CETMIC   05378
CENTRO DE TECNOLOGIA DE RECURSOS MINERALES Y CERAMICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of the surfactant loading on the magnetite content and the saturation magnetization of magnetic-organo-montmorillonite systems
Autor/es:
BARRAQUÉ, FACUNDO; TORRES SÁNCHEZ, ROSA MARÍA; FERNÁNDEZ, MARIELA ALEJANDRA; MERCADER, ROBERTO CARLOS; MONTES, MARÍA LUCIANA; CANDAL, ROBERTO
Lugar:
santiago de chile
Reunión:
Conferencia; XVI Latin American Conference on the applications of the Mössbauer Effect.; 2019
Resumen:
Montmorillonite (Mt) has been widely used as sorbent of heavy metals and organiccompounds, due to its large surface area, cation-exchange capacity, swelling ability,abundance, eco-friendliness and low cost. The incorporation of quaternary aminocompounds to montmorillonite has proved to extend and improve its organic pollutantssorption spectrum, due to the contribution of non-polar groups. Besides, the production ofmagnetic clays has attracted scientific interest due to its sorbent ability and isolationcapacity by application of external magnetic fields, which reduces the pollutant exposition.This work reports the structural, magnetic and hyperfine characterization of threemagnetic-organic-Mt samples, produced by 1) loading montmorillonite with HDTMA,(hexadecyltrimethylammonium bromide) at 50, 100 or 150% of its cation exchangecapacity (CEC) and 2) further synthesizing magnetite by controlled alkaline oxidation ofiron (II) sulfate. Magnetite was also synthesized on untreated montmorillonite. The XRDpatterns indicate the existence of Fe oxides. Mössbauer spectra reveal the existence ofmagnetite as the major magnetic Fe oxide (around 60 %), a minor contribution of goethite(around 5%), the paramagnetic sites characteristic of montmorillonite, and asuperparamagnetic relaxation. The magnetic-organic-Mt with 100% of the CEC exchangeddisplays the highest saturation magnetization, Ms = 20.3±0.5 Am2/kg. There is a clearlinear dependence of Ms on the CEC percentage exchanged, despite the low Ms value formagnetic-organic-Mt with 150% CEC. The linear behavior between HDTMA amountexchanged and the Ms value is attributed to the HDTMA presence at the Mt interlayerspace which produces a steric hindrance to iron and consequently enhances themagnetite/goethite formation at the outer surface. After 100% CEC of HDTMA loading, thesaturation of the interlayer space and outer surface prevents the Fe interaction with theclay surface, thus decreasing the magnetite/goethite formation in the Magnetic-organic-Mtsystems.