Analisi dei parametri operativi e dell'efficienza di recupero di terre rare in sistemi a base di argille

Rare Earths (REs) are considered critical and strategic materials because of their high technology applications and their high supply risk. For these reasons the study of targeted and efficient processes to obtain REs raw materials is of increasing interest. In particular, a REs recovering process from Waste Electric and Electronic Equipment (WEEE) can only lead to economic, environmental and social benefits. In the field of hydrometallurgy, several separation technologies have been used for the recovery of metal ions from aqueous solutions. Among them, solid-liquid extractions are characterized by: high recovery, short extraction time, high enrichment factor, low cost, and low consumption of organic solvents. Furthermore, clays as solid sorbents present some outstanding advantages, such as convenient solid−liquid separation, low cost, good acid tolerance, high mechanical intensity, and excellent reusability. The aim of this work was to study the possibility of REs recovery from WEEE by using a chelating agent immobilized on clays. During the research activity two natural smectite clays (STx-1b and SWy-2) were modified intercalating a PEG-ylated ethylene diamine; then the modified clays were contacted with aqueous solutions of lanthanum at known concentration (chosen as representing element of REs family) and analyzing the lanthanum content in the liquid phase it was possible to deduce the lanthanum captured by the modified clays. The polymer intercalation occurred and the synthesized organo-clays were effective in lanthanum uptake. Furthermore the polymer concentration was varied to get the effect on the system: the amount of intercalated polymer increased for both the clays increasing the polymer initial concentration, while the lanthanum uptake as a function of the intercalated polymer presented an optimum value, above which the addition of polymer did not positively affect the uptake