PEO TEMPLATED NiO NANOFIBERS: SYNTHESIS, CHARACTERIZATION AND DYE DEGRADATION APPLICATION

Abstract

Waste water treatment presents one of the most challenging tasks in large industries. Various techniques or methodologies have been exploited to treat the industrial effluents, but these are highly expensive to be applicable. Here, nanotechnology provides inexpensive and simple tools to curb this problem, among which one dimensional metal oxide nanostructures are the most extensively explored in various fields of research especially in the photocatalysis. Herein, we have fabricated one dimensional nickel oxide (NiO) nanofibers using inexpensive and simplistic electrospinning technique to evaluate their efficient applicability as a photocatalyst in the dye - degradation processes present as pollutant in the waste water. In the present study, polyethylene oxide (PEO) has been used as a template to synthesize NiO nanofibers. The synthesis part involves the preparation of sol-gel by mixing PEO and nickel acetate tetrahydrate (NiAc) in a particular ratio (1:3), fabrication of PEO/NiAc nanofibers using electrospinning and subsequent calcination of the as prepared nanofibers at 500°C in the presence of air to obtain phase pure cubic NiO nanofibers of NaCl type structure which were further characterized using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). All these characterization results give an insight about the physical and chemical properties of NiO nanofibers. Chemical changes occurred during calcination process responsible for NiO formation was investigated using thermogravimetric analysis (TGA). Furthermore, the photocatalytic activity of these NiO nanofibers along with their kinetics of degradation was studied with the photodegradation of model dye congo red (CR) under visible light irradiation. The decrease in the concentration of the dye molecules was observed spectrophotometrically as well as visually. Besides this, the photocatalytic activity was found to be dependent on the amount of nanofibers loaded in the aqueous solution of dye and it was clearly demonstrated by evaluating the rate constants for each concentration of the catalyst. Interestingly, the photocatalytic properties of NiO nanofibers were found better than that of the nanoparticles when compared under same experimental conditions elucidating the nanofibers more manageable and efficient than the corresponding nanoparticles. This study also provides vision about the stability of the nanofibers in the aqueous solution along with their reusability studies enhancing the effectiveness as well as the economy of the dye degradation process. Therefore in brief, NiO nanofibers presents highly cost-effective, simple and reliable tool for the efficient treatment of waste water containing hazardous dyes.