NMR studies of emulsion microstructure approaching the phase inversion point

Ling, Nicholas N. A.; Haber, Agnes; May, Eric F.; Fridjonsson, Einar O.; Johns, Michael L.

doi:10.1016/j.colsurfa.2014.08.031

Cited by 37 publications

(36 citation statements)

References 40 publications

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“…Over all practical experimental parameter space, the BGP method has been demonstrated to provide improved predictions of droplet radius a [39] compared to the SGP and GPD models. The consistency of this method was demonstrated in several previous studies [30,[45][46][47][48] and will be deployed in this work.…”

Section: Full Papersupporting

confidence: 57%

“…All droplet sizing was performed using the stimulated echo pulsed field gradient (STE PFG); the relevant pulse sequence is shown in Figure 2. The successful implementation of this pulsed field gradient technique for emulsion droplet sizing has been detailed in a number of our previous publications [30][31][32][33].…”

Section: Nuclear Magnetic Resonancementioning

confidence: 99%

“…As demonstrated in the work of Hollingsworth and Johns [50], a generalized cross validation (GCV) method can be used to determine the required regularisation parameters. This regularisation approach to determine P(a) has been extensively used and validated in several previous studies [30,[45][46][47][48].…”

Section: Full Papermentioning

confidence: 99%

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Explosive Emulsion Characterisation using Nuclear Magnetic Resonance

Hayward

Ling

Johns

2019

Propellants Explo Pyrotec

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Explosive emulsions are frequently employed in mining operations as they offer a comparatively robust, safe and effective product. These are typically formulated as concentrated ammonium nitrate solutions dispersed in an oil phase in the form of a highly concentrated water‐in‐oil emulsion. Being highly concentrated, determining the droplet size distribution (which is critical to assessing long‐term emulsion stability and explosive effectiveness) of these emulsions is challenging. Here we demonstrate that this is readily achieved using bench‐top Nuclear Magnetic resonance (NMR) Pulsed Field Gradient (PFG) techniques. The initial mean droplet size is shown to decrease with an increase in the concentration of ammonium nitrate or emulsifier or when inert salt was added to the composition, it was found to increase as the concentration of the aqueous (oxidiser) phase was increased. The emulsion droplet size distributions were observed to remain constant for a 3‐month period over the composition range explored.

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Section: Full Papersupporting

confidence: 57%

Section: Nuclear Magnetic Resonancementioning

confidence: 99%

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Explosive Emulsion Characterisation using Nuclear Magnetic Resonance

Hayward

Ling

Johns

2019

Propellants Explo Pyrotec

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“…Our implementation is detailed in a number of publications, 23,24,42,43 the salient features of which are reported here for clarity. With respect to the pulse sequence Energy Fuels XXXX, XXX, XXX−XXX in Figure 4, the acquired NMR signal, S, can be related to the free self-diffusion of molecules (e.g., water), D, via the Stejskal Tanner equation: 44…”

Section: Energy and Fuelsmentioning

confidence: 99%

NMR Studies of the Effect of CO₂ on Oilfield Emulsion Stability

et al. 2016

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Formation of water-in-crude oil emulsions is a pervasive problem for crude oil production and transportation.Here we investigate the effectiveness of a comparatively low pressure CO 2 treatment in terms of breaking these water-in-crude oil emulsions. To this end, we used unique benchtop nuclear magnetic resonance (NMR) technology to measure the droplet size distribution (DSD) of the emulsions. Treatment with 50 bar CO 2 for 2 h resulted in significant emulsion destabilization; this was replicated when CO 2 was replaced by N 2 O, which has a solubility in both the aqueous and oil phases similar to that of CO 2 . Low solubility gases, N 2 and CH 4 , by contrast had no effect on emulsion stability. Treatment with CO 2 was also found to have no effect on a model water-in-paraffin oil emulsion stabilized by a synthetic surfactant (Span 80). Collectively, this supported the hypothesis that emulsion destabilization results from CO 2 precipitation of asphaltenes as opposed to emulsion droplet film disruption during depressurization, which are the two competing theories reported in the literature to explain the observed supercritical CO 2 destabilization of emulsions. Treatment of a water-in-crude oil emulsion featuring partial removal of asphaltenes from the oil phase was consistent with this hypothesis, as the effect of the CO 2 treatment on emulsion destabilization was significantly more pronounced.

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“…The value of λ which minimises this GCV score is the optimal smoothing parameter; this is a methodology that we have widely used to interpret NMR data for emulsions [e.g. 20,22,23] and porous media [24].…”

Section: Regularisationmentioning

confidence: 99%