Carbonaceous particle hydration

Microgravimetric measurements of the hydration of several different black c arbons or soots and a series of commercial carbon blacks have been carried out, over a relative humidity range of 20-85%, in an extension of earlier w ork with the model n-hexane soot. All adsorption isotherms are of type III and were analyzed by the use of the Dubinin-Radush-kevich (DR) equation whi ch, although applicable over a limited range of intermediate relative humid ity values, allows identification of chemisorption limit and onset of multi layer formation. While surface area determines the maximum adsorption possi ble for a given type, surface functionalities are determinative at lower hu midity and are characteristic of the soot-producing fuel. Aging of carbon p articles and oxygen chemisorption as well as O-2, physisorption strongly in fluence the extent of hydration for those soots studied, such as JP-S aviat ion and diesel fuels. Infrared spectra confirm the surface oxidation of JP- 8 soot by its reaction with O-3, a reaction of probable atmospheric importa nce, as underlying its increased hydration. (C) 1999 Elsevier Science Ltd. All rights reserved.