Optimisation of parameters in a solar light-induced photoelectrocatalytic process with a TiO2/Ti composite electrode prepared by paint-thermal decomposition

• The highest photoelectrocatalytic activity was derived from the synergistic effect between a modified TiO2/Ti composite electrode, applied bias and optimized PEC system parameters.
• Optimisation of photoelectrocatalytic system is used as initial step toward scaling up of titanium dioxide electrode.
• Energy demand in PEC system meets acceptable energy consumption barrier as in other AOPs.

This paper presents an outline of the effects of photoelectrocatalytic operating parameters in a batch reactor on the kinetics of photo(electro) catalytic (PEC) oxidation, using phenol as a model compound. Process parameters and electrode configuration were varied to examine which mechanism becomes dominant under which conditions. The parameters studied were: the effect of the TiO2 layer thickness, agitation, different light intensities (UV300–400), and the initial concentration of phenol in an aqueous solution as encountered in practice.The findings show that there is an optimal catalyst-layer thickness for oxidation efficiency, which is six layers. A higher initial concentration of phenol led to a higher overall degradation percentage of phenol as well, highlighting the importance of the surface area of the catalyst. Increasing the solar light intensity increased the kinetics of phenol oxidation due to the increasing concentration of reactive OH. However, the energy efficiency for the lower intensities was in the range of 0.1–2.7 kW h m−3 and was up to 1.3 times more energy efficient than the system using higher intensities. At low light intensity reactions, the electron–hole recombination effect was negligible. A trade-off exists between the energy efficiency of the system and the desired level of degradation of the chosen pollutant to obtain the desired rate of the reaction with an optimal energy consumption. The results can be used to optimize the performance of photoelectrocatalytic reactors to be used for the treatment of water containing micropollutants.

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