Mineralogy and Arsenic Adsorption of Major Soil Classes in Minas Gerais State-Brazil.

The objective of this work was to study a mineralogical characterization in the samples clays of soils in Minas Gerais State – Brazil, using chemical analysis (dithionite-citrate and ammonium oxalate), powder X-ray diffraction, and thermal analysis and determine the maximum adsorption for Arsenic. We performed X-ray diffraction of samples at the natural and after treatment with KCl 1.0 mol L^-1 with heating at 550°C for 3 hours, and MgCl 1.0 mol L^-1 with glycerol. Thermogravimetric Analysis (TGA) made in the range 25°C to 800°C (heating 10° C per minute). We found hematite, goethite, gibbsite, mica, magnetite, hydroxy-interlayered vermiculite (HIV), and predominance of kaolinite at all soils. In the Red-Yellow Argisols (Rhodic-Xanthic Ultisols) and Red-Yellow Latosols (Rhodic-Xanthic Oxisols), peaks kaolinite and goethite are present in all samples, and hematite in lower intensity. In Latosols, it was found characteristic peaks of maghemite/magnetite, and variable presence of gibbsite, with peaks at 0,48, 0,43 and 0,24 nm, more pronounced in soils weathered and acidic. The maximum adsorption of As for all soils was determined.