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Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions
Journal of Molecular Liquids xxx (xxxx) xxx
Contents lists available at ScienceDirect
Journal of Molecular Liquids journal homepage: www.elsevier.com/locate/molliq
Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions Ivo Safarik a, b, *, Jitka Prochazkova a, Eva Baldikova a, Kristyna Pospiskova b a b
Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05, Ceske Budejovice, Czech Republic Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71, Olomouc, Czech Republic
a r t i c l e i n f o
a b s t r a c t
Article history: Received 24 July 2019 Received in revised form 5 October 2019 Accepted 11 October 2019 Available online xxx
Textile modified with methyltrioctylammonium thiosalicylate ionic liquid was successfully used for Magnetic textile solid phase extraction of copper ions. After extraction process the modified textile changed color to gray and black. The textile photos were employed for image analysis using HSB and RGB color spaces. It was shown that values of saturation (S) and red channel values (R) were proportional to the copper ions concentration in the analyzed samples; the value of saturation was almost linearly proportional to copper ions concentration in the range 103 e 105 mol L1. This inexpensive, simple and elution free assay has a potential to be a useful alternative to existing semiquantitative determination procedures for copper ions analysis. © 2019 Elsevier B.V. All rights reserved.
Keywords: Methyltrioctylammonium thiosalicylate Ionic liquid Magnetic textile solid phase extraction Copper ions
1. Introduction Ionic liquids (ILs) represent a relatively new class of compounds exhibiting very interesting properties. They are usually defined as compounds composed from organic cation and small organic or inorganic anion, which are liquid below 100 C. ILs melting at room temperature are called room-temperature ionic liquids (RTILs). Both native ILs and many ILs derivatives have been already used for many applications [1]. ILs immobilized on the surface or within the pores of a solid support can be efficiently used in analytical chemistry for preconcentration and analysis of target analytes from food, environmental and biological samples using solid-phase extraction, solidphase microextraction, hollow-fiber solid-phase microextraction, stir-bar sorptive extraction and biosensors [1]. Magnetic textile solid phase extraction (MTSPE) is a new preconcentration method, based on the use of magnetically modified textile [2]. A piece (usually a square) of textile is used as a carrier for the immobilization of a specific affinity, hydrophobic or ion exchange ligand. Magnetic iron-based wire (usually a staple) is inserted in the textile material using an office stapler to prepare magnetically responsive adsorbent. Laboratory magnetic stirrers enable to move magnetically modified pieces of textile adsorbent.
* Corresponding author. Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05, Ceske Budejovice, Czech Republic. E-mail address: [email protected] (I. Safarik).
At the end of the extraction process, the piece of textile is easily and rapidly separated magnetically. The adsorbed analyte can be eluted from the textile and subsequently analyzed [2,3], or the textile bound dyed compounds can be analyzed using image analysis procedure [4]. Surface modified textile can be efficiently used for the separation and removal of heavy metals. Typical examples comprehend ion-exchanger grafted textiles for removal of Cu(II) and Cd(II) ions [5], double network hydrogel based on waste cotton fabrics and polyacrylamide for Cd(II), Cu(II), Pb(II) and Zn(II) removal [6] or cellulose-based waste textile modified by carboxymethylation and crosslinking reactions for Cd(II) removal [7]. In this work appropriate textile material was modified with methyltrioctylammonium thiosalicylate ionic liquid to prepare a textilebased adsorbent for the preconcentration of copper ions from water solutions and subsequent image analysis. 2. Materials and methods 2.1. Materials and software Methyltrioctylammonium thiosalicylate (TOMATS; cat. No. 08354) was purchased from Sigma-Aldrich while copper sulfate heptahydrate was from Lachema, Brno, Czech Republic. Nonwoven textile (Bastelfiltz, 10 30 cm, 150 g m2, white 100% acrylic felt) was from Max Bringmann KG-folia (Germany), while fine woven cotton textile (100 g m2) was obtained locally. An office stapler
https://doi.org/10.1016/j.molliq.2019.111910 0167-7322/© 2019 Elsevier B.V. All rights reserved.
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
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I. Safarik et al. / Journal of Molecular Liquids xxx (xxxx) xxx
2.2. Preparation of IL loaded textile TOMATS was dissolved in acetone to obtain 5% (w/w) solution. Textile squares (2 2 cm) were immersed in IL solution (the ratio 1 textile square per 1 mL) in a closed glass bottle. After 1 h mixing the textile squares were pulled out and air dried at 50 C. Only freshly prepared textile squares were used for the extraction step. Fig. 1. Chemical structure of methyltrioctylammonium thiosalicylate (TOMATS).
2.3. MTSPE of copper ions and common iron-based staples were obtained from a local stationery. Freely available software (XnView and ImageJ) was used for photographs adjustment and image analysis, respectively.
Magnetically responsive IL modified textile square (22 cm) was inserted into 100 mL of copper sulfate heptahydrate solution; the concentration range was 103 e 107 mol L1. The extraction was performed for 60 min at room temperature by means of either a standard horizontal shaker or (due to the presence of magnetic
Fig. 2. Scanning electron microscopy of native acrylic non-woven textile (A), non-woven textile modified with ionic liquid (B), IL modified non-woven textile after interaction with copper ions (C), native cotton woven textile (D), cotton textile modified with ionic liquid (E) and IL modified cotton textile after interaction with copper ions (F).
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
I. Safarik et al. / Journal of Molecular Liquids xxx (xxxx) xxx
3
2.4. Image analysis Image analysis was performed as described recently [4]. Photographs of IL modified magnetic textile squares after Cu2þ ions extraction were taken by Canon EOS 2000D camera under standard illumination (normal daylight). The square or rectangle covering maximum of homogeneously colored textile (without the staple) was cropped from the original image using XnView software. Color Inspector 3D plugin (an integral part of ImageJ software) was used to analyze the images. In this plugin Median Cut option was used to reduce original range of colors into a single one “median” color. Then the HSB color space was applied to obtain the saturation (S) values, while the RGB color space was used to obtain red channel (R) values. 2.5. Other procedures The structure of native and IL modified fibers of both the acrylic non-woven and cotton woven textiles used was studied by scanning electron microscopy (SEM), using a Hitachi SU6600 scanning electron microscope (Hitachi, Tokyo, Japan) with accelerating voltage 1.0 or 1.5 kV. Energy dispersive X-ray spectra (EDS) were acquired in SEM using Thermo Noran System 7 (Thermo Scientific, Waltham, MA, USA) with Si(Li) detector; accelerating voltage was 15 kV and acquisition time was 300 s. 3. Results and discussion
Fig. 3. Energy dispersive spectroscopy of native acrylic non-woven textile (A), textile modified with ionic liquid (B) and IL modified textile after interaction with copper ions (C).
staple) by a magnetic stirrer. Then, the textile square with the adsorbed copper ions was taken out from solution using a permanent magnet and a photograph was taken immediately.
Methyltrioctylammonium thiosalicylate (TOMATS; see Fig. 1) is a task-specific, water-insoluble ionic liquid which can be dissolved in various organic solvents. This IL, prepared via a halide free synthesis route, has been successfully evaluated as an extracting agent for heavy metals from aqueous solutions obtaining high distribution coefficients [8,9]. Extraction of copper ions by TOMATS has caused dark coloration of ionic liquid [10]; this property was successfully employed for MTSPE of copper ions as described later. TOMATS was also successfully immobilized on palm shell activated carbon and this composite was used as an adsorbent for the
Fig. 4. Examples of native textile squares, IL modified textile squares and magnetically responsive IL modified textile squares (from left to right). Top e acrylic non-woven textile; bottom e cotton woven textile.
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
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I. Safarik et al. / Journal of Molecular Liquids xxx (xxxx) xxx
Fig. 5. Examples of IL modified non-woven textile after extraction of copper ions from 100 mL of 104 M (left) and 103 M (right) CuSO4$5H2O solution. The images were cropped from the original photos to enable subsequent image analysis.
removal of mercury from aqueous solutions during the batch adsorption process [11]. In our experiments TOMATS dissolved in acetone was used to coat textile fibers in two types of textile (cotton woven textile and acrylic non-woven textile). Various amounts of TOMATS were bound; cotton woven textile was modified with 4.2 mg per one square (2 2 cm, 4 cm2) while acrylic non-woven textile was modified with 32 mg per one square. SEM images of native acrylic fibers of non-woven textile show their slightly rough surface (Fig. 2A). After TOMATS coating the fiber surface was smooth, thus documenting successful binding of IL (Fig. 2B). The fiber appearance changed after copper ions binding, the fiber surface became rough (Fig. 2C). SEM images of cotton woven textile exhibit similar appearance (Fig. 2D,E,F), but due to the lower amount of IL bound to this type of textile the interaction with copper ions is less pronounced (Fig. 2F). The energy-dispersive X-ray spectroscopy analysis confirmed the presence of typical elements on native and modified acrylic nonwoven textile. Fig. 3A presents peaks typical for acrylic fibers. After TOMATS textile modification the additional sulfur peak (2.307 kV) is clearly visible which confirms the TOMATS presence on textile fibers (Fig. 3B). After extraction of Cu2þ ions by the IL modified textile two copper peaks (0.93 kV and 8.04 kV) appeared in the spectrum (Fig. 3C). Freshly prepared TOMATS coated textile squares (Fig. 4 shows typical appearance of adsorbent materials prepared from both acrylic non-woven textile and cotton woven textile) were used for MTSPE of copper ions from water solutions. Insertion of magnetic iron staple into textile squares enabled their movement in the
Fig. 7. Dependence of red channel values (R) on the concentration of analyzed Cu2þ solutions. Cotton woven textile (), acrylic non-woven textile (△).
analyzed solution and their simple magnetic separation. During the extraction process the color of IL modified textile changed to gray and black one, depending on Cu2þ ions concentration (see Fig. 5). Reaction time 60 min was optimal for the extraction procedure. In order to determine the copper ions concentration of the analyzed solutions, image analysis of textile squares was used because adsorption of copper ions caused darkening the IL modified textile. As described in Methods, analysis of the photos was performed using appropriate freeware (ImageJ). Two color spaces were used for color analysis, namely HSB (hue e saturation e brightness) color space and RGB (red e green e blue) color space. In a typical experiment shown in Fig. 6, the values of saturation (S) are almost linearly proportional to copper ions concentrations in the range 103 e 105 mol L1; however, smooth calibration curve can enable measurement up to the concentration 106 mol L1. Both cotton woven textile and acrylic nonwoven textile can be used successfully, but there is a visible difference in the saturation values between both textiles. The lower response of cotton woven textile is caused by the lower amount of bound TOMATS. Using RGB color space it was shown that the red channel values (R) are proportional to the copper ions concentrations of the analyzed samples; smooth calibration curves have been obtained in the concentration range 103 e 106 mol L1 (see Fig. 7). Also in this case both IL modified textiles exhibited slightly different behavior. 4. Conclusions This proof of concept paper clearly shows that textile bound methyltrioctylammonium thiosalicylate ionic liquid can be efficiently employed for inexpensive, elution free assay of copper ions. Image analysis of the textile photos enabled the Cu2þ concentration determination. The only equipment necessary is a digital camera and a computer with a freely available software. The developed assay has a potential to be a useful alternative to existing semiquantitative determination procedures for copper ions analysis. Conflicts of interest There is no conflict of interest. Acknowledgements
Fig. 6. Dependence of values of saturation (S) on the concentration of analyzed Cu solutions. Cotton woven textile (), acrylic non-woven textile (△).
2þ
This research was supported by the ERDF (European Regional Development Fund)/ESF (European Social Fund) projects “New
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
I. Safarik et al. / Journal of Molecular Liquids xxx (xxxx) xxx
Composite Materials for Environmental Applications” (No. CZ.02.1.01/0.0/0.0/17_048/0007399) and “Nanotechnologies for Future” (No. CZ.02.1.01/0.0/0.0/16_019/0000754) of the Ministry of Education, Youth and Sports of the Czech Republic. This work was carried out in the frame of the COST Actions CA16215 (European network for the promotion of portable, affordable and simple analytical platforms) and CA17107 (European Network to connect research and innovation efforts on advanced Smart Textiles). References [1] K. Yavir, L. Jedrkiewicz, R. Marcinkowska, J. Namiesnik, A. Kloskowski, Analytical applications and physicochemical properties of ionic liquid-based hybrid materials: a review, Anal. Chim. Acta 1054 (2019) 1e16. [2] I. Safarik, E. Baldikova, M. Safarikova, K. Pospiskova, Magnetically responsive textile for a new preconcentration procedure: magnetic textile solid phase extraction, J. Ind. Text. 48 (2018) 761e771. [3] I. Safarik, S. Mullerova, K. Pospiskova, Magnetically responsive textile for preconcentration of acid food dyes, Mater. Chem. Phys. 232 (2019) 205e208. [4] I. Safarik, S. Mullerova, K. Pospiskova, Semiquantitative determination of food acid dyes by magnetic textile solid phase extraction followed by image
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analysis, Food Chem. 274 (2019) 215e219. [5] S. Lacour, J.-C. Bollinger, B. Serpaud, P. Chantron, R. Arcos, Removal of heavy metals in industrial wastewaters by ion-exchanger grafted textiles, Anal. Chim. Acta 428 (2001) 121e132. [6] J. Ma, Y. Liu, O. Ali, Y. Wei, S. Zhang, Y. Zhang, T. Cai, C. Liu, S. Luo, Fast adsorption of heavy metal ions by waste cotton fabrics based double network hydrogel and influencing factors insight, J. Hazard Mater. 344 (2018) 1034e1042. [7] J.K. Bediako, W. Wei, Y.-S. Yun, Low-cost renewable adsorbent developed from waste textile fabric and its application to heavy metal adsorption, J. Taiwan Inst. Chem. Eng. 63 (2016) 250e258. [8] L. Fischer, T. Falta, G. Koellensperger, A. Stojanovic, D. Kogelnig, M. Galanski, R. Krachler, B.K. Keppler, S. Hann, Ionic liquids for extraction of metals and metal containing compounds from communal and industrial waste water, Water Res. 45 (2011) 4601e4614. [9] A. Stojanovic, B.K. Keppler, Ionic liquids as extracting agents for heavy metals, Separ. Sci. Technol. 47 (2012) 189e203. [10] R.S. Kalb, M.J. Kotschan, Trioctylmethylammonium thiosalicylate (TOMATS). A novel, high-performance, task-specific ionic liquid for the extraction of heavy metals from aqueous solutions, ChemFiles 6 (9) (2006), 13-13. [11] A.A. Ismaiel, M.K. Aroua, R. Yusoff, Palm shell activated carbon impregnated with task-specific ionic-liquids as a novel adsorbent for the removal of mercury from contaminated water, Chem. Eng. J. 225 (2013) 306e314.
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
Contents lists available at ScienceDirect
Journal of Molecular Liquids journal homepage: www.elsevier.com/locate/molliq
Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions Ivo Safarik a, b, *, Jitka Prochazkova a, Eva Baldikova a, Kristyna Pospiskova b a b
Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05, Ceske Budejovice, Czech Republic Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71, Olomouc, Czech Republic
a r t i c l e i n f o
a b s t r a c t
Article history: Received 24 July 2019 Received in revised form 5 October 2019 Accepted 11 October 2019 Available online xxx
Textile modified with methyltrioctylammonium thiosalicylate ionic liquid was successfully used for Magnetic textile solid phase extraction of copper ions. After extraction process the modified textile changed color to gray and black. The textile photos were employed for image analysis using HSB and RGB color spaces. It was shown that values of saturation (S) and red channel values (R) were proportional to the copper ions concentration in the analyzed samples; the value of saturation was almost linearly proportional to copper ions concentration in the range 103 e 105 mol L1. This inexpensive, simple and elution free assay has a potential to be a useful alternative to existing semiquantitative determination procedures for copper ions analysis. © 2019 Elsevier B.V. All rights reserved.
Keywords: Methyltrioctylammonium thiosalicylate Ionic liquid Magnetic textile solid phase extraction Copper ions
1. Introduction Ionic liquids (ILs) represent a relatively new class of compounds exhibiting very interesting properties. They are usually defined as compounds composed from organic cation and small organic or inorganic anion, which are liquid below 100 C. ILs melting at room temperature are called room-temperature ionic liquids (RTILs). Both native ILs and many ILs derivatives have been already used for many applications [1]. ILs immobilized on the surface or within the pores of a solid support can be efficiently used in analytical chemistry for preconcentration and analysis of target analytes from food, environmental and biological samples using solid-phase extraction, solidphase microextraction, hollow-fiber solid-phase microextraction, stir-bar sorptive extraction and biosensors [1]. Magnetic textile solid phase extraction (MTSPE) is a new preconcentration method, based on the use of magnetically modified textile [2]. A piece (usually a square) of textile is used as a carrier for the immobilization of a specific affinity, hydrophobic or ion exchange ligand. Magnetic iron-based wire (usually a staple) is inserted in the textile material using an office stapler to prepare magnetically responsive adsorbent. Laboratory magnetic stirrers enable to move magnetically modified pieces of textile adsorbent.
* Corresponding author. Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05, Ceske Budejovice, Czech Republic. E-mail address: [email protected] (I. Safarik).
At the end of the extraction process, the piece of textile is easily and rapidly separated magnetically. The adsorbed analyte can be eluted from the textile and subsequently analyzed [2,3], or the textile bound dyed compounds can be analyzed using image analysis procedure [4]. Surface modified textile can be efficiently used for the separation and removal of heavy metals. Typical examples comprehend ion-exchanger grafted textiles for removal of Cu(II) and Cd(II) ions [5], double network hydrogel based on waste cotton fabrics and polyacrylamide for Cd(II), Cu(II), Pb(II) and Zn(II) removal [6] or cellulose-based waste textile modified by carboxymethylation and crosslinking reactions for Cd(II) removal [7]. In this work appropriate textile material was modified with methyltrioctylammonium thiosalicylate ionic liquid to prepare a textilebased adsorbent for the preconcentration of copper ions from water solutions and subsequent image analysis. 2. Materials and methods 2.1. Materials and software Methyltrioctylammonium thiosalicylate (TOMATS; cat. No. 08354) was purchased from Sigma-Aldrich while copper sulfate heptahydrate was from Lachema, Brno, Czech Republic. Nonwoven textile (Bastelfiltz, 10 30 cm, 150 g m2, white 100% acrylic felt) was from Max Bringmann KG-folia (Germany), while fine woven cotton textile (100 g m2) was obtained locally. An office stapler
https://doi.org/10.1016/j.molliq.2019.111910 0167-7322/© 2019 Elsevier B.V. All rights reserved.
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
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I. Safarik et al. / Journal of Molecular Liquids xxx (xxxx) xxx
2.2. Preparation of IL loaded textile TOMATS was dissolved in acetone to obtain 5% (w/w) solution. Textile squares (2 2 cm) were immersed in IL solution (the ratio 1 textile square per 1 mL) in a closed glass bottle. After 1 h mixing the textile squares were pulled out and air dried at 50 C. Only freshly prepared textile squares were used for the extraction step. Fig. 1. Chemical structure of methyltrioctylammonium thiosalicylate (TOMATS).
2.3. MTSPE of copper ions and common iron-based staples were obtained from a local stationery. Freely available software (XnView and ImageJ) was used for photographs adjustment and image analysis, respectively.
Magnetically responsive IL modified textile square (22 cm) was inserted into 100 mL of copper sulfate heptahydrate solution; the concentration range was 103 e 107 mol L1. The extraction was performed for 60 min at room temperature by means of either a standard horizontal shaker or (due to the presence of magnetic
Fig. 2. Scanning electron microscopy of native acrylic non-woven textile (A), non-woven textile modified with ionic liquid (B), IL modified non-woven textile after interaction with copper ions (C), native cotton woven textile (D), cotton textile modified with ionic liquid (E) and IL modified cotton textile after interaction with copper ions (F).
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
I. Safarik et al. / Journal of Molecular Liquids xxx (xxxx) xxx
3
2.4. Image analysis Image analysis was performed as described recently [4]. Photographs of IL modified magnetic textile squares after Cu2þ ions extraction were taken by Canon EOS 2000D camera under standard illumination (normal daylight). The square or rectangle covering maximum of homogeneously colored textile (without the staple) was cropped from the original image using XnView software. Color Inspector 3D plugin (an integral part of ImageJ software) was used to analyze the images. In this plugin Median Cut option was used to reduce original range of colors into a single one “median” color. Then the HSB color space was applied to obtain the saturation (S) values, while the RGB color space was used to obtain red channel (R) values. 2.5. Other procedures The structure of native and IL modified fibers of both the acrylic non-woven and cotton woven textiles used was studied by scanning electron microscopy (SEM), using a Hitachi SU6600 scanning electron microscope (Hitachi, Tokyo, Japan) with accelerating voltage 1.0 or 1.5 kV. Energy dispersive X-ray spectra (EDS) were acquired in SEM using Thermo Noran System 7 (Thermo Scientific, Waltham, MA, USA) with Si(Li) detector; accelerating voltage was 15 kV and acquisition time was 300 s. 3. Results and discussion
Fig. 3. Energy dispersive spectroscopy of native acrylic non-woven textile (A), textile modified with ionic liquid (B) and IL modified textile after interaction with copper ions (C).
staple) by a magnetic stirrer. Then, the textile square with the adsorbed copper ions was taken out from solution using a permanent magnet and a photograph was taken immediately.
Methyltrioctylammonium thiosalicylate (TOMATS; see Fig. 1) is a task-specific, water-insoluble ionic liquid which can be dissolved in various organic solvents. This IL, prepared via a halide free synthesis route, has been successfully evaluated as an extracting agent for heavy metals from aqueous solutions obtaining high distribution coefficients [8,9]. Extraction of copper ions by TOMATS has caused dark coloration of ionic liquid [10]; this property was successfully employed for MTSPE of copper ions as described later. TOMATS was also successfully immobilized on palm shell activated carbon and this composite was used as an adsorbent for the
Fig. 4. Examples of native textile squares, IL modified textile squares and magnetically responsive IL modified textile squares (from left to right). Top e acrylic non-woven textile; bottom e cotton woven textile.
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
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I. Safarik et al. / Journal of Molecular Liquids xxx (xxxx) xxx
Fig. 5. Examples of IL modified non-woven textile after extraction of copper ions from 100 mL of 104 M (left) and 103 M (right) CuSO4$5H2O solution. The images were cropped from the original photos to enable subsequent image analysis.
removal of mercury from aqueous solutions during the batch adsorption process [11]. In our experiments TOMATS dissolved in acetone was used to coat textile fibers in two types of textile (cotton woven textile and acrylic non-woven textile). Various amounts of TOMATS were bound; cotton woven textile was modified with 4.2 mg per one square (2 2 cm, 4 cm2) while acrylic non-woven textile was modified with 32 mg per one square. SEM images of native acrylic fibers of non-woven textile show their slightly rough surface (Fig. 2A). After TOMATS coating the fiber surface was smooth, thus documenting successful binding of IL (Fig. 2B). The fiber appearance changed after copper ions binding, the fiber surface became rough (Fig. 2C). SEM images of cotton woven textile exhibit similar appearance (Fig. 2D,E,F), but due to the lower amount of IL bound to this type of textile the interaction with copper ions is less pronounced (Fig. 2F). The energy-dispersive X-ray spectroscopy analysis confirmed the presence of typical elements on native and modified acrylic nonwoven textile. Fig. 3A presents peaks typical for acrylic fibers. After TOMATS textile modification the additional sulfur peak (2.307 kV) is clearly visible which confirms the TOMATS presence on textile fibers (Fig. 3B). After extraction of Cu2þ ions by the IL modified textile two copper peaks (0.93 kV and 8.04 kV) appeared in the spectrum (Fig. 3C). Freshly prepared TOMATS coated textile squares (Fig. 4 shows typical appearance of adsorbent materials prepared from both acrylic non-woven textile and cotton woven textile) were used for MTSPE of copper ions from water solutions. Insertion of magnetic iron staple into textile squares enabled their movement in the
Fig. 7. Dependence of red channel values (R) on the concentration of analyzed Cu2þ solutions. Cotton woven textile (), acrylic non-woven textile (△).
analyzed solution and their simple magnetic separation. During the extraction process the color of IL modified textile changed to gray and black one, depending on Cu2þ ions concentration (see Fig. 5). Reaction time 60 min was optimal for the extraction procedure. In order to determine the copper ions concentration of the analyzed solutions, image analysis of textile squares was used because adsorption of copper ions caused darkening the IL modified textile. As described in Methods, analysis of the photos was performed using appropriate freeware (ImageJ). Two color spaces were used for color analysis, namely HSB (hue e saturation e brightness) color space and RGB (red e green e blue) color space. In a typical experiment shown in Fig. 6, the values of saturation (S) are almost linearly proportional to copper ions concentrations in the range 103 e 105 mol L1; however, smooth calibration curve can enable measurement up to the concentration 106 mol L1. Both cotton woven textile and acrylic nonwoven textile can be used successfully, but there is a visible difference in the saturation values between both textiles. The lower response of cotton woven textile is caused by the lower amount of bound TOMATS. Using RGB color space it was shown that the red channel values (R) are proportional to the copper ions concentrations of the analyzed samples; smooth calibration curves have been obtained in the concentration range 103 e 106 mol L1 (see Fig. 7). Also in this case both IL modified textiles exhibited slightly different behavior. 4. Conclusions This proof of concept paper clearly shows that textile bound methyltrioctylammonium thiosalicylate ionic liquid can be efficiently employed for inexpensive, elution free assay of copper ions. Image analysis of the textile photos enabled the Cu2þ concentration determination. The only equipment necessary is a digital camera and a computer with a freely available software. The developed assay has a potential to be a useful alternative to existing semiquantitative determination procedures for copper ions analysis. Conflicts of interest There is no conflict of interest. Acknowledgements
Fig. 6. Dependence of values of saturation (S) on the concentration of analyzed Cu solutions. Cotton woven textile (), acrylic non-woven textile (△).
2þ
This research was supported by the ERDF (European Regional Development Fund)/ESF (European Social Fund) projects “New
Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910
I. Safarik et al. / Journal of Molecular Liquids xxx (xxxx) xxx
Composite Materials for Environmental Applications” (No. CZ.02.1.01/0.0/0.0/17_048/0007399) and “Nanotechnologies for Future” (No. CZ.02.1.01/0.0/0.0/16_019/0000754) of the Ministry of Education, Youth and Sports of the Czech Republic. This work was carried out in the frame of the COST Actions CA16215 (European network for the promotion of portable, affordable and simple analytical platforms) and CA17107 (European Network to connect research and innovation efforts on advanced Smart Textiles). References [1] K. Yavir, L. Jedrkiewicz, R. Marcinkowska, J. Namiesnik, A. Kloskowski, Analytical applications and physicochemical properties of ionic liquid-based hybrid materials: a review, Anal. Chim. Acta 1054 (2019) 1e16. [2] I. Safarik, E. Baldikova, M. Safarikova, K. Pospiskova, Magnetically responsive textile for a new preconcentration procedure: magnetic textile solid phase extraction, J. Ind. Text. 48 (2018) 761e771. [3] I. Safarik, S. Mullerova, K. Pospiskova, Magnetically responsive textile for preconcentration of acid food dyes, Mater. Chem. Phys. 232 (2019) 205e208. [4] I. Safarik, S. Mullerova, K. Pospiskova, Semiquantitative determination of food acid dyes by magnetic textile solid phase extraction followed by image
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Please cite this article as: I. Safarik et al., Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2019.111910