Development of Titania Based Composite Nano-Materials for Simultaneous Removal of Organic & Inorganic Impurities from Water

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).