Investigation of Solid Precipitate that Prevents Etching of Silicon in a Solution of Ethylenediamine and Pyrocatechol

AbstractA mathematical model of waste dissolution that includes the formation of secondary solid precipitate(s) explicitly is formulated. For a static type of experiment, the model indicates that the concentration of the highly soluble species compared to the concentration of the main component of the matrix is equal to their corresponding density in the matrix (i.e., congruent release). For low solubility nuclides, the solubility limit of precipitate(s) may be exceeded (depending on the waste composition) and a supersaturated solution is temporarily achieved. From the model, the concentration of radionuclides and mass flux at the waste form surface in a geologic repository is obtained. Numerical results (Sr-90) indicate that the liquid-surface concentration rises very rapidly after dissolution starts. In the first week, the solubility limit of Sr precipitate(s) is exceeded and Sr solid precipitate(s) will be formed. Subsequently the concentration decreases and becomes almost equal to the solubility limit and remains so for up to 1 year. It decreases later due to radioactive decay. After the first week, the surface concentration and surface mass flux are independent of the retardation coefficient throughout the leaching process. The mass transfer rate is determined by the matrix dissolution rate and not by the solubility of the precipitate.

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Isolation and Crystallographic Characterization of a Solid Precipitate/Intermediate in the Preparation of 5-Substituted 1H-Tetrazoles from Nitrile in Water

Inorganic Chemistry ◽

10.1021/ic034116i ◽

2003 ◽

Vol 42 (13) ◽

pp. 3969-3971 ◽

Cited By ~ 115

Author(s):

Li-Zhong Wang ◽

Zhi-Rong Qu ◽

Hong Zhao ◽

Xi-Sen Wang ◽

Ren-Gen Xiong ◽

...

Keyword(s):

Solid Precipitate

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In situ monitoring the viscosity change of an electrolyte in a Li–S battery

Chemical Communications ◽

10.1039/c7cc04841f ◽

2017 ◽

Vol 53 (73) ◽

pp. 10152-10155 ◽

Cited By ~ 14

Author(s):

Ning Ding ◽

Xiaodong Li ◽

Sheau Wei Chien ◽

Zhaolin Liu ◽

Yun Zong

Keyword(s):

Substance P ◽

In Situ Monitoring ◽

Soluble Substance ◽

Viscosity Change ◽

Solid Precipitate

Li2S2is not a solid precipitate, but an electrolyte–soluble substance.

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The effect of the synthesis conditions on structure and photocatalytic activity of Nb2O5 nanostructures

Processing and Application of Ceramics ◽

10.2298/pac1803218g ◽

2018 ◽

Vol 12 (3) ◽

pp. 218-229 ◽

Cited By ~ 1

Author(s):

Caterine Gómez ◽

Jorge Rodríguez-Páez

Keyword(s):

Acetic Acid ◽

Niobium Pentoxide ◽

Precipitation Method ◽

X Ray Diffraction ◽

Photo Degradation ◽

Synthesis Conditions ◽

Transmission Electron ◽

Heat Treated ◽

Solid Precipitate ◽

Controlled Precipitation

In this work, niobium pentoxide (Nb2O5) nanoparticles of varying sizes and morphology were synthesized using the controlled precipitation method. Ammonium niobate oxylate hydrate (NH4)H2[NbO(C2O4)3] ? 3H2O was used as a niobium precursor and distilled water or acetic acid was used as solvent. The obtained solids were characterized using Fourier transform infrared and Raman spectroscopies, X-ray diffraction and transmission electron microscopy. The as-synthesized solid precipitate was amorphous, but after heat treatment between 500?C and 600?C, the T-Nb2O5 phase was obtained. The size of the primary particles of the niobium pentoxide was nanometric (<100 nm), with agglomerate size of >500 nm, when water was used as a solvent for synthesis. Considering the nature of the process, a possible reaction mechanism of the precursor with the water and NH4OH was proposed, which explains the formation of the solid within an aqueous solution. Considering one potential use of Nb2O5 synthesized in this work, the photo-degradation action of the particles on the organic molecule methylene blue was tested. The sample synthesized in acetic acid at pH ~9.0 and heat treated at 600?C showed the highest photo-degradation capacity, with a degradation of ~60% of the dye for 60 minutes.

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Nucleation of a solid precipitate along a dislocation

Applied Scientific Research ◽

10.1007/bf03184587 ◽

1954 ◽

Vol 4 (4) ◽

pp. 266-272 ◽

Cited By ~ 2

Author(s):

Josef Nyström

Keyword(s):

Solid Precipitate

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Profiling Pvp/Ps Homopolymer Interfaces Using Core-Loss Electron Energy-Loss Spectroscopy

Microscopy and Microanalysis ◽

10.1017/s143192760002417x ◽

1998 ◽

Vol 4 (S2) ◽

pp. 810-811

Author(s):

K. Siangchaew ◽

P. Prayoonthong ◽

M. Libera

Keyword(s):

Electron Scattering ◽

Core Loss ◽

Polymer Interfaces ◽

Digital Analysis ◽

Bright Field ◽

Spatially Resolved ◽

Optical Electron ◽

Solid Precipitate ◽

Electron Energy Loss ◽

Technological Significance

Despite the physical and technological significance of polymer interfaces (1), they have not been extensively studied using techniques based on electron scattering. Spontak et al. (2) used digital analysis of bright-field images to study Os-stained polystyrene-polydiene block copolymer interfaces, but work in this area has been lacking largely because of difficulties with staining or uncertainties in the distribution of stain at the nanometer length scales relevant to interfaces. Studies of polymer interfaces are now largely done by neutron scattering (3) This research explores the application of spatially-resolved electron energyloss spectroscopy to measure compositional widths of polymer-polymer interfaces. These first studies focus on blends of poly(2-vinyl pyridine) (PVP) dispersed in poly(styrene) (PS) to establish the various electron-optical, electron-scattering, and specimen-dependent limitations (4) to resolving such an interfacial width. The uncompatibilized PS/PVP interface should be relatively sharp.Blends of PS (M.W. 190,000) and PVP ( M.W. 200,000) were made using a 5wt% solution of polymer in THF with a PS/PVP ratio of 7/3. The solution was cast into methanol. The resulting solid precipitate was removed and annealed under vacuum at 120°C for 36 hours.

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Optical pump–terahertz probe spectroscopy of dyes in solutions: Probing the dynamics of liquid solvent or solid precipitate?

The Journal of Chemical Physics ◽

10.1063/1.1633256 ◽

2004 ◽

Vol 120 (2) ◽

pp. 912-917 ◽

Cited By ~ 7

Author(s):

Filip Kadlec ◽

Christelle Kadlec ◽

Petr Kužel ◽

Petr Slavı́ček ◽

Pavel Jungwirth

Keyword(s):

Optical Pump ◽

Solid Precipitate ◽

Probe Spectroscopy

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One-pot room-temperature conversion of cyclohexane to adipic acid by ozone and UV light

Science ◽

10.1126/science.1259684 ◽

2014 ◽

Vol 346 (6216) ◽

pp. 1495-1498 ◽

Cited By ~ 50

Author(s):

Kuo Chu Hwang ◽

Arunachalam Sagadevan

Keyword(s):

Adipic Acid ◽

Room Temperature ◽

Uv Light ◽

Acid Synthesis ◽

Acid Oxidation ◽

One Pot ◽

Uv Light Irradiation ◽

Free Process ◽

Solid Precipitate ◽

Nitric Acid Oxidation

Nitric acid oxidation of cyclohexane accounts for ~95% of the worldwide adipic acid production and is also responsible for ~5 to 8% of the annual worldwide anthropogenic emission of the ozone-depleting greenhouse gas nitrous oxide (N2O). Here we report a N2O-free process for adipic acid synthesis. Treatment of neat cyclohexane, cyclohexanol, or cyclohexanone with ozone at room temperature and 1 atmosphere of pressure affords adipic acid as a solid precipitate. Addition of acidic water or exposure to ultraviolet (UV) light irradiation (or a combination of both) dramatically enhances the oxidative conversion of cyclohexane to adipic acid.

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Continuous-Melter Vitrification of Fernald Mixed Wastes: Distribution of Contaminants Between Glass, Scrubber Solutions and Off-Gases

MRS Proceedings ◽

10.1557/proc-333-487 ◽

1993 ◽

Vol 333 ◽

Author(s):

Keith S. Matlack ◽

Hamid Hojaji ◽

Sabrina S. Fu ◽

Ian L. Pegg ◽

Pedro B. Macedo

Keyword(s):

Minimum Amount ◽

Gaseous Emissions ◽

Two Stage ◽

Low Level ◽

Regulatory Limits ◽

Mixed Wastes ◽

Solid Precipitate ◽

Continuous Feeding

ABSTRACTResults are presented from treatability studies on the vitrification of hazardous and low-level radioactive soils and sludges from the Fernald site. The majority of the contaminants of concern are contained in large volumes of sludges accumulated from uranium and thorium production operations that are presently stored in pits at Fernald. These sludges present particular challenges to the vitrification process in that they contain significant amounts of fluorides (mostly magnesium and calcium). In this study, glass formulations used sludges, soils and a minimum amount of additives resulting in waste loadings as high as 94%. Several of these formulations were evaluated by continuous feeding of slurries into a joule-heated vitrification system. Melter off-gases were treated in a two-stage NaOH scrubbing system. HF acid fumes were neutralized, resulting in the formation of a NaF solid precipitate which is removed from the scrubber and recycled to subsequent melter feeds. Elemental and isotope compositions of the glasses, scrubber solutions, NaF precipitate and off-gases show that greater than 99.7% of uranium and thorium, 95% of Pb, Cd, Ni, Sb, Cr, and Hg were retained in the glass. Fluoride and other gaseous emissions from the scrubber system were below regulatory limits, even before HEPA filtration.

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Adsorption experiments with radium D and Radium E

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1926.0056 ◽

1926 ◽

Vol 111 (757) ◽

pp. 134-143 ◽

Cited By ~ 2

Keyword(s):

Solid Solution ◽

Active Compound ◽

Silver Chloride ◽

Barium Sulphate ◽

Common Element ◽

Active Compounds ◽

Adsorption Effect ◽

Solid Precipitate ◽

The Subject ◽

Insoluble Salt

Our knowledge of the behaviour of radio-elements in precipitation reactions is mainly due to Fajans and his co-workers, who investigated the relation existing between the completeness of the removal of the radio-element from solution and the solubility of its salt. They found that, when a filterable quantity of the precipitate of a common element was brought down in a solution containing an infinitesimal quantity of a radio-element, the radio-element itself was precipitated, if its corresponding compound was also insoluble. This general conclusion was later investigated by Fajans and Richter ( loc. cit .) with respect to thorium B, and it was further established that the degree of removal of the radio-element was dependent on the solubility of the precipitate of the ordinary element. Thus with very insoluble precipitates such as bismuth sulphide and barium sulphate, thorium B was completely precipitated, while less insoluble precipitates like silver chloride carried down only part of the radio-element. It was also suggested that when the precipitate was the insoluble salt of an isotope, the removal of the radio-element was to be ascribed to its solid solution in the isotopic precipitate, whereas removal by precipitates of dissimilar elements was an adsorption effect. This last fact, the connection between the adsorption of radio-elements by various substances and the solubility of the corresponding active compounds, was the subject of detailed researches by Paneth, and by Horovitz and Paneth. As a result, it was proved that the connection between the magnitude of the completeness of removal of the radio-element and the solubility of the analogous radio-active compound, held for a solid precipitate added to the solution as well as for the case of a precipitate brought down in the solution. Experiments have also been conducted in this field by Ebler and van Rhyn and others.

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