The production of activated carbons from grain sorghum with phosphoric acid
activation has been studied by means of two processes, i.e., one-stage and
two-stage. The former comprises simultaneous carbonization and activation
after impregnation; the latter, the carbonization of the precursor at 300 d
egreesC for 15 min, followed by the activation of the resultant char after
impregnation with phosphoric acid. The preparation conditions, e.g., activa
tion duration, phosphoric acid concentration, and activation temperature, h
ave been varied to determine the optimal processing conditions. The optimal
activation conditions for the highest surface areas have been determined t
o be 600 and 500 degreesC with a phosphoric acid concentration of 35% for t
he one-stage and two-stage processes, respectively. The two-stage process h
as been found to greatly enhance the porosity development, especially the m
icroporosity. (C) 2001 Elsevier Science Ltd. All rights reserved.