Organo/LDH nanocomposite as an adsorbent of polycyclic aromatic hydrocarbons in water and soil-water systems.

Polycyclic aromatic hydrocarbons (PAHs) are considered as priority pollutants because of their high risk to human health. In this paper, we addressed the issue of using hydrotalcite-based nanocomposites as adsorbents of six low molecular weight PAHs (acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene) to reduce their negative effects on the environment. A nanocomposite (HT-DDS) was prepared by intercalating the organic anion dodecylsulfate (DDS) in a Mg-Al hydrotalcite (HT), and then characterized using several analytical techniques. A Mediterranean soil was selected for being a high-risk scenario of groundwater contamination by leaching of pollutants. The nanocomposite displayed enhanced affinity for the PAHs in water as compared to carbonate-hydrotalcite (HTCO(3)) and its calcined product (HT500), and showed a high irreversibility of the adsorption process (hysteresis coefficient, H<0.15). The results revealed an increase of the pollutants retention in the soil by the addition of the nanocomposite that depended on the nanocomposite application rate and also on the hydrophobicity of each PAH. Accordingly, the use of HT-DDS as an amendment or barrier in contaminated soil is proposed for reducing the mobility of PAHs and, consequently, the adverse effect derived from rapid transport losses of the pollutants to the adjoining environmental compartments.