Study of iron compounds in clay using Mössbauer spectroscopy

Clays are a class of clay minerals that make up almost every soil type and are generally found in the pure state in mineral deposits. They are used as raw material in the chemical processing industries (catalysis, pollutant removal, cosmetics). Characterization studies of raw materials have been carried out in the search for alternatives to improve the quality of the products obtained. In this work, magnetic nanoparticles were characterized to identify which material(s) make up the samples of commercial clays Algiers and Volclay, provided by Bentonit União (BUN). The primary experimental method used in the characterization was Mössbauer spectroscopy, with the samples being analyzed from 77 to 300 K temperature range. The experimental data were fitted using programs NORMOS (WSITE and WDIST versions). Other experimental techniques had already been used in the same samples to characterize the clays’ fundamental components, but none of them brought relevant information about the magnetic phase. For the Volclay sample, infrared spectroscopy (FTIR) revealed the presence of iron ions, with a higher concentration, and, by Mössbauer spectroscopy, it was possible to detect the presence of akaganeite. For the Algiers sample, the presence of akaganeite and, probably, lepidocrocite has been detected.