Phenol Flux Research Articles

Diffusion of Phenol in the Presence of a Complexing Agent, Tetrahydrofuran

AbstractThe effect of a complexing agent, tetrahydrofuran, on the diffusion of phenol across a stagnant fluid layer has been studied. At a given activity of free phenol, the steady-state flux of phenol appearing in an acceptor phase was greatly enhanced. However, as the fraction of phenol associated with the complexing agent increased, the flux of phenol decreased, since the transport was then controlled by the diffusion of the complex, a larger structure. A mathematical model of simultaneous association and diffusion was derived to determine whether the diffusional behavior of two associating species could be accounted for in terms of the association equilibrium constant and Fick’s second law. Experimental results supported the model. It was concluded that the presence of a complexing agent tends to reduce the rate of diffusion, the effect being more pronounced at high concentrations of complexing agent.

Effect of Self-Association of Phenol on Its Transport across Polyethylene Film

Phenol diffusion across a high density polyethylene film from isooctane, in which phenol self-associates, demonstrated nonideal behavior. The steady-state flux of phenol across the film was not directly proportional to its concentration in the donor phase. At higher donor phase concentrations, negative steady-state flux deviations were observed. These negative deviations were due to phenol self-association in the donor phase and the resulting decreases in thermodynamic activity. By using a monomer-pentamer model for phenol self-association in isooctane, the steady-state flux was shown to be directly proportional to the phenol monomer concentration in the donor phase. Although steady-state flux concentration deviations were observed, the diffusion time lag was independent of the permeant concentration and reflected the intrinsic diffusivity of the film to phenol.