AMINO ACIDS AS NEW METAL CHELATORS FOR SOIL REMEDIATION IN AQUEOUS AND ORGANIC MEDIA

Contamination of soils and sediments by heavy metals is a worldwide recognized problem associated with public health. Methods of soils/sediments remediation usually involve use of chelators. Strong and efficient chelators are mostly non-biodegradable, so search for environmentally-friendly chelators is continuing. Strong chelators (like EDTA) usually consist of an acetate group attached to nitrogen atom, which obviously forms an amino acid core. However, EDTA is not environmentally-friendly, opposite to natural amino acids.

Metal complexes of amino acids are stable and are well-studied. Nonetheless, up to our knowledge, amino acids have not been used as chelators for soil remediation, despite their availability and nontoxicity. We have tested natural amino acids towards heavy metal extraction from contaminated soils and sediments. Aqueous solution and critical solution mixture of water-miscible biodegradable organic solvents were applied to dissolve both hydrophilic and hydrophobic amino acids. Critical solution, being two phase system at room temperature, and homogeneous at mild heating, allows to direct the extracted pollutants either to aqueous or to organic phase, depending on hydrophobicity of the chelators.

It appears that amino acids are fair chelators for moderately contaminated soils, and organic solvents assist amino acids to extract some hazardous metals with high efficiency due to better contact with organic soil matter. The results will be presented and discussed in the poster. Our research explores new approaches to heavy metal extraction from the contaminated soils, and thus it contributes to an important and intensively developing area of soil remediation, and to environmental sciences in general.