Effect of catalyst type on the kinetics of the photoelectrochemical disinfection of water inoculated with E. coli

The rates of the photoelectrochemical disinfection of Escherichia coli at TiO ₂ electrodes were measured as a function of concentration and applied potential. Two different TiO ₂ photoelectrodes were used: a thermally treated titanium plate and a porous film prepared by a sol-gel hydrolysis technique. The kinetics of the disinfection process were found to depend upon the nature of the electrode material. For the thermal film they were first order, and half order for the sol-gel film. It was also found that the catalytic activity per unit surface area of catalyst is many orders of magnitude greater than that observed using TiO ₂ slurries; this was attributed to the reduced rate of electron-hole recombination afforded by the application of a small potential bias (∼1 V vs Ag/AgCl), and hence the exploitation of the electric field enhancement (EFE) effect.