Photocatalytic reactor with multiphase digital control of luminous radiation

This paper investigates the effect of controlled periodic illumination by visible LEDs on the performances of a visible-light-active N-doped TiO₂ photocatalyst (N - TiO₂) immobilized on glass spheres for wastewater treatment, using Methylene Blue (MB) dye as a model pollutant. Different LED dimming techniques are investigated and compared, including a classical Pulse Width Modulation (PWM) technique and a novel proposed Variable-Peak PWM technique. A modulation of dimming duty-cycle is adopted as well, which allows to control the light irradiation in a new way with respect to previously used methods. Experimental results highlight the improvement in MB photocatalytic degradation process obtained by using the proposed modulation techniques.