The superior photocatalytic performance of loofah sponges impregnated with Nb2O5

In this work, a photocatalytic support based on a loofah sponge with a high capacity for photocatalytic discoloration of rhodamine B dye was synthesized in a simple and fast way. For this, loofah sponges were impregnated with Nb2O5 using a microwave-assisted hydrothermal method, where the time (1, 15, 30, and 60 min) and temperature (120, 130, 140, 150, and 160 °C) of synthesis were evaluated. Higher synthesis temperatures lead to a more fragile loofah sponge. Nb2O5 impregnated the shallow channels and folds of the sponges and presented low crystallinity due to the low temperature applied. In the photocatalytic process, the loofah sponges caused complete discoloration of rhodamine B in a short time interval (20 min) for the samples impregnated at lower temperatures (120 and 130 °C). The reuse of the samples, after 4 cycles, showed a drop in performance compared to the first cycle, but with a constant profile from the 2nd to the 4th cycle, discoloring between 80 and 90 % of rhodamine B in 60 min of analysis. Moreover, scavenger tests showed that positive charges (h+), negative charges (e-) and hydroxyl radicals (HO∗) are important in the photocatalytic process. Thus, this work provides an easy methodology for the construction of photocatalytic supports based on ecological materials, with high performance in capturing organic pollutants, in addition to presenting simplicity in the reuse of the material. The photocatalytic support stands out for its low cost, performance, availability and for being environmentally friendly.