Photocatalytic reduction of chromium (VI) using niobium-doped PVDF/TiO2 nanofibers

Abstract The combination of polymeric nanofibers and photocatalysts represents a promising strategy for the treatment and recovery of contaminated water, offering the advantage of reuse without loss of efficiency. In this work, Nb-doped TiO 2 nanoparticles (TiO 2 –Nb) were deposited onto PVDF nanofibers obtained by electrospinning, and their efficiency in the photocatalytic reduction of chromium was investigated. Parameters such synthesis time (2 and 4 h) and dopant concentration (1 and 2%) were varied to evaluate the structural and optical modifications of TiO 2 and their influence on the photocatalytic process. After 45 min of UV irradiation, the nanofiber containing TiO 2 prepared in 2 h and 1% niobium achieved 99% reduction of Cr(VI)–Cr(III), attributed to factors such as bandgap energy and a lower charge carrier recombination rate. Tests in the presence of inorganic anions, organic matter, and with pH variation were performed to observe changes in reduction capacity. Radical scavenger experiments and EPR analysis revealed that electrons and hydroxyl radicals are the main active species. Furthermore, the photocatalytic performance was maintained at 76% after fifteen reuse cycles, confirming the material’s reusability and highlighting a new composite with great potential for environmental remediation applications.