- Email: [email protected]
Study of the preparation of NI–Mn–Zn ferrite using spent NI–MH and alkaline Zn–Mn batteries
Journal of Magnetism and Magnetic Materials 398 (2016) 196–199
Contents lists available at ScienceDirect
Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm
Study of the preparation of NI–Mn–Zn ferrite using spent NI–MH and alkaline Zn–Mn batteries Guoxi Xi n, Yuebin Xi, Huidao Xu, Lu Wang Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, PR China
art ic l e i nf o
a b s t r a c t
Article history: Received 21 October 2014 Received in revised form 3 September 2015 Accepted 9 September 2015 Available online 11 September 2015
Magnetic nanoparticles of Ni–Mn–Zn ferrite have been prepared by a sol–gel method making use of spent Ni–MH and Zn–Mn batteries as source materials. Characterization by X-ray diffraction was carried out to study the particle size. The presence of functional groups was identified by Fourier transform infrared spectroscopy. From studies by thermogravimetry and differential scanning calorimetry, crystallization occurred at temperatures above 560 °C. The magnetic properties of the final products were found to be directly influenced by the average particle size of the product. The Ms values increase and the Hc values decrease as the size of the Ni–Mn–Zn ferrite particles increases. & 2015 Elsevier B.V. All rights reserved.
Keywords: Magnetic materials Sol–gel growth Thermogravimetric analysis Magnetic properties Ferrite
1. Introduction The consumption of batteries has increased in the last few decades because of their versatility, low maintenance, and reduced costs, and because of the requirements of the electronics industry [1]. On the other hand, a large quantity of spent batteries has been disposed of as waste. They have to be treated as a special residue because of the heavy metals which they contain. This presents a major environmental and health threat [2]. Waste batteries are causing serious concern owing to their toxicity, abundance, and permanence in the environment [3]. Therefore, reutilization and recycling of materials in order to minimize this waste are being considered. On a resource management level, spent batteries could be considered as secondary raw materials. Valuable metals can be recovered and put on the market for the manufacture of new batteries or of other products. The use of recycled metals instead of virgin metals in battery production or other products would have a positive environmental impact through reduced energy use and reduced pollution related to the mining of the virgin sources. Overviews of current techniques, including pyrometallurgical and hydrometallurgical processes and combinations of the two, for the recycling of spent nickel–metal hydride (Ni–MH) and Zn–Mn batteries have been presented elsewhere [1,4–9]. The large energy n
Corresponding author. Fax: þ86 373 3326336. E-mail addresses: [email protected] (G. Xi), [email protected] (H. Xu). http://dx.doi.org/10.1016/j.jmmm.2015.09.047 0304-8853/& 2015 Elsevier B.V. All rights reserved.
consumption, high cost, low efficiency, and serious secondary pollution of the traditional techniques make it desirable to find an economic and environmental friendly process to treat and recycle these spent batteries. Recently, the use of spent Zn–Mn batteries as a raw material to synthesize Zn–Mn ferrite magnetic materials has been developed because there are adequate amounts of Mn, Zn, and Fe in spent Zn–Mn batteries. Kanemaru et al. [10] cleaned material from spent batteries with water after dismantling and roasting, and then synthesized Zn–Mn ferrites using Zn, Mn, and Fe oxides prepared from this material. Xi et al. [11] presented studies of the preparation of Zn–Mn ferrites by a coprecipitation method in which spent Zn–Mn batteries were dissolved in 3 mol/L H2SO4 þ2.4% H2O2. Nan et al. [12] reported a novel process for reclaiming spent zinc–manganese dioxide batteries through synthesizing Zn–Mn ferrite magnetic materials. Ferrites exhibit ferrimagnetism due to a superexchange interaction between the electrons of the metal ions and oxide ions. Owing to the intrinsic atomic-level interaction between the oxide and metal ions, ferrites have a higher resistivity than ferromagnetic metals [13,14]. This enables ferrites to find applications at higher frequencies and makes them technologically very valuable. The most important commercial forms of these ferrites are Zn2 þ -substituted Ni and Mn ferrites, referred to as Ni–Zn and Mn– Zn ferrites, respectively. The major difference between these two types of ferrites is in their resistivity values. Mn–Zn ferrites are technologically important because of their permeability and high magnetization. However, their eddy current loss is higher at higher
G. Xi et al. / Journal of Magnetism and Magnetic Materials 398 (2016) 196–199
frequencies because of their low resistivity. These ferrites have been widely used in electronic applications such as transformers, coils, and recording heads. Ni–Zn ferrites, on the other hand, possess a high resistivity but a relatively low permeability at high frequencies. These ferrites have been extensively used as magnetic core materials in a large number of devices and electrical components such as phase shifters, circulators, isolators, inductors, and transformers. Magnetic applications, such as computer memory and pulse transformers operating at high frequencies, require a high resistivity, a high saturation magnetization, a high Néel temperature, and low magnetic losses. Although Mn–Zn and Ni– Zn ferrites have been investigated extensively, the literature on combinations of these two ferrites is inadequate, especially with respect to combinations obtained by using spent Ni–MH and alkaline Zn–Mn batteries as raw materials. In the present investigation, spent Ni–MH and alkaline Zn–Mn batteries were used as source materials to prepare Ni–Mn–Zn ferrites employing a sol–gel combustion technique. Characterization of the prepared Ni–Mn–Zn ferrites was done employing various techniques to study the particle size and to explore other parameters of interest.
2. Experimental The cylindrical spent Ni–MH and alkaline Zn–Mn batteries used in this work were kindly provided by Henan Huanyu Power Source Co. Ltd. The positive electrodes of the spent Ni–MH batteries were composed of a formed nickel substrate and an Ni(OH)2 active material; the negative electrodes consisted of an AB5-type hydrogen storage alloy powder and an iron or copper-mesh substrate. The spent alkaline Zn–Mn batteries were composed of ZnO, MnO, Mn2O3, Mn3O4, and MnO2 within an iron shell, as well as remnant Zn, after discharging of the batteries. The contents of the various substances in the two types of batteries were similar to those in commercial batteries of the same size on the market. The batteries used as raw materials to prepare Ni–Mn–Zn ferrites in this study were dissolved in 5 mol/L nitric acid solution containing 2.5 wt% hydrogen peroxide. After complete dissolution, the solution was filtered and the filtrate was analyzed by atomic absorption spectroscopy to determine the concentrations of Fe, Ni, Mn, and Zn (using a model Z-5000 atomic absorption spectrophotometer from Hitachi, Japan). In order to prepare the ferrites, suitable amounts of analytical-grade nickel nitrate, manganous nitrate, zinc nitrate, and iron nitrate were added to adjust the concentrations of Ni, Mn, Zn, and Fe. Then, an appropriate amount of citric acid was put into the solution to adjust the molar ratio of the total concentrations of metal ions and added citric acid to 1:1. During this procedure, the solution was continuously stirred using a magnetic agitator, and the temperature was controlled at 50 °C. When the citric acid was completely dissolved, ammonia solution was added dropwise to obtain a brown solution. The solution was kept at 80 °C to remove the residual nitric acid and hydrogen peroxide until the solution became a brown–red sol. The pH of the sol was maintained between 7 and 8. Then, the sol was put into a dish and dried in an oven at 100 °C for 2 h to transform it into a dried gel. The gel formed was ground and then heated at 800 °C for 3 h. A loose black powder, which consisted of nanocrystalline ferrite, was obtained as a result of combustion of the dried gel. The experimental procedure is shown in Fig. 1.
197
Fig. 1. Flowsheet for the preparation of Ni–Mn–Zn ferrite from spent batteries.
3. Results and discussion 3.1. Thermal studies Thermal-analysis measurements of the dried gel powder by thermogravimetry (TG), differential thermogravimetry (DTG), and differential scanning calorimetry (DSC) were carried out in a dynamic air atmosphere (20 mL min 1) with a nonisothermal linear regime. An STA 449C analyzer from Netzsch Instruments was used for the experiments. Samples of the dried gel powder, with masses from 10 to 15 mg, contained in Al2O3 crucibles, were heated from room temperature to about 800 °C at a heating rate of 10 °C min 1. The TG and DTG curves (Fig. 2) indicated that the weight loss occurred in two distinct steps. The first step showed a large weight loss in the temperature range from room temperature to 560 °C, which can be attributed to an oxidation–reduction reaction between the nitrate and the citric acid. The second step was observed between 590 and 800 °C and showed only a small weight loss, which can be attributed to decomposition of the remaining organic matter. It was observed that simultaneous evolution of lattice oxygen, oxidation of complexes, and formation of semiorganic carbon–metal/ metal oxide particles occurred. It is believed that the formation of metal oxides took place at this stage [15,16]. Crystallization occurred at temperatures above 560 °C [17]. No weight loss occurred in the samples at temperatures above 800 °C. From the TG/DTG curves, it can be seen that the first weight loss step finished completely at 590 °C and, in the second step, the samples were thermally stable at 800 °C.
Fig. 2. TG/DTG/DSC curves of dried gel.
198
G. Xi et al. / Journal of Magnetism and Magnetic Materials 398 (2016) 196–199
Fig. 3. XRD patterns of Ni–Mn–Zn ferrite nanoparticles at different temperatures: a 560 °C, b 650 °C, c 750 °C, d 850 °C.
The thermal events observed in the DSC curve (Fig. 2) are in concordance with those observed in the TG/DTG curves. The DSC curve clearly shows two exothermic peaks, indicating that the decomposition occurs in two stages, whereas this is not easily perceived from the DTG curves. 3.2. Structural studies X-ray diffraction (XRD) patterns of all of the samples of Ni–Mn– Zn ferrite nanoparticles that we synthesized by the sol–gel combustion technique are depicted in Fig. 3. All of the characteristic peaks of Ni–Mn–Zn ferrite nanoparticles are present in all of the diffraction patterns (a, b, c, and d, corresponding to calcination temperatures of 560, 650, 750, and 850 °C). It was found that all diffraction peaks could be indexed perfectly with a cubic spinel structure, and no peaks corresponding to impurities were detected in the XRD patterns. The mean crystallite sizes were estimated from the linewidth of the (311) XRD peak using the Scherrer equation as follows:
D=
Fig. 4. IR spectra of the dried gels before combustion (a) and after combustion (b) at 750 °C.
carboxyl group. In addition, characteristic peaks of the NO3 ion were also observed at 1403.45, 1114.44, and 846.22 cm 1. This indicates that the NO3 ion existed as a group in the structure of the citrate gels during the process of gelation. After combustion, as shown in Fig. 4(b), a characteristic peak of Ni–Mn–Zn ferrite was observed at 585.36 cm 1. By comparing Fig. 4(a) and (b), it can be seen that the characteristic bands of the O–H group, the carboxyl group, and the NO3 ion disappear after combustion, which shows that the O–H group, the carboxyl group, and the NO3 ion took part in the reaction and that Ni–Mn–Zn ferrite was formed simultaneously during combustion. 3.3. Magnetic studies The field dependence of the magnetization of the as-obtained spinel Ni–Mn–Zn ferrite products was measured using a vibrating sample magnetometer at 300 K with an applied field of 7 kOe rH r7 kOe. Fig. 5 illustrates the magnetic hysteresis loops of the Ni–Mn–Zn ferrite at different temperatures. All the samples showed small coercivities Hc, characteristic of soft
Kλ β cos θ
where D is the mean crystallite size, K is the shape factor, β is the half-width of the relevant diffraction peak, λ is the X-ray wavelength, and θ is the angle of diffraction. The mean crystallite sizes estimated from the (311) peak were found to be in the region of 30, 38, 47, and 59 nm, for firing temperatures of 560, 650, 750, and 850 °C, respectively. The crystallinity of the Ni–Mn–Zn ferrite was observed to increase sharply as the firing temperature was increased. This clearly shows that the particle size increased with increasing calcination temperature in a manner similar to that observed in previous studies [18–21]. The chemical and structural changes that take place during calcination can be monitored by spectroscopic analysis. Infrared spectroscopic studies were performed with the aim of ascertaining the state of the metals and oxygen in the product and to follow the dehydration process. Fig. 4 shows IR spectra of dried gels before combustion and after combustion in the wavenumber range 400–4000 cm 1. Before combustion, as shown in Fig. 4(a), characteristic peaks of citric acid appeared at 3191.40 and 1591.75 cm 1, which correspond to the stretching vibration of the O–H group and the antisymmetric stretching vibration of the
Fig. 5. The magnetic hysteresis loops of Ni–Mn–Zn ferrite nanoparticles at different temperatures: a 560 °C, b 650 °C, c 750 °C, d 850 °C.
G. Xi et al. / Journal of Magnetism and Magnetic Materials 398 (2016) 196–199
magnetic materials. As can be seen, the values of the saturation magnetization Ms were 8.471, 16.559, 19.582, and 26.883 emu/g for the four samples, corresponding to average sizes of the Ni–Mn–Zn ferrite particles of 30, 38, 47, and 59 nm, respectively. The corresponding coercivity values were 34.547, 33.937, 32.852, and 27.877 Oe, respectively. So, we observe that the Ms values increase and the Hc values decrease as the size of the Ni–Mn–Zn ferrite particles increases.
4. Conclusions We have shown that nanocrystalline Ni–Mn–Zn ferrites can be prepared by a sol–gel combustion method using spent Ni–MH and alkaline Zn–Mn batteries as raw materials. This may provide an alternative way to recycle a mixture of spent Ni–MH and alkaline Zn–Mn batteries. The magnetic properties of the ferrite could be controlled by changing the heat treatment. The presence of functional groups was identified by Fourier transform infrared spectroscopy. From TG–DSC studies, we observed that crystallization occurred at temperatures above 560 °C. The magnetic properties of the final products were found to be directly influenced by the average particle size. The Ms values increase and the Hc values decrease as the size of the Ni–Mn–Zn ferrite particles increases.
Acknowledgment This study was supported by National Science Foundation of China (No. 51174083). It also was supported by Specialized Research Fund for the Doctoral Program of Higher Education (No. 20114104110004).
References [1] C.C.B. Martha de Souza, D. Corrêa de Oliveira, J.A.S. Tenório, Characterization of used alkaline batteries powder and analysis of zinc recovery by acid leaching, J. Power Sources 103 (2001) 120–126. [2] S. Kierkegaard, Charging up the batteries: squeezing more capacity and power into the new EU Battery Directive, Comput. Law Secur. Rev. 23 (2007)
199
357–364. [3] Y. Li, G. Xi, The dissolution mechanism of cathodic active materials of spent Zn–Mn batteries in HCl, J. Hazard. Mater. 127 (2005) 244–248. [4] I. De Michelis, F. Ferella, E. Karakaya, F. Beolchini, F. Vegliò, Recovery of zinc and manganese from alkaline and zinc–carbon spent batteries, J. Power Sources 172 (2007) 975–983. [5] D.P. Mantuano, G. Dorella, R.C.A. Elias, M.B. Mansur, Analysis of a hydrometallurgical route to recover base metals from spent rechargeable batteries by liquid–liquid extraction with Cyanex 272, J. Power Sources 159 (2006) 1510–1518. [6] L. Pietrelli, B. Bellomo, D. Fontana, M.R. Montereali, Rare earths recovery from NiMH spent batteries, Hydrometallurgy 66 (2002) 135–139. [7] E. Sayilgan, T. Kukrer, G. Civelekoglu, F. Ferella, A. Akcil, F. Veglio, M. Kitis, A review of technologies for the recovery of metals from spent alkaline and zinc–carbon batteries, Hydrometallurgy 97 (2009) 158–166. [8] P. Zhang, T. Yokoyama, O. Itabash, Y. Wakui, T.M. Suzuki, K. Inoue, Recovery of metal values from spent nickel–metal hydride rechargeable batteries, J. Power Sources 77 (1999) 116–122. [9] P. Zhang, T. Yokoyamab, O. Itabashib, Y. Wakuib, T.M. Suzukib, K. Inouec, Hydrometallurgical process for recovery of metal values from spent nickel–metal hydride secondary batteries, Hydrometallurgy 50 (1998) 61–75. [10] T. Kanemaru, T. Iwasaki, S. Suda, T. Kitagawa, Preparation of ferrite from used dry cells, Google Patents, 1998. [11] G. Xi, Y. Li, Y. Liu, Study on preparation of manganese–zinc ferrites using spent Zn–Mn batteries, Mater. Lett. 58 (2004) 1164–1167. [12] J. Nan, D. Han, M. Cui, M. Yang, L. Pan, Recycling spent zinc manganese dioxide batteries through synthesizing Zn–Mn ferrite magnetic materials, J. Hazard. Mater. 133 (2006) 257–261. [13] G. Ritcey, T. Lo, M. Baird, C. Hanson, Handbook of Solvent Extraction, Wiley, New York (1983), p. 673. [14] B.D. Cullity, C.D. Graham, Introduction to Magnetic Materials, Wiley, Hoboken, 2011. [15] V. Šepelák, I. Bergmann, A. Feldhoff, P. Heitjans, F. Krumeich, D. Menzel, F. J. Litterst, S.J. Campbell, K.D. Becker, Nanocrystalline nickel ferrite, NiFe2O4: mechanosynthesis, nonequilibrium cation distribution, canted spin arrangement, and magnetic behavior, J. Phys. Chem. C 111 (2007) 5026–5033. [16] E.K. Nyutu, W.C. Conner, S.M. Auerbach, C.-H. Chen, S.L. Suib, Ultrasonic nozzle spray in situ mixing and microwave-assisted preparation of nanocrystalline spinel metal oxides: nickel ferrite and zinc aluminate, J. Phys. Chem. C 112 (2008) 1407–1414. [17] S. Maensiri, C. Masingboon, B. Boonchom, S. Seraphin, A simple route to synthesize nickel ferrite (NiFe2O4) nanoparticles using egg white, Scr. Mater. 56 (2007) 797–800. [18] M.K. Roy, B. Haldar, H.C. Verma, Characteristic length scales of nanosize zinc ferrite, Nanotechnology 17 (2006) 232–237. [19] L. Zhao, Y. Cui, H. Yang, L. Yu, W. Jin, S. Feng, The magnetic properties of Ni0.7Mn0.3GdxFe2 xO4 ferrite, Mater. Lett. 60 (2006) 104–108. [20] S. Dey, A. Roy, J. Ghose, R.N. Bhowmik, R. Ranganathan, Size dependent magnetic phase of nanocrystalline Co0.2Zn0.8Fe2O4, J. Appl. Phys. 90 (2001) 4138–4142. [21] M.K. Shobana, S. Sankar, Synthesis and characterization of Ni1 xCoxFe2O4 nanoparticles, J. Magn. Magn. Mater. 321 (2009) 3132–3137.
Contents lists available at ScienceDirect
Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm
Study of the preparation of NI–Mn–Zn ferrite using spent NI–MH and alkaline Zn–Mn batteries Guoxi Xi n, Yuebin Xi, Huidao Xu, Lu Wang Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, PR China
art ic l e i nf o
a b s t r a c t
Article history: Received 21 October 2014 Received in revised form 3 September 2015 Accepted 9 September 2015 Available online 11 September 2015
Magnetic nanoparticles of Ni–Mn–Zn ferrite have been prepared by a sol–gel method making use of spent Ni–MH and Zn–Mn batteries as source materials. Characterization by X-ray diffraction was carried out to study the particle size. The presence of functional groups was identified by Fourier transform infrared spectroscopy. From studies by thermogravimetry and differential scanning calorimetry, crystallization occurred at temperatures above 560 °C. The magnetic properties of the final products were found to be directly influenced by the average particle size of the product. The Ms values increase and the Hc values decrease as the size of the Ni–Mn–Zn ferrite particles increases. & 2015 Elsevier B.V. All rights reserved.
Keywords: Magnetic materials Sol–gel growth Thermogravimetric analysis Magnetic properties Ferrite
1. Introduction The consumption of batteries has increased in the last few decades because of their versatility, low maintenance, and reduced costs, and because of the requirements of the electronics industry [1]. On the other hand, a large quantity of spent batteries has been disposed of as waste. They have to be treated as a special residue because of the heavy metals which they contain. This presents a major environmental and health threat [2]. Waste batteries are causing serious concern owing to their toxicity, abundance, and permanence in the environment [3]. Therefore, reutilization and recycling of materials in order to minimize this waste are being considered. On a resource management level, spent batteries could be considered as secondary raw materials. Valuable metals can be recovered and put on the market for the manufacture of new batteries or of other products. The use of recycled metals instead of virgin metals in battery production or other products would have a positive environmental impact through reduced energy use and reduced pollution related to the mining of the virgin sources. Overviews of current techniques, including pyrometallurgical and hydrometallurgical processes and combinations of the two, for the recycling of spent nickel–metal hydride (Ni–MH) and Zn–Mn batteries have been presented elsewhere [1,4–9]. The large energy n
Corresponding author. Fax: þ86 373 3326336. E-mail addresses: [email protected] (G. Xi), [email protected] (H. Xu). http://dx.doi.org/10.1016/j.jmmm.2015.09.047 0304-8853/& 2015 Elsevier B.V. All rights reserved.
consumption, high cost, low efficiency, and serious secondary pollution of the traditional techniques make it desirable to find an economic and environmental friendly process to treat and recycle these spent batteries. Recently, the use of spent Zn–Mn batteries as a raw material to synthesize Zn–Mn ferrite magnetic materials has been developed because there are adequate amounts of Mn, Zn, and Fe in spent Zn–Mn batteries. Kanemaru et al. [10] cleaned material from spent batteries with water after dismantling and roasting, and then synthesized Zn–Mn ferrites using Zn, Mn, and Fe oxides prepared from this material. Xi et al. [11] presented studies of the preparation of Zn–Mn ferrites by a coprecipitation method in which spent Zn–Mn batteries were dissolved in 3 mol/L H2SO4 þ2.4% H2O2. Nan et al. [12] reported a novel process for reclaiming spent zinc–manganese dioxide batteries through synthesizing Zn–Mn ferrite magnetic materials. Ferrites exhibit ferrimagnetism due to a superexchange interaction between the electrons of the metal ions and oxide ions. Owing to the intrinsic atomic-level interaction between the oxide and metal ions, ferrites have a higher resistivity than ferromagnetic metals [13,14]. This enables ferrites to find applications at higher frequencies and makes them technologically very valuable. The most important commercial forms of these ferrites are Zn2 þ -substituted Ni and Mn ferrites, referred to as Ni–Zn and Mn– Zn ferrites, respectively. The major difference between these two types of ferrites is in their resistivity values. Mn–Zn ferrites are technologically important because of their permeability and high magnetization. However, their eddy current loss is higher at higher
G. Xi et al. / Journal of Magnetism and Magnetic Materials 398 (2016) 196–199
frequencies because of their low resistivity. These ferrites have been widely used in electronic applications such as transformers, coils, and recording heads. Ni–Zn ferrites, on the other hand, possess a high resistivity but a relatively low permeability at high frequencies. These ferrites have been extensively used as magnetic core materials in a large number of devices and electrical components such as phase shifters, circulators, isolators, inductors, and transformers. Magnetic applications, such as computer memory and pulse transformers operating at high frequencies, require a high resistivity, a high saturation magnetization, a high Néel temperature, and low magnetic losses. Although Mn–Zn and Ni– Zn ferrites have been investigated extensively, the literature on combinations of these two ferrites is inadequate, especially with respect to combinations obtained by using spent Ni–MH and alkaline Zn–Mn batteries as raw materials. In the present investigation, spent Ni–MH and alkaline Zn–Mn batteries were used as source materials to prepare Ni–Mn–Zn ferrites employing a sol–gel combustion technique. Characterization of the prepared Ni–Mn–Zn ferrites was done employing various techniques to study the particle size and to explore other parameters of interest.
2. Experimental The cylindrical spent Ni–MH and alkaline Zn–Mn batteries used in this work were kindly provided by Henan Huanyu Power Source Co. Ltd. The positive electrodes of the spent Ni–MH batteries were composed of a formed nickel substrate and an Ni(OH)2 active material; the negative electrodes consisted of an AB5-type hydrogen storage alloy powder and an iron or copper-mesh substrate. The spent alkaline Zn–Mn batteries were composed of ZnO, MnO, Mn2O3, Mn3O4, and MnO2 within an iron shell, as well as remnant Zn, after discharging of the batteries. The contents of the various substances in the two types of batteries were similar to those in commercial batteries of the same size on the market. The batteries used as raw materials to prepare Ni–Mn–Zn ferrites in this study were dissolved in 5 mol/L nitric acid solution containing 2.5 wt% hydrogen peroxide. After complete dissolution, the solution was filtered and the filtrate was analyzed by atomic absorption spectroscopy to determine the concentrations of Fe, Ni, Mn, and Zn (using a model Z-5000 atomic absorption spectrophotometer from Hitachi, Japan). In order to prepare the ferrites, suitable amounts of analytical-grade nickel nitrate, manganous nitrate, zinc nitrate, and iron nitrate were added to adjust the concentrations of Ni, Mn, Zn, and Fe. Then, an appropriate amount of citric acid was put into the solution to adjust the molar ratio of the total concentrations of metal ions and added citric acid to 1:1. During this procedure, the solution was continuously stirred using a magnetic agitator, and the temperature was controlled at 50 °C. When the citric acid was completely dissolved, ammonia solution was added dropwise to obtain a brown solution. The solution was kept at 80 °C to remove the residual nitric acid and hydrogen peroxide until the solution became a brown–red sol. The pH of the sol was maintained between 7 and 8. Then, the sol was put into a dish and dried in an oven at 100 °C for 2 h to transform it into a dried gel. The gel formed was ground and then heated at 800 °C for 3 h. A loose black powder, which consisted of nanocrystalline ferrite, was obtained as a result of combustion of the dried gel. The experimental procedure is shown in Fig. 1.
197
Fig. 1. Flowsheet for the preparation of Ni–Mn–Zn ferrite from spent batteries.
3. Results and discussion 3.1. Thermal studies Thermal-analysis measurements of the dried gel powder by thermogravimetry (TG), differential thermogravimetry (DTG), and differential scanning calorimetry (DSC) were carried out in a dynamic air atmosphere (20 mL min 1) with a nonisothermal linear regime. An STA 449C analyzer from Netzsch Instruments was used for the experiments. Samples of the dried gel powder, with masses from 10 to 15 mg, contained in Al2O3 crucibles, were heated from room temperature to about 800 °C at a heating rate of 10 °C min 1. The TG and DTG curves (Fig. 2) indicated that the weight loss occurred in two distinct steps. The first step showed a large weight loss in the temperature range from room temperature to 560 °C, which can be attributed to an oxidation–reduction reaction between the nitrate and the citric acid. The second step was observed between 590 and 800 °C and showed only a small weight loss, which can be attributed to decomposition of the remaining organic matter. It was observed that simultaneous evolution of lattice oxygen, oxidation of complexes, and formation of semiorganic carbon–metal/ metal oxide particles occurred. It is believed that the formation of metal oxides took place at this stage [15,16]. Crystallization occurred at temperatures above 560 °C [17]. No weight loss occurred in the samples at temperatures above 800 °C. From the TG/DTG curves, it can be seen that the first weight loss step finished completely at 590 °C and, in the second step, the samples were thermally stable at 800 °C.
Fig. 2. TG/DTG/DSC curves of dried gel.
198
G. Xi et al. / Journal of Magnetism and Magnetic Materials 398 (2016) 196–199
Fig. 3. XRD patterns of Ni–Mn–Zn ferrite nanoparticles at different temperatures: a 560 °C, b 650 °C, c 750 °C, d 850 °C.
The thermal events observed in the DSC curve (Fig. 2) are in concordance with those observed in the TG/DTG curves. The DSC curve clearly shows two exothermic peaks, indicating that the decomposition occurs in two stages, whereas this is not easily perceived from the DTG curves. 3.2. Structural studies X-ray diffraction (XRD) patterns of all of the samples of Ni–Mn– Zn ferrite nanoparticles that we synthesized by the sol–gel combustion technique are depicted in Fig. 3. All of the characteristic peaks of Ni–Mn–Zn ferrite nanoparticles are present in all of the diffraction patterns (a, b, c, and d, corresponding to calcination temperatures of 560, 650, 750, and 850 °C). It was found that all diffraction peaks could be indexed perfectly with a cubic spinel structure, and no peaks corresponding to impurities were detected in the XRD patterns. The mean crystallite sizes were estimated from the linewidth of the (311) XRD peak using the Scherrer equation as follows:
D=
Fig. 4. IR spectra of the dried gels before combustion (a) and after combustion (b) at 750 °C.
carboxyl group. In addition, characteristic peaks of the NO3 ion were also observed at 1403.45, 1114.44, and 846.22 cm 1. This indicates that the NO3 ion existed as a group in the structure of the citrate gels during the process of gelation. After combustion, as shown in Fig. 4(b), a characteristic peak of Ni–Mn–Zn ferrite was observed at 585.36 cm 1. By comparing Fig. 4(a) and (b), it can be seen that the characteristic bands of the O–H group, the carboxyl group, and the NO3 ion disappear after combustion, which shows that the O–H group, the carboxyl group, and the NO3 ion took part in the reaction and that Ni–Mn–Zn ferrite was formed simultaneously during combustion. 3.3. Magnetic studies The field dependence of the magnetization of the as-obtained spinel Ni–Mn–Zn ferrite products was measured using a vibrating sample magnetometer at 300 K with an applied field of 7 kOe rH r7 kOe. Fig. 5 illustrates the magnetic hysteresis loops of the Ni–Mn–Zn ferrite at different temperatures. All the samples showed small coercivities Hc, characteristic of soft
Kλ β cos θ
where D is the mean crystallite size, K is the shape factor, β is the half-width of the relevant diffraction peak, λ is the X-ray wavelength, and θ is the angle of diffraction. The mean crystallite sizes estimated from the (311) peak were found to be in the region of 30, 38, 47, and 59 nm, for firing temperatures of 560, 650, 750, and 850 °C, respectively. The crystallinity of the Ni–Mn–Zn ferrite was observed to increase sharply as the firing temperature was increased. This clearly shows that the particle size increased with increasing calcination temperature in a manner similar to that observed in previous studies [18–21]. The chemical and structural changes that take place during calcination can be monitored by spectroscopic analysis. Infrared spectroscopic studies were performed with the aim of ascertaining the state of the metals and oxygen in the product and to follow the dehydration process. Fig. 4 shows IR spectra of dried gels before combustion and after combustion in the wavenumber range 400–4000 cm 1. Before combustion, as shown in Fig. 4(a), characteristic peaks of citric acid appeared at 3191.40 and 1591.75 cm 1, which correspond to the stretching vibration of the O–H group and the antisymmetric stretching vibration of the
Fig. 5. The magnetic hysteresis loops of Ni–Mn–Zn ferrite nanoparticles at different temperatures: a 560 °C, b 650 °C, c 750 °C, d 850 °C.
G. Xi et al. / Journal of Magnetism and Magnetic Materials 398 (2016) 196–199
magnetic materials. As can be seen, the values of the saturation magnetization Ms were 8.471, 16.559, 19.582, and 26.883 emu/g for the four samples, corresponding to average sizes of the Ni–Mn–Zn ferrite particles of 30, 38, 47, and 59 nm, respectively. The corresponding coercivity values were 34.547, 33.937, 32.852, and 27.877 Oe, respectively. So, we observe that the Ms values increase and the Hc values decrease as the size of the Ni–Mn–Zn ferrite particles increases.
4. Conclusions We have shown that nanocrystalline Ni–Mn–Zn ferrites can be prepared by a sol–gel combustion method using spent Ni–MH and alkaline Zn–Mn batteries as raw materials. This may provide an alternative way to recycle a mixture of spent Ni–MH and alkaline Zn–Mn batteries. The magnetic properties of the ferrite could be controlled by changing the heat treatment. The presence of functional groups was identified by Fourier transform infrared spectroscopy. From TG–DSC studies, we observed that crystallization occurred at temperatures above 560 °C. The magnetic properties of the final products were found to be directly influenced by the average particle size. The Ms values increase and the Hc values decrease as the size of the Ni–Mn–Zn ferrite particles increases.
Acknowledgment This study was supported by National Science Foundation of China (No. 51174083). It also was supported by Specialized Research Fund for the Doctoral Program of Higher Education (No. 20114104110004).
References [1] C.C.B. Martha de Souza, D. Corrêa de Oliveira, J.A.S. Tenório, Characterization of used alkaline batteries powder and analysis of zinc recovery by acid leaching, J. Power Sources 103 (2001) 120–126. [2] S. Kierkegaard, Charging up the batteries: squeezing more capacity and power into the new EU Battery Directive, Comput. Law Secur. Rev. 23 (2007)
199
357–364. [3] Y. Li, G. Xi, The dissolution mechanism of cathodic active materials of spent Zn–Mn batteries in HCl, J. Hazard. Mater. 127 (2005) 244–248. [4] I. De Michelis, F. Ferella, E. Karakaya, F. Beolchini, F. Vegliò, Recovery of zinc and manganese from alkaline and zinc–carbon spent batteries, J. Power Sources 172 (2007) 975–983. [5] D.P. Mantuano, G. Dorella, R.C.A. Elias, M.B. Mansur, Analysis of a hydrometallurgical route to recover base metals from spent rechargeable batteries by liquid–liquid extraction with Cyanex 272, J. Power Sources 159 (2006) 1510–1518. [6] L. Pietrelli, B. Bellomo, D. Fontana, M.R. Montereali, Rare earths recovery from NiMH spent batteries, Hydrometallurgy 66 (2002) 135–139. [7] E. Sayilgan, T. Kukrer, G. Civelekoglu, F. Ferella, A. Akcil, F. Veglio, M. Kitis, A review of technologies for the recovery of metals from spent alkaline and zinc–carbon batteries, Hydrometallurgy 97 (2009) 158–166. [8] P. Zhang, T. Yokoyama, O. Itabash, Y. Wakui, T.M. Suzuki, K. Inoue, Recovery of metal values from spent nickel–metal hydride rechargeable batteries, J. Power Sources 77 (1999) 116–122. [9] P. Zhang, T. Yokoyamab, O. Itabashib, Y. Wakuib, T.M. Suzukib, K. Inouec, Hydrometallurgical process for recovery of metal values from spent nickel–metal hydride secondary batteries, Hydrometallurgy 50 (1998) 61–75. [10] T. Kanemaru, T. Iwasaki, S. Suda, T. Kitagawa, Preparation of ferrite from used dry cells, Google Patents, 1998. [11] G. Xi, Y. Li, Y. Liu, Study on preparation of manganese–zinc ferrites using spent Zn–Mn batteries, Mater. Lett. 58 (2004) 1164–1167. [12] J. Nan, D. Han, M. Cui, M. Yang, L. Pan, Recycling spent zinc manganese dioxide batteries through synthesizing Zn–Mn ferrite magnetic materials, J. Hazard. Mater. 133 (2006) 257–261. [13] G. Ritcey, T. Lo, M. Baird, C. Hanson, Handbook of Solvent Extraction, Wiley, New York (1983), p. 673. [14] B.D. Cullity, C.D. Graham, Introduction to Magnetic Materials, Wiley, Hoboken, 2011. [15] V. Šepelák, I. Bergmann, A. Feldhoff, P. Heitjans, F. Krumeich, D. Menzel, F. J. Litterst, S.J. Campbell, K.D. Becker, Nanocrystalline nickel ferrite, NiFe2O4: mechanosynthesis, nonequilibrium cation distribution, canted spin arrangement, and magnetic behavior, J. Phys. Chem. C 111 (2007) 5026–5033. [16] E.K. Nyutu, W.C. Conner, S.M. Auerbach, C.-H. Chen, S.L. Suib, Ultrasonic nozzle spray in situ mixing and microwave-assisted preparation of nanocrystalline spinel metal oxides: nickel ferrite and zinc aluminate, J. Phys. Chem. C 112 (2008) 1407–1414. [17] S. Maensiri, C. Masingboon, B. Boonchom, S. Seraphin, A simple route to synthesize nickel ferrite (NiFe2O4) nanoparticles using egg white, Scr. Mater. 56 (2007) 797–800. [18] M.K. Roy, B. Haldar, H.C. Verma, Characteristic length scales of nanosize zinc ferrite, Nanotechnology 17 (2006) 232–237. [19] L. Zhao, Y. Cui, H. Yang, L. Yu, W. Jin, S. Feng, The magnetic properties of Ni0.7Mn0.3GdxFe2 xO4 ferrite, Mater. Lett. 60 (2006) 104–108. [20] S. Dey, A. Roy, J. Ghose, R.N. Bhowmik, R. Ranganathan, Size dependent magnetic phase of nanocrystalline Co0.2Zn0.8Fe2O4, J. Appl. Phys. 90 (2001) 4138–4142. [21] M.K. Shobana, S. Sankar, Synthesis and characterization of Ni1 xCoxFe2O4 nanoparticles, J. Magn. Magn. Mater. 321 (2009) 3132–3137.