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

NARIO NICOLAS; LORENZETTI, A.S.; SAMUELSEN LUCEA, CLAUS; GOMEZ N.A.; GRUHUT MARCOS; CORA JOFRE F; AZCÁRATE S; CAMIÑA J.; SILVA, MARÍA F.; GOMEZ, FEDERICO J. V.; DOMINI C.

Congreso; WCCE11-11th Wolrld Congress of Chemical Engineering; 2023

The environmental study of heavy metals in soils and sediments is of utmost importance, being the European Community Bureau of Reference (BCR) one of the most widely used extraction methods1. It allows the quantification of available 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 method is 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 solvents regarding their sustainability, extraction efficiency, and low cost2. They usually consist of natural components, being hydrogen bonds the main driving force for their obtention. One of their most attractive and promising characteristics is the 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. According to the preliminary results in CRM-BCR 701 sediment, the eutectic solvent LGH (an acidic mixture of lactic acid, glucose and water) is the most promising extractant. In Figure 1, the obtained concentration of the analyzed metals employing an MIP-OES for detection is shown. As it can be seen, exchangeable and reducible fractions were successfully extracted in almost all of the metals. Nevertheless, only for Cd and Pb, the oxidisable fraction was reached.