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Washing Procedure (washing + procedure)

Distribution by Scientific Domains
Chemistry66%

Selected Abstracts

Waschverfahren partikulär-disperser Systeme , Verfahrensspektrum und Aspekte der Verfahrensauswahl

CHEMIE-INGENIEUR-TECHNIK (CIT), Issue 9 2003
B. Hoffner Dipl.-Ing.
Abstract Die Waschung disperser Feststoffsysteme ist ein weit verbreiteter und komplexer Verfahrensschritt. Durch die Tatsache, dass er meist in andere Prozessoperationen eingebunden ist, unterliegt er vielfältigen Anforderungen, die deutlich über die primären Ansprüche eines hohen Abtrenngrades und niedrigen Waschflüssigkeitsbedarfs hinausgehen. Aufgrund der Wirkungsweise und Grenzen unterschiedlicher Waschverfahren ist die Auswahl eines geeigneten Waschverfahrens schwierig, da die dominierenden Wirkmechanismen z.,T. nicht ausreichend bekannt sind. Dieser Beitrag gibt einen Überblick über bestehende Waschverfahren, deren zahlreiche Einflussgrößen und über Anforderungen, die an sie gestellt werden. Eine Kategorisierung von Waschprozessen, zusammen mit der Einordnung der Verfahren hinsichtlich makroskopischer Transporteigenschaften, führt zur Entwicklung eines Bewertungsschemas, das bestehende Waschprozesse bewertet, vergleicht und Grenzen der einzelnen Verfahren aufzeigt. Die Arbeit dient als grober Leitfaden für die Auswahl eines geeigneten Waschverfahrens. Washing of Disperse Solid Systems , Existing Washing Processes and Guidelines for Choosing the Appropriate Washing Procedure Washing of disperse solid systems is a widely used and complex operation. Since the washing-step is mostly integrated into other process operations, it is subject to numerous demands, which exceed the primary demands like a good separation result and a low specific wash liquid demand. Because of the phenomenology and limits of different washing procedures it is difficult to choose an appropriate washing process. Additionally, the acting transport mechanisms of some washing procedures are not yet sufficiently understood. This work shows a broad overview over the existing washing processes, the numerous parameters and the demands they have to fulfill. A categorization of washing procedures as well as a classification of the processes concerning their macroscopic transport phenomena are the base for a broad decision chart which compares and evaluates existing washing processes and shows their individual limits. The work can be seen as a rough guideline for choosing the appropriate washing procedure. [source]

Characterization of Pectins and Some Secondary Compounds from Theobroma cacao Hulls

JOURNAL OF FOOD SCIENCE, Issue 5 2001
M. Arlorio
ABSTRACT This paper describes the chemical characterization of cocoa hulls, a potential source of high-methoxyl pectins (HMP). The content of some antinutritive compounds and potentially toxic compounds is also reported. Use of 2-propanol is proposed for the preliminary clean-up of the hulls and for the washing of the gel. Antinutritive and potentially toxic compounds seem not to limit the use of cocoa hulls. Lindane and ochratoxin A were easily removed together with fat using 2-propanol during preliminary clean up. The pectins (partially purified, yield: 1.29 ± 0.08%) showed a high methoxylation degree (%DE) of 60.53 ± 6.09%, and a viscosity of 16,200 cPs (5 rpm 20 °C). Washing procedures permit the decrease of the gel acidity from pH 1.97 to pH 3.76. [source]

Self-Propagating Domino-like Reactions in Oxidized Graphite

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
Franklin Kim
Abstract Graphite oxide (GO) has received extensive interest as a precursor for the bulk production of graphene-based materials. Here, the highly energetic nature of GO, noted from the self-propagating thermal deoxygenating reaction observed in solid state, is explored. Although the resulting graphene product is quite stable against combustion even in a natural gas flame, its thermal stability is significantly reduced when contaminated with potassium salt by-products left from GO synthesis. In particular, the contaminated GO becomes highly flammable. A gentle touch with a hot soldering iron can trigger violent, catastrophic, total combustion of such GO films, which poses a serious fire hazard. This highlights the need for efficient sample purification methods. Typically, purification of GO is hindered by its tendency to gelate as the pH value increases during rinsing. A two-step, acid,acetone washing procedure is found to be effective for suppressing gelation and thus facilitating purification. Salt-induced flammability is alarming for the fire safety of large-scale manufacturing, processing, and storage of GO materials. However, the energy released from the deoxygenation of GO can also be harnessed to drive new reactions for creating graphene-based hybrid materials. Through such domino-like reactions, graphene sheets decorated with metal and metal oxide particles are synthesized using GO as the in situ power source. Enhanced electrochemical capacitance is observed for graphene sheets loaded with RuO2 nanoparticles. [source]

Self-Propagating Domino-like Reactions in Oxidized Graphite

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
Franklin Kim
Abstract Graphite oxide (GO) has received extensive interest as a precursor for the bulk production of graphene-based materials. Here, the highly energetic nature of GO, noted from the self-propagating thermal deoxygenating reaction observed in solid state, is explored. Although the resulting graphene product is quite stable against combustion even in a natural gas flame, its thermal stability is significantly reduced when contaminated with potassium salt by-products left from GO synthesis. In particular, the contaminated GO becomes highly flammable. A gentle touch with a hot soldering iron can trigger violent, catastrophic, total combustion of such GO films, which poses a serious fire hazard. This highlights the need for efficient sample purification methods. Typically, purification of GO is hindered by its tendency to gelate as the pH value increases during rinsing. A two-step, acid,acetone washing procedure is found to be effective for suppressing gelation and thus facilitating purification. Salt-induced flammability is alarming for the fire safety of large-scale manufacturing, processing, and storage of GO materials. However, the energy released from the deoxygenation of GO can also be harnessed to drive new reactions for creating graphene-based hybrid materials. Through such domino-like reactions, graphene sheets decorated with metal and metal oxide particles are synthesized using GO as the in situ power source. Enhanced electrochemical capacitance is observed for graphene sheets loaded with RuO2 nanoparticles. [source]

Waschverfahren partikulär-disperser Systeme , Verfahrensspektrum und Aspekte der Verfahrensauswahl

CHEMIE-INGENIEUR-TECHNIK (CIT), Issue 9 2003
B. Hoffner Dipl.-Ing.
Abstract Die Waschung disperser Feststoffsysteme ist ein weit verbreiteter und komplexer Verfahrensschritt. Durch die Tatsache, dass er meist in andere Prozessoperationen eingebunden ist, unterliegt er vielfältigen Anforderungen, die deutlich über die primären Ansprüche eines hohen Abtrenngrades und niedrigen Waschflüssigkeitsbedarfs hinausgehen. Aufgrund der Wirkungsweise und Grenzen unterschiedlicher Waschverfahren ist die Auswahl eines geeigneten Waschverfahrens schwierig, da die dominierenden Wirkmechanismen z.,T. nicht ausreichend bekannt sind. Dieser Beitrag gibt einen Überblick über bestehende Waschverfahren, deren zahlreiche Einflussgrößen und über Anforderungen, die an sie gestellt werden. Eine Kategorisierung von Waschprozessen, zusammen mit der Einordnung der Verfahren hinsichtlich makroskopischer Transporteigenschaften, führt zur Entwicklung eines Bewertungsschemas, das bestehende Waschprozesse bewertet, vergleicht und Grenzen der einzelnen Verfahren aufzeigt. Die Arbeit dient als grober Leitfaden für die Auswahl eines geeigneten Waschverfahrens. Washing of Disperse Solid Systems , Existing Washing Processes and Guidelines for Choosing the Appropriate Washing Procedure Washing of disperse solid systems is a widely used and complex operation. Since the washing-step is mostly integrated into other process operations, it is subject to numerous demands, which exceed the primary demands like a good separation result and a low specific wash liquid demand. Because of the phenomenology and limits of different washing procedures it is difficult to choose an appropriate washing process. Additionally, the acting transport mechanisms of some washing procedures are not yet sufficiently understood. This work shows a broad overview over the existing washing processes, the numerous parameters and the demands they have to fulfill. A categorization of washing procedures as well as a classification of the processes concerning their macroscopic transport phenomena are the base for a broad decision chart which compares and evaluates existing washing processes and shows their individual limits. The work can be seen as a rough guideline for choosing the appropriate washing procedure. [source]

Characterisation of Nanohybrids of Porphyrins with Metallic and Semiconducting Carbon Nanotubes by EPR and Optical Spectroscopy

CHEMPHYSCHEM, Issue 13 2008
Sofie Cambré
Abstract Single-walled carbon nanotubes (SWCNTs) are noncovalently functionalised with octaethylporphyrins (OEPs) and the resulting nanohybrids are isolated from the free OEPs. Electron paramagnetic resonance (EPR) spectroscopy of cobalt(II)OEP, adsorbed on the nanotube walls by ,,,-stacking, demonstrates that the CNTs act as electron acceptors. EPR is shown to be very effective in resolving the different interactions for metallic and semiconducting tubes. Moreover, molecular oxygen is shown to bind selectively to nanohybrids with semiconducting tubes. Water solubilisation of the porphyrin/CNT nanohybrids using bile salts, after applying a thorough washing procedure, yields solutions in which at least 99,% of the porphyrins are interacting with the CNTs. Due to this purification, we observe, for the first time, the isolated absorption spectrum of the interacting porphyrins, which is strongly red-shifted compared to the free porphyrin absorption. In addition a quasi-complete quenching of the porphyrin fluorescence is also observed. [source]

DNA AND PROTEIN RECOVERY FROM WASHED EXPERIMENTAL STONE TOOLS,

ARCHAEOMETRY, Issue 4 2004
O. C. SHANKS
Traces of protein and DNA are preserved on stone tools used to process animals. Previous research documents the identification of protein residues from tools sonicated in 5% ammonium hydroxide, but it remains untested whether the same treatment yields useable DNA. In this study we report both DNA and protein recovery using 5% ammonium hydroxide from residues on stone tools. We extracted 13-year-old residues from experimentally manufactured stone tools used to butcher a single animal. We also show that surface washing procedures typically used to curate stone tools remove only a small fraction of the DNA and protein deposited during animal butchery. [source]

Waschverfahren partikulär-disperser Systeme , Verfahrensspektrum und Aspekte der Verfahrensauswahl

CHEMIE-INGENIEUR-TECHNIK (CIT), Issue 9 2003
B. Hoffner Dipl.-Ing.
Abstract Die Waschung disperser Feststoffsysteme ist ein weit verbreiteter und komplexer Verfahrensschritt. Durch die Tatsache, dass er meist in andere Prozessoperationen eingebunden ist, unterliegt er vielfältigen Anforderungen, die deutlich über die primären Ansprüche eines hohen Abtrenngrades und niedrigen Waschflüssigkeitsbedarfs hinausgehen. Aufgrund der Wirkungsweise und Grenzen unterschiedlicher Waschverfahren ist die Auswahl eines geeigneten Waschverfahrens schwierig, da die dominierenden Wirkmechanismen z.,T. nicht ausreichend bekannt sind. Dieser Beitrag gibt einen Überblick über bestehende Waschverfahren, deren zahlreiche Einflussgrößen und über Anforderungen, die an sie gestellt werden. Eine Kategorisierung von Waschprozessen, zusammen mit der Einordnung der Verfahren hinsichtlich makroskopischer Transporteigenschaften, führt zur Entwicklung eines Bewertungsschemas, das bestehende Waschprozesse bewertet, vergleicht und Grenzen der einzelnen Verfahren aufzeigt. Die Arbeit dient als grober Leitfaden für die Auswahl eines geeigneten Waschverfahrens. Washing of Disperse Solid Systems , Existing Washing Processes and Guidelines for Choosing the Appropriate Washing Procedure Washing of disperse solid systems is a widely used and complex operation. Since the washing-step is mostly integrated into other process operations, it is subject to numerous demands, which exceed the primary demands like a good separation result and a low specific wash liquid demand. Because of the phenomenology and limits of different washing procedures it is difficult to choose an appropriate washing process. Additionally, the acting transport mechanisms of some washing procedures are not yet sufficiently understood. This work shows a broad overview over the existing washing processes, the numerous parameters and the demands they have to fulfill. A categorization of washing procedures as well as a classification of the processes concerning their macroscopic transport phenomena are the base for a broad decision chart which compares and evaluates existing washing processes and shows their individual limits. The work can be seen as a rough guideline for choosing the appropriate washing procedure. [source]