Environmental pollution by contaminants of emerging concern, among these various pesticides, has been a concern of environmentalists and scientists around the world. Thus, efforts to mitigate the impacts of these substances have been carried out, and the use of advanced oxidation processes, such as photocatalysis, is an alternative. This work sought to synthesize a composite photocatalyst based on iron oxides and titanium dioxide to assess its applicability in degrading the herbicide bentazon (BTZ) by a lamp that simulates the solar spectrum (visible, ultraviolet A and ultraviolet B) and sunlight. Photocatalytic degradation reached 51% in 120 min with a rate constant k = 0.0058 min-1 when a UV-Vis lamp of 300 W was used. The applicability was demonstrated under sunlight radiation, reaching 38% degradation of a bentazon solution (4.1 × 10-4 mol L-1) after 320 min. TiO2 and Fe2O3 were synthesized similarly but showed no degradation under the same conditions. Thus, Fe2O3-TiO2 is an inexpensive and non-toxic material capable of efficiently conducting the photocatalytic degradation of organic compounds, such as the bentazon herbicide.

Polymeric films have been increasingly investigated due to the ease of miniaturization and integration in several sensor devices. Films obtained from the electrospinning technique have a controlled diameter and homogeneity, and substances can be incorporated into the polymeric network. Electrospinning fiber of chitosan (Ch) and poly(ethylene oxide) (PEO) was obtained from solutions prepared at different concentrations in acetic acid, and varying the distance and the voltage applied. The obtained films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and UV-Visible specular reflectance spectra (UV-SRS). The best conditions for electrospinning were obtained for a 2% m/v (Ch + PEO) solution in the ratio 90:10% m/m (Ch:PEO), applied voltage of 18 kV, and 18 cm distance between the capillary tube and collector. Acridine orange, sodium fluorescein, and erythrosine fluorescence dyes were successfully incorporated into Ch:PEO films. The spectrofluorometric spectra of the films showed excitation and emission processes and the acridine orange film showed evidence of excimer formation by the presence of an excitation peak at 569 nm. Ch-PEO films with the incorporation of fluorescent dyes may well be used as flexible probes or sensors in colorimetric devices in biochemical applications.

The market for hair dye involves a growing range of products, which requires greater understanding of hair properties, mechanisms of action and color development. In this work, we present a critical analysis of the classification, physical and chemical characteristics, chemical analysis and toxicological/mutagenic potential of dyes used in the hair dyeing process. A compilation of some studies was carried out, focusing on the available knowledge about these dyes and their effects on the environment and human health.