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УДК 661.183.123
CHARACTERIZATION OF ION-EXCHANGE RESINS UNDER THERMAL LOADING
LUCIE ZARYBNICKA, Institute of Chemistry and Technology of Macromolecular Materials, Faculty of Chemical Technology, University of Pardubice (Studentska 573,532 1 0 Pardubice, Czech Republic) ELISKA STRANSKA, MemBrain s.r.o., (Pod Vinici 87,471 27 Strazpod Ralskem, Czech Republic) JANA MACHOTOVA, Institute of Chemistry and Technology of Macromolecular Materials, Faculty of Chemical Technology, University of Pardubice (Studentska 573,532 1 0 Pardubice, Czech Republic) EVA CERNOSKOVA, Joint Laboratory of Solid State Chemistry of the Institute of Macromolecular Chemistry of AS CR and University of Pardubice, Faculty of Chemical Technology, University of Pardubice (Studentska 573,532 1 0 Pardubice, Czech Republic) KLARA MELANOVA, Institute of Macromolecular Chemistry AS CR (Heyrovskehonam 2,162 06 Praha)
E-mail: zarybnicka.l@email.cz ABSTRACT. The present work deals with the influence of temperature on the ion-exchange capacity of selected ion-exchangers. Technological operations running at elevated temperatures (drying, homogenization) can influence the lead or ion-exchange capability of ion-exchangers, which may affect values of the ion-exchange capacity. Several types of anion and cation-exchangers have been chosen for its application in practice. Samples of selected ion-exchangers were subjected to thermal stress in the temperature range of 75-160°C at different times of exposure. It was shown that the optimum processing temperature for anion and cation-exchange resins is in the range of 105-115°C.
Keywords: ion-exchange resins, ion-exchange capacity, thermal loading, anion-exchange resin, cation-exchange resin.
1. INTRODUCTION
Porous types of ion-exchange resins are used in membrane processes such as ultrafiltration, nanofiltration or microfiltration. Gelatinous types of ion-exchange resins are used for processes such as reverse osmosis, electro membranes processes [1].
Anion-exchange resin is a high molecular substance (e.g. on the basis of copolymer of styrene-divinyl benzene (S-DVB) or polyacrylate) whose molecule contains functional groups capable of dissociation in an aqueous medium. Ion-exchange resins can be divided into anion resins (anion-exchange resin) and cation resins (cation-exchange resin) and am pholytic ion exchange-resins, which are able to exchange both anions and cations [2, 3].
Anion-exchange resins themselves can be strongly basic, if the functional group is a quaternary ammonium group on the surface of copolymer. There are two types of strongly basic anion exchangers - type I which has a nitrogen atom bound to three methyl groups. Type II which has a nitrogen atom bound to different groups (two methyl groups and one hydroxyethyl group) [4-8]. The other group is represented by weakly basic anion-exchange resin which contain amino groups on their surface. Cation-exchange resin can be divided into strongly and weakly acidic types containing sulphonic and carboxyl groups, respectively [9-10].
The main characteristics of ion-exchange resins include ion-exchange capacity, pore size, nature of the counterions, ion charge, polarizability, and swellability. Ion-exchange resins can be used in many applications, e.g. deionisation, demineralisation or decarbonisation of water, selective removal of heavy metals [2, 11].
During the preparation of anion-exchange membrane, ion-exchange resins pass through a number of technological operations during which their resins are thermally loaded. For example, temperatures about 110°C are used
for washing and drying, while homogenization of ion-exchange resins occurs around 140C. Operations taking place at elevated temperatures can influence the conductivity or the ion-exchange capability, thereby affecting the value of ion-exchange capacity and functionality of the ion-exchange resin.
Degradation by thermal loading in the case of cation-exchange resins with functional sulphonic groupsis as follows: first, sulphonic acid is dehydrated and then decomposed into sulfur dioxide [12, 13].The thermal decomposition of anion-exchange resins with matrix of S-DVB with functional quaternary ammonium groups is shown in Figure 1. For OH- form type I the thermal de-compositionoc cured at 60°C, for Cl- form the type I, the degradation was determined at 80°C [14,15].
Figure 1. Scheme of thermal decomposition of anion-exchange resin
In this paper, ion-exchange resins were tested from the point of their thermal stability. As the ion-exchange resins (cation and anion) are frequently used as components of ion-exchange membranes that are subjected to
Table 1
Characteristics of selected commercially available ion-exchange resins
Name Type Matrix Functional group Ionic form Type
Amberlite IRC 747 Strongly acidic S-DVB -CH2-NH-CH2-PO3Na2 H+ Macroporous
Amberlite IRC 748 Strongly acidic S-DVB -CH2N(CH2COOH)2 H+ Macroporous
Purolite A420S Strongly basic S-DVB Trimethyl amonium Cl- Gel
Amberjet 4200 Cl Strongly basic S-DVB Trimethyl amonium Cl- Gel
Amberlite IRA 478 Cl Strongly basic Acrylic Type i with trimethyl amonium Cl- Gel
Amberlite IRA 900 Cl Strongly basic S-DVB Trimethyl amonium Cl- Macroporous
thermal load during the processes of washing and drying, their thermal stability affecting the ion-exchange capacity plays the key role in their applicability.
2. EXPERIMENTAL
2.1. Materials
The tested samples of ion-exchange resins were tested in the H+ cycle and Cl- cycle in a wet and dried state. Two types of cation-exchange resins and four types of anion-exchange resins were chosen, they are shown in Table 1, namely the macroporous and gel types [16].
From the viewpoint of the mechanical resistance, the ion-exchange resins of the gel type exhibit lower resistance than the macroporous ion-exchange resins which have a regular structure. Conversely, these ion-exchange resins have a smaller volumetric capacity. Before testing the ion-exchange capacity (IEC), the ion-exchange resins were subjected to conditioning.
Samples were subjected to thermal loading in the temperature range of 75-160C at different regimes, namely at 105C for 1 hour, at 140°C for 1 and 4 hours, at 160°C for 4 hours. Overview of the tested ion-exchange resins is shown in Figure 2.
For samples of anion-exchange resins and cation-exchange resins, the ion-exchange capacity was determined
as an indicator of the functionality of ion-exchange resins before and after thermal loading. Futher, the residual moisture content, the particle size distribution and the swelling extent were determined. Also, samples were characterized in terms of thermal behaviour using a ther-mogravimetric analysis (TGA) and differential scanning calorimetry (DSC).
2.2. Used equipment
• laboratory thermo-balances KERN MRS 120-3 Moisture Analyser for measuring of the residual moisture;
• dispersion unit Hydro 2000MU for determining particle size distribution in a wetstate (Malvern Instrument, MasterSizer 2000);
• Titroprocessor 682 with 665 Dosimat for determining the exchange capacity;
• electron microscope QUANTA FEG 450;
• differential scanning calorimeter Mettler DSC 13E, the measurement was carried out in the temperature range of 25-400C and with a heating rate of 5°C/min;
• thermogravimetry was performed on a device assembled from a computer, oven and Sartorius BP210E S balance. Measurements were performed in quartz ampoules in the temperature range 25-950C at a heating rate of 5°C/min.
2.3. Preparation of ion-exchange resins
Samples of commercially available ion-exchange resins were first kept in demineralised water to swell for 8 hours. Samples were conditioned, i.e. 5 g of cation-exchange resin material and 10 g of anion-exchange resin material. Samples were grouted with 1 M NaOH solution and left on a shaker for 8 hours at room temperature. After that the samples were rinsed with demineralised water and added into 1 M HCl solution for 12 hours. After being infused in to 1 M HCl solution, the samples were thoroughly rinsed. A half of each ion-exchange resin sample was then dried at 75°C.
The ion-exchange capacity (before and after heat loading) was determined particle-size distribution (before heat loading) and swelling (before and after heat loading) were determined. Electron microscope images (before and after heat loading) were used for comparison. The thermal behaviour of ion-exchange resins was characterized using thermogravimetry (TGA) and differential scanning calorimetry (DSC).
2.4. Determination of ion-exchange capacity
After conditioning in H+ cycles, the ion-exchange capacity of cation-exchange resins was investigated out in the following manner: 0,5 g of the cation-exchange resin
Figure 2. Overview of the tested ion-exchange resins
sample was grouted with 50 mL of 0.1 M NaOH, then the sample was left on a shaker for 1 hour at room temperature. Thereafter, for the actual determination, 10 mL of the solution was pipetted and diluted to 30 mL with demineralised water. Subsequently, a magnetic stirrer and a glass electrode were inserted into the solution, being continuously stirred, the sample was titrated with 0,1 M HCl and the equivalence point was determined using a titroprocessor. The ion-exchange capacity of the cation-exchange resins per gram of dry matter was calculated from the decrease of sodium hydroxide using the relation:
f \
IEC„
"HOI
V1
L)
NaOH
VM
mc. resin
where:
CNaOH — concentration of the NaOH solution added (g/mol);
CHCl — concentration of the HCl titrant (g/mol); VJNaOH — amount of the NaOH solution taken
for titration (10 mL);
V
NaOH
— amount of 0,1 M NaOH added (50 mL);
mc resin — weight of dried cation resin (g).
After conditioning in Cl- cycles, the ion-exchange capacity of anion-exchange resins was carried out in the following manner: 1 g of the anion resin sample was grouted with 50 mL of 4% NaNO3, then the sample was left on a shaker for 1 hour at room temperature. Thereafter, for the actual determination, 10 mL of solution was pipetted into a 50 mL beaker and diluted to 30 mL with demineralised water. Subsequently, 5 drops of the indicator K2CrO4 were added to the solution. The prepared sample is titrated with 0.1 M solution of AgNO3 until the colour changed from yellow to orange by adding one superfluous drop of silver nitrate. The ion-exchange capacity of the anion-exchange resins per gram of dry matter was calculated from the decrease of sodium hydroxide using the relation:
r v \
CAgN03 ' VAgN03
IEC.
V1
v M
2.6. Determination of particle-size distribution
For the initial samples of ion-exchange resins, the particle size distribution was determined in a wet state using the dispenser Hydro 2000MU.
2.7. Thermogravimetry
Thermogravimetry was performed on the device consisting of the computer, oven and Sartorius balance BP210E S. It was measured in a quartz ampoule in the temperature range of 25-950°C at a heating rate of 5°C/min. The samples were measured before thermal loading.
2.8. Differential scanning calorimetry
The commercially supplied samples of ion-exchange resins were subjected to differential scanning calorimet-ry where the samples were measured in the atmosphere under aerobic conditions, at a heating rate of 5°C/min in the temperature range 35-220°C. For comparison, the samples were measured before and after thermal loading.
3. RESULTS AND DISCUSSION
3.1 Determination of ion-exchange capacity
To evaluate the functionality of selected cation resins, the ion-exchange capacity was chosen as an evaluative property. The ion-exchange capacity refers to a number of ions that the system is able to bind [17]. The ion exchange capacity was also determined for the initial samples without thermal loading. The results are shown in Table 2. Also, the ion-exchange capacity was determined for ion-exchange resins in the H+ cycle and Cl- cycle after thermal loading. The results are shown in Table 3 and Table 4.
Table 2
The ion-exchange capacity (IEC) of the tested ionexchange resins
m„
Initial sample IEC given by supplier (eq/l) [16] IEC determined at 75°C (eg/l)
Amberlite IRC 747 > 1,75 1,61
Amberlite IRC 748 > 1,35 1,58
Purolite A420S > 0,8 1,05
Amberjet 4200 Cl 1,3 0,96
Amberlite IRA 478 Cl > 1,15 1,09
Amberlite IRA 900 Cl > 1,0 1,11
where:
VAgNO3
(g/mol); C
AgNO3
(g/mol); V1
NaNO3
(10 mL);
V m
NaNO3
— concentration of the AgNO3 solution added
— concentration of the HCl titrant AgNO3 —amount of the solution taken for titration
— amount of 0.1 M NaNO3 added (50 mL);
— weight of dried anion resin (g).
2.5. Determination of swelling
The determination of swelling was carried out as follows: samples of the ion-exchange resins were left for 12 hours to swell in demineralised water, and then the amount of absorbed water was weighed. The entire volume of the measuring cylinder was then transferred to a filter paper and dried in an oven to a constant weight (1 hour at 75°C, then at 105°C for 4 hours).
The results show that the IEC values decrease for the cation-exchange resins in the H+ cycle with increasing thermal load, which is caused by degradation of the functional groups -CH2-NH-CH2-PO3Na2 and -CH2N(CH2COOH)2 in the structure of the cation-exchange resin. As expected, IEC values for anion-exchange resins in the Cl- cycle decrease with increasing heat load too, according to the expected Hoffman mechanism of degradation induced by thermal load [18]. The results of IEC values for Amberlite IRC 747 and Amberlite 748 indicate that thermal stress at 140°C for 1 hour occurs probably to the accessing all functional groups consisting crosslinked copolymer based S-DVB. This effect was reflected by increasing the IEC values. For anion-exchange resins, this effect is not so obvious. Conservation of IEC for cation-exchange resins after heat loading 160°C for 4 hours was in the range 50-60%. Conservation of IEC
Table 3
Ion-exchange capacity for wet and dried state of the tested cation-exchange resins
Cation-exchange resin in H+ cycle IEC (eq/l) Conservation of IEC (%)
75°C 105°C 140°C/1 hour 140°C/4 hours 160°C/4 hours
Wet samples
Amberlite IRC 747 — 2,56 3,20 1,99 1,93 75,39
Amberlite IRC 748 — 1,58 1,68 1,77 0,87 55,06
Dried samples
Amberlite IRC 747 1,61 1,56 1,94 1,81 1,50 93,49
Amberlite IRC 748 1,58 1,65 1,71 1,55 0,76 48,89
Table 4
Ion-exchange capacity for wet and dried state of the tested anion-exchange resins
Anion-exchange resin in Cl- cycle IEC (eq/l) Conservation of IEC (%)
75°C 105°C 140°C/1 hour 140°C/4 hours 160°C/4 hours
Wet samples
Purolite A420S — 1,12 1,12 1,05 1,11 99,56
Amberjet 4200 Cl — 0,81 0,81 0,77 0,72 89,13
Amberlite IRA 478 Cl — 1,17 1,17 1,14 1,16 99,34
Amberlite IRA 900 Cl — 1,16 1,16 1,09 1,03 88,35
Dried samples
Purolite A420S 1,11 1,21 1,11 1,06 1,09 96,09
Amberjet 4200 Cl 0,83 0,84 0,77 0,73 0,79 95,11
Amberlite IRA 478 Cl 1,15 1,32 1,17 1,19 1,13 98,58
Amberlite IRA 900 Cl 1,17 1,33 1,24 1,25 1,11 94,98
for anion-exchange resins after heat loading 160°C for 4 hours was in the range 90-99%.
3.2. Determination of swelling
Determination of swelling is of great importance in terms of applicability of the ion-exchange resin. With a higher swelling value we can also expect higher conductivity values, which is associated with higher levels of affinity to ions [2]. The determination of swelling was carried out both for samples thermally unloaded and for samples after thermal load at 160°C for 4 hours. There is a theoretical assumption that there should be a decrease in the swelling after thermal load due to the reduced number of functional groups that have higher affinity to water molecules compared with the molecular structure of DVB or acrylic matrix [17].
Table 5
Results of the determination of swelling
Table 5 shows that the best conversation of the swelling function can be seen with the anion resin Amberlite
IRA 478 Cl and Amberlite IRA 900 Cl that exhibit 98% of conversation of swelling after thermal load at 160°C for 4 hours. Conversely, the lowest conversation of swelling ability can be seen in the case of the cation-exchange resin Amberlite IRC 747 which exhibits nearly 80% of conversation of swelling after thermal load.The results of the conservation swelling function for anion-exchange resin indicate the same trend as the results of conservation of IEC. Conversely, for cation-exchange resin the results differ.
3.3. Determination the particle-size distribution
The results from Table 6 for each commercially available ion-exchange resin allow us to state that the area capable of the ion-exchange is similar. At the same time, the results of the determination of particle size distribution are in accordance with the values declared by the manufacturers.
Table 6
Results of the determination of particle size distribution
Sample of ionexchange resin Range of the particle size (^m) Range of the particle sizes declared by the manufacturer (^m)
d (0,1)* (Mm) d (0,9)* (Mm)
Amberlite IRC 747 530,78 816,28 300-1200
Amberlite IRC 748 674,12 942,11 300-1200
Purolite A420S 624,22 920,41 300-1200
Amberjet 4200 Cl 737,22 1000,24 300-1200
Amberlite IRA Cl 719,91 978,27 300-1200
Amberlite IRA 900 Cl 685,89 969,66 300-1200
^Representation by means of the percentile.
Sample of ionexchange resin Swellinc (ml/g) Conservation of the swelling function (%)
Without thermal loading After thermal loading (160°C/ 4 hours)
Amberlite IRC 747 2,41 1,92 79,66
Amberlite IRC 748 2,85 2,67 93,68
Purolite A420S 2,49 2,35 94,37
Amberjet 4200 Cl 3,20 3,07 95,94
Amberlite IRA 478 Cl 2,78 2,73 98,20
Amberlite IRA 900 Cl 2,82 2,77 98,23
3.4. Examining particles using a scanning electron microscope
To compare the ion-exchange resins before and after thermal load (160°C/4 hours), images were made using an electron microscope and they are shown in Table 7. Table 7
Scanning electron microscope images for ion-exchange resins before and after thermal loading at 160°C for 4 hours
On the surface of ion-exchange resins after thermal load we can observe slight deformations that, as assumed, are related to the degradation of functional groups in the polymeric structure of the ion-exchange resin leading to decrease swelling in water.
3.5. Examining degradation curves by thermogravi-metry
To characterize the ion-exchange resins in terms of thermal loading, a thermogravimetric analysis was performed. Record of TG analysis for samples of cation and anion-exchange resins are shown in Figure 3 and Figure 4.
It is evident that degradation of cation and anion-ex-change resins proceeds in several steps. At temperatures below 200 °C, there is a first weight loss associated with the degradation of functional groups in the polymeric structure. It can be observed from the results given in Table 8 that the cation-exchange resin Amberlite IRC 747 exhibits the highest onset of degradation (420°C). In the case of the samples of anion-exchange resins, the onset of degradation can be observed at about 270°C.
Figure 3. Record of thermogravimetric analysis for samples of cation-exchange resins without thermal loading
Figure 4 . Record of thermogravimetric analysis for samples of anion-exchange resins without thermal loading
Table 8
Results of thermogravimetric analysis for the tested ionexchange resins
Sample Onset of degradation (°C) Temperature at 50% of weight loss (°C)
Amberlite IRC 747 420 535,5
Amberlite IRC 748 280 449,3
Purolite A420S 270 435,6
Amberjet 4200 Cl 270 438,8
Amberlite IRA 478 Cl 270 432,4
Amberlite IRA 900 Cl 280 433,8
3.6. Differential scanning calorimetry
The results of differential scanning calorimetry show that thermal loading induces an endothermic decomposition of functional groups in the tested cation and an-ion-exchange resins, which can be observed from the measuring results which they are shown in Table 9. The results of conservation of functional groups are shown in Table 9.
In the Table 10 compares the results conservation of functional anion and cation-exchange resins after thermal loading 160°C/4 hours using conservation values of ion-exchange capacity, conservation of the swelling fiction and conservation enthalphy of functional groups.
As the most accurate indicator of evaluating the functionality used measurement of the ion-exchange capacity and DSC.
Table 9
DSC Results from the point of enthalpy changes for samples of ion-exchange resins without and after thermal loading
Sample Enthalpy (J/g) Conservation enthalpy of functional groups (%)
Without thermal loading 140°C/1 hour 140°C/4 hours 160°C/4 hours
Amberlite IRC 747 439,0 278,0 241,0 231,0 52,6
Amberlite IRC 748 194,0 191,0 140,0 135,0 69,5
Purolite A420S 121,0 115,7 110,0 110,6 91,4
Amberjet 4200 Cl 85,4 71,2 77,4 76,0 88,9
Amberlite IRA 478 Cl 97,2 89,2 88,3 87,4 89,9
Amberlite IRA 900 Cl 159,0 129,0 116,0 117,2 73,7
Table 10
Comparison of the results for the IEC, swelling and DSC — conservation of properties after thermal loading 160°C/ 4 hours
Sample Conservation of IEC* (%) Conservation of the swelling function* (%) Conservation enthalpy of functional groups (%)
Amberlite IRC 747 76,9 79,6 48,0
Amberlite IRC 748 50,3 93,7 69,5
Purolite A420S 97,8 86,4 91,4
Amberjet 4200 Cl 92,1 95,9 88,9
Amberlite IRA 478 Cl 98,9 98,2 88,9
Amberlite IRA 900 Cl 91,6 98,2 73,7
*Averages of IEC for dry and wet samples.
4. CONCLUSION
Authors can conclude that the selected commercially available types of cation-exchange resins with functional groups -CH2-NH-CH2-PO3Na2 and -CH2N(CH2COOH)2lose their ion-exchange ability as a result of thermal loading. This fact can be attributed to the degradation of functional groups. It was shown that the ion-exchange capacity of cation-exchange resins was maintained up to temperatures of about 105°C. When compared to cation-exchange resins, anion-exchange resins after thermal loading at 160°C for 4 hours exhibit a higher conversation of the ion-exchange capacity. The optimum processing temperature for anion-exchange resins is in the range of 105-115°C. On the surface of ion-exchange resins after thermal load we can observe slight deformations that are probably related to the degradation of functional groups in the polymeric structure of the ion-exchange resin leading to decrease in water swelling.
ACKNOWLEDGMENT
The authors wish to give thanks for the support to the project No. CZ.1.05/2.100/03.0084 entitled «Membrane Innovation Center».
REFERENCES
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2. Zagorodni AA. Ion-exchange Materials: Properties and Applications. Elsevier, UK 2006.
3. Strathmann H. Electrodialysis and related processes, in: R.D. Nobe, S.A. Stern (Eds.), Membrane Separation Technology-Principles and Applications, Elsevier Science B.V., 1995, pp. 214-278.
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monium groups. Polymers for Advanced Technologies, 2004, no. 15, pp. 61-64.
6. Wang J., Zhang S. Synthesis and characterization of cross-linked poly(arylene ether ketone) containing pendant quaternary ammonium groups for anionexchange membranes. J. Membr. Sci., 2012, vol. 415-416, pp. 205-212.
7. Qian W., Shang Y, Fang M, Wang S, Xie X., Wang J. Sulfonated polybenzimidazole/zirconium phosphate composite membranes for high temperature applications. International Journal of Hydrogen Energy, 2012, vol. 37, pp. 12919-12924.
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11. Zeng Q.H., Liu Q.L., Broadwell I., Zhu AM., Xiong Y, Tu X.P. Anion exchange membranes based on quaternized-polystyreneblock-poly(ethylene-ran butylene)-block-polystyre-ne for direct methanol alkaline fuel cells. J MembrSci, 2010, vol. 349, pp. 237-243.
12. Singare P.U., Lokhande R.S., Madyal R.S. Thermal Degradation Studies of Some Strongly Acidic Cation Exchange Resins. Open Journal of Physical Chemistry, 2011, no. (1) 2, pp. 45-54.
13. Zhang J., Qion H. Thermal behaviour of typical weak basic ion exchange resin. Journal of Thermal Analysis and Ca-lorimetry, 2014, vol. 115, pp. 875-880.
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16. Datasheets from suppliers. Available at: www.purolite. com, www.dow.com. (accessed March 11, 2015).
17. Dye A., Hudson M.J., Williams PA. Progress in Ion-exchange: Advances and Applications. Elsevier, UK 1997.
18. Chempath S, Einsla B.R., Pratt L.R., Macomber C.S. Mechanism of Tetraalkylammonium Headgroup Degradation in Alkaline Fuel Cell Membranes. J. Phys. Chem. C., 2008, (8)112, 3179-3182.
ХАРАКТЕРИСТИКИ ИОННООБМЕННЫХ СМОЛ ПРИ ТЕПЛОВОМ НАГРУЖЕНИИ
LUCIE ZARYBNICKA, Институт химии и технологии высокомолекулярных материалов, химико-технологического факультета, Университет Пардубице (Чехия, 532 10 Пардубице)
ELISKA STRANSKA, MemBrain (Чехия, г. Страж-под-Ралскем, 47127, Под Виницы, д 87)
JANA MACHOTOVA, Институт химии и технологии высокомолекулярных материалов, химико-технологического факультета, Университет Пардубице (Чехия, 532 10 Пардубице)
CERNOSKOVA, Совместная лаборатория химии твердого тела Института химии высокомолекулярных соединений АН ЧР и Университет Пардубице, химико-технологического факультета, Университет Пардубице (Чехия, 532 10 Пардубице)
KLARA MELANOVA, Институт химии высокомолекулярных соединений AS CR (Чехия, 162 06 Прага)
E-mail: zarybnicka.l@email.cz
АННОТАЦИЯ
Настоящая работа посвящена влиянию температуры на ионообменную емкость выбранных ионообменников. Технологические операции, проходящие при повышенных температурах, (сушка, гомогенизация) могут влиять на ионообменную способность ионообменников и на значения ионообменной емкости. Несколько типов анионитов и катионитов были выбраны для исследования его применения на практике. Образцы выбранных ионообменников, были подвергнуты термической нагрузке в интервале температур 75-160°С в зависимости от времени экспозиции. Было показано, что оптимальная температура обработки для анионных и катионообменных смол находится в интервале 105-115°С.
Ключевые слова: ионообменные смолы, ионообменная емкость, тепловая нагрузка, анионообменная смола, катионооб-менная смола.
СПИСОК ЛИТЕРАТУРЫ
1. Vogel C.; Meier-Haack J. Preparation of ion-exchange materials and membranes // Desalination, 2014, vol. 342, pp. 156-174.
2. Zagorodni A.A. Ion-exchange Materials: Properties and Applications. Elsevier, UK 2006.
3. Strathmann H. Electrodialysis and related processes, in: R.D. Nobe, S.A. Stern (Eds.), Membrane Separation Technology-Principles and Applications. Elsevier Science B.V., 1995, pp. 214-278.
4. Shen K., Pang J., Feng S. Synthesis and properties of a novel poly(aryl ether ketone)s with quaternary ammonium pendant groups for anion exchange membranes.// J. Membr. Sci., 2013, vol. 440, pp. 20-28.
5. Kang J., Li W., Lin Y., Xiao X., Fang S. Synthesis and ionic conductivity of a polysiloxane containing quaternary ammonium groups. // Polymers for Advanced Technologies, 2004, no. 15, pp. 61-64.
6. Wang J., Zhang S. Synthesis and characterization of cross-linked poly(arylene ether ketone) containing pendant quaternary ammonium groups for anionexchange membranes. // J. Membr. Sci., 2012, vol. 415-416, pp. 205-212.
7. Qian W., Shang Y., Fang M., Wang S., Xie X., Wang J. Sulfonated polybenzimidazole/zirconium phosphate composite membranes for high temperature applications. // International Journal of Hydrogen Energy, 2012, vol. 37, pp. 12919-12924.
8. Neaugu V., Avram E., Lisa G. N-methylimidazolium functionalized strongly basic anion exchanger: Synthesis, chemical and thermal stability. // Reactive and Functional Polymers, 2010, vol. 70, pp. 88-97.
9. Smid J. MeniceiontU, jejichvlastnosti apouziti, SNTL, Praha 1954. (На чешском яз.).
10. Inamuddin L.M. Ion-exchange technology I: theory and materials. 1 ed. London: Springer; 2012.
11. Zeng Q.H., Liu Q.L., Broadwell I., Zhu A.M., Xiong Y., Tu X.P. Anion exchange membranes based on quaterni-zedpolystyreneblock-poly(ethylene-ran butylene)-block-polystyrene for direct methanol alkaline fuel cells. // J MembrSci, 2010, vol. 349, pp. 237-243.
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