Iron rich self-assembly micelles on the Doce River continental shelf

Abstract

After the Fundão iron ore mining dam rupture in November 2015, yellow/ocher emulsions never before reported on the continental shelf adjacent to the Doce River began to be seen, both in coalesced and foam forms. XRD analyses pointed to a prevailing composition of iron and kaolinite with a substantial contribution of an organic-metallic compound, measured in multiple periods over 2 years of sampling. Optical microscopy images allowed the identification of micelles composed of nanoparticles of iron oxyhydroxide making up this emulsion. The generation of dendritic snowflake-shaped microcrystals on fiber filters after water sample filtration and heating confirmed the presence of micelles composed of iron oxyhydroxide nanoparticles enveloped by organic polymers. After losing water, the micelles may act as a self-assembly template seed, where the polymer acts in the oriented adsorption of nanoparticles according to their crystallographic structure. The study brought to light the distinct behavior of a portion of the tailings material, which has already been reported to not have the same flocculation process as the clay minerals previously found in the suspended particulate material (SPM) before the dam rupture.