Abstract:
To combat widespread environmental pollution, use of titanium dioxide (TiO2)
among other semiconductors has been witnessed as one of the interesting and
auspicious photocatalyst in view of its stability, efficiency, cost-effectiveness and low
toxicity. However, the use of TiO2 is limited due to its larger band-gap for absorbing
light in ultraviolet region and recombination of electrons and holes at faster rate. In
consideration of above mentioned challenges, TiO2 based composite nanomaterials
have been explored with main focus on treatment of water in particular dyeing
wastewater. The overview of experimental work in this research followed three main
phases linked to each other. In the first phase, nanomaterials were used in powdered
form. The results were in good accordance but reusability of photocatalyst was a matter
of concern which paved a path for immobilization of nanomaterials on a substrate (NF
membrane) in order to overcome regeneration step (Phase II). The membrane surface
inherited antifoul properties in consequence of immobilization but loss of
photocatalytic active sites impelled us to produce high surface area nanofibers. And the
results obtained from phase III brought closer to a cost-effective practical application
of water purification. Investigation for removal of textile dyes and hexavalent chromium from
synthetic wastewater was studied in first phase of this research work using TiO2/CAC
composite. The synthesized nanocomposite was characterized using X-ray Diffraction
Spectroscopy (XRD), Scanning Electron Microscopy (SEM) coupled with Energy
Dispersive X-ray Spectroscopy (EDS). Drimarene Brilliant Red (DBR), a synthetic
reactive dye and chromium (VI) were used as model pollutants. The optimum
conditions for photocatalytic degradation were achieved for DBR at 150 mg catalyst
dose in 60 min with 15 mg/L initial concentration whereas for chromium (VI) at 4 g/L
catalyst dosage in 120 min at pH 4 with 10 mg/L initial concentration. But in the mixed
solution of DBR and chromium (VI), photoreduction of Cr (VI) and oxidation of DBR
was much higher in the first 60 min of reaction. The results were in accordance with
the fact that presence of organic compounds would enhance the photoreduction of Cr
(VI).
