Section 4: Arsenic remediation and removal technologies. Influence of the Al-for Fe substitution in the adsorption of As(V) onto goethites-morphological surface characterization

ANA E. TUFO; M. C. MARCHI ; S. M. LANDI; MARIA DOS SANTOS AFONSO; ELSA E. SILEO

One Century of the Discovery of Arsenicosis in Latin America (1914-2014)

CRC Press

Lugar: London; Año: 2014; p. 699 - 701

Arsenic derived from natural and anthropogenic sources occurs in groundwater, and its mobility is highly influ-enced by goethite and ferrihydrite. As the substitution of Al-for-Fe in natural goethites is well documented, our aim was explore the adsorption of As(V) onto several Al-substituted goethites, and analyze by STEM micrographs the possible formation of FeAsO4 as a surface precipitate that blocks ulterior sorption. Adsorption isotherms ([As]adsorbed vs. [As]solution) of all samples were ob-tained, and an uncommon bell shaped curve with a maximum at 0.25 mmolL-1 was found for all goethites. The STEM micrographs of the As-adsorbed Al-goethites were obtained at [As]>0.25 mmolL-1 confirmed that no surface precipitates were formed. Based in these results the formation of bidentated complexes were proposed to explain the decrease of the adsorption by As(V) coordination to two metal sites.