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Aldrich

Activated Alumina - Technical Information Bullletin

AL-143 Mineral Adsorbents, Filter Agents and Drying Agents

 Activated Alumina

Aldrich offers various grades of Al2O3, four of which are products designed for column chromatography and adsorptive filtration: acidic, basic and neutral activated aluminas from Camag (Brockmann I grade). Highly porous in nature, aluminas can be effective desiccants and have numerous applications in catalysis as well. Fieser and Fieser’s Reagents for Organic Synthesis² give examples of synthetic applications of activated aluminas.

A. Conversion of Brockmann I to Brockmann IIV grades

Although Camag aluminas are the adsorbents of choice in a wide range of uses in column chromatography and adsorptive filtration, chemists have yet to exploit the ease with which Brockmann I grades can be converted to grades of lower activity simply by adding water.

Taking the precautions to shake well (to disintegrate lumps) and to allow the material to equilibrate in a closed vessel for at least overnight, one can use the following guide to prepare modest quantities of Brockmann IIV grades of alumina simply by adding the appropriate amount of water to the respective Brockmann I grade.
 

Grade designation Brockmann Number Amount of water to be
added to Brockmann I grade
(%)
Approx. water content
(%, Karl Fischer method)
5016-A-II, 507-C-II II 3 4-4.5
5016-A-III, 507-C-III III 6 7-7.5
5016-A-IV, 507-C-IV IV 10 11-11.5
5016-A-V, 507-C-V V 15 16-16.5

 

B. Typical particle-size distribution (mesh analysis)of all grades of activated alumina

 

Sieve opening (mm) Mesh size % Retained
0.25 60 0.1 (max.)
0.20 ~ 75 25
0.15 100 1520
0.10 ~ 150 5565
0.07 ~ 210 7285
0.04 ~ 360 9598

 

Properties and Characteristics of Camag Standard Grades of Activated Alumina
 

Catalog Number 199443 199974 199966 267740
Brockmann Number 1 1 1 1
Grade 5016-A-I 507-C-I 504-C-I 504-C-I
Type basic neutral acidic weakly acidic
pH (5% stirred aq. suspension) 9.5 ± 0.3 7.5 ± 0.5 4.5 ± 0.5 6.0 ± 0.5
Aprrox. particle size (mesh) 150 150 150 150
Sureface area (m2/g) 150 150 150 150
Pore diameter (Å) 58 58 58 58
Cl- (mval/g) 0.03 0.14 0.06
Na2O (%) 0.4 0.4 0.4 0.4
Fe2O2 (% max.) 0.02 0.02 0.02 0.02
SiO2(% max.) 0.02 0.02 0.02 0.02
H2O (%, approx.) 1.5 1.5 1.5 1.5