Humic Acid-Fe(Hydr)oxide Composites Supported on Montmorillonite: Synthesis, Characterization, and Atrazine Adsorption

Much progress has been made involving the interaction of atrazine (Atz) with natural geosorbents like Fe(hydr) oxides, organic matter, and clay minerals. However, the properties of the humic acid-Fe(hydr) oxides-clay composites differ from their individual member phases, exerting an influence on the adsorption capacity and stability of the system. In this work, the evaluation of Atz adsorption onto humic acid-Fe(hydr)oxide supported on montmorillonite (HA-FeM) was performed. A combination of the X-ray diffraction pattern and batch adsorption experiments at different pH and ionic strength conditions were performed. The identification of the surface groups involved in the interaction FeM-Atz was carry out using X-ray photoelectron spectroscopy. The presence of Fe(hydr)oxides and humic acid improve the adsorption capacity of montmorillonite. Acidic pH and high ionic strength conditions further increases the adsorption. The heterogeneity of the surface sites and cooperative effect contributes to the adsorption process. However, the hydrophobic character of the herbicide is the key factor controlling adsorption. The results obtained from this work give insights about the adsorption mechanism of Atz onto humic acid Fe(hydr)oxides-clay composites and provide information about the potentiality of this type of material to be used to remove organic pollutants present in the aquatic environment.