Synthesis of Nano-Hematite for Possible Use in Sunscreens

Abstract

Hematite nanoparticles were synthesized for ultraviolet filtration application by the precipitation method followed by calcination at different temperatures. A range of crystallite sizes between 37 and 85 nm (as determined by the Scherrer formula) was obtained, according to the temperature used for the calcination. An increase in the absorbance with increasing crystallite size was observed over the whole ultraviolet B and A range. The experimental band gap was 2.94 eV for the sample calcined at 500 degrees C and 3.08 eV for the sample calcined at 300 degrees C. The in vitro sun protection factor and protection factor-ultraviolet A of a water-in-oil emulsion made with the sample calcined at 500 degrees C as active ingredient were 9.21 and 8.81, respectively, which is higher than the protection factor-ultraviolet A values obtained for titanium dioxide and zinc oxide at the same mass concentration. The emulsion was found to be photostable.

A hydroxyapatite–Fe2O3 based material of natural origin as an active sunscreen filter

“…39 Analogously, the absorption in the visible region, and hence the colour of the powder, can also depend on the crystallite size. 13 The presence of a peak at about 290-300 nm was also observed for iron-substituted HAp; 40,41 these data are, therefore, in agreement with the hypothesis of iron incorporation into the HAp lattice. This would also explain why we have such a strong absorbance throughout the UVA and UVB regionsabove 60% from 290-400 nmwith such a small amount (no more than 2 wt%) of hematite.…”

“…1,12 Recently, however, its potential as a UV absorber has been also considered. Truffault, 13 for instance, showed that water-oil emulsions containing hematite nanoparticles can provide effective sun protection for both UVA and UVB ranges.…”

Evaluation of the Impacts of Four Weathering Methods on Two Acrylic Paints: Showcasing Distinctions and Particularities

“…Table 2 indicates that red oxide is present in the formulation of the Paint 2. This compound, has strong capacity to absorb in the UV region [40,41]. Techniques of accelerated weathering are almost all based on the use of higher intensity UV radiation to accelerate the rate of degradation.…”

The influence of the size of hematite particles on the properties of polyethylene/hematite composites

“…There is also a potential of hematite to act as an UV stabilizer i.e. UV blocking agent due to its UV absorption capability [5]. From UV-Vis-NIR spectra of polyethylene/hematite, Figures 3 and 4, it can be seen that some differences are observed in comparison with the pure polyethylene.…”