title: Recovery of valuable metals from electronic scraps by clays and organo-clays: Study on bi-ionic model solutions.
abstract: The demand of valuable metals, as precious metals and rare earths, is constantly increasing in the global market, as many and different technological applications exploit these materials because of their unique properties. Since natural resources are located just in focused areas, an interesting possibility could be the recovery of metals from Waste Electrical and Electronic Equipment (WEEE). The aim of this work is to evaluate the recovery potentialities of clays and organo-clay based systems towards the metals contained in the solutions of electronic scraps dissolved in strong acid, by preliminary tests on bi-ionic model solutions. Lanthanum has been chosen as representative of the rare earths while copper has been considered since it is by far the most used metal in electric and electronic equipment. The considered sorbents are a montmorillonitic clay and two polyamine based organo-clays. Uptake and release processes have been carried out in order to assess the performances of these solids and to evaluate the uptake and release mechanisms. The results showed that the cationic exchange is the prevailing mechanism in the case of pristine clay, while both coordinating effect due to amino groups and cationic exchange occur in the case of modified clays, respectively accounting for copper and lanthanum uptake. Furthermore the pH was found having a great influence in both the adsorption and desorption phenomena.
authors.affiliation: Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Piazza Leonardo Da Vinci 32, 20133 Milano, Italy. Electronic address: elenamaria.iannicelli@polimi.it.
authors.forename: Elena Maria
authors.initials: EM
authors.lastname: Iannicelli-Zubiani
authors.affiliation: Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Piazza Leonardo Da Vinci 32, 20133 Milano, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Cristiani
authors.affiliation: Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Piazza Leonardo Da Vinci 32, 20133 Milano, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Dotelli
authors.affiliation: Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Piazza Leonardo Da Vinci 32, 20133 Milano, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Gallo Stampino
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D000077215:Clay; D003300:Copper / Q000737:chemistry / Q000302:isolation & purification*; D059029:Electronic Waste; D007811:Lanthanum / Q000737:chemistry / Q000302:isolation & purification*; D059027:Recycling / Q000379:methods*; D012996:Solutions / Q000737:chemistry; D018505:Waste Management / Q000379:methods
chemical_list: D000538:Aluminum Silicates; D012996:Solutions; D007811:Lanthanum; D003300:Copper; D000077215:Clay
keywords: Clays; Copper; Electronic waste; Lanthanum; Organo-clays; Recovery