Use of 1H NMR to study transport processes in sulfidogenic granular sludge

1997 ◽  
Vol 36 (6-7) ◽  
pp. 157-163 ◽  
Author(s):  
Piet Lens ◽  
Look Hulshoff Pol ◽  
Gatze Lettinga ◽  
Henk Van As
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Granular Sludge ◽  
Transport Processes ◽  
Data Set ◽  
Apparent Diffusion ◽  
General Parameter ◽  
Nmr Techniques

Pulsed field gradient nuclear magnetic resonance (NMR) techniques have been applied to study diffusion and flow in a sulfidogenic granular sludge bed. When sulfidogenic granular sludge is exposed to a 20 MHz magnetic field, a multi-exponential spin-spin relaxation (T2) with at least 5 populations is observed. One of these populations (T2 ≈ 30 ms) is intracellular water. Diffusion measurements at 22°C with 1H-water as tracer indicated that sulfidogenic granular sludge contains a distribution of diffusion coefficients between 1.0 × 10−9 m2/s and 2.1 × 10−9 m2/s. Analysing the data set using a monoexponential fit gives a general parameter that can be used to describe the apparent diffusion coefficient in granular sludge. This approach showed that sulfidogenic granular sludge cultivated in different reactor configurations (UASB, USSB and baffled reactors) has comparable diffusional characteristics. Finally, the use of flow and imaging measurements in sulfidogenic granular sludge beds is discussed.

Induced polarization and pore radius — A discussion

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. D519-D526 ◽  
Author(s):  
Andreas Weller ◽  
Zeyu Zhang ◽  
Lee Slater ◽  
Sabine Kruschwitz ◽  
Matthias Halisch
Keyword(s):  
Diffusion Coefficient ◽  
Relaxation Time ◽  
Diffusion Coefficients ◽  
Pore Radius ◽  
Mercury Porosimetry ◽  
Induced Polarization ◽  
Reliable Estimate ◽  
Characteristic Relaxation Time ◽  
A Value ◽  
Apparent Diffusion

Permeability estimation from induced polarization (IP) measurements is based on a fundamental premise that the characteristic relaxation time [Formula: see text] is related to the effective hydraulic radius [Formula: see text] controlling fluid flow. The approach requires a reliable estimate of the diffusion coefficient of the ions in the electrical double layer. Others have assumed a value for the diffusion coefficient, or postulated different values for clay versus clay-free rocks. We have examined the link between a widely used single estimate of [Formula: see text] and [Formula: see text] for an extensive database of sandstone samples, in which mercury porosimetry data confirm that [Formula: see text] is reliably determined from a modification of the Hagen-Poiseuille equation assuming that the electrical tortuosity is equal to the hydraulic tortuosity. Our database does not support the existence of one or two distinct representative diffusion coefficients but instead demonstrates strong evidence for six orders of magnitude of variation in an apparent diffusion coefficient that is well-correlated with [Formula: see text] and the specific surface area per unit pore volume [Formula: see text]. Two scenarios can explain our findings: (1) the length scale defined by [Formula: see text] is not equal to [Formula: see text] and is likely much longer due to the control of pore-surface roughness or (2) the range of diffusion coefficients is large and likely determined by the relative proportions of the different minerals (e.g., silica and clays) making up the rock. In either case, the estimation of [Formula: see text] (and hence permeability) is inherently uncertain from a single characteristic IP relaxation time as considered in this study.

A Power-Law Mixing Rule for Predicting Apparent Diffusion Coefficients of Binary Gas Mixtures in Heavy Oil

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Hyun Woong Jang ◽  
Daoyong Yang ◽  
Huazhou Li
Keyword(s):  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Heavy Oil ◽  
Diffusion Coefficients ◽  
Gas Mixtures ◽  
Gas Diffusion ◽  
Gas Mixture ◽  
Mixing Rule ◽  
Heavy Oils ◽  
Apparent Diffusion

A power-law mixing rule has been developed to determine apparent diffusion coefficient of a binary gas mixture on the basis of molecular diffusion coefficients for pure gases in heavy oil. Diffusion coefficient of a pure gas under different pressures and different temperatures is predicted on the basis of the Hayduk and Cheng's equation incorporating the principle of corresponding states for one-dimensional gas diffusion in heavy oil such as the diffusion in a pressure–volume–temperature (PVT) cell. Meanwhile, a specific surface area term is added to the generated equation for three-dimensional gas diffusion in heavy oil such as the diffusion in a pendant drop. In this study, the newly developed correlations are used to reproduce the measured diffusion coefficients for pure gases diffusing in three different heavy oils, i.e., two Lloydminster heavy oils and a Cactus Lake heavy oil. Then, such predicted pure gas diffusion coefficients are adjusted based on reduced pressure, reduced temperature, and equilibrium ratio to determine apparent diffusion coefficient for a gas mixture in heavy oil, where the equilibrium ratios for hydrocarbon gases and CO2 are determined by using the equilibrium ratio charts and Standing's equations, respectively. It has been found for various gas mixtures in two different Lloydminster heavy oils that the newly developed empirical mixing rule is able to reproduce the apparent diffusion coefficient for binary gas mixtures in heavy oil with a good accuracy. For the pure gas diffusion in heavy oil, the absolute average relative deviations (AARDs) for diffusion systems with two different Lloydminster heavy oils and a Cactus Lake heavy oil are calculated to be 2.54%, 14.79%, and 6.36%, respectively. Meanwhile, for the binary gas mixture diffusion in heavy oil, the AARDs for diffusion systems with two different Lloydminster heavy oils are found to be 3.56% and 6.86%, respectively.

scholarly journals Diffusional Properties of Methanogenic Granular Sludge: 1H NMR Characterization

2003 ◽  
Vol 69 (11) ◽  
pp. 6644-6649 ◽  
Author(s):  
Piet N. L. Lens ◽  
Rakel Gastesi ◽  
Frank Vergeldt ◽  
Adriaan C. van Aelst ◽  
Antonio G. Pisabarro ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Diffusion Coefficients ◽  
Metal Sulfide ◽  
Free Water ◽  
Granular Sludge ◽  
Self Diffusion ◽  
Nmr Characterization ◽  
Self Diffusion Coefficient

ABSTRACT The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion coefficients of H2O in the investigated series of mesophilic aggregates were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion coefficients of H2O were independent of the aggregate size for the size fractions investigated. Diffusional transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor) or at high (55°C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10°C) temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90°C for 30 min) modified the diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl2 did not affect the H2O self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both physical (porosity) and chemical (metal sulfide precipitates) factors.

Diffusion of Lead from a Perforated Titanium-Shell Lead-Matrix Container

1991 ◽  
Vol 257 ◽  
Author(s):  
P. Mani Mathew ◽  
Paul A. Krueger ◽  
M. Krause
Keyword(s):  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Element Model ◽  
Dry Mass ◽  
Silica Sand ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion ◽  
Buffer Mixture ◽  
Source Concentration

ABSTRACTThis paper describes experiments and analyses conducted to determine the range of apparent diffusion coefficients of lead diffusing from an intentionally perforated lead-matrix titanium-shell container into a compacted 1:1 (by dry mass) silica-sand/sodium-bentonite buffer mixture saturated with Standard Canadian Shield Saline Solution at 363 K. Analysis of the experimental data using a single apparent diffusion coefficient could not explain the findings. A possible explanation of the behaviour is presented here. It uses a 2–D finite-element model with six lead species having six different apparent diffusion coefficients. The model can explain the data satisfactorily. Sixty-three percent of the source concentration consisted of slow-moving species, with an apparent diffusion coefficient of 10-15 m2 /s, whereas the fastest species, with an apparent diffusion coefficient of 10-10 m2 /s, constituted only three percent of the source concentration.

Effect of Carbonate on the Migration Behavior of Lanthanides in Compacted Bentonite

MRS Advances ◽  
2018 ◽  
Vol 3 (21) ◽  
pp. 1155-1160 ◽  
Author(s):  
Kazuya Idemitsu ◽  
Kazuyuki Fujii ◽  
Noriyuki Maeda ◽  
Yuki Kakoi ◽  
Noriya Okubo ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Atomic Number ◽  
Diffusion Coefficients ◽  
Chemical Species ◽  
Dry Density ◽  
Migration Behavior ◽  
Bicarbonate Concentration ◽  
Apparent Diffusion Coefficients ◽  
Carbonate Ion ◽  
Apparent Diffusion

ABSTRACTThe apparent diffusion coefficients of La, Nd, Eu, Dy, Er, and Lu in compacted bentonites were investigated at various bicarbonate concentrations. The apparent diffusion coefficients of these lanthanides tended to decrease with increasing dry density. At bicarbonate concentrations below 0.25 M, lanthanum had the largest diffusion coefficient (ca. 10-13 m2/s) at 1.0 Mg/m3, and the diffusion coefficient decreased with increasing atomic number. On the other hand, at bicarbonate concentrations above 0.25 M, lutetium had the largest diffusion coefficient, and the diffusion coefficient decreased with decreasing atomic number. In particular, lanthanum and neodymium had diffusion coefficients below 10-14 m2/s, even at 1.0 Mg/m3. The diffusion coefficient of europium was around 10-13 m2/s at 1.0 Mg/m3 and was influenced less by the bicarbonate concentration. The diffusion coefficient of lutetium increased from 2 × 10-14 to 10-12 m2/s as the bicarbonate concentration was increased to 1.0 M. The concentration of carbonate ion in the pore water of bentonite is estimated to be much lower than that in solutions in contact with bentonite from the viewpoints of solubility and chemical species of lanthanides.

scholarly journals Distinguishing Positional Uncertainty from True Mobility in Single-Molecule Trajectories That Exhibit Multiple Diffusive Modes

2012 ◽  
Vol 18 (4) ◽  
pp. 793-797 ◽  
Author(s):  
Mark Kastantin ◽  
Daniel K. Schwartz
Keyword(s):  
Diffusion Coefficient ◽  
Single Molecule ◽  
Apparent Motion ◽  
Diffusion Coefficients ◽  
Hydrophobic Surface ◽  
Time Interval ◽  
Apparent Diffusion Coefficients ◽  
Positional Uncertainty ◽  
Apparent Diffusion ◽  
Diffusive Modes

AbstractAlthough imperfect spatial localization in single-molecule object tracking experiments has long been recognized to induce apparent motion in an immobile population of molecules, this effect is often ignored or incorrectly analyzed for mobile molecules. In particular, apparent motion due to positional uncertainty is often incorrectly assigned as a distinct diffusive mode. Here we show that, due to both static and dynamic contributions, positional uncertainty does not introduce a new apparent diffusive mode into trajectories, but instead causes a systematic shift of each measured diffusion coefficient. This shift is relatively simple: a factor of σ2/Δt is added to each diffusion coefficient, where σ is the positional uncertainty length scale and Δt is the time interval between observations. Therefore, by calculating the apparent diffusion coefficients as a function of Δt, it is straightforward to separate the true diffusion coefficients from the effective positional uncertainty. As a concrete demonstration, we apply this approach to the diffusion of the protein fibrinogen adsorbed to a hydrophobic surface, a system that exhibits three distinct modes of diffusion.

scholarly journals Reduction in Water and Metabolite Apparent Diffusion Coefficients During Energy Failure Involves Cation-Dependent Mechanisms. A Proton Nuclear Magnetic Resonance Study of Rat Cortical Brain Slices

2000 ◽  
Vol 20 (2) ◽  
pp. 405-411 ◽  
Author(s):  
Juhana M. Hakumäki ◽  
Tiina R. M. Pirttilä ◽  
Risto A. Kauppinen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Diffusion Coefficients ◽  
Brain Slices ◽  
Proton Nuclear Magnetic Resonance ◽  
Tissue Water ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion ◽  
Energy Failure ◽  
Nuclear Magnetic

Proton (1H) nuclear magnetic resonance (NMR) diffusion spectroscopy was used to assess apparent diffusion coefficients (ADCs) in rat brain slices. Aglycemic hypoxia caused reductions in the ADC of N-acetylaspartate (NAA) (0.15 to 0.09 × 10−3 mm2/s) and “slow” diffusion coefficient ( D2) of tissue water (0.51 to 0.37 × 10−3 mm2/s), together with a 32 ± 11% increase in tissue water volume, attributable to tissue swelling. The ADC and D2 reductions were diminished, however, by removing external Ca2+, and under 10 mmol/L Mg2+, normoxic diffusion coefficients persisted until 40 minutes of hypoxia. The data suggest that the shift of water into the intracellular space alone cannot satisfactorily explain the reduced cerebral diffusion upon energy failure and that external Mg2+ and Ca2+ play crucial modulatory roles.

Methods to measure apparent diffusion coefficients in compacted bentonite clays and data interpretation

1989 ◽  
Vol 16 (4) ◽  
pp. 434-443 ◽  
Author(s):  
S. C. H. Cheung
Keyword(s):  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Data Interpretation ◽  
Clay Particles ◽  
Apparent Diffusion Coefficients ◽  
Compacted Bentonite ◽  
Diffusion Parameters ◽  
Apparent Diffusion ◽  
Bentonite Clays

The methods used to determine apparent diffusion coefficients and the appropriate parameters for modelling diffusion through compacted bentonite–water systems are assessed and discussed. The measured apparent diffusion coefficient can vary between methods. The discrepancies are shown to be due to heterogeneous diffusivities arising from the proximity of the surface of clay particles. Two different diffusivity pathways are identified and the diffusive flux is shown to be dictated by the charge of diffusing species, diffusion time, and soil fabric. Key words: apparent diffusion coefficient, methods, compacted bentonite, heterogeneous diffusion, parameters, pathways.

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