Synthetic carbons activated with phosphoric acid - II. Porous structure

Synthetic activated carbons were prepared by H3PO4 activation of a chloromethylated and sulfonated copolymer of styrene and divinylbenzene, using an impregnation weight ratio of 0.75 and carbonization temperatures in the 400-1000 degreesC range. Other impregnation ratios (0.93 and 1.11) were also used at a carbonization temperature of 800 degreesC. The porous texture of the resulting carbons was characterized by N-2 adsorption at -196 degreesC and CO2 adsorption at 0 degreesC. All carbons exhibited a multimodal pore size distribution with maxima in the micropore and meso/macropore regions. Maxima in pore volume were attained at 900 degreesC for micropores and at 500 and 900 degreesC for mesopores. The mesopore volume was less sensitive than the micropore volume to changes in the impregnation ratio. It is concluded that the porous texture is not a prime factor in determining the outstanding cation exchange capacities of these carbons. (C) 2002 Elsevier Science Ltd. All rights reserved.