resumo
Two anionic surfactants, dodecylsulfate (DDS) and dodecylbenzenesulfonate (DBS), were intercalated into layered zinc hydroxide salts (LHS) using the direct alkaline co-precipitation method, and characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) and thermogravimetric analysis/differential thermal analysis (TGA/DTA). Different UV-absorbing organic molecules, like salicylates, cinnamates and benzophenones, were adsolubilized in the LHS interlayer following two different procedures (conventional microwave treatment and microwave with hydrothermal treatment). The adsolubilized products were investigated by PXRD, FTIR, diffuse reflectance UV-Vis (DRUV-Vis) and luminescence spectroscopies before and after exposure to UV radiation. Most of the products showed a good absorption in the UV region, from UVC to UVA, and good stability under UV radiation. The photodegradation tests showed that DDS-intercalated compounds were more stable than those intercalated with DBS. Adsolubilization in LHS can be an interesting alternative to immobilize neutral molecules with UV absorption capability, to prepare materials to be used in sunscreen formulations.
palavras-chave
MICROWAVE-HYDROTHERMAL TREATMENT; NITRATE; ADSORPTION; DYES; FUNCTIONALIZATION; NANOCOMPOSITES; IRRADIATION; ABSORPTION; SUNSCREENS; BEHAVIOR
categoria
Chemistry
autores
Cursino, ACT; Rives, V; Carlos, LD; Rocha, J; Wypych, F
nossos autores
João Rocha
Prof. Catedrático
Luís Carlos
Professor Catedráticoagradecimentos
We gratefully acknowledge the Brazilian research agencies CNPq, CAPES, FINEP and the project Nennan (Fundacao Araucaria/CNPq) for their financial support of this work. A. C. T. C. thanks Ciencias sem Fronteiras/CNPq and CAPES for the doctorate grant and V. R. acknowledges a grant from MICINN (MAT2009-08526) and ERDF.