PFG NMR diffusion experiments for complex systems

Momot, Konstantin I.; Kuchel, Philip W.

doi:10.1002/cmr.a.20056

Cited by 74 publications

(71 citation statements)

References 65 publications

(132 reference statements)

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“…23,24 We propose that the discrepancy could be due to the chemical reactivity of dissolved CO 2 with water as shown in eq 7. Bicarbonate dissociation has a negligible presence under our experimental (pH) conditions and therefore was omitted from consideration.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Diffusivity of Carbon Dioxide in Aqueous Solutions under Geologic Carbon Sequestration Conditions

et al. 2018

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Accurate assessment of the long-term security of geologic carbon sequestration requires knowledge of the mobility of carbon dioxide in brines under pressure and temperature conditions that prevail in subsurface aquifers. Here, we report Raman spectroscopic measurements of the rate of CO 2 diffusion in water and brines as a function of pressure, salinity, and concentration of CO 2 . In pure water at 50 ± 2°C and 90 ± 2 bar, we find the diffusion coefficient, D, to be (3.08 ± 0.03) × 10 −9 m 2 /s, a value that is consistent with a recent microfluidic study but lower than earlier PVT measurements. Under reservoir conditions, salinity affects the mobility of CO 2 significantly and D decreased by 45% for a 4 M solution of NaCl. We find significant differences of diffusivity of CO 2 in brines (0−4 M NaCl), in both the absolute values and the trend compared to the Stokes−Einstein prediction under our experimental conditions. We observe that D decreases significantly at the high CO 2 concentrations expected in subsurface aquifers (∼15% reduction at 0.55 mol/kg of CO 2 ) and provides an empirical correction to the commonly reported D values that assume a tracer concentration dependence on diffusivity.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Diffusivity of Carbon Dioxide in Aqueous Solutions under Geologic Carbon Sequestration Conditions

et al. 2018

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“…In addition, pulsed-field gradient spin-echo (PGSE) NMR and NMR relaxation techniques have also been applied to study the association behaviors of pluronic P105 in this work. It is known that the former technique is sensitive to large-scale motions, i.e., the overall translational motion of the unimers or the micelles in solution [23][24][25][26], while the latter technique has been demonstrated to be sensitive to the fast local motions in polymer chains [27][28][29]. Hence, the combination of 1 H NMR spectroscopy, PGSE NMR, and NMR relaxation techniques will give complete information of the effects of temperature and concentration on the microenvironment, large-scale motions, and segmental dynamics in each part of the block copolymer within the unimers, unimer-micelle transition, and micelle regions.…”

Section: Introductionmentioning

confidence: 99%

Micellization in aqueous solution of an ethylene oxide–propylene oxide triblock copolymer, investigated with 1H NMR spectroscopy, pulsed-field gradient NMR, and NMR relaxation

Chen

Tang

et al. 2007

Journal of Colloid and Interface Science

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“…[1][2][3][4][5][6][7][8] Magnetic resonance ͑MR͒ based techniques are among the most important methodologies for probing porous media, owing to their noninvasive and nonperturbing nature. Several valuable properties can be quantified to obtain valuable information about the pores.…”

Section: Introductionmentioning

confidence: 99%

Detecting diffusion-diffraction patterns in size distribution phantoms using double-pulsed field gradient NMR: Theory and experiments

Shemesh

Özarslan

Basser

et al. 2010

The Journal of Chemical Physics

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NMR observable nuclei undergoing restricted diffusion within confining pores are important reporters for microstructural features of porous media including, inter-alia, biological tissues, emulsions and rocks. Diffusion NMR, and especially the single-pulsed field gradient ͑s-PFG͒ methodology, is one of the most important noninvasive tools for studying such opaque samples, enabling extraction of important microstructural information from diffusion-diffraction phenomena. However, when the pores are not monodisperse and are characterized by a size distribution, the diffusion-diffraction patterns disappear from the signal decay, and the relevant microstructural information is mostly lost. A recent theoretical study predicted that the diffusion-diffraction patterns in double-PFG ͑d-PFG͒ experiments have unique characteristics, such as zero-crossings, that make them more robust with respect to size distributions. In this study, we theoretically compared the signal decay arising from diffusion in isolated cylindrical pores characterized by lognormal size distributions in both s-PFG and d-PFG methodologies using a recently presented general framework for treating diffusion in NMR experiments. We showed the gradual loss of diffusion-diffraction patterns in broadening size distributions in s-PFG and the robustness of the zero-crossings in d-PFG even for very large standard deviations of the size distribution. We then performed s-PFG and d-PFG experiments on well-controlled size distribution phantoms in which the ground-truth is well-known a priori. We showed that the microstructural information, as manifested in the diffusion-diffraction patterns, is lost in the s-PFG experiments, whereas in d-PFG experiments the zero-crossings of the signal persist from which relevant microstructural information can be extracted. This study provides a proof of concept that d-PFG may be useful in obtaining important microstructural features in samples characterized by size distributions.

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PFG NMR diffusion experiments for complex systems

Cited by 74 publications

References 65 publications

Diffusivity of Carbon Dioxide in Aqueous Solutions under Geologic Carbon Sequestration Conditions

Diffusivity of Carbon Dioxide in Aqueous Solutions under Geologic Carbon Sequestration Conditions

Micellization in aqueous solution of an ethylene oxide–propylene oxide triblock copolymer, investigated with 1H NMR spectroscopy, pulsed-field gradient NMR, and NMR relaxation

Detecting diffusion-diffraction patterns in size distribution phantoms using double-pulsed field gradient NMR: Theory and experiments

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