2020
Volume 20, Number 2, pp. 60-67
The kinetics of disinfection by semiconductor photocatalysts
J.J. Ramsden
Clore Laboratory, the University of Buckingham, MK 18 1EG, England
The kinetics of photocatalytic disinfection of microorganisms (bacteria, fungi and viruses) are quantified from literature data. The goal of this work is to separate the contribution of transport and determine how quickly a single microorganism in contact with the photocatalyst is inactivated. Two kinds of experiments are examined: "suspension", in which the microorganisms are mixed with photocatalyst particles and illuminated; and "surface" in which a suspension of the microorganisms is in contact with an illuminated film of the photocatalyst. In suspension, actual inactivation rates are found to be well below the diffusion limit, probably because only a small fraction of the photocatalyst particles are illuminated at any instant. On the other hand in the surface experiments the rates are much faster than predicted from the diffusion limited reaction, probably because the inactivating entities are diffusing from the photocatalyst into the solution.
Keywords: antimicrobial, bacterium, diffusion, microorganism, virus