Superior photocatalytic aptitude of MWCNT/TiO2 for the removal of Cr (VI) from polluted water

The potential behavior of Cr (VI) in the water makes the significance of the current research. The addition of multi-walled carbon nanotubes (MWCNT) into the TiO2 alters its properties and will enhance the photoactivity for the reduction of Cr (VI). The photocatalyst was synthesized using sol–gel method and characterized using SEM, EDS, XRD, UV–Vis, and FTIR. The UV–Vis spectra of CNT/TiO2 are clearly reflecting the absorption of light in the visible region and supporting the better efficiency compared to bare TiO2. The XRD spectra of CNT-TiO2 show the monophase of the anatase structure. The presence of C modification was further confirmed by EDS. The surface characterization and chemical composition were confirmed with SEM and FTIR. The maximum efficiency of Cr (VI) to Cr (III) was achieved by the optimized conditions of pH 3, initial dosage of 1 g/L. The removal efficiency of Cr (VI) was achieved within 90 min of natural sunlight illumination. The kinetic studies of Cr (VI) follow the pseudo-first-order kinetics. Except for TiO2, both CNTs and CNT/TiO2 showed higher removal efficiency under natural sunlight illumination when comparing removal efficiency between UV and natural sunlight. Formic acid was used in all of the experiments, and it worked well as a hole scavenger. The prepared material showed an excellent reusable capacity as well it is a great advantage on the industrial scale.