A comparative study of Neutral Red decoloration by photo-Fenton and photocatalytic processes

Neutral Red was subjected to two different advanced oxidative processes, namely the photo-Fenton process and the photocatalytic process. The dye was found to undergo substantial and rapid decoloration by both the methods, however, the photo-Fenton-mediated decoloration of the dye was much more efficient. Conditions were optimized in both set of experiments to achieve the most efficient dye decoloration. Additionally the effects of added anions on photocatalytic and photo-Fenton-mediated dye decoloration were examined and compared to our previously published results with photolytic and Fenton-mediated Neutral Red decoloration. Most of the ions tested had an inhibitory effect on photo-Fenton process, but unexpectedly enhanced the photocatalytic process, except for chloride, which inhibited both the processes. The kinetics data in both the cases fitted well to the first-order equation. Comparison of the results among the four different advanced oxidation processes shows that Neutral Red is most efficiently degraded by photo-Fenton process, followed by Fenton process, then photolytic, and then with photocatalytic process.