Surfactant-Free Hydrothermal Synthesis of Mesoporous Niobia Samples and Their Photoinduced Decomposition of Terephthalic Acid (TPA)

This study introduces a low temperature surfactant-free hydrothermal method to synthesize mesoporous Nb2O5 photocatalysts using NbCl5 and H2O2 as precursors that are subsequently calcinated at 300, 400 and 450 A degrees C and are assigned as mNb(2)O(5)-300, mNb(2)O(5)-400 and mNb(2)O(5)-450, respectively. Commercial niobia sample was used as reference sample for comparison purpose. All of materials were characterized by XRD, SEM, UV-Vis DRS, FTIR, TG/DTG and BET techniques. The synthesized Nb2O5 particles especially mNb(2)O(5)-300 sample shows a high surface area (240 m(2)/g), a large pore volume (0.21 cm(3)/g) and an identifying morphology of these features. Photocatalytic decomposition of terephthalic acid was evaluated using UV-Vis spectrophotometer. The photocatalytic reactions followed pseudo-first-order kinetics with an apparent rate constant of k = 105 x 10(-3) min(-1) for mNb(2)O(5)-300 sample with the highest activity among all samples at natural pH (pH = 6). Meanwhile, it was observed that optimum pH of 4 resulted in fast photocatalytic reaction for mNb(2)O(5)-300 sample.