Hyperfine and magnetic characterization of synthetic beidellite with different cation exchange capacity.

BARRAQUÉ, FACUNDO; BRENDLÉ, JOCELYNE; MONTES, MARÍA LUCIANA; TAYLOR, MARCELA ANDREA; TORRES SÁNCHEZ, ROSA MARÍA; MERCADER, ROBERTO CARLOS

Santiago de Chile

Conferencia; XVI Latin American Conference on the applications of the Mössbauer Effect.; 2018

Magnetic nanomaterials find applications in a wide variety of fields. Currently, to decrease the particle aggregation and Fe oxidation, clays serve as matrix materials in their production. In the pursuit of manufacturing this type of nanomaterials, this work reports the synthesis of magnetic beidellites (BDL0.6Mag and BDL0.8Mag) based on two beidellites, Na+ 0.6 [Si4+ 3.4Al3+0.6)Al2O10(OH,F)2 (BDL0.6) and Na+ 0.8 [Si4+ 3.2Al3+ 0.8)Al2O10(OH,F)2 (BDL0.8). The beidellite syntheses were performed ina hydrothermal reactor adding the corresponding concentrations of SiO2, Al2O3, NaF,HF and distilled water. BDL0.6Mag and BDL0.8Mag were synthetized in batchcondition by alkaline oxidation of ferrous sulfate in the presence of BDL0.6 or BDL0.8, respectively. The materials were characterized by Mössbauer spectroscopy and its magnetic properties measured in a Lake Shore vibrating sample magnetometer. The fitting of the Mössbauer spectra yielded parameters belonging to two Fe3+ doublets, two sites assigned to magnetite, a magnetic phase assigned to goethite and a fourth magnetic site with  = 0.7 mm/s,  = -0.05 mm/s and H = 40 T. A paramagnetic relaxation site was also needed to account for the spectra. From this characterization, it can be concluded that the permanent magnetism at room temperature of the systems arise mainly from the magnetite presence. The magnetite relative spectral area was (61±4)% for BDL06Mag and (48±4)% for BDL08Mag. The saturation magnetization resulted higher for BDL06Mag, 13.7±0.5 Am2/kg, than for BDL0.8Mag, 11.1±0.5 Am 2/kg. The higher amount of magnetite and the higher magnetization value obtained for BDL06Mag can be explained by the high cation exchange capacity value of BDL08, which is able to sorb more Fe in its interlayer space, probably decreasing the available Fe to magnetite formation. The hyperfine and magnetic results indicate thatDBL0.6Mag can be manipulated easier than BDL0.8Mag, making DBL0.6Mag a moresuitable material to be used as a sorbent material of hazardous pollutants.