Supporting Information Oil Recovery from Water under ...
Supporting Information
Oil Recovery from Water under Environmentally Relevant Conditions Using Magnetic Nanoparticles Seyyedali Mirshahghassemi and Jamie R. Lead* Center for Environmental Nanoscience and Risk (CENR), Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina 29208, United States
AUTHOR INFORMATION Corresponding Author *Phone: (803) 777-0091. E-mail: [email protected]. Supporting information includes 8 pages, 4 tables and 1 figure.
S1
Methodology Measurement of oil removal by fluorescence spectroscopy Emission spectra of oil samples were recorded by employing an excitation wavelength of 337 nm and emission range from 350 to 650 nm. This excitation wavelength has been widely reported in the literature to detect PAHs of crude oil.1 Oil concentrations were calculated using a calibration plot based on known oil concentration samples from the fluorescence spectroscopy. Based on the calibration curve and the integration of the fluorescence spectrum for oil samples before and after magnetic separation, the oil sorption efficiency was quantified. Moreover, fluorescence excitation-emission matrixes (EEMs) of samples were measured by collecting emission scans from 250 nm to 600 nm and varying excitation wavelengths ranging from 240 to 480 nm. GC-MS analysis GC-MS analysis was performed on an Agilent 6890N gas chromatography system and an Agilent 5975 mass spectrometer equipped with an autosampler (Agilent 7683B). The analytical column was an Agilent TG-5MS (30 m × 0.25mm I.D., 0.25 µm film thickness) coated with 5% phenylmethylsiloxane stationary phase. High-purity helium (99.9%) at a constant flow rate of 1.5 mL min-1 was used as the carrier gas. The injection port was maintained at 250 °C in the splitless mode and 1µl of extracted sample was injected. Spectra were obtained in the electron impact mode (70 eV) scanning from 40 m/z to 400 m/z. The oven temperature was operated from 40 °C to 300 °C rising at 10 °C/min. A full scan mode was used and saturated hydrocarbons were monitored in the oil samples before and after the NPs based separation. The detected hydrocarbons were approximately 8% of total components in the reference oil sample, although saturated carbon of sample was 56% of total components.2
S2
Result and discussion Measurement of oil removal by UV-vis spectroscopy Table S1 summarizes oil sorption efficiency of the NPs using different NP concentration, as obtained from the UV-vis data. For optimum NP concentration (17.6 ppm), 99.3% of oil was removed after 40 minutes of magnetic separation. The difference between removal percentage values based on the peak height and absorbance integration is due to the background of NP signal overlapping with the oil signal. Table S1. Effect of NP concentration on oil removal efficiency, Based on UV-Vis. (Oil experiment in ultra-pure water, separation time = 40 minutes) NP concentration
Oil concentration (g L-1)
(ppm)
Oil removal based on
Oil removal based
peak height (%)
on integration (%)
2.2
0.20
1.4
23.8
4.4
0.16
24.1
18.4
8.8
0.08
61.2
80.8
17.6
0.03
86.2
99.3
35.2
0.05
76.6
98.0
Table S2 shows the effect of separation time on the oil removal efficiency measured by UV-vis. After 5 minutes of magnetic separation, the oil concentration was 0.05 g L-1, indicating excellent oil removal capacity of NPs in a short time. After 25 minutes of magnetic separation 79.5% of
S3
oil was removed and oil remaining concentration was 0.01 g L-1. UV-vis data shows no significant difference between oil concentration after 25 minutes and 40 minutes of separation which can be due to the background of NP remaining. Table S2. Effect of Separation time on oil removal efficiency, Based on UV-Vis. (Oil experiment in ultra-pure water, NP concentration = 17.6 ppm) Separation time
Oil concentration (g L-1)
(Minutes)
Oil removal based on
Oil removal based
peak height (%)
on integration (%)
5
0.05
60.6
46.0
10
0.03
65.8
79.8
15
0.02
75.7
97.1
20
0.02
76.3
95.4
25
0.01
79.5
100.0
30
0.01
78.7
100.0
40
0.01
80.1
100.0
Based on the integration of UV-vis absorbance, by using different NP concentrations near 90% of oil was removed from sea water in the presence of SRFA (Table S3). This result is in agreement with fluorescence results which showed high removal percentage even by using low concentration of NP.
S4
Table S3. Effect of NP concentration on oil removal efficiency, Based on UV-Vis. (Oil experiment in sea water in the presence of SRFA, SRFA concentration = 1ppm, separation time = 1 h) NP concentration
Oil concentration (g L-1)
(ppm)
Oil removal based on
Oil removal based
peak height (%)
on integration (%)
4.4
0.05
58.9
90.3
8.8
0.06
64.0
87.3
17.6
0.05
56.4
99.6
35.2
0.04
65.3
99.4
70.4
0.05
59.5
99.3
Table S4 summarizes oil sorption efficiency of the NPs under different SRFA concentration. In the presence of SRFA, by using higher NP concentration (35.2 ppm) 100% of oil was removed. Table S4. Effect of SRFA on oil removal efficiency, Based on UV-Vis. (Oil experiment in sea water, separation time = 1 h) SRFA concentration
Oil concentration (g L-1)
(ppm)
Oil removal based on
Oil removal based
peak height (%)
on integration (%)
0
0.03
75.5
100.0
0.25
0.04
74.00
99.9
1
0.04
65.3
99.4
S5
Fluorescence EEM plots Figure S1 shows EEMs of oil-water mixture before and after magnetic separation for optimum experiment conditions. Results suggest that aromatic compounds concentration were significantly decrease in all types of solutions (Figure S1). a)
b)
c)
d)
e)
Figure S1. Fluorescence EEMs of oil-water mixture before and after magnetic separation. (a) oil-water mixture before the NP based separation, oil remaining solution for the oil experiment in
S6
(b) ultra-pure water, (c) sea water without SRFA, (d) sea water with 0.25 ppm SRFA and (e) sea water with 1 ppm SRFA. Comparison between synthesis techniques A comparison between selected synthesis techniques in terms of total cost and required materials for producing 100 gr of PVP-coated iron oxide NPs was performed. The calculations are based on stoichiometric reactions and the Sigma-Aldrich website was used for material cost (for nonbulk ordering). Based on the calculations, the material cost for the hydrothermal synthesis technique is 50% cheaper compared to our previous solvothermal synthesis technique and generally cheaper compared to other techniques.3,
4
This comparison is reported as a
representative of the material cost for producing magnetic nanoparticles. Palchoudhury et al4: 429 ml Triethylene glycol, 300 gr Fe(acac)3 and 128 gr PVP. (Total material cost: $139.3) The hydrothermal synthesis technique: 60 gr FeCl2, 240 gr FeCl3, 375 ml ammonium hydroxide and 180 gr PVP. (Total material cost: $71)”
S7
References
1. Ryder, A., Analysis of Crude Petroleum Oils Using Fluorescence Spectroscopy. In Reviews in Fluorescence 2005, Geddes, C.; Lakowicz, J., Eds. Springer US: 2005; Vol. 2005, pp 169-198. 2. BP, Gulf Science Data Reference Oil Characterization Data. Website: http://gulfsciencedata.bp.com/. directory: Oil. subdirectory: Oil Characteristics – additional reference oils. filename: OilChemistry_O‐04v01‐01.zip 2014. 3. Zhang, B.; Tu, Z.; Zhao, F.; Wang, J., Superparamagnetic iron oxide nanoparticles prepared by using an improved polyol method. Appl. Surf. Sci. 2013, 266, (0), 375-379. 4. Palchoudhury, S.; Lead, J. R., A Facile and Cost-Effective Method for Separation of Oil-Water Mixtures Using Polymer-Coated Iron Oxide Nanoparticles. Environ. Sci. Technol. 2014, 48, (24), 14558-14563.
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Oil Recovery from Water under Environmentally Relevant Conditions Using Magnetic Nanoparticles Seyyedali Mirshahghassemi and Jamie R. Lead* Center for Environmental Nanoscience and Risk (CENR), Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina 29208, United States
AUTHOR INFORMATION Corresponding Author *Phone: (803) 777-0091. E-mail: [email protected]. Supporting information includes 8 pages, 4 tables and 1 figure.
S1
Methodology Measurement of oil removal by fluorescence spectroscopy Emission spectra of oil samples were recorded by employing an excitation wavelength of 337 nm and emission range from 350 to 650 nm. This excitation wavelength has been widely reported in the literature to detect PAHs of crude oil.1 Oil concentrations were calculated using a calibration plot based on known oil concentration samples from the fluorescence spectroscopy. Based on the calibration curve and the integration of the fluorescence spectrum for oil samples before and after magnetic separation, the oil sorption efficiency was quantified. Moreover, fluorescence excitation-emission matrixes (EEMs) of samples were measured by collecting emission scans from 250 nm to 600 nm and varying excitation wavelengths ranging from 240 to 480 nm. GC-MS analysis GC-MS analysis was performed on an Agilent 6890N gas chromatography system and an Agilent 5975 mass spectrometer equipped with an autosampler (Agilent 7683B). The analytical column was an Agilent TG-5MS (30 m × 0.25mm I.D., 0.25 µm film thickness) coated with 5% phenylmethylsiloxane stationary phase. High-purity helium (99.9%) at a constant flow rate of 1.5 mL min-1 was used as the carrier gas. The injection port was maintained at 250 °C in the splitless mode and 1µl of extracted sample was injected. Spectra were obtained in the electron impact mode (70 eV) scanning from 40 m/z to 400 m/z. The oven temperature was operated from 40 °C to 300 °C rising at 10 °C/min. A full scan mode was used and saturated hydrocarbons were monitored in the oil samples before and after the NPs based separation. The detected hydrocarbons were approximately 8% of total components in the reference oil sample, although saturated carbon of sample was 56% of total components.2
S2
Result and discussion Measurement of oil removal by UV-vis spectroscopy Table S1 summarizes oil sorption efficiency of the NPs using different NP concentration, as obtained from the UV-vis data. For optimum NP concentration (17.6 ppm), 99.3% of oil was removed after 40 minutes of magnetic separation. The difference between removal percentage values based on the peak height and absorbance integration is due to the background of NP signal overlapping with the oil signal. Table S1. Effect of NP concentration on oil removal efficiency, Based on UV-Vis. (Oil experiment in ultra-pure water, separation time = 40 minutes) NP concentration
Oil concentration (g L-1)
(ppm)
Oil removal based on
Oil removal based
peak height (%)
on integration (%)
2.2
0.20
1.4
23.8
4.4
0.16
24.1
18.4
8.8
0.08
61.2
80.8
17.6
0.03
86.2
99.3
35.2
0.05
76.6
98.0
Table S2 shows the effect of separation time on the oil removal efficiency measured by UV-vis. After 5 minutes of magnetic separation, the oil concentration was 0.05 g L-1, indicating excellent oil removal capacity of NPs in a short time. After 25 minutes of magnetic separation 79.5% of
S3
oil was removed and oil remaining concentration was 0.01 g L-1. UV-vis data shows no significant difference between oil concentration after 25 minutes and 40 minutes of separation which can be due to the background of NP remaining. Table S2. Effect of Separation time on oil removal efficiency, Based on UV-Vis. (Oil experiment in ultra-pure water, NP concentration = 17.6 ppm) Separation time
Oil concentration (g L-1)
(Minutes)
Oil removal based on
Oil removal based
peak height (%)
on integration (%)
5
0.05
60.6
46.0
10
0.03
65.8
79.8
15
0.02
75.7
97.1
20
0.02
76.3
95.4
25
0.01
79.5
100.0
30
0.01
78.7
100.0
40
0.01
80.1
100.0
Based on the integration of UV-vis absorbance, by using different NP concentrations near 90% of oil was removed from sea water in the presence of SRFA (Table S3). This result is in agreement with fluorescence results which showed high removal percentage even by using low concentration of NP.
S4
Table S3. Effect of NP concentration on oil removal efficiency, Based on UV-Vis. (Oil experiment in sea water in the presence of SRFA, SRFA concentration = 1ppm, separation time = 1 h) NP concentration
Oil concentration (g L-1)
(ppm)
Oil removal based on
Oil removal based
peak height (%)
on integration (%)
4.4
0.05
58.9
90.3
8.8
0.06
64.0
87.3
17.6
0.05
56.4
99.6
35.2
0.04
65.3
99.4
70.4
0.05
59.5
99.3
Table S4 summarizes oil sorption efficiency of the NPs under different SRFA concentration. In the presence of SRFA, by using higher NP concentration (35.2 ppm) 100% of oil was removed. Table S4. Effect of SRFA on oil removal efficiency, Based on UV-Vis. (Oil experiment in sea water, separation time = 1 h) SRFA concentration
Oil concentration (g L-1)
(ppm)
Oil removal based on
Oil removal based
peak height (%)
on integration (%)
0
0.03
75.5
100.0
0.25
0.04
74.00
99.9
1
0.04
65.3
99.4
S5
Fluorescence EEM plots Figure S1 shows EEMs of oil-water mixture before and after magnetic separation for optimum experiment conditions. Results suggest that aromatic compounds concentration were significantly decrease in all types of solutions (Figure S1). a)
b)
c)
d)
e)
Figure S1. Fluorescence EEMs of oil-water mixture before and after magnetic separation. (a) oil-water mixture before the NP based separation, oil remaining solution for the oil experiment in
S6
(b) ultra-pure water, (c) sea water without SRFA, (d) sea water with 0.25 ppm SRFA and (e) sea water with 1 ppm SRFA. Comparison between synthesis techniques A comparison between selected synthesis techniques in terms of total cost and required materials for producing 100 gr of PVP-coated iron oxide NPs was performed. The calculations are based on stoichiometric reactions and the Sigma-Aldrich website was used for material cost (for nonbulk ordering). Based on the calculations, the material cost for the hydrothermal synthesis technique is 50% cheaper compared to our previous solvothermal synthesis technique and generally cheaper compared to other techniques.3,
4
This comparison is reported as a
representative of the material cost for producing magnetic nanoparticles. Palchoudhury et al4: 429 ml Triethylene glycol, 300 gr Fe(acac)3 and 128 gr PVP. (Total material cost: $139.3) The hydrothermal synthesis technique: 60 gr FeCl2, 240 gr FeCl3, 375 ml ammonium hydroxide and 180 gr PVP. (Total material cost: $71)”
S7
References
1. Ryder, A., Analysis of Crude Petroleum Oils Using Fluorescence Spectroscopy. In Reviews in Fluorescence 2005, Geddes, C.; Lakowicz, J., Eds. Springer US: 2005; Vol. 2005, pp 169-198. 2. BP, Gulf Science Data Reference Oil Characterization Data. Website: http://gulfsciencedata.bp.com/. directory: Oil. subdirectory: Oil Characteristics – additional reference oils. filename: OilChemistry_O‐04v01‐01.zip 2014. 3. Zhang, B.; Tu, Z.; Zhao, F.; Wang, J., Superparamagnetic iron oxide nanoparticles prepared by using an improved polyol method. Appl. Surf. Sci. 2013, 266, (0), 375-379. 4. Palchoudhury, S.; Lead, J. R., A Facile and Cost-Effective Method for Separation of Oil-Water Mixtures Using Polymer-Coated Iron Oxide Nanoparticles. Environ. Sci. Technol. 2014, 48, (24), 14558-14563.
S8
