Interaction between active hydrogen sites on carbon black surface and alcohol molecules

Abstract

The interaction of active hydrogen sites on carbon black surface with alcohol molecules was studied using a calorimetrical method. The immersional heats of the blacks into ethanol and n-butanol increase linearly with an increase in the content of active hydrogen on the surface. This tendency is quite similar to that observed for the immersional heats into water. The energy contributions of the active hydrogen containing functional groups to the heats of immersion into ethanol and n-butanol were 37.7 and 34.2 kJ/mol respectively. They are approx. 1 4 of the value observed in the case of water (142.4 kJ/mol). The hydrogen bonding energy between n-butanol molecules and active hydrogen sites on the surface of Peerless-155 was determined by applying the analytical procedure of average electrostatic field strength described by Zettlemoyer. The electrostatic interaction energy of the field on the carbon black's surface with the dipole of the n-butanol molecule, q μ and the hydrogen bonding energy of its active hydrogen site with n-butanol molecule, q μ , were 17.8 and 16.4 kJ/mol respectively, per 1 mole of the surface active hydrogen. The energy contribution of the active hydrogen to the heat of immersion into n-butanol, 34.2 kJ/mol, agrees with the sum of q μ and q h . It is concluded that the interaction of the active hydrogen site with the immersed molecule is electrostatic and of hydrogen bonding type in the case of alcohols, whereas, in the case of water, dissociation-hydration reactions are also involved (as was suggested previously).