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Ceramic hollow fiber membranes are investigated with respect to the fouling behavior. Constant pressure dead-end filtration experiments have been performed using alginate as model substance for extracellular polymeric substances. In addition to the evaluation of the filtration data using conventional cake filtration model, nuclear magnetic resonance imaging (MRI) was used to elucidate the influence of Ca2+ on the fouling layer structure for alginate filtration within ceramic hollow fiber membranes. To visualize the alginate layers inside the opaque ceramic hollow fiber membranes by means of MRI, specific contrast agents were applied. Supplementary to multi slice multi echo imaging, flow velocity measurements were performed to gain more insight into the hydrodynamics in the fouled membranes. MRI reveals the structure of the alginate layers with the finding that the addition of Ca2+ to the alginate feed solution promotes the formation of a dense alginate gel layer on the membrane's surface. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2459-2467, 2016 [ABSTRACT FROM AUTHOR]

Abstract: The progress of the cure reaction of hydroxyl-terminated (poly)butadiene (HTPB) and isophorone diisocyanate (IPDI) to a polyurethane is of major importance for the adjustment of process parameters as well as final product properties. Simultaneous low field nuclear magnetic resonance relaxometry and near infrared spectroscopy are applied in-situ to study the progress of the cure reaction with respect to time. The sensitive spots of both methods are coincident, allowing quantitative comparison of the results of both methods, as the same region of the sample is examined. The aim is to get a more comprehensive insight into the reaction by the combination of the two analytical methods. Molecular dynamics as provided by NMR relaxation data and chemical concentration information via near infrared spectroscopy allow detailed monitoring and deeper insight into the complex reaction. [Copyright &y& Elsevier]

For the successful production of functional multiple emulsions, it is crucial to monitor the amount of encapsulated inner phase and thus the encapsulation efficiency EE. In order to do this, only few methods are available for oil-in-water-in-oil emulsions. We compare two possible methods – rheometric determination of EE and determination by NMR. These techniques are applied to OWO emulsions with internally gelled water phase, the main purpose of this being an increased stability against coalescence of inner oil droplets due to reduced droplet movement. It can be seen that both measurement techniques are suitable for qualitative comparison of OWO emulsions’ EE. Harsher processing conditions result in smaller outer droplet sizes and reduced EE. It is also shown that a higher amount of the hydrophilic emulsifier chosen improves the EE at sensitive production. Higher stability is provided by gelling of the water phase by hydrocolloids. [ABSTRACT FROM AUTHOR]

We explore the capability of 1H NMR spectroscopy, relaxation and diffusion for the characterization of thermally-induced degradation of fresh motor oils. Temperature dependent measurements of diffusion show a weak sensitivity to thermal degradation. In contrast, both the transverse relaxation at 1H Larmor frequencies of 20 MHz and 400 MHz, as well as the longitudinal relaxation at 60 kHz showed to be sensitive to thermally-induced effects at measured temperatures within the range −10 °C to 30 °C. Results show that the highest sensitivity significance can be reached by fast field-cycling NMR relaxometry measurements at low magnetic fields. Image 1 • 1H NMR Spectroscopy, Diffusometry and Relaxometry are used to characterize thermally-induced degradation of motor oil. • The sensitivity and capability of detection of each technique is analyzed. • NMR diffusion and longitudinal relaxation are completely insensitive in the MHz regime. • Transverse relaxation is sensitive at low temperatures (around 0 °C or lower). • Longitudinal relaxation measured at 60 kHz and room temperature is much more sensitive. [ABSTRACT FROM AUTHOR]

Highlights • NMR monitors oil degradation by relaxation and diffusion. • Quality control of oils can be achieved by low field NMR. • Fast field cycling as well as single-sided NMR allow to study oil aging. Abstract Time domain, also named lowfield nuclear magnetic resonance is used to monitor oil degradation by measuring relaxation and diffusion. As quality control of oils is indispensable to optimize oil change intervals while simultaneously preventing machinery damage, the technique was applied to detect the degradation state of engine oils as time domain nuclear magnetic resonance is known as a well suited tool to measure quality control parameters for example in food industry. Correlations with commonly applied oil analytics like viscosity measurements and inductively coupled plasma optical emission spectrometry allow to interpret relaxation and diffusion data in detail and finally to deepen the understanding of oil aging processes. Additionally, the measurement temperature was varied to achieve the maximum sensitivity towards oil aging. Low field NMR is not only realized in form of table top instruments, but also in form of field cycling and single sided NMR devices. Fast field cycling as well as single-sided NMR were also explored to study oil aging and to provide valuable insight. The latter device was used to obtain information about translational diffusion and transverse relaxation of oils simultaneously. [ABSTRACT FROM AUTHOR]

O/W/O double emulsions are studied by means of 1 H nuclear magnetic resonance (NMR) and confocal laser scanning microscopy (CLSM) with respect to their structural and diffusion properties. Due to the structure of double emulsions, common droplet sizing techniques such as laser scattering methods show limited applicability, especially with respect to the inner droplet size distribution and dynamic effects on the molecular level. However, geometrical and structural information can be extracted from pulsed field gradient stimulated echo (PFG-STE) NMR measurements, as the molecules in the different phases experience hindered and restricted diffusion due to the interfaces. Additionally, the permeability of the interfaces and the diffusion across the intermediate (hetero) phase can be observed either by PFG-STE NMR or by exploiting the possibilities of paramagnetic relaxation enhancement. The NMR results are confirmed by CLSM with respect to both the droplet size distribution and the exchange of molecules in this publication especially for the O/W/O type of double emulsions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Droplet size distribution by NMR diffusometry. [•] Disperse phase ratios by NMR spectroscopy. [•] Molecular exchange between phases via NMR diffusometry and paramagnetic relaxation enhancement. [•] Kinetics of dye diffusion between phases driven by concentration gradients and observed by CLSM. [Copyright &y& Elsevier]