Kinetics of adsorption of water vapour and electrical conduction in bovine plasma albumin

Abstract

A vacuum microbalance has been constructed, and used to make rate and equilibrium studies of the adsorption of water vapour on bovine plasma albumin. A rapid rise of temperature occurs over the first few minutes, and thereafter the kinetics may be described by a modification of the Roginsky-Zeldovich equation. dm//_dt=Kp^0.6exp –(α′m//_pRT). This equation is interpreted in terms of repulsive interaction between the charge-transfer dipoles of water molecules “adsorbed” by hydrogen bonds on to >CO … H—N< groups. The model, which is generalized as an impurity semiconductor model, also gives a qualitative account of heat of adsorption and electrical conductance as a function of amount of water adsorbed.