File Silica gel bag open with beads.jpg thumb Silica gel A desiccant is a hygroscopic substance that induces or sustains a state of dryness desiccation in its local vicinity in a moderately well sealed ... of water molecules. Pre packaged desiccant is most commonly used to remove excessive humidity ... , and molecular sieve s. A specific usage of a desiccant would be in Insulated glazing insulated windows ... condensation between the panes. Toxicity A desiccant may be chosen for a particular task based ... desirable for a desiccant to be substantially chemically stable or chemically inert , and a number ... gel, chalk and clay based desiccants. Performance efficiency One measure of desiccant efficiency is the ratio or percentage of water storable in the desiccant, relative to the mass of desiccant. Another ... of any desiccant varies with temperature and both relative humidity and absolute humidity . To some extent, desiccant performance can be precisely described, but most commonly, the final choice of which desiccant best suits a given situation, how much of it to use, and in what form, is made based ... right thumb Indicating Silica Gel Often some sort of humidity indicator is included in the desiccant to show, by color changes, the degree of water saturation of the desiccant. One commonly used indicator ... with the desiccant. Often, the desiccant will react with moisture to form an insoluble solid that can .... year 1982 title Second Law Analysis of Desiccant Cooling Systems journal Journal of Solar Energy ... volume 25 pages 269 issue 3 External links http www.absorcare.net desiccantDesiccant Science and Tehnology Published Paper http foodsave.net controlled atmosphere requiremen.htm Desiccant Requirement Chart printable http www.qiaoyun.net desiccant desiccant.htm Latest US desiccants patents information. http www.agmcontainer.com desiccantcity desiccant calculator.php A Desiccant Requirements Calculator ... en Education Center http solarteam.org page.php?id 641 Liquid Desiccant Waterfall for attractive building ... more details
The term drying agent has different meanings Desiccant for materials that absorb moisture and water Oil drying agent s for compounds that speed up the drying oil hardening of oils , often used in painting disambig ... more details
A desiccant is a substance that absorbs water. It is most commonly used to remove humidity that would normally degrade or even destroy products sensitive to moisture. see also desiccant List of desiccants Activated alumina Aerogel Benzophenone Bentonite Bentonite clay Calcium chloride Calcium sulfate Cobalt II chloride Copper II sulfate Lithium chloride Lithium bromide Magnesium sulfate Magnesium perchlorate Molecular sieve Potassium carbonate Silica gel Sodium Sodium chlorate Sodium chloride Sodium hydroxide Sodium sulfate Sucrose External links http www.mallbaker.com techlib documents americas 3045.html Desiccant Selection Guide http www.merck chemicals.com is bin INTERSHOP.enfinity WFS Merck International Site en US USD ViewProductDetail Attachments?ProductUUID 0Y.b.s1ORWYAAAEWCLMW4z8f&PortalCatalogUUID Uc6b.s1LfzAAAAEW6tYfVhTl&SelectedDocumentType Bro ankerBrochures Drying agents brochure from Merck http www.sud chemie.com scmcms web content.jsp?nodeId 3944&lang en Education Center Category Desiccants Category Chemistry lists Desiccants pt Anexo Lista de dessecantes nl Lijst van droogmiddelen ... more details
Image chem drying tubes.jpg thumb right 250px A variety of empty glass drying tubes. When used, they are packed with a desiccant, usually calcium chloride. A drying tube or guard tube is a tube like piece of apparatus used to house a disposable solid desiccant , wherein at one end the tube like structure terminates in a ground glass joint for use in connecting the drying tube to a reaction vessel, for the purpose of keeping that reaction vessel free of moisture. ref CUBoulder Organic Chemistry. Glassware Drying Tubes. Consulted on 17 November 2011. http orgchem.colorado.edu equipment glassware drytube.html ref The tube like structure is often bent and can also widen to form a bulb desiccant reservoir. Typically a drying tube is 1 2 cm wide and 5 10 cm long and bent at an angle of about 90 degrees. In use, the drying tube is filled with a rechargeable desiccant such as calcium chloride , and the open end of drying tube is partially blocked e.g. with wool, glasswool or a bung cork which has a small bore made in it and the drying tube is connected to the apparatus to be kept dry via the ground glass joint. If the drying tube is bent the bend is oriented so that solid desiccant does not fall into the reaction vessel. Some drying tubes have a glass sinter to prevent desiccant falling into the reaction vessel. Drying tubes are often prepared in advance and the desiccant can be replaced when exhausted. Reactions which are being heated, or which evolve gases, must never be sealed because an overpressure may shatter the vessel. Drying tubes are usually fitted on top of the reflux condenser laboratory condenser , allowing the pressure to be relieved while excluding atmospheric moisture. ref Unidata. Drying Tubes. Consulted on 17 November 2011. http www.unidata.com.au products starflow 6603dt index.html ref Drying tubes are often used in less demanding applications, typically in organic syntheses . While the reaction is often carried out at room temperature, the solv ... more details
for the chambers used in chemistry Desiccator A dry box is a storage container in which the interior is kept at a low level of humidity. Dry boxes are used to safely store items which would otherwise be damaged or adversely affected by excessive humidity , such as Camera cameras and Camera lens lenses to prevent fungal growth , and musical instruments to prevent humidity induced swelling or shrinkage of wooden instrument parts . They are also used in the storage of surface mount electronic components prior to circuit board assembly. Types Desiccant boxes A simple dry box can consist of nothing more than a sealed, airtight box containing a desiccant such as silica gel or anhydrous calcium chloride. These can be easily built at relatively low cost. However, the humidity level in such boxes cannot be controlled or regulated owing to the difficulty of gauging the quantity of desiccant required to achieve a certain humidity level. Electronic dry boxes Electronic dry boxes contain a small Thermoelectric cooling peltier cooler , which remove moisture from the air by condensing it out. A control dial is usually provided which permits the user rough adjustment of the humidity level. More sophisticated designs link the cooler to a settable digital hygrometer, allowing very precise humidity level control. References references http www.XDry.com Xdry.com http www.drycabinets.com DryCabinets.com http www.2spi.com catalog boxes basic glove.shtml http www.2spi.com catalog boxes nitro box.shtml Category Tools tool stub ... more details
Cleanup date August 2010 A humidity indicator is a moisture sensitive chemical that changes color when the indicated relative humidity is exceeded. Some chemicals are cobalt II chloride toxic blue to pink copper II chloride yellow to blue There are other colors like Orange colour orange See also Moisture analysis Humidity indicator card Desiccant http www.healthocrates.com Chemical Sensitive Chemical Sensitive Chem stub DEFAULTSORT Humidity Indicator Category Desiccation ... more details
People Mitsuda is a Japanese surname. People with the name Mitsuda include Ken Mitsuda , actor Takuya Mitsuda , manga artist Yasunori Mitsuda , video game composer Other users Mitsuda e , painting with litharge used as a desiccant ref cite web url http www.aisf.or.jp jaanus deta m mitsudae.htm title Mitsuda e publisher Japanese Architecture and Art Net Users System accessdate 9 March 2012 ref References Reflist disambiguation ... more details
Refimprove date December 2008 File Active Al2O3.jpg thumb 300px Activated alumina Activated alumina is manufactured from aluminium hydroxide by dehydroxylating it in a way that produces a highly porous material this material can have a surface area significantly over 200 square metres g. The compound is used as a desiccant to keep things dry by absorbing water from the air and as a filter water filter of fluoride , arsenic and selenium in drinking water . It is made of aluminium oxide alumina Al sub 2 sub O sub 3 sub , the same chemical substance as sapphire and rubies but without the impurities that give those gems their color . It has a very high surface area to weight ratio. That means it has a lot of very small pores, almost like tunnels, that run throughout it. Uses Catalyst applications Activated alumina is used for a wide range of adsorbent and catalyst applications including the adsorption of catalysts in polyethylene production, in hydrogen peroxide production, as a selective adsorbent for many chemicals including arsenic , fluoride , in sulfur removal from gas streams Claus Catalyst process . Desiccant Use as a desiccant, it works by a process called adsorption . The water in the air actually sticks to the alumina itself in between the tiny passages, as the air passes through them. The water molecules become trapped so that the air is dried out as it passes through the filter. This process is reversible, and if the alumina desiccant is heated to about 200 C it will release all of the water stored in it. This process is called regenerating the desiccant. Air always has some water in it one way to measure the amount of water in the air is the air s dew point . Fluoride adsorbent Activated alumina is also widely used to remove fluoride from drinking water. In the US, there are widespread water fluoridation programs to fluoridate drinking water. However, in certain regions, such as the Jaipur region of India, there is enough fluoride in the water to cause fluo ... more details
Unreferenced date December 2009 Humidity buffering refers to the ability of materials to moderate changes in relative humidity by absorbing and desorbing water vapour from surrounding air. This is also referred to as moisture buffering . The phenomenon has long been exploited for preserving items from damage that could be caused by either excessively moist or dry conditions. Examples 1. Cigars are usually kept in a wooden box called a humidor . A pan of water is placed in the humidor so that the wood will absorb water vapor at close to 100 Relative Humidity . It is then used to store the cigars at fairly constant relative humidity, between 45 50 . 2. Silica Gel is widely used in the opposite way, as a desiccant to buffer relative humidity inside museum display cases, packaged clothing, electronics and anything that might be damaged by condensation. Recently, there has been an interest in the field of building science and architecture in using humidity buffering as a passive indoor climate control, thus reducing the need for air conditioning and Ventilation architecture ventilation . br See also Desiccant Humectant DEFAULTSORT Humidity Buffering Category Atmospheric thermodynamics Category Heating, ventilating, and air conditioning ... more details
Orphan date February 2009 In pharmacology , diapalma from Latin Lat dia , made of palma , palm ref name OED OED diapalma ref is a desiccant desiccating or drying plaster , named for the wood of the palm tree , from which the spatula is made that is used to stir the mixture while boiling. ref name cycl 1728 ref It was formerly composed of common oil, hogs fat, and litharge of gold ref name cycl or also of palm oil , litharge, and zinc sulfate . Now, it is made of white wax, emplastrum simplex, and sulfate of zinc. ref name OED References references Category Desiccants dermatologic drug stub ... more details
temperatures resulting in better performance. Desiccant dryer The term desiccant dryer refers ... with an absorbent media such as activated alumina, silica gel , molecular sieve or other desiccant material. The desiccant can bring the dewpoint of the water vapor in the air down to 40 degrees C ... water until it is cooled to 40 degrees C 40 degrees F . In practice, two cylinders with desiccant .... The regeneration of the desiccant vessel can be during three different methods Heatless pressure swing drying, which uses part of the dry compressed air coming from the other vessel to dry the desiccant ... more details
Wiktionarypar dryer drier A dryer or drier most commonly means Hair dryer Hand dryer Clothes dryer , also known as a tumble dryer Belt dryer Cereal dryer , for food preservation Desiccant , a substance that absorbs or adsorbs water Grain dryer for storage grain bin s Oil drying agent , an additive which accelerates the film formation of a drying oil People Fred Dryer , American pro football player and actor Ivan Dryer , Designer of laser light shows Moosie Drier , American actor Sally Dryer , American voice actress from the 1960s Thomas J. Dryer , 19th century American newspaper publisher Music Dryer band , a Saratoga Springs, NY based band See also Dreier Drying disambig it Essiccatoio ko ja tr Kurutma makinesi ... more details
oxide with magnesium in the presence of hydrogen CaO Mg H sub 2 sub CaH sub 2 sub MgO Use as a desiccant ..., filtration, or decantation. As calcium hydride is a relatively mild desiccant, it is safe compared ... used as a desiccant for base chemistry basic solvents such as amine s and pyridine . ref Gawley ... prior to the use of a more reactive desiccant. Drawbacks Although CaH sub 2 sub is indeed convenient ... more details
to burn a wide variety of liquid fuels. Desiccant Wheel A desiccant wheel is very similar to a thermal .... The desiccant is normally Silica Gel . As the wheel turns, the desiccant passes alternately through ... the desiccant is dried and the moisture expelled. The wheel continues to rotate and the adsorbent ... or steam coil, or a direct fired gas burner. Thermal wheels and desiccant wheels are often used ... more details
primarysources date May 2009 File Drierite.jpg thumb A jar of drierite. File Drierite indicateur cropped.jpg thumb Left dry Right moist Drierite is the brand name and registered trademark of a variety of desiccant s made from anhydrous calcium sulfate gypsum . Some varieties contain 3 cobalt II chloride , a moisture sensitive color indicator that shows when that material s activity has been depleted. Drierite is manufactured in the USA by the W.A. Hammond Drierite Co., Ltd., founded by William Archie Hammond and headquartered in Xenia, Ohio . ref name WAHammond cite web last Cosenza first Curt title Drierite Desiccants url https secure.drierite.com catalog3 page3.cfm work Drierite accessdate 3 February 2012 ref After drierite has been exposed to moisture, it can be regenerated by baking at 210 C for an hour. ref name WAHammondtech cite web last Cosenza first Curt title Technical Data Regeneration of Drierite Desiccants url https secure.drierite.com catalog3 page19b.cfm work Drierite accessdate 3 February 2012 ref References reflist Category Laboratory equipment Category Desiccants fr Drierite ... more details
Image Toluene with sodium benzophenone.jpg right thumb Before Toluene is refluxed with sodium benzophenone to dry and deoxygenate it. Image Toluene with sodium benzophenone intense blue.jpg right thumb After The deep blue coloration of the benzophenone ketyl radical shows that the toluene to be distilled is dry and oxygen free. A ketyl group in organic chemistry is an anion radical chemistry radical with the general structure C O sup . sup in which an oxygen radical chemistry radical is bonded directly to carbon . This radical is very unstable and appears in chemical reactions as a reactive intermediate . Another mesomer mesomeric structure has the radical position on carbon and the negative charge on oxygen ref GoldBookRef title ketyls file K03389 ref . Image Ketyl structure.svg 200px A ketyl Ketyls can be formed as radical ion radical anion s by one electron reduction of carbonyl s with alkali metal s. Ketyls are also involved in the pinacol coupling reaction and the McMurry reaction . They can also be used as reagent for determining small amounts of water. The ketyl molecule is intensely colored. Ketyl radicals can be found in the use of sodium benzophenone as a desiccant in distilling solvents. Sodium reduces benzophenone to the soluble ketyl radical, which reacts quickly with the water and oxygen dissolved in the solvent. The deep blue coloration qualitatively indicates dry, oxygen free conditions. References Reflist Category functional groups Category Free radicals de Ketylradikal es Cetilo ja ru ... more details
gun before he can finish. Instead, he tries to take the desiccant packs from the clothing ... and unknowingly drops one of the desiccant packs in the salsa sauce salsa dip . Speed Dial Meanwhile ... of her emergency speed dials. Later, she is poisoned by eating desiccant from Putumayo s clothing ... more details
Moisture Sensitivity Level relates to the packaging and handling precautions for some semiconductors. The MSL is an Electronics electronic standard for the time period in which a moisture sensitive device can be exposed to ambient room conditions approximately 30 C 60 RH . Increasingly, semiconductors have been manufactured in smaller sizes. Components such as thin fine pitch devices and ball grid array s could be damaged during Surface mount technology SMT reflow when moisture trapped inside the component expands. The expansion of trapped moisture can result in internal separation delamination of the plastic from the die or lead frame, wire bond damage, die damage, and internal cracks. Most of this damage is not visible on the component surface. In extreme cases, cracks will extend to the component surface. In the most severe cases, the component will bulge and pop. This is known as the popcorn effect. IPC electronics IPC Association Connecting Electronic Industries created and released IPC M 109, Moisture sensitive Component Standards and Guideline Manual. Moisture sensitive devices are packaged in a moisture barrier antistatic bag with a desiccant and a moisture indicator card which is sealed. IPC M 109 includes seven documents. According to http www.siliconfareast.com msl.htm IPC JEDEC s J STD 20 Moisture Reflow Sensitivity Classification for Plastic Integrated Circuit IC SMDs, there are eight levels of moisture sensitivity. Components must be mounted and reflowed within the allowable period of time floor life out of the bag . MSL 6 Mandatory Bake before use MSL 5A 24 hours MSL 5 48 hours MSL 4 72 hours MSL 3 168 hours MSL 2A 4 weeks MSL 2 1 year MSL 1 Unlimited Category Integrated circuits Category Semiconductors de Moisture Sensitive Level ... more details
Orphan date January 2011 Image M SG reducing agent.svg right 500px frame M SG reductions benzyl chloride reduction to bibenzyl , dibenzothiophene reduction to biphenyl and naphthalene reduction to dihydronaphthalene In M SG an alkali metal is absorbed into silica gel at elevated temperatures. The resulting black powder material is an effective reducing agent and safe to handle as opposed to the pure metal. The material can also be used as a desiccant and as a hydrogen source ref Alkali Metals Plus Silica Gel Powerful Reducing Agents and Convenient Hydrogen Sources James L. Dye, Kevin D. Cram, Stephanie A. Urbin, Mikhail Y. Redko, James E. Jackson, and Michael Lefenfeld J. Am. Chem. Soc. , 127 26 , 9338 9339, 2005 http pubs.acs.org cgi bin abstract.cgi jacsat 2005 127 i26 abs ja051786 .html Abstract ref . The metal is either sodium or a sodium potassium alloy NaK Na sub 2 sub K . The molten metal is mixed with silica gel under constant agitation at room temperature . This phase 0 material must be handled in an inert atmosphere. Heating phase 0 at convert 150 C F takes it to phase I . When this material is exposed to dry oxygen the reducing power is not affected. At further heating to convert 400 C F phase II can be handled safely in an ambient environment. The metal reacts with the silicon gel in an exothermic reaction in which Na sub 4 sub Si sub 4 sub nanotechnology nanoparticles are formed. The powder reacts with water to form hydrogen . Compounds such as biphenyl and naphthalene are reduced by the powder and form highly coloured radical ion radical anion s. The powder can also be introduced in a column chromatography setup and eluted with organic reactants in order to probe the reducing power. The powder is mixed with additional wet silica gel which provides additional hydrogen. A Birch reduction of naphthalene takes 5 minutes elution time . The column converts benzyl chloride to bibenzyl in a Wurtz coupling and in a similar fashion dibenzothiophene is reduced to ... more details
Palladium on carbon , often referred to as Pd C , is a form of palladium used for catalysis . It is usually used for catalytic hydrogenation s in organic chemistry . When the metal is distributed over finely divided carbon, the surface area is larger and the catalyst is more reactive. Palladium on carbon has also been used as the palladium 0 catalyst in the Suzuki reaction , Stille reaction ref Liebeskind, L. S. Pe a Cabrera, E. Organic Syntheses , Coll. Vol. 10, p.9 2004 Vol. 77, p.135 2000 . http www.orgsyn.org orgsyn prep.asp?prep v77p0135 Article ref , and related reactions. Preparation Palladium on carbon is commercially available, with a Chemical Abstracts Service CAS number of 7440 05 3. It can also be prepared in the laboratory. In a typical procedure, palladium II chloride and hydrochloric acid are added to sodium acetate sodium acetate trihydrate . Then nitric acid washed activated carbon is added and the mixture is hydrogenated. This composite is then vacuum filtered and dried in a vacuum desiccator over a desiccant such as potassium hydroxide or calcium chloride . The palladium loading is typically between 5 and 10 . ref OrgSynth author Ralph Mozingo title Palladium Catalysts collvol 3 collvolpages 685 prep cv3p0685 year 1955 ref Safety Palladium on carbon is pyrophoric under certain conditions Fact date November 2007 . References reflist See also Lindlar catalyst Platinum on carbon Raney nickel Category catalysts Category palladium compounds fr Palladium sur charbon nl Palladium op koolstof ja ru zh ... more details
original research date April 2009 primarysources date April 2009 Infobox Disease Name PAGENAME Image Appy5.jpg Caption A fecalith marked by the arrow which has resulted in acute appendicitis. DiseasesDB ICD10 ICD10 K 38 1 k 35 ICD9 ICD9 560.39 ICDO OMIM MedlinePlus eMedicineSubj eMedicineTopic MeshID A fecaloma , also called fecalith , fecolith and coprolith , i.e., a stone made of feces , is a hardening of feces into lumps of varying size inside the Colon anatomy colon , which may appear whenever chronic obstruction of transit occurs, such as in megacolon and chronic constipation . Some diseases, such as Chagas disease , Hirschsprung s disease and others damage the autonomic nervous system in the colon s mucosa Auerbach s plexus and may cause extremely large or giant fecalomas, which must be surgically removed disimpaction . Rarely, a fecalith will form around a hairball Bezoar Trichobezoar , or other hygroscopic or desiccant nucleus. Distal or sigmoid, fecalomas can often be disimpacted digitally or by a catheter which carries a flow of disimpaction fluid water or other solvent or lubricant . Fecal impaction and attempts at removal can have severe and even lethal effects, such as the rupture of the colon wall by catheter or an acute angle of the fecaloma stercoral perforation , followed by septicemia . A small fecalith is one cause of both appendicitis and acute diverticulitis . See also Fecal impaction Coprolith is also used to mean Coprolite geologically fossilized feces . References reflist cite journal author Garisto J, Campillo L, Edwards E, Harbour M, Ermocilla R title Giant fecaloma in a 12 year old boy a case report journal Cases volume 2 127 issue 1 page 127 year 2009 pmid 19196473 pmc 2642792 doi 10.1186 1757 1626 2 127 url http casesjournal.com casesjournal article view 7674 3106 format dead link date April 2010 Digestive system diseases Category Diseases of appendix Category Feces ca Fecaloma de Kotstein es Fecaloma fr F calome it Fecaloma pt Fecaloma ... more details
Unreferenced date December 2009 Convectant Drying Convectant drying has emerged in the last few years as an alternative to conventional drying techniques. Convectant drying is an open system incorporating heat and air movement to provide positive air pressure with high heat and therefore low relative humidity. One hundred percent outside air is heated and repeatedly exchanged with the saturated air from the building. Convectant drying heats outside air and therefore requires cool dry air to reach maximum potential. Knowing the conditions, limitations, and benefits will help you select the proper drying dehumidification tool. Other Methods of Drying Refrigerant dehumidifiers, conventional Operation range 65F to 90F 18 C to 32 C . Temperatures above or below are out of the effective range. Inexpensive, portable, easy to set up. If used properly and in sufficient quantities can reduce RH to 60 . Low Grain Refrigerants LGR s Effective in lower temperature conditions than conventional refrigerants. Manufacturers claim 33 degrees Fahrenheit. Humidity levels to 40 RH. More expensive and more labor intensive than conventional dehumidifiers. Can be an effective structural drying tool. dehumidifier Desiccant dehumidifiers Work on the principle of absorption chemistry absorption . Wet air is attracted to moisture absorbent material. Operation range from 10F to 90F. Excellent structural drying tool, can lower RH to 5 . Does not operate on the principles of heat and therefore can be used year round in all environments. DEFAULTSORT Convectant Drying Category Dried foods ... more details
chembox Watchedfields changed verifiedrevid 277558827 ImageFile Trifluoroacetic anhydride.svg ImageSize IUPACName trifluoroacetic anhydride OtherNames Section1 Chembox Identifiers CASNo Ref cascite CASNo 407 25 0 PubChem 9845 SMILES C O C F F F OC O C F F F Section2 Chembox Properties C 4 F 6 O 3 Appearance Density 1.487 g mL MeltingPtC 65 BoilingPtC 40 Solubility Section3 Chembox Hazards EUClass Harmful Xn Corrosive C ExternalMSDS http msds.chem.ox.ac.uk TR trifluoroacetic anhydride.html Oxford MSDS FlashPt Autoignition Trifluoroacetic anhydride TFAA is the acid anhydride of trifluoroacetic acid . In particular, trifluoroacetic anhydride is the perfluorinated derivative of acetic anhydride . Like many acid anhydrides, it may be used to introduce the corresponding trifluoroacetyl group. The corresponding trifluoroacetyl chloride , is a gas, making it inconvenient to work with. Trifluoroacetic anhydride is the recommended desiccant for trifluoroacetic acid. ref cite book author Chai, Christina Li Lin Armarego, W. L. F. title Purification of laboratory chemicals publisher Butterworth Heinemann location Oxford year 2003 pages 376 isbn 0 7506 7571 3 url http books.google.com books?id SYzm1tx2z3QC&pg PA376 format Google Books excerpt ref Preparation Trifluoroacetic anhydride may be prepared from trifluoroacetic acid by dehydrating with excess &alpha halogenated acid chloride s. For example, with dichloroacetyl chloride ref Cite patent US 4595541 ref 2 CF sub 3 sub COOH Cl sub 2 sub CHCOCl &rarr CF sub 3 sub CO sub 2 sub O Cl sub 2 sub CHCOOH HCl References references Category Acid anhydrides Category Organofluorides de Trifluoressigs ureanhydrid fa ja ... more details
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