Tailoring a new Natural Deep Eutectic Solvent to assist the extraction of metals from sediments

NICOLAS A. NARIO; ANABELA S. LORENZETTI; CLAUS SAMUELSEN LUCEA; NATALIA A. GOMEZ; MARCOS GRÜNHUT; FLORENCIA CORA JOFRE; MARIANELA SAVIO; SILVANA M. AZCARATE; JOSE M. CAMIÑA; MARIA F. SILVA; FEDERICO J. V. GOMEZ; CLAUDIA E. DOMINI

Buenos Aires

Congreso; 11th World Congress of Chemical Engineering; 2023

AAIQ - Asociación Argentina de Ingenieros Químicos

The environmental study of heavy metals in soils and sediments is of utmost importance, being the EuropeanCommunity Bureau of Reference (BCR) one of the most widely used extraction methods1. It allows the quantification ofavailable and mobilizable metals through a 3-step sequential extraction scheme, composed of 3 non-residual fractions(exchangeable, reducible and oxidisable) and a residual one (metals bound to the mineral matrix). However, this methodis laborious, time-consuming (51 h) and uses toxic solvents.In the last few years, Natural Deep Eutectic Solvents (NADES) have become the most promising green solventsregarding their sustainability, extraction efficiency, and low cost2. They usually consist of natural components, beinghydrogen bonds the main driving force for their obtention. One of their most attractive and promising characteristics isthe capacity to adapt their physicochemical properties according to the ratio and nature of their components2.In this work, the metal extraction capacity of several NADES with different physicochemical properties (pH, viscosity)was evaluated, with the aim to develop a new, greener and faster extraction method for sediment samples. Accordingto the preliminary results in CRM-BCR 701 sediment, the eutectic solvent LGH (an acidic mixture of lactic acid, glucoseand water) is the most promising extractant. In Figure 1, the obtained concentration of the analyzed metals employingan MIP-OES for detection is shown. As it can be seen, exchangeable and reducible fractions were successfully extractedin almost all of the metals. Nevertheless, only for Cd and Pb, the oxidisable fraction was reached.