including the type of extractant, concentration of extractant, initial aqueous pH, temperature, and operating matrix, namely sulfate and chloride were
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investigated under batch experimental conditions. Also, stripping processes were studied to separate the metal ions and to send the aqueous solutions to the electrowinning section for preparation of metals from cobalt and the other valuable ions. 2. Experimental 2.1. Chemicals and reagents The acidic organophosphorous extractants such as di(2-ethylhexyl) phosphoric acid (D2EHPA), bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex301) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272) were purchased from Aldrich. The amine extractants, such as commercial grade Alamine 336 and tri-Octyl amine (TOA) were provided by the NetSun Company of China, and used without any further purification. The physicochemical properties of these extractants are shown in Table 1. Kerosene with main component of saturated aliphatic hydrocarbons, was used as a diluent for organic phases; it was purchased from Tehran Petroleum Refinery. The other materials such as 1-decanol, toluene and carbon tetrachloride were provided by Merck for experiments with various diluents. Industrial grade of cobalt sulfate or chloride was with 80% purity supplied by Azma Sanat Zeynali Company. For experiments with the presence of impurities in the aqueous phase, the lithium, nickel, copper and aluminum chlorides were prepared from Aldrich. 2.2. Preparation of the solutions The synthetic Co(II) solutions without impurities were formed by using certain amounts of Co(II) chloride hexahydrate in distilled water. The initial pH of the solutions for experiments with acidic extractants was adjusted to a desired value by employing dilute HCl and NH4OH solution. For experiments with amine extractants, fuming HCl was added to the aqueous solutions in order to produce solutions at various molarities of acids. The total cobalt ion concentration in each synthetic solution was fixed to 1000 mg/L. The synthetic solution with impurities, simulating leach liquor of the spent lithium ion batteries after iron precipitation and containing 350 mg/L Li, 1000 mg/L Co, 400 mg/L Cu, 100 mg/L Al and
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100 mg/L Ni was provided by dissolving the required amount of analytical grade metal chlorides in distilled water. The aqueous solution of HCl or H2SO4 with the desired concentration was used in the stripping conditions, and the loaded organic phase containing cobalt and other components was utilized as the organic phase. 2.3. Procedure In the extraction and stripping experiments, 10 mL of aqueous phase and 10 mL of organic phase containing an extractant were mixed and shaken in reagent bottles using a thermostatic water shaker adjusted to 25 ºC. All experiments were carried out at a fixed contact time of 30 min, based on the results of the preliminary experiments indicating that 15 min should be sufficient to achieve equilibrium. After reaching equilibrium, the phases were separated by means of a separation funnel. Metal ion concentrations in the aqueous phase before and after extraction were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). 2.4. Distribution coefficient and separation factor The distribution coefficient for cobalt was calculated as follows: (1)
where [Co]initial is the initial cobalt concentration in the aqueous phase before the extraction and [Co]aq is the cobalt concentration in the aqueous phase after the extraction. The extraction efficiency for cobalt or the other metals in the experiments was defined as follows: (2)
The distribution coefficient for other metals is calculated in the same way as that of cobalt (Eq.1).The efficiency of separation of cobalt from lithium, nickel or other metals is defined by the separation factor β: (3)
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where, Dmetal denotes the distribution coefficients for lithium, copper, aluminum and nickel in the experiments. The stripping percent (%S) for the experiments was calculated as follows: (4)
where, [M]aq,a is the equilibrium concentration of metal ion in the stripping acid and [M]org,t is the initial concentration of metal ion in the loaded organic phase, respectively. 3. Results and discussion The experiments for cobalt extraction were carried out in two steps. In the first step, the extraction of Co(II) without impurities by using three acids and two basic extractants was investigated. The effects of various parameters such as aqueous phase acidity, extractant concentration, temperature and stripping conditions on the extraction efficiency were studied. In the second step, the extraction and separation of cobalt from the synthetic leach liquor of the spent lithium ion batteries were investigated and the effect of the type of the extractant on the extraction and stripping was studied. 3.1. Extraction cobalt without impurities 3.1.1. Effect of contacting time The effect of the contacting time on the cobalt extraction from 1 to 30 min is shown in Fig.1. The results show that the optimum equilibrium time equal to 30 min is appropriate to reach equilibrium with various extractants. 3.1.2. Effect of aqueous phase acidity The effect of pH on the extraction of Co(II) ions from chloride aqueous solutions using three acidic extractants is shown in Fig.2a. The reaction is reversible and cobalt can be stripped from the organic phase by the increase in the aqueous phase acidity. Hence, the higher pH leads to the extraction of cobalt with the acidic extractants (Cyanex301, Cyanex272, D2EHPA). Therefore, the optimum value of pH (pH=7.2) is controlled by using one drop of ammonia solution, because the main problem is resolved with the change of pH in the aqueous phase after equilibrium with the organic phase when acidic extractants are used. The pH control problem in the experiments is usually solved by the addition of appropriate quantities of ammonia solution. The higher amount of 6
ammonia (pH>8) leads to the formation of deposits; consequently, it is not suitable for the extraction experiments. In the experiments with TOA and Alamine336, the optimal aqueous phase acidity is determined by varying the HCl concentration of the aqueous phase, the results of which are shown in Fig.2b. Obviously, the extraction efficiency of cobalt increases with increasing HCl concentration to a maximum of 6 M. Then, the decrease in the extraction efficiency of Co(II) at a higher HCl concentration is observed. This behavior is attributed to the extraction of the excess HCl and the form of the hydrogen dichloride ion [HCl2-]. 3.1.3. Effect of extractant concentration In order to compare the concentration of the acidic and basic extractants for cobalt extraction; the results are shown in Fig.3.
Experimental data illustrate that the trioctylamine extractant is a
promising asset for cobalt extraction in chloride acidic aqueous solution (6 M HCl), while the Cynex301 extractant with a lower concentration range (0.1-0.25 M) is appropriate for the diluted aqueous chloride solution (pH=6-7). The results show that the extraction cobalt with Cyanex301 is inferior to the other acidic extractants. The higher extraction efficiency for cobalt could be obtained in aqueous solution when using Cyanex301 as an extractant and, but environmental effects limit the use of it in industrial processes. 3.1.4. Determination of stoichiometric coefficients for extraction equations Acidic extractants (D2EHPA, Cyanex301 and Cyanex272) in kerosene exist in the form of dimer, and are used for the extraction of cobalt as represented by the Eq. (5): (5) (6) where, H2A2 represents the dimer forms of the acidic extractants in the above equations. The relationship between the logarithmic distribution coefficient and equilibrium pH is shown in Fig. 4. The slope is about 2 for the acidic extractants indicating that the two moles of hydrogen ion
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are released when one mole of cobalt is extracted and put into the organic phase by the acidic extractants (D2EHPA, Cyanex301 and Cyanex272). Fig.5 shows the relationship between the logarithmic distribution coefficient and the equilibrium concentration for the acidic extractants. The slope of log–log linear relationship between the equilibrium extractant concentrations with the corresponding distribution ratio is found to be around two for three acidic extractants, illustrating the participation of the two molecules of the acidic extractants in the extracted metals species. Aligned with the obtained results, the extraction reaction is given as follows: (7) Amine extractants (TOA or Alamine336) extract cobalt from chloride aqueous solution by the following reaction: (8) (9) where R3N represents the trioctylamine or Alamine336 extractants (R = alkyl group, N = nitrogen). The relationship between logarithmic distribution coefficient and equilibrium concentration for Alamine336 or TOA is given in Fig. 6a. The value of slopes (equal to 2) in this figure indicates that the participation of the two molecules of Alamine336 or TOA in the extracted metals species. Fig. 6b shows the relationship between log D and log[HCl]; the slope is about 2 for two basic extractants. Therefore, the extraction reaction with the amine extractants could be summarized by Eq. (10): (10)
3.1.5. Effect of temperature The variations in the extraction efficiency of cobalt at temperatures (25–55 °C) were investigated. Evidently, the extraction efficiency increased with increasing temperature from 25 to 55 °C. Results
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in Fig.7 show that the increase in temperature is favorable for the cobalt extraction with these extractants. 3.1.6. Effect of solvent as diluent The effect of the solvent as a diluent on the extraction of Co(II) is reported in Table 2, and the picture of cobalt extraction with 1-decanol solvent is shown in Fig.8. It is observed that the extraction of Co(II) varies with the nature of diluents. The extraction efficiency increases with the decrease in the dielectric constant (ε) and dipole moment of the diluents. This can be explained by the fact that the interactions between the basic and acidic extractants in this research work (D2EHPA, Cyanex301, Cyanex272, Alamine336 and TOA) with diluents having a high dielectric constant are generally stronger than those of low dielectric constant such as kerosene. The strong interaction of diluents and extractants leads to the lower extraction efficiency for cobalt. Therefore, kerosene with high extraction efficiency is appropriate for cobalt extraction. 3.1.7. Effect of sulfate or chloride in aqueous phase The variation in the sulfate or chloride ions in aqueous phase solutions is illustrated in Fig.9. The results show that the type of operating matrix in aqueous solution (chloride or sulfate ions) have almost no effect on the extraction of cobalt from chloride or sulfate solution with acidic extractants (Cyanex301, Cyanex272, D2EHPA), whereas the slight increase in cobalt extraction was observed with basic extractants (TOA and Alamine336), because the reaction rate between the basic extractants and sulfate ion is higher than that of the chloride ions. 3.1.8. Stripping experiments from loaded organic phase The effect of various concentrations of aqueous acid solutions with HCl and H2SO4 on the stripping of cobalt from the loaded organic phase is surveyed, the results of which are shown in Fig.10. According to the experimental results, sulfuric acid can be considered as an acceptable stripping solution with (2 M concentration) as it could reach the fair extraction of cobalt from the loaded organic phase with D2EHPA, Cyanex272 or Cyanex301 extractants. For the basic extractants (TOA
9
and Alamine336), sulfuric acid with a lower concentration (1 M) is appropriate to reach the maximum stripping efficiencies. 3.2. Extraction of cobalt with impurities The extraction of cobalt from the aqueous solutions with the presence of impurities (Ni(II), Li(I), Al(III) and Cu(II)) was investigated. The schematic diagram of the solvent extraction process is shown in Fig.11. The extraction efficiency for cobalt and the other metals with three acidic and two basic extractants is shown in Fig.12. The result shows that the extraction efficiency with Cyanex301 is higher than with D2EHPA and Cyanex272 extractants. Also, the extraction of copper and nickel with Cyanex301 is lower than that with the other acidic extractants. The extraction of cobalt with TOA extractant is higher than that with the Alamine336 extractant, but the nickel extraction with amine extractants is higher than that with the acidic extractant. The stripping experiments for the recovery of cobalt from the loaded organic phases with the basic and acidic extractants were carried out; the results are shown in Fig.13, which highlights the point that the recovery of cobalt from the organic phase was obtained with a stripping percentage is higher than 90% for the five extractants. The stripping percent (%S) for lithium ions is very low with these extractant. Therefore, lithium was separated from cobalt in the experimental data with the separation factor (βCo/Li) equal to 611.9, 19.7, 13.6, 76.3 and 36.7 for Cyanex301, D2EHPA, Cyanex272, TOA and Alamine336, respectively. For better separation of cobalt from the other metals, two or three stages are required in the solvent extraction process. The results show that Cyanex301 and TOA extractants are more suitable for the extraction and recovery of cobalt from mixture of metals in the aqueous phase. 4. Conclusion In this research work, the solvent extraction process was used to recover cobalt from the used lithium ion batteries by means of three acid extractants (Cyanex301, D2EHPA, Cyanex272) and two base extractants (Alamine336, TOA). The results indicated that cyanex301 extractant in comparison with other organic acid extractants (D2EHPA, Cyanex272) showed the higher extraction efficiency in the solvent extraction process. The results show that D2EHPA extractant is
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failed to completely separate Co from Ni. The extraction of nickel with this extractant was higher than with the other extractants, therefore, D2EHPA extractant required a large number of extraction stages. In addition, experimental results show that trioctylamine extractant was a promising asset for cobalt extraction in the chloride acidic aqueous solution (6 M HCl) in comparison with Alamine336 extractant. The separation of lithium from cobalt was achieved with the separation factor (βCo/Li) equal to 611.9, 19.7, 13.6, 76.3 and 36.7 for Cyanex301, D2EHPA, Cyanex272, TOA and Alamine336, respectively. The results will be useful in the hydrometallurgical process for the recovery of cobalt from the used lithium ion batteries.
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[22] C.Y. Cheng, M.D. Urbani, M.G. Davies, Y. Pranolo, Z. Zhu, Recovery of nickel and cobalt from leach solutions of nickel laterites using a synergistic system consisting of Versatic 10 and Acorga CLX 50, Miner. Eng., 77 (2015) 17-24. [23] N.A. Grigorieva, I.Y. Fleitlikh, Cobalt extraction from sulfate media with bis(2,4,4trimethylpentyl)dithiophosphinic acid in the presence of electron donor additives, Hydrometallurgy, 138 (2013) 71-78. [24] Z. Zhu, W. Zhang, Y. Pranolo, C.Y. Cheng, Separation and recovery of copper, nickel, cobalt and zinc in chloride solutions by synergistic solvent extraction, Hydrometallurgy, 127-128 (2012) 1-7. [25] A.A.Nayl, M. M.Hamed, S.E.Rizk, Selective extraction and separation of metal values from leach liquor of mixed spent Li-ion batteries, J. Taiwan Inst. Chem. Eng. , 55 (2015) 119-125. [26] S.H. Joo, S.M. Shin, D. Shin, C. Hyun, J.P. Wang, Extractive separation studies of manganese from spent lithium battery leachate using mixture of PC88A and Versatic 10 acid in kerosene, Hydrometallurgy, 156 (2015) 136-141. [27] I.V.d. Voorde, L. Pinoy, E. Courtijn, F. Verpoort, Influence of acetate ions and the role of the diluents on the extraction of copper (II), nickel (II), cobalt (II), magnesium(II) and iron (II, III) with different types of extractants, Hydrometallurgy, 78 (2005) 92-106. [28] X. Chen, T. Zhou, J. Kong, H. Fang, Y. Chen, Separation and recovery of metal values from leach liquor of waste lithium nickel cobalt manganese oxide based cathodes, Sep. Purif. Technol., 141 (2015) 76-83. [29] C.Y. Cheng, K.R. Barnard, W. Zhang, Z. Zhu, Y. Pranolo, Recovery of nickel, cobalt, copper and zinc in sulphate and chloride solutions using synergistic solvent extraction, Chinese J. Chem. Eng., 24 (2016) 237-248. [30] R.K. MISHRA, P.C. ROUT, K. SARANGI, K.C. NATHSARMA, Solvent extraction of zinc, manganese, cobalt and nickel from nickel laterite bacterial leach liquor using sodium salts of TOPS99 and Cyanex 272, Trans. Nonferrous Met. Soc. China, 26 (2016) 306-316.
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Figure Captions Fig.1. Effect of time on the extraction of Co(II) from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants) Fig.2. Effect of aqueous phase acidity on the Co(II) extraction from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; Time=30 min) Fig.3. Effect of extractant concentration on the Co(II) extraction from chloride solution (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants; Time=30 min) Fig.4. Relationship between logarithmic distribution coefficient (log D) and equilibrium pH for acidic extractants (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; Time=30 min) Fig.5. Relationship between logarithmic distribution coefficient (log D) and equilibrium concentration for acidic extractants (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants) Fig.6. Relationship between logarithmic distribution coefficient (log D) and (a) equilibrium concentration; (b) log [HCl] for amine extractants (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L) Fig.7. Effect of temperature on the extraction of Co(II) from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 4 M for basic extractants) Fig.8. Cobalt extraction by using 1-decanol as a diluent in the organic phase
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Fig.9. Effect of chloride and sulfate ions on the cobalt extraction (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants) Fig.10. Stripping behavior of cobalt with different concentrations of mineral acids from loaded organic phase (Conditions: aqueous/organic phase volume ratio =1; T = 298.15 K; Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); [Co(II)]=0.8 g/L in the loaded organic phase) Fig.11. Schematic diagram for extraction and stripping cobalt from synthetic leach lithium batteries by using three acidic and two basic extractants Fig.12. Extraction efficiency for cobalt and the other metals from synthetic leach lithium batteries by using three acidic and two basic extractants Fig.13. Stripping percentage for recovery of cobalt and the other metals from the loaded organic phase
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Table Captions: Table 1. Physicochemical properties of acidic organophosphorous and amine extractants Table 2. Effect of various diluents on the extraction of cobalt from aqueous solution by using organophosphorous and amine extractants
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Table 1. Physicochemical properties of acidic organophosphorous and amine extractants solubility Commercial
density structure
molecular
chemical name
in water pKa
3
name
(Kg/m ) weight (mg/L) bis(2,4,4trimethylpentyl)
Cyanec301
950
322.55
7
2.61
920
290.42
0.38
6.37
965
322.43
0.01
3.24
809
353.67
0.05
-
821
395.75
0.05
-
dithiophosphinic acid bis(2,4,4Cyanex272
trimethylpentyl) phosphinic acid di(2-ethylhexyl)
D2EHPA phosphoric acid TOA
tri-octyl amine mixture of tri
Alamine336
R3N
(octyl-decyl) amine
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Table 2. Effect of various diluents on the extraction of cobalt from aqueous solution by using organophosphorous and amine extractants Dielectric Dipole Diluent
constant
moment
(ε)
(D)
8.1
Extraction Efficiency (%)
Cyanex301 D2EHPA Cyanex272 TOA
Alamine336
1.6
91.46
72.73
62.84
1.60
0.70
Chloroform 4.81
1.04
81.17
76.75
69.69
7.71
4.55
Toluene
2.38
0.36
92.89
79.48
72.42
86.82
79.43
Kerosene
1.8
0
96.65
82.83
86.15
94.45
88.88
1-decanol
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Fig.1. Effect of time on the extraction of Co(II) from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants)
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Fig.2. Effect of aqueous phase acidity on the Co(II) extraction from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; Time=30 min)
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Fig.3. Effect of extractant concentration on the Co(II) extraction from chloride solution (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants; Time=30 min)
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Fig.4. Relationship between logarithmic distribution coefficient (log D) and equilibrium pH for acidic extractants (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; Time=30 min)
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Fig.5. Relationship between logarithmic distribution coefficient (log D) and equilibrium concentration for acidic extractants (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2)
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Fig.6. Relationship between logarithmic distribution coefficient (log D) and (a) equilibrium concentration; (b) log [HCl] for amine extractants (Conditions: aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L)
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Fig.7. Effect of temperature on the extraction of Co(II) from chloride solution (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 4 M for basic extractants)
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Fig.8. Cobalt extraction by using 1-decanol as a diluent in the organic phase
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Fig.9. Effect of chloride and sulfate ions on the cobalt extraction (Conditions: Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); aqueous/organic phase volume ratio = 1; T = 298.15 K; [Co(II)]=1 g/L; pH=7.2 for acidic extractants and HCl 6 M for basic extractants)
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Fig.10. Stripping behavior of cobalt with different concentrations of mineral acids from loaded organic phase (Conditions: aqueous/organic phase volume ratio =1; T = 298.15 K; Cyanex301 (0.1 M); D2EHPA (0.5 M); Cyanex272 (0.75 M); TOA (0.5 M); Alamine336 (0.4 M); [Co(II)]=0.8 g/L in the loaded organic phase)
29
Fig.11. Schematic diagram for extraction and stripping cobalt from synthetic leach lithium batteries by using three acidic and two basic extractants
30
Fig.12. Extraction efficiency for cobalt and the other metals from synthetic leach lithium batteries by using three acidic and two basic extractants
31
Fig.13. Stripping percentage for recovery of cobalt and the other metals from the loaded organic phase
32
Highlights Cyanex301, D2EHPA, Cyanex272, Alamine336 and TOA extractants were investigated. TOA and Cyanex301 extractants were appropriate extractants for cobalt extraction. Recovery of cobalt from the leach liquor of the spent lithium ion batteries were obtained. The effects of operating variables were studied for recovery and separation of cobalt.
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Graphical abstract
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