Graphene oxide (GO) has an excellent adsorption capacity toward metal ions. Therefore, it is wide... more Graphene oxide (GO) has an excellent adsorption capacity toward metal ions. Therefore, it is widely recognized as an auspicious material for fabrication of membranes applied in metal ions separation. However, the GO membranes are not stable in aqueous solution, due to the electrostatic repulsion between the GO nanosheets which are negatively charged. This paper shows that stable GO membranes can be easily obtained by the noncovalent interaction of GO with oxidized carbon nanotubes (CNTs). The experiment shows also that the GO/CNTs membranes can be used for the effective adsorption of metal ions. The kinetic data, adsorption isotherms, competitive adsorption experiment and X-ray photoelectron spectroscopy indicate that the adsorption of metal ions is based on chemisorption. The membranes are remarkably durable in acidic, neutral and basic solutions. Although, the significant stabilization of the membranes by CNTs is observed, they strongly influence the adsorption process. Our study reveals that even small amount of CNTs (GO/CNTs in ratio 8:1) significantly reduces adsorption capacities of the membranes which were: 37, 40, 50, 42, 48, 98 mg g-1 for Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II), respectively. The reduction of the membranes adsorption capacities results from the creation of micro- and nano-channels formed by entangled CNTs. Durability and adsorptive properties of studied membranes indicate their potential use for the removal of metals from water.
The preconcentration of trace elements on multiwalled carbon nanotubes (MWCNTs) followed by a wav... more The preconcentration of trace elements on multiwalled carbon nanotubes (MWCNTs) followed by a wavelength-dispersive X-ray fluorescence analysis (WDXRF) has been investigated. The proposed preconcentration procedure is based on the sorption of trace elements on MWCNTs dispersed in analyzed solution. After sorption, the MWCNTs with the metal ions were collected onto the filter, and then the preconcentrated elements were determined directly by WDXRF. The preconcentration method was optimized, and in consequence, in order to obtain satisfactory recoveries using 100 mL of samples, the sorption process was performed with 1 mg of MWCNTs within 5 min. Some conditions of the preconcentration process such as the pH of analyte solution, amounts of MWCNTs, the volume of the sample, the contact time between analytes and MWCNTs (stirring time), and the effects of foreign metals are discussed in detail in the paper. Adsorption onto raw and oxidized MWCNTs was also studied. The proposed procedure allows obtaining the detection limits of 0.
A method of wavedispersive XRF analysis of Pb(Zr x Ti 1-x)O 3 type nanocrystalline ferroelectric ... more A method of wavedispersive XRF analysis of Pb(Zr x Ti 1-x)O 3 type nanocrystalline ferroelectric powders (PZT) has been presented. Matrix effects have been minimized by using the thin layer method. Preparation of the nature sample has consisted in digesting 25 mg of the materials in hydrochloric acid and 30% hydrogen peroxide (1+1), diluting up to 25 mL, and placing 0.5 mL of the obtained solution on a substrate. Standard samples of the same chemical composition but varied masses have been prepared to simplify calibration. Determined elements in nature samples occur within the following concentration ranges: Pb from 66.72% to 69.84%, Zr from 8.54% to 14.04%, and Ti from 3.68% to 9.16%. The detection limits for 0.5 mg samples were obtained: Pb = 1.1 × 10-3 mg (0.22%), Zr = 1.3 × 10-3 mg (0.26%), Ti = 2.3 × 10-4 mg (0.05%). Opracowano metodê mikroanalizy XRF nanokrystalicznych proszków ferroelektrycznych typu Pb(Zr x Ti 1-x)O 3 (PZT). W celu wyeliminowania efektów matrycy zastosowano technikê cienkiej warstwy. Przygotowanie próbek naturalnych do analizy sprowadza siê do roztworzenia 25 mg badanego materia³u w kwasie chlorowodorowym i 30% nadtlenku wodoru (1+1), rozcieñczeniu do objêtoci 25 mL i nakropleniu 0.5 mL uzyskanego roztworu na po-d³o¿e. Do kalibracji wykorzystano wielopierwiastkowe wzorce syntetyczne o tym samym sk³adzie jakociowym lecz ró¿nych masach. Oznaczane pierwiastki wystêpowa³y w zakresach stê¿eñ: Pb od 66.72% do 69.84%, Zr od 8.54% do 14.04% i Ti od 3.68% do 9.16%. Granice wykrywalnoci dla 0.5 mg próbki wynosz¹: Pb = 1.1 × 10-3 mg (0.22%), Zr = 1.3 × 10-3 mg (0.26%), Ti = 2.3 × 10-4 mg (0.05%).
An ultrasound-assisted methodology for the determination of dissolved silicate in water has been ... more An ultrasound-assisted methodology for the determination of dissolved silicate in water has been developed by combining the miniaturized ion-associated based preconcentration method with energy dispersive X-ray fluorescence spectrometry (EDXRF). The method has been devised for the determination of silicate through molybdenum in the ion-associated complex between 12-molybdosilicate and crystal violet. Because silicate is determined indirectly via molybdenum fluorescent radiation the difficulties resulting from low fluorescence yield and low energy of silicon radiation were successfully overcome. A good ratio of silicon to molybdenum (1 to 41) and a sensitive Kα line of molybdenum make possible the determination of low concentration of silicon in the form of dissolved silicate. Under optimized conditions, good linearity, up to 5 μg of silicon in the form of silicate (r = 0.9990) and a detection limit of 9 ng mL(-1) were achieved. The total RSD for the EDXRF determination of silicate, followed by precipitation of the ion-associated complex and its dissolution in a microdrop of isoamyl alcohol, was 6.5%. The enrichment factor was equal to 142. The developed method was used to determine the dissolved silica content in surface waters. The accuracy and repeatability of the proposed procedure were checked by the standard addition method and compared to the results obtained using the ICP-OES technique. The recovery (in the 93-97% range) was satisfactory and indicated the usefulness of the developed procedure.
A method of determination of high Zn and Pb concentrations by means of EDXRF (energy-dispersive X... more A method of determination of high Zn and Pb concentrations by means of EDXRF (energy-dispersive X-ray fluorescence spectrometry) is presented. Zn and Pb concentration in soil samples from contaminated areas ranged within a limit of Zn: 800-2000ppm and Pb: 200-600ppm. Soil analysis was conducted directly after the samples had been dried and powdered, as well as in situ in polluted areas. Due to the absence of the certificate reference materials for soils with such high Zn and Pb concentrations, samples of soil with the Pb and Zn amounts determined using the AAS method were used to perform calibration. The obtained detection limits are 30ppm and 19ppm for Zn and Pb, respectively. Because of the high analytes concentration and material heterogeneity, the repeatability of the results was examined according to the sample holder's various positions in EDXRF analyzer; repeatability the of the results while putting into the sample holder and out of it, together with the repeatability of making the calibration. The results obtained using the EDXRF method were compared to these obtained using AAS and wavelength-dispersive X-ray fluorescence spectrometry (WDXRF).
ABSTRACT A new method for sample preparation using graphene oxide (GO) as a novel sorbent was dev... more ABSTRACT A new method for sample preparation using graphene oxide (GO) as a novel sorbent was developed for the preconcentration of trace amounts of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II). The proposed preconcentration procedure is based on dispersive micro-solid phase extraction (DMSPE). It means that GO was dispersed in aqueous samples containing trace elements to be determined. During the stirring of the analyte solution containing the GO suspension, metal ions were sorbed by GO. After the sorption, the solution was filtered under vacuum and GO with the metal ions was collected onto a membrane filter. The obtained samples were analyzed directly by energy-dispersive X-ray fluorescence spectrometry (EDXRF). The parameters affecting the extraction and preconcentration process were optimized. The pH of the analyte solution, the amount of GO, the sample volume, the contact time between analytes and sorbent (stirring time), and the effects of foreign metals are discussed in detail in this paper. The proposed procedure allows us to obtain the detection limits of 0.5, 0.7, 1.5, 1.8 and 1.4 ng mL−1 for Co(II), Ni(II), Cu(II), Zn(II) and Pb(II), respectively. The linearity of the method is in the range of 5-100 ng mL−1. The proposed method was successfully applied in the analysis of water. The accuracy of the method was verified using spiked samples and inductively coupled plasma optical emission spectrometry (ICP-OES) as a comparative technique. The recoveries over the range of 94-106% were obtained. This paper shows the great potential of GO as an excellent sorbent in the preconcentration field of analytical chemistry. The proposed method meets green chemistry rules.
The authors have presented a sin1ple lllethod for the detern1ination of possible inhon10geneity o... more The authors have presented a sin1ple lllethod for the detern1ination of possible inhon10geneity of thin san1ples in a wavedispersive XRF analysis after previous exan1ination of intensity distribution of exciting radiation on sa111ple's surface. Investigations were carried out using as an exa111ple 111icrosan1ples of1110no-and polycrystals. Sa111ples were prepared by digesting an analyzed n1aterial directly on the substrate. The obtained results have been presented in a graphical way. Autorzy przedstawili prosty spos6b wyznaczania ewentualnej niejednorodnosci cienkich pr6bek w falowodyspersyjnej analizie XRF po uprzednin1 przebadaniu rozkladu nat((zenia pron1ieniowania wzbudzaj'tcego na powierzchni pr6bki.•Badania przeprowadzono na przykladzie n1ikropr6bek n10no-i polikryszta16w. Pr6bki przygotowywano poprzez roztwarzanie badanego n1aterialu bezposrednio na podlozu. Uzyskane wyniki przedstawiono graficznie.
Separation and Purification Technology, Dec 1, 2021
(2021). Graphene oxide decorated with fullerenol nanoparticles for highly efficient removal of Pb... more (2021). Graphene oxide decorated with fullerenol nanoparticles for highly efficient removal of Pb(II) ions and ultrasensitive detection by total-reflection X-ray fluorescence spectrometry.
A dispersive micro-solid phase extraction (DMSPE) with graphene as a solid adsorbent and ammonium... more A dispersive micro-solid phase extraction (DMSPE) with graphene as a solid adsorbent and ammonium pyrrolidinedithiocarbamate (APDC) as a chelating agent was proposed for speciation and detemination of inorganic selenium by the energy-dispersive X-ray fluorescence spectrometry (EDXRF). In developed DMSPE, graphene particles are dispersed throughout the analyzed solution, therefore reaction between Se(IV)-APDC complexes and graphene nanoparticles occurs immediately. The concentration of Se(VI) is calculated as the difference between the concentration of selenite after and before prereduction of selenate. A central composite face-centered design with 3 center points was performed in order to optimize conditions and to study the effect of four variables (pH of the sample, concentration of APDC, concentration of Triton-X-100, and sample volume). The best results were obtained when suspension consisting of 200 mg of graphene nanosheets, 1.2 mg of APDC and 0.06 mg of Triton-X-100 was rapidly injected to the 50 mL of the analyzed solution. Under optimized conditions Se ions can be determined with a very good recovery (97.7 75.0% and 99.2 76.6% for Se(IV) and Se(VI), respectively) and precision (RSD¼5.1-6.6%). Proposed DMSPE/EDXRF procedure allowed to obtain low detection limits (0.032 ng mL À 1) and high enrichment factor (1013715). The proposed methodology was successfully applied for the determination of Se in mineral, tap, lake and sea water samples as well as in biological materials (Lobster Hepatopancreas and Pig Kidney).
Graphene oxide (GO) covalently bonded to the spherical silica. Very stable sorbent for SPE of met... more Graphene oxide (GO) covalently bonded to the spherical silica. Very stable sorbent for SPE of metal ions. Excellent contact with solution due to the softness and flexibility of GO nanosheets. Several adsorption-elution cycles without any loss of adsorptive properties. High adsorption capacity due to the wrinkled structure of GO nanosheets.
Novel adsorbents are described for the preconcentration of chromium(VI). Graphene oxide (GO) was ... more Novel adsorbents are described for the preconcentration of chromium(VI). Graphene oxide (GO) was modified with various amino silanes containing one, two, or three nitrogen atoms in the molecule. These include 3-aminopropyltriethoxysilane (APTES), N-(3-trimethoxysilylpropyl)ethylenediamine (TMSPEDA), and N 1-(3-trimethoxysilylpropyl)diethylenetriamine (TMSPDETA). The resulting GO derivatives were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray fluorescence spectrometry (EDXRF). Adsorption studies show that these GO based sorbents are highly selective for Cr(VI) in the presence of Cr(III) at pH 3.5. Although the amino silanes applied in modification of GO contain different numbers of nitrogen atoms, the maximum adsorption capacities of GO derivatives are very similar (13.3-15.1 mg•g −1). Such results are in accordance with spectroscopy studies which show that the amount of amino silanes attached to GO decreases in the order of APTES > TMSPEDA > TMSPDETA. The APTES-modified GO was applied to selective and sensitive extraction of Cr(VI) ions prior to quantitation by low-power EDXRF using the Cr K α line. The Cr(VI) ions need not be eluted from the solid adsorbent. The method has a 0.17 ng•mL −1 detection limit, and the recovery is 99.7 ± 2.2% at a spiking level of 10 ng•mL −1. The method was successfully applied to the determination of Cr(VI) in water samples.
ABSTRACT This article gives an overview of the state-of-the-art of recent preconcentration strate... more ABSTRACT This article gives an overview of the state-of-the-art of recent preconcentration strategies published in X-ray fluorescence spectrometry (XRF), including the use of microextraction procedures, nanomaterials, filters and activated thin layers. We give special attention to current XRF instrumentation and the advantages and the limitations of each mode (including large-scale instrumentation, bench-top spectrometers and hand-held systems). Also, we comment on and discuss trends and future perspectives of XRF spectrometry in trace and ultratrace analysis of liquid samples.
The aminosilanized graphene oxide (GO-NH 2) was prepared for selective adsorption of Pb(II) ions.... more The aminosilanized graphene oxide (GO-NH 2) was prepared for selective adsorption of Pb(II) ions. Graphene oxide (GO) and GO-NH 2 prepared through the aminosilanization of GO with 3-aminopropyltriethoxysilane were characterized by scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The batch experiments show that GO-NH 2 is characterized by high selectivity toward Pb(II) ions. Adsorption isotherms suggest that sorption of Pb(II) on GO-NH 2 nanosheets is monolayer coverage, and adsorption is controlled by a chemical process involving the surface complexation of Pb(II) ions with the nitrogen-containing groups on the surface of GO-NH 2. Pb(II) ions can be quantitatively adsorbed at pH 6 with maximum adsorption capacity of 96 mg g −1. The GO-NH 2 was used for selective and sensitive determination of Pb(II) ions by electrothermal atomic absorption spectrometry (ET-AAS). The preconcentration of Pb(II) ions is based on dispersive micro solid-phase extraction in which the suspended GO-NH 2 is rapidly injected into analyzed water sample. Such features of GO-NH 2 nanosheets as wrinkled structure, softness, flexibility, and excellent dispersibility in water allow achieving very good contact with analyzed solution, and adsorption of Pb(II) ions is very fast. The experiment shows that after separation of the solid phase, the suspension of GO-NH 2 with adsorbed Pb(II) ions can be directly injected into the graphite tube and analyzed by ET-AAS. The GO-NH 2 is characterized by high selectivity toward Pb(II) ions and can be successfully used for analysis of various water samples with excellent enrichment factors of 100 and detection limits of 9.4 ng L −1 .
In this paper, graphene oxide/cellulose membranes were prepared in order to perform effective ads... more In this paper, graphene oxide/cellulose membranes were prepared in order to perform effective adsorption of heavy metal ions: cobalt, nickel, copper, zinc, cadmium and lead.
Graphene oxide (GO) has an excellent adsorption capacity toward metal ions. Therefore, it is wide... more Graphene oxide (GO) has an excellent adsorption capacity toward metal ions. Therefore, it is widely recognized as an auspicious material for fabrication of membranes applied in metal ions separation. However, the GO membranes are not stable in aqueous solution, due to the electrostatic repulsion between the GO nanosheets which are negatively charged. This paper shows that stable GO membranes can be easily obtained by the noncovalent interaction of GO with oxidized carbon nanotubes (CNTs). The experiment shows also that the GO/CNTs membranes can be used for the effective adsorption of metal ions. The kinetic data, adsorption isotherms, competitive adsorption experiment and X-ray photoelectron spectroscopy indicate that the adsorption of metal ions is based on chemisorption. The membranes are remarkably durable in acidic, neutral and basic solutions. Although, the significant stabilization of the membranes by CNTs is observed, they strongly influence the adsorption process. Our study reveals that even small amount of CNTs (GO/CNTs in ratio 8:1) significantly reduces adsorption capacities of the membranes which were: 37, 40, 50, 42, 48, 98 mg g-1 for Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II), respectively. The reduction of the membranes adsorption capacities results from the creation of micro- and nano-channels formed by entangled CNTs. Durability and adsorptive properties of studied membranes indicate their potential use for the removal of metals from water.
The preconcentration of trace elements on multiwalled carbon nanotubes (MWCNTs) followed by a wav... more The preconcentration of trace elements on multiwalled carbon nanotubes (MWCNTs) followed by a wavelength-dispersive X-ray fluorescence analysis (WDXRF) has been investigated. The proposed preconcentration procedure is based on the sorption of trace elements on MWCNTs dispersed in analyzed solution. After sorption, the MWCNTs with the metal ions were collected onto the filter, and then the preconcentrated elements were determined directly by WDXRF. The preconcentration method was optimized, and in consequence, in order to obtain satisfactory recoveries using 100 mL of samples, the sorption process was performed with 1 mg of MWCNTs within 5 min. Some conditions of the preconcentration process such as the pH of analyte solution, amounts of MWCNTs, the volume of the sample, the contact time between analytes and MWCNTs (stirring time), and the effects of foreign metals are discussed in detail in the paper. Adsorption onto raw and oxidized MWCNTs was also studied. The proposed procedure allows obtaining the detection limits of 0.
A method of wavedispersive XRF analysis of Pb(Zr x Ti 1-x)O 3 type nanocrystalline ferroelectric ... more A method of wavedispersive XRF analysis of Pb(Zr x Ti 1-x)O 3 type nanocrystalline ferroelectric powders (PZT) has been presented. Matrix effects have been minimized by using the thin layer method. Preparation of the nature sample has consisted in digesting 25 mg of the materials in hydrochloric acid and 30% hydrogen peroxide (1+1), diluting up to 25 mL, and placing 0.5 mL of the obtained solution on a substrate. Standard samples of the same chemical composition but varied masses have been prepared to simplify calibration. Determined elements in nature samples occur within the following concentration ranges: Pb from 66.72% to 69.84%, Zr from 8.54% to 14.04%, and Ti from 3.68% to 9.16%. The detection limits for 0.5 mg samples were obtained: Pb = 1.1 × 10-3 mg (0.22%), Zr = 1.3 × 10-3 mg (0.26%), Ti = 2.3 × 10-4 mg (0.05%). Opracowano metodê mikroanalizy XRF nanokrystalicznych proszków ferroelektrycznych typu Pb(Zr x Ti 1-x)O 3 (PZT). W celu wyeliminowania efektów matrycy zastosowano technikê cienkiej warstwy. Przygotowanie próbek naturalnych do analizy sprowadza siê do roztworzenia 25 mg badanego materia³u w kwasie chlorowodorowym i 30% nadtlenku wodoru (1+1), rozcieñczeniu do objêtoci 25 mL i nakropleniu 0.5 mL uzyskanego roztworu na po-d³o¿e. Do kalibracji wykorzystano wielopierwiastkowe wzorce syntetyczne o tym samym sk³adzie jakociowym lecz ró¿nych masach. Oznaczane pierwiastki wystêpowa³y w zakresach stê¿eñ: Pb od 66.72% do 69.84%, Zr od 8.54% do 14.04% i Ti od 3.68% do 9.16%. Granice wykrywalnoci dla 0.5 mg próbki wynosz¹: Pb = 1.1 × 10-3 mg (0.22%), Zr = 1.3 × 10-3 mg (0.26%), Ti = 2.3 × 10-4 mg (0.05%).
An ultrasound-assisted methodology for the determination of dissolved silicate in water has been ... more An ultrasound-assisted methodology for the determination of dissolved silicate in water has been developed by combining the miniaturized ion-associated based preconcentration method with energy dispersive X-ray fluorescence spectrometry (EDXRF). The method has been devised for the determination of silicate through molybdenum in the ion-associated complex between 12-molybdosilicate and crystal violet. Because silicate is determined indirectly via molybdenum fluorescent radiation the difficulties resulting from low fluorescence yield and low energy of silicon radiation were successfully overcome. A good ratio of silicon to molybdenum (1 to 41) and a sensitive Kα line of molybdenum make possible the determination of low concentration of silicon in the form of dissolved silicate. Under optimized conditions, good linearity, up to 5 μg of silicon in the form of silicate (r = 0.9990) and a detection limit of 9 ng mL(-1) were achieved. The total RSD for the EDXRF determination of silicate, followed by precipitation of the ion-associated complex and its dissolution in a microdrop of isoamyl alcohol, was 6.5%. The enrichment factor was equal to 142. The developed method was used to determine the dissolved silica content in surface waters. The accuracy and repeatability of the proposed procedure were checked by the standard addition method and compared to the results obtained using the ICP-OES technique. The recovery (in the 93-97% range) was satisfactory and indicated the usefulness of the developed procedure.
A method of determination of high Zn and Pb concentrations by means of EDXRF (energy-dispersive X... more A method of determination of high Zn and Pb concentrations by means of EDXRF (energy-dispersive X-ray fluorescence spectrometry) is presented. Zn and Pb concentration in soil samples from contaminated areas ranged within a limit of Zn: 800-2000ppm and Pb: 200-600ppm. Soil analysis was conducted directly after the samples had been dried and powdered, as well as in situ in polluted areas. Due to the absence of the certificate reference materials for soils with such high Zn and Pb concentrations, samples of soil with the Pb and Zn amounts determined using the AAS method were used to perform calibration. The obtained detection limits are 30ppm and 19ppm for Zn and Pb, respectively. Because of the high analytes concentration and material heterogeneity, the repeatability of the results was examined according to the sample holder's various positions in EDXRF analyzer; repeatability the of the results while putting into the sample holder and out of it, together with the repeatability of making the calibration. The results obtained using the EDXRF method were compared to these obtained using AAS and wavelength-dispersive X-ray fluorescence spectrometry (WDXRF).
ABSTRACT A new method for sample preparation using graphene oxide (GO) as a novel sorbent was dev... more ABSTRACT A new method for sample preparation using graphene oxide (GO) as a novel sorbent was developed for the preconcentration of trace amounts of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II). The proposed preconcentration procedure is based on dispersive micro-solid phase extraction (DMSPE). It means that GO was dispersed in aqueous samples containing trace elements to be determined. During the stirring of the analyte solution containing the GO suspension, metal ions were sorbed by GO. After the sorption, the solution was filtered under vacuum and GO with the metal ions was collected onto a membrane filter. The obtained samples were analyzed directly by energy-dispersive X-ray fluorescence spectrometry (EDXRF). The parameters affecting the extraction and preconcentration process were optimized. The pH of the analyte solution, the amount of GO, the sample volume, the contact time between analytes and sorbent (stirring time), and the effects of foreign metals are discussed in detail in this paper. The proposed procedure allows us to obtain the detection limits of 0.5, 0.7, 1.5, 1.8 and 1.4 ng mL−1 for Co(II), Ni(II), Cu(II), Zn(II) and Pb(II), respectively. The linearity of the method is in the range of 5-100 ng mL−1. The proposed method was successfully applied in the analysis of water. The accuracy of the method was verified using spiked samples and inductively coupled plasma optical emission spectrometry (ICP-OES) as a comparative technique. The recoveries over the range of 94-106% were obtained. This paper shows the great potential of GO as an excellent sorbent in the preconcentration field of analytical chemistry. The proposed method meets green chemistry rules.
The authors have presented a sin1ple lllethod for the detern1ination of possible inhon10geneity o... more The authors have presented a sin1ple lllethod for the detern1ination of possible inhon10geneity of thin san1ples in a wavedispersive XRF analysis after previous exan1ination of intensity distribution of exciting radiation on sa111ple's surface. Investigations were carried out using as an exa111ple 111icrosan1ples of1110no-and polycrystals. Sa111ples were prepared by digesting an analyzed n1aterial directly on the substrate. The obtained results have been presented in a graphical way. Autorzy przedstawili prosty spos6b wyznaczania ewentualnej niejednorodnosci cienkich pr6bek w falowodyspersyjnej analizie XRF po uprzednin1 przebadaniu rozkladu nat((zenia pron1ieniowania wzbudzaj'tcego na powierzchni pr6bki.•Badania przeprowadzono na przykladzie n1ikropr6bek n10no-i polikryszta16w. Pr6bki przygotowywano poprzez roztwarzanie badanego n1aterialu bezposrednio na podlozu. Uzyskane wyniki przedstawiono graficznie.
Separation and Purification Technology, Dec 1, 2021
(2021). Graphene oxide decorated with fullerenol nanoparticles for highly efficient removal of Pb... more (2021). Graphene oxide decorated with fullerenol nanoparticles for highly efficient removal of Pb(II) ions and ultrasensitive detection by total-reflection X-ray fluorescence spectrometry.
A dispersive micro-solid phase extraction (DMSPE) with graphene as a solid adsorbent and ammonium... more A dispersive micro-solid phase extraction (DMSPE) with graphene as a solid adsorbent and ammonium pyrrolidinedithiocarbamate (APDC) as a chelating agent was proposed for speciation and detemination of inorganic selenium by the energy-dispersive X-ray fluorescence spectrometry (EDXRF). In developed DMSPE, graphene particles are dispersed throughout the analyzed solution, therefore reaction between Se(IV)-APDC complexes and graphene nanoparticles occurs immediately. The concentration of Se(VI) is calculated as the difference between the concentration of selenite after and before prereduction of selenate. A central composite face-centered design with 3 center points was performed in order to optimize conditions and to study the effect of four variables (pH of the sample, concentration of APDC, concentration of Triton-X-100, and sample volume). The best results were obtained when suspension consisting of 200 mg of graphene nanosheets, 1.2 mg of APDC and 0.06 mg of Triton-X-100 was rapidly injected to the 50 mL of the analyzed solution. Under optimized conditions Se ions can be determined with a very good recovery (97.7 75.0% and 99.2 76.6% for Se(IV) and Se(VI), respectively) and precision (RSD¼5.1-6.6%). Proposed DMSPE/EDXRF procedure allowed to obtain low detection limits (0.032 ng mL À 1) and high enrichment factor (1013715). The proposed methodology was successfully applied for the determination of Se in mineral, tap, lake and sea water samples as well as in biological materials (Lobster Hepatopancreas and Pig Kidney).
Graphene oxide (GO) covalently bonded to the spherical silica. Very stable sorbent for SPE of met... more Graphene oxide (GO) covalently bonded to the spherical silica. Very stable sorbent for SPE of metal ions. Excellent contact with solution due to the softness and flexibility of GO nanosheets. Several adsorption-elution cycles without any loss of adsorptive properties. High adsorption capacity due to the wrinkled structure of GO nanosheets.
Novel adsorbents are described for the preconcentration of chromium(VI). Graphene oxide (GO) was ... more Novel adsorbents are described for the preconcentration of chromium(VI). Graphene oxide (GO) was modified with various amino silanes containing one, two, or three nitrogen atoms in the molecule. These include 3-aminopropyltriethoxysilane (APTES), N-(3-trimethoxysilylpropyl)ethylenediamine (TMSPEDA), and N 1-(3-trimethoxysilylpropyl)diethylenetriamine (TMSPDETA). The resulting GO derivatives were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray fluorescence spectrometry (EDXRF). Adsorption studies show that these GO based sorbents are highly selective for Cr(VI) in the presence of Cr(III) at pH 3.5. Although the amino silanes applied in modification of GO contain different numbers of nitrogen atoms, the maximum adsorption capacities of GO derivatives are very similar (13.3-15.1 mg•g −1). Such results are in accordance with spectroscopy studies which show that the amount of amino silanes attached to GO decreases in the order of APTES > TMSPEDA > TMSPDETA. The APTES-modified GO was applied to selective and sensitive extraction of Cr(VI) ions prior to quantitation by low-power EDXRF using the Cr K α line. The Cr(VI) ions need not be eluted from the solid adsorbent. The method has a 0.17 ng•mL −1 detection limit, and the recovery is 99.7 ± 2.2% at a spiking level of 10 ng•mL −1. The method was successfully applied to the determination of Cr(VI) in water samples.
ABSTRACT This article gives an overview of the state-of-the-art of recent preconcentration strate... more ABSTRACT This article gives an overview of the state-of-the-art of recent preconcentration strategies published in X-ray fluorescence spectrometry (XRF), including the use of microextraction procedures, nanomaterials, filters and activated thin layers. We give special attention to current XRF instrumentation and the advantages and the limitations of each mode (including large-scale instrumentation, bench-top spectrometers and hand-held systems). Also, we comment on and discuss trends and future perspectives of XRF spectrometry in trace and ultratrace analysis of liquid samples.
The aminosilanized graphene oxide (GO-NH 2) was prepared for selective adsorption of Pb(II) ions.... more The aminosilanized graphene oxide (GO-NH 2) was prepared for selective adsorption of Pb(II) ions. Graphene oxide (GO) and GO-NH 2 prepared through the aminosilanization of GO with 3-aminopropyltriethoxysilane were characterized by scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The batch experiments show that GO-NH 2 is characterized by high selectivity toward Pb(II) ions. Adsorption isotherms suggest that sorption of Pb(II) on GO-NH 2 nanosheets is monolayer coverage, and adsorption is controlled by a chemical process involving the surface complexation of Pb(II) ions with the nitrogen-containing groups on the surface of GO-NH 2. Pb(II) ions can be quantitatively adsorbed at pH 6 with maximum adsorption capacity of 96 mg g −1. The GO-NH 2 was used for selective and sensitive determination of Pb(II) ions by electrothermal atomic absorption spectrometry (ET-AAS). The preconcentration of Pb(II) ions is based on dispersive micro solid-phase extraction in which the suspended GO-NH 2 is rapidly injected into analyzed water sample. Such features of GO-NH 2 nanosheets as wrinkled structure, softness, flexibility, and excellent dispersibility in water allow achieving very good contact with analyzed solution, and adsorption of Pb(II) ions is very fast. The experiment shows that after separation of the solid phase, the suspension of GO-NH 2 with adsorbed Pb(II) ions can be directly injected into the graphite tube and analyzed by ET-AAS. The GO-NH 2 is characterized by high selectivity toward Pb(II) ions and can be successfully used for analysis of various water samples with excellent enrichment factors of 100 and detection limits of 9.4 ng L −1 .
In this paper, graphene oxide/cellulose membranes were prepared in order to perform effective ads... more In this paper, graphene oxide/cellulose membranes were prepared in order to perform effective adsorption of heavy metal ions: cobalt, nickel, copper, zinc, cadmium and lead.
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Papers by Rafał Sitko