Arsenate removal from aqueous solution by montmorillonite and organo-montmorillonite magnetic materials

BARRAQUÉ, FACUNDO; MONTES, MARÍA L.; FERNÁNDEZ, MARIELA A.; CANDAL, ROBERTO; TORRES SÁNCHEZ, ROSA M.; MARCO BROWN, JOSE L.

ENVIRONMENTAL RESEARCH

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2021 vol. 192 p. 110247 - 110257

0013-9351

Magnetic-clay (MtMag) and magnetic-organoclay (O100MtMag) nanocomposites were synthesized, characterized and evaluated for arsenic adsorption. Batch arsenic adsorption experiments were performed varying pH conditions and initial As(V) concentration, while successive adsorption cycles were made in order to evaluate the materials reuse. The highest As(V) removal efficiency (9 ± 1 mg g-1 and 7.8 ± 0.8 mg g-1 for MtMag and O100MtMag, respectively) was found at pH 4.0, decreasing at neutral and alkaline conditions. From As(V) adsorption isotherm, two adsorption processes or two different surface sites were distinguished. Nanocomposites resulted composed by montmorillonite or organo-montmorillonite and magnetite as the principal iron oxide, with saturation magnetization of 8.5 ± 0.5 Am2 Kg-1 (MtMag) and 20.3 ± 0.5 Am2 Kg-1 (O100MtMag). Thus, both materials could be separated and recovered from aqueous solutions using external magnetic fields. Both materials allowed achieving arsenic concentrations lower than the World Health Organization (WHO) recommended concentration limit after two consecutive adsorption cycles (2.25 and 4.5 μg L-1 for MtMag and O100MtMag, respectively).