Low-cost tangerine peel waste mediated production of Titanium Dioxide Nanocrystals: Synthesis and characterization

Abstract

Nanocrystalline Titanium Dioxide is a promising nanomaterial with myriads of applications in diverse fields, from biotechnology to space science. Although several different methods have been proposed for the synthesis of such material, just a few have considered both the economic and environmental impact of the production protocols. In this study, based on previous works it is proposed a fast and low-cost green synthesis method of Titanium Dioxide Nanocrystals (TiO2-NCs). This method works by transforming a Titanium Dioxide (TiO2) precursor in TiO2-NCs, using two volumetric ratios of tangerine peels, an organic waste, as bio-mediator of chemical reactions. Nanocrystals produced with this alternative synthesis reduce the environmental impact by effectively using waste that would otherwise end up disposed in sanitary landfills. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis of the obtained TiO2, show nanocrystals with clear boundaries and diameters between 50–150 nm and the presence of nanocrystals agglomerations. The tendency to agglomeration was also confirmed by the dynamic light scattering (DLS) measurements. Energy-dispersive X-ray spectroscopy (EDX) measurements show the remaining traces of Calcium and Potassium from the tangerine extract. X-ray diffraction (XRD) patterns show that TiO2-NCs obtained are composed mainly by anatase crystalline phase (around 90 % anatase and 10 % rutile). UV–vis spectrophotometry shows absorbance characteristic peaks around 300 nm and 350 nm for the TiO2-NCs. Finally, the effects of increasing the volume of tangerine peels extract used in the synthesis were evaluated, showing that a relatively large concentration of phytochemicals is crucial for the growth and formation of TiO2-NCs.