Using cherry stones (CS) as starting material and commonly air as activatin
g agent, formation of oxygen structures in activated carbon is investigated
. In the preparation of samples, CS was first heated at temperatures betwee
n 450 and 900 degrees C in N-2 atmosphere. Then, in a successive activation
stage, the product carbonized at 600 degrees C was maintained in contact w
ith an air stream at 25-325 degrees C for 24 h, 300-600 degrees C for 1 h,
and 250 degrees C for 1-96 h. The rest of the carbonization products of CS
were also heated at 250 degrees C in air for 24 h. Moreover. the product ca
rbonized at 900 degrees C was activated at 750 or 900 degrees C in CO2 for
1 h. Furthermore, in a second activation stage, the products activated at s
uch temperatures in CO2 and those at 300-600 degrees C in air were heated a
t 250 degrees C in air for 24 h. The starting material, carbonized products
, and activated carbons were examined by FT-IR spectroscopy. A number of ca
rbon-hydrogen atomic groupings and of oxygen groups and structures, i.e., O
H, C=O, and C-O-C) have been identified in CS, The yield of the activation
and carbonization processes and also the chemical structure of the resultan
t products are strongly dependent on the carbonization temperature. In the
products carbonized at 600-900 degrees C, only ether type structures are de
tected. The activation at 250 degrees C in air results in activated carbons
that contain different oxygen structures when CS is carbonized at 450 or 6
00 degrees C. At 750 or 900, by contrast, oxygen structures are not formed
as a result of the activation treatment. This also applies when the carboni
zation product of CS at 900 degrees C is activated solely in CO2 or first i
n CO2 and then in air. The heating conditions in air greatly influence the
formation of oxygen structures (specifically, of lactonic and ion-radical t
ypes) to a large extent. It only occurs when activating at relatively low t
emperatures for a long time; at 300-600 degrees C for 1 h, however, the oxy
gen structures are not formed. (C) 1999 Elsevier Science Ltd. All rights re
served.