Drying Agent Selection Guide
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Drying Agent
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Suitable for Drying
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NOT Suitable for Drying
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Residual Water mg H2O/L Dried Air
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g H2O/g Desiccant
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Regeneration
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Reaction Mechanism
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Aluminum Oxide
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Hydrocarbons, air, ammonia,
argon, helium, nitrogen, oxygen, Freon, H2O, CO2,
SO2
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0.003
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0.2
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175ºC
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Chemisorption Adsorption
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ANHYDRONE® (Magnesium
Perchlorate anhydrous)
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Inert gas, air
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Most Organics
(May form explosive
compound when exposed to organic vapors.)
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0.001
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0.2
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250ºC with Vacuum
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Hydration
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Barium Oxide
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Organic bases, alcohols,
aldehydes, amines
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Acidic Compounds, CO2
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0.00065
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0.1
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Not Recommended
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Absorption and Adsorption
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Boric Anhydride
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Formic Acid
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0.8
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450ºC
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Calcium Chloride (<20
Mesh)
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Alkyl and Aryl Halides,
most esters, saturated and aromatic hydrocarbons, ethers
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Alcohols, amines, phenols,
aldehydes, amides, amino acids, some esters, ketones
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0.14-0.25
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0.2 (1H2O)
0.3 (2H2O)
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250ºC
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Hydration
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Calcium Oxide
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Alcohols, amines and
ammonia gas
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Acidic compounds, esters
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0.007
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0.3
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1000ºC
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Chemisorption
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Calcium Sulfate
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Most organic compounds
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0.005
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0.066
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235ºC
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Absorption
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Cupric Sulfate
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Esters, alcohols (excellent
for benzene and toluene)
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1.4
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0.6
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200ºC
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Lithium Aluminum Hydride
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Aldehydes, ketones,
esters, carboxylic acids, peroxides, acid anhydrides, acid chlorides,
ethers
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Acid and its derivatives,
aromatic nitro compounds
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Magnesium Oxide
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Hydrocarbons, aldehydes,
alcohols, basic gases, amines
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Acidic compounds
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0.008
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0.5
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800ºC
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Hydration
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Magnesium Sulfate
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Most compounds, incl.
Acids, ketones, aldehydes, esters, nitriles
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Acid sensitive compounds
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1.0
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0.2 0.8
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200ºC and red heat
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Hydration
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Molecular Sieve Activated
Type 3A
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Molecules of diameter
>3 angstroms
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Molecules of diameter
<3 angstroms
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0.18
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117-260ºC
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Adsorption
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Molecular Sieve Activated
Type 4A
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Molecules of diameter
>4 angstroms
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Molecules of diameter
<4 angstroms, Ethanol, H2S, CO2, SO2,
C2H4, C3H4, and strong acids
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0.001
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0.18
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250ºC
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Adsorption
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Molecular Sieve Activated
Type 5A
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Molecules of diameter
> 5 angstroms, e.g., branched chain compounds and those having 4 carbon
or larger rings
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Molecules of diameter
<5 angstroms, e.g., butanol, n-C4H10 to n-C22H46
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0.003
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0.18
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250ºC
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Adsorption
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Phosphoric Acid
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0.003
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Not recommended
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Absorption and Solution
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Phosphorous Pentoxide
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Saturated hydrocarbons,
aromatic hydrocarbons, ethers, alkyl halides, aryl halides, nitriles,
anhydrides, nitrites, esters
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Alcohols, acids, amines,
ketones, HF and HCl vapors
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3x10-5
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0.5
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No
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Chemisorption leading
to H3PO4
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Potassium Carbonate
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Alcohols, nitriles,
ketones, esters, amines
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Acids, phenols
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0.2
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300º C
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Hydrate Formation
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Potassium Hydroxide
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Amines, organic bases
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Acids, phenols, esters,
amides, acidic gases, aldehydes
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0.3
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Indeterminate
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No
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Hydration and Solution
Formation
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Silica Gel 6-16 Mesh
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Most organics
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HF vapors
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0.03
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0.2
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200-350ºC
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Adsorption
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Sodium
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Saturated and aromatic
hydrocarbons, ethers
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Acids, alcohols, aldehydes,
ketones, amines, esters, organic halides, and any substance with high
water content
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Not Recommended
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Leads to
NaOH + H2
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Sodium Hydroxide Pellets
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Amines
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Acids, phenols, esters,
amides
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0.16
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Indefinite
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Not Recommended
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Absorption and Solution
Formation
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Sodium Sulfate Anhydrous
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Alkyl halides, aryl
halides, aldehydes, ketones, acids
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12
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1.2
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150ºC
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Hydration
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Sulfuric Acid
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Inert gases, HCl, Cl2,
CO, SO2, air used in desiccators
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Too reactive to actually
contact organic materials
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0.003
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Indefinite
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No
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Hydration
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Zinc Chloride
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Hydrocarbons
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Ammonia, amines, alcohol
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0.9
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0.2
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110ºC
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Hydration
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