Visible-light driven photodegradation of phenol over niobium oxide-loaded fibrous silica titania composite catalyst

Abstract

BACKGROUND: Heterogeneous photocatalysis has been demonstrated to be a promising alternative to treating emerging pollutants in wastewater. Phenol, an extremely toxic substance among existing pollutants, can cause long-term unintended effects when improperly disposed. An effective measure to address this problem is to develop suitable heterojunctions. Among various photocatalyst, titanium dioxide (TiO2) appears to be an excellent photocatalyst in the degradation of organic pollutants. RESULTS: Synthetization of well-constructed heterojunction composite of niobium oxide (Nb2O5) and fibrous silica titania (FST) for enhanced photocatalytic degradation of phenol has been investigated. The photocatalytic performance demonstrated that 5 wt% Nb2O5 loaded on FST (5 Nb/FST) gave the maximum phenol degradation rate (1.70 × 10-2 mM min-1) of 10 mg L-1 phenol at pH 5 using 1000 mg L-1 catalyst within 180 min. Meanwhile, under the same conditions, 1 Nb/FST, FST, 10 Nb/FST and Nb2O5 only delivered 1.51 × 10-2, 1.30 × 10-2, 1.01 × 10-2 and 0.07 × 10-2 mM min-1, respectively. Further phenol photocatalytic degradation routes by 5 Nb/FST reveal that the main intermediates detected are hydroquinone, catechol, maleic, fumaric, and malonic acid. CONCLUSION: In this work, 5 Nb2O5/FST composite, as an effective-performance photocatalyst for phenol degradation, was well-constructed. The advanced activity can primarily be attributed to the regulated Nb2O5 loading with FST and the effect of Nb/FST microsphere heterojunctions, synergistically. Besides, larger crystallite size, high impurity levels and Si-O-Nb and Nb–O–Ti bonds, offers excellent phenol degradation.