Characterization of a Neoteric Clay-Based Composite for the Removal of Heavy Metals from Mining Water

Abstract

The rapid expansion of urban areas and the continuous population growth has resulted in a dramatic increase in the contamination of water bodies with heavy metals, toxic anions, and organic pollutants. As a result, scientists concentrated their efforts on developing new environmentally-friendly composite materials to remove various pollutants from wastewaters through adsorption techniques. Herein, the preparation of a neoteric clay-based material is reported that is capable of complexing metal ions. This new material was obtained from montmorillonite and dopamine-functionalized poly(benzofurane-co-arylacetic) acid. The structure, morphology, and chemical composition of the synthesized material, as well as its sorption capacity for heavy metals, were investigated using a variety of analytical techniques that included scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and atomic absorption spectrometry (AAS). Stock solutions of Cu, Zn, Mn, Fe, Pb, Cd, Cr, Ni and contaminated surface water samples collected from Roșia River (Roșia Montană Mining Area) were used to evaluate the material’s suitability for metal removal from wastewaters. The results obtained with the new clay-based material highlight its selectivity for certain metals and excellent removal efficiencies on stock solutions (87-100% adsorption efficiency for Fe, Cu, Pb, Cr and Cd) and real contaminated wastewaters (100% adsorption efficiency for Cr and Cd, 96% for Fe and 79% for Cu). Further research should be conducted to optimize the structure of clay-based materials for this type of environmental application in order to increase the number of pollutants adsorbed simultaneously.