The adsorption of 3,4-benzpyrene and pyrene by carbon blacks.

the previous paper it was reported that up to seven different aromatic polycyclic hydrocarbons, including 3,4-benzpyrene, were extracted with benzene from most carbon blacks made by the furnace process, but from no channel blacks (3). This difference cannot be explained on the basis of differences in raw materials. Soot formed in the laboratory from gas, which is similar to that used in the channel process, also yielded aromatic hy drocarbons on extraction. Both the channel and furnace processes use a temperature so high (1,100°†" 1,600° C.) that nearly complete decom position of the raw materials into amorphous car bon and hydrogen is assured. However, a few radi cals of the nature of â€oenascentacetylene†• might form and polymerize to produce the observed aromatic hydrocarbons. These compounds would, therefore, be expected to be formed in both proc esses unless special precautions are taken which have not been publicized. Failure to find the aromatic hydrocarbons in the channel blacks, therefore, constituted something of a mystery. One of the most important differences between the hydrocarbon-free channel blacks and the fur nace blacks rich in extractable hydrocarbons seems to be the smaller average particle size of the former. The furnace blacks are said to vary from 30 to 160 ms in average particle diameter; the channel blacks from 10 to SO mis. It is well known that the smaller the average particle size, the larger is the surface area, and that surface area is one of the factors responsible for the adsorptive power of active carbons. Hassler (4) described the physical and chemical behavior of active carbon in detail. A study of the adsorption of aromatic hy drocarbons having pen-condensed ring systems on carbon blacks of varying particle size was there fore undertaken as a possible explanation for the differences in polycyclic aromatic hydrocarbon content of channel and furnace blacks.