An overview on nanostructured TiO2-containing fibers for photocatalytic degradation of organic pollutants in wastewater treatment

Nanotechnology has become one of the most promising fields of research due to the possibility to develop new advanced materials for many applications. Nevertheless, the development of an efficient and stable nanostructured photocatalyst, such as titanium dioxide (TiO2), remains a challenge. In this paper, a review is presented on titania-containing nanofibers for heterogeneous photocatalysis. Nanofibers are commonly obtained by electrospinning, which is a relatively simple and versatile method for the manufacturing of fibers with a large range of diameters 10-1000 nm. The advantage of the photocatalyst in the form of fibers is the ease of recycling. Nano-TiO2 fibers are envisaged for application in wastewater treatment. The nanofibers have been tested mostly for degradation of dyes such as CR, MB, MO, RB5, and RhB in concentration from 10 to 20 mg L-1. The photocatalysis has been carried out under UV light (50-800 W) in variable times (60-240 min). Other parameters that affect photocatalysis activity - as doping and calcination temperature - have been reported. In general, the nanofibers showed good stability and could be reused in at least three cyclical experiments. In the degradation of pharmaceuticals, the removal reached 80 % and was dependent on the thickness of TiO2 nanofibers immobilized on the support. The degradation of other organic contaminants reached up to 70 % for phenol, 50 % for 4-Nitrophenol and 50 % for the herbicide paraquat. A critical view of materials and process limitations, research challenges, and future trends is included.