scholarly journals Silica Fouling in Reverse Osmosis Systems–Operando Small-Angle Neutron Scattering Studies

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 413
Author(s):  
Vitaliy Pipich ◽  
Thomas Starc ◽  
Johan Buitenhuis ◽  
Roni Kasher ◽  
Winfried Petry ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Volume Fraction ◽  
Cross Flow ◽  
Bragg Diffraction ◽  
Layer Formation ◽  
Permeate Flux ◽  
Cake Layer

We present operando small-angle neutron scattering (SANS) experiments on silica fouling at two reverse osmose (RO) membranes under almost realistic conditions of practiced RO desalination technique. To its realization, two cells were designed for pressure fields and tangential feed cross-flows up to 50 bar and 36 L/h, one cell equipped with the membrane and the other one as an empty cell to measure the feed solution in parallel far from the membrane. We studied several aqueous silica dispersions combining the parameters of colloidal radius, volume fraction, and ionic strength. A relevant result is the observation of Bragg diffraction as part of the SANS scattering pattern, representing a crystalline cake layer of simple cubic lattice structure. Other relevant parameters are silica colloidal size and volume fraction far from and above the membrane, as well as the lattice parameter of the silica cake layer, its volume fraction, thickness, and porosity in comparison with the corresponding permeate flux. The experiments show that the formation of cake layer depends to a large extent on colloidal size, ionic strength and cross-flow. Cake layer formation proved to be a reversible process, which could be dissolved at larger cross-flow. Only in one case we observed an irreversible cake layer formation showing the characteristics of an unstable phase transition. We likewise observed enhanced silica concentration and/or cake formation above the membrane, giving indication of a first order liquid–solid phase transformation.

Characterization of alumina powder using multiple small-angle neutron scattering. I. Theory

1985 ◽  
Vol 18 (6) ◽  
pp. 467-472 ◽  
Author(s):  
N. F. Berk ◽  
K. A. Hardman-Rhyne
Keyword(s):  
Particle Size ◽  
Phase Shift ◽  
Neutron Scattering ◽  
Multiple Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Volume Fraction ◽  
Scattering Data ◽  
Alumina Powder ◽  
Beam Broadening

Microstructural parameters of high-purity alumina powder are determined quantitatively throughout the bulk of the material using small-angle neutron scattering techniques. A unified theoretical and experimental approach for analyzing multiple scattering data is developed to obtain values for particle size, volume fraction and surface area. It is shown how particle size and volume fraction can be measured in a practical way from SANS data totally dominated by incoherent multiple scattering (`beam broadening'). The general phase-shift dependence of single-particle scattering is incorporated into the multiple scattering formalism, and it is also shown that the diffractive limit (small phase shift) applies even for phase shifts as large as unity (particle radii of order 1 μm). The stability of the Porod law against multiple scattering and the phase-shift scale are described, a useful empirical formula for analysis of beam broadening data is exhibited, and the applicability of the formulations to polydispersed systems is discussed.

Determination of γ′ solution temperature in Re-rich Ni-base superalloy by small-angle neutron scattering

2001 ◽  
Vol 34 (5) ◽  
pp. 541-548 ◽  
Author(s):  
Pavel Strunz ◽  
Debashis Mukherji ◽  
Ralph Gilles ◽  
Albrecht Wiedenmann ◽  
Hartmut Fuess
Keyword(s):  
Neutron Scattering ◽  
Temperature Dependence ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Volume Fraction ◽  
Solidus Temperature ◽  
Solution Temperature ◽  
Incipient Melting ◽  
Relative Volume Fraction

A harmful segregation of heavy elements (e.g.W, Mo, Re) during solidification of Ni-base superalloys can only be eliminated by using a homogenizing heat treatment, which needs to be carried out in the single-phase (γ) field above the γ′ solvus temperature but below the solidus temperature. Small-angle neutron scattering (SANS) was employed forin situobservation of the dissolution of precipitates in an Re-rich superalloy. The temperature dependence of the relative volume fraction and the size distribution of smaller γ′ precipitates, and the specific surface of large inhomogeneities as well as some other parameters were determined from the two-dimensional scattering curves measured for as-cast and heat-treated samples. Overlap of the incipient melting region with the region where a certain amount of precipitates remained undissolved was observed, thus complicating a determination of the temperature at which all γ′ precipitates are already dissolved. Nevertheless, conclusions about the temperature at which the precipitates dissolve and about the temperature at which the incipient melting starts could be formulated. The total scattering probability is suggested as the measure of the overall homogeneity of the distribution of elements in the sample. The temperature dependence of this parameter indicates the optimum solution procedure.

scholarly journals VC-Precipitation Kinetics Studied by Small-Angle Neutron Scattering in Nano-Steels

2018 ◽  
Vol 941 ◽  
pp. 236-244 ◽  
Author(s):  
Chrysoula Ioannidou ◽  
Zaloa Arechabaleta ◽  
Arjan Rijkenberg ◽  
Robert M. Dalgliesh ◽  
A.A. van Well ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Neutron Scattering ◽  
Small Angle ◽  
Inductively Coupled Plasma ◽  
Small Angle Neutron Scattering ◽  
Volume Fraction ◽  
Optical Emission ◽  
Scattering Data ◽  
High Tech ◽  
Precipitation Kinetics

Nanosteels are used in automotive applications to accomplish resource-efficiency while providing high-tech properties. Quantitative data and further understanding on the precipitation kinetics in Nanosteels can contribute to fulfil this goal. Small-Angle Neutron Scattering measurements are performed on a Fe-C-Mn-V steel, previously heat-treated in a dilatometer at 650°C for several holding times from seconds to 10 hours. The evolution of the precipitate volume fraction, size distribution and number density is calculated by fitting the experimental Small-Angle Neutron Scattering curves. The effect of phase transformation on precipitation kinetics is also discussed. Complementary Transmission Electron Microscopy, Scanning Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy measurements are performed to support the Small-Angle Neutron Scattering data analysis.

A small-angle neutron scattering study of fine-scale NbC precipitation kinetics in the α-Fe–Nb–C system

2006 ◽  
Vol 39 (4) ◽  
pp. 473-482 ◽  
Author(s):  
F. Perrard ◽  
A. Deschamps ◽  
F. Bley ◽  
P. Donnadieu ◽  
P. Maugis
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Volume Fraction ◽  
Fine Scale ◽  
Precipitation Kinetics ◽  
Maximum Reaction Rate ◽  
Maximum Reaction ◽  
Neutron Scattering Study ◽  
Precipitate Nucleation

The fine-scale precipitation of NbC in ferrite has been quantitatively characterized in the temperature range 873–1073 K for two alloy compositions, containing respectively 800 p.p.m. Nb and 400 p.p.m. Nb (by weight). Transmission electron microscopy (TEM) has revealed that the precipitates are located on dislocations, and have a plate-like morphology with an average aspect ratio between 2 and 3. Small-angle neutron scattering (SANS) has been systematically used to determine the precipitation kinetics. The validity of the quantitative SANS measurements of size and volume fraction has been assessed by TEM image analysis and chemical dissolution experiments. The precipitation kinetics is observed to depend strongly on temperature but to be similar for the two alloy compositions. From the measurements, it is inferred that precipitate nucleation is extremely rapid, in relation to the nature of the nucleation sites. A time–temperature transformation diagram is built from the kinetic data, showing a maximum reaction rate between 973 and 1073 K.

scholarly journals Mitigating background caused by extraneous scattering in small-angle neutron scattering instrument design

2021 ◽  
Vol 54 (2) ◽  
Author(s):  
John George Barker ◽  
Jeremy C. Cook ◽  
Jean Philippe Chabot ◽  
Steven R. Kline ◽  
Zhenhuan Zhang ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Incoherent Scattering ◽  
Instrument Design ◽  
Bragg Diffraction ◽  
Primary Sources ◽  
Angular Range ◽  
Beam Stop ◽  
Design Ideas

Measurements, calculations and design ideas to mitigate background caused by extraneous scattering in small-angle neutron scattering (SANS) instruments are presented. Scattering includes processes such as incoherent scattering, inelastic scattering and Bragg diffraction. Three primary sources of this type of background are investigated: the beam stop located in front of the detector, the inside lining of the detector vessel and the environment surrounding the sample. SANS measurements were made where materials with different albedos were placed in all three locations. Additional measurements of the angle-dependent scattering over the angular range of 0.7π–0.95π rad were completed on 16 different shielding materials at five wavelengths. The data were extrapolated to cover scattering angles from π/2 to π rad in order to estimate the materials' albedos. Modifications to existing SANS instruments and sample environments to mitigate extraneous scattering from surfaces are discussed.

SANS Study of Carbon Addition in Ti–45Al–5Nb

2011 ◽  
Vol 1295 ◽  
Author(s):  
P. Staron ◽  
F.-P. Schimansky ◽  
C. Scheu ◽  
H. Clemens
Keyword(s):  
Neutron Scattering ◽  
Size Distribution ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Tial Alloy ◽  
Small Volume ◽  
Volume Fraction ◽  
Atom Probe ◽  
Carbon Addition ◽  
Small Volume Fraction

ABSTRACTThe distribution of carbon in Ti–45Al–5Nb–0.5C was studied using small-angle neutron scattering (SANS). In an earlier study, carbon had been found to form small perovskite precipitates in a γ-TiAl alloy without Nb, which significantly increase the strength of the material. In the Nb-containing alloy, however, no strengthening precipitates were observed, but most of the C was found to be homogeneously distributed. Atom probe investigations revealed only few C-enriched regions. The present SANS investigation was carried out to confirm the presence and size distribution of these C-enriched regions in the material. The SANS results show that a small volume fraction of such C-enriched regions is present, while the large number of small precipitates found in the alloy without Nb is indeed missing in the Nb-containing alloy.

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