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The rice reference should be moved to a section on food hygroscopy and a new section should be added about dessicants in chemical processes. Jmldalton 20:50, 2 May 2007 (UTC)
— Preceding unsigned comment added by 212.143.106.185 ( talk) 13:17, 6 August 2007 (UTC)
There is a paragraph regarding personal use of dessicants. Is this appropriate? Might be original research. —Preceding unsigned comment added by 129.128.204.252 ( talk) 17:32, 11 September 2007 (UTC)
what are the effects of swallowing the contents of the small packets and athe benefits of drinking plenty of water? — Preceding unsigned comment added by 98.27.39.14 ( talk) 15:44, 31 May 2008 (UTC)
A cost-effective, low-energy, continuous-cycle desiccant dehumidifier or desiccant regeneration system can be easily designed from off-the-shelf component parts.
Would anyone care to elaborate the above statement and tell me how this is possible? AFAIK from googling about this is that it isn't very easy regenerating desiccants.
— Preceding unsigned comment added by Grokking ( talk) 04:01, 25 June 2008 (UTC)
Is desiccant re-usable ? How is it dried to be re-used ? —Preceding unsigned comment added by 159.245.32.2 ( talk) 20:48, 15 December 2010 (UTC)
Desiccants aren't "chemically stable or chemically inert". P2O5 (phosphorous pentoxide, phosphoric acid anhydride) is often used as a dessicant IN THE CHEMICAL LAB, as are several alkali metals (such as sodium). These chemically react with the water. Sulfuric Acid (98%) is another common - and reactive dessicant. (These chemical reactions can be violent (explosive)). Although almost any desiccant warms as it absorbs water (exothermic), reversible desiccants are generally only mildly exothermic. Desiccants used in commercial packaging are usually inert (otherwise they wouldn't be safe to ship). Dririte is a trademarked name, dririte can be reused many times by drying it out in an oven (I wouldn't use a gas oven, burning gas gives off water), dririte turns color after it reaches a certain water content, but that level may or may not be acceptable - depends on application. Desiccants normally rely on air movement (or fluid mixing). Most molecular sieves contain heavy metals and shouldn't be used with foods or medicines (unless precautions are taken). In an air stream many dessicants become air-borne and pose a risk to the lungs. Lets see, what other nonsense does this article contain? Oh, silica gel or amorphous silica is used as a desiccant, crystalline silica (sand) is not. There are a variety of ways to measure effectiveness of a desiccant, they include speed of absorption, amount of water absorbed, and level of humidity that can be reached at any given temperature (for the common desiccants, the reactions are reversible - meaning they are equilibrium reactions with the humidity in the air and may become increasing ineffective below a certain humidity (this means the difference between a humectant and a desiccant depends on what you accept as being "dry"). Most desiccants are less effective at higher temperatures. Most desiccants are not suitable for situations which require rapid desiccation, especially physical absorbants (chemically reacting materials generally absorb much faster, but are limited since their surfaces tend to become covered with reaction products). I can't think of a desiccant which is not dependent on its surface area for effectiveness (speed). (Amorphous silica has surface areas measured in dozens or hundreds of square meters per gram). Some materials (humectants) can be both humidifiers and dehumidifiers. Some desiccants are less sensitive to relative humidity, but generally all are to some extent. So we have air (fluid) flow, temperature, humidity and type of desiccant as important variables. In some situations, the number of cycles of use and regeneration may be important, and most desiccants effectiveness diminishes with number of cycles. With very few exceptions most surfaces on Earth have water on them, often described as a layer of absorbed water, but this may or may not be an actual "layer". There are tables available to determine suitable materials (especially chemical mixtures) which can be used to control humidity to a given RH. (Althoght desiccants are typically assumed to remove "most" of the humidity regardless of RH, in practice this just ain't so). 216.96.77.183 ( talk) 20:36, 2 November 2015 (UTC)
…but whoever cannot tell the difference between absorption and adsorption should stay far away from articles such as this. The latter term presently appears nowhere in this article, which thus fundamentally fails.
The major supplier SorbentSystems.com puts it into small words and simple concepts —
A desiccant packet could be said to absorb moisture, but the water is being adsorbed by the silica or clay or carbon or whatever. While some conjugation of adsorb appears 11 times in Silica gel, it is entirely absent in Desiccant.
FWIW: desiccants are used to control not just excess moisture, but volatiles as well, in part to reduce disagreeable odors. This is also completely overlooked.
And in the commercial world,
molecular sieve is something entirely different from
silica gel. They will be sold side-by-side, but nowhere have I seen silica gel called molecular sieve. Unless some credible scientific source can be offered up to support continuation of this confusion, all such ought be scrubbed from here and related articles.
Weeb Dingle (
talk)
16:01, 27 January 2019 (UTC)