The identification of surface sulfide and polysulfide species based on the curve fitting of S2p photoelectron\ud spectra and, for the first time, of X-ray excited S KLL Auger spectra has been performed. The different sulfur\ud chemical states present on the surface (sulfide S2, central S and terminal S in polysulfide chains) could be\ud unambiguously assigned in the chemical state plot. Sulfur atoms in the central or terminal position,\ud respectively, are found on a line with slope ca. 3 irrespective of the cation indicating similar initial state\ud effects. On the other hand, for a given polysulfide, e.g. K2Sn, sulfur atoms both in central or terminal\ud positions are found on the same line with slope 1 indicating similar final state effects. This behavior can\ud be rationalized with the fact that the negative charge in polysulfide chains is located mainly on sulfur\ud atoms in the terminal position; indeed, sulfur present as central S shows a binding energy shift of 0.6\ud eV with respect to elemental sulfur (S8), and sulfur in terminal S a shift of 2.4 eV. An application of this\ud approach tested on commercial alkali polysulfides is provided for the curve fitting of SKLL signals and\ud sulfur speciation of three different sulfide minerals enargite (Cu3AsS4), chalcopyrite (CuFeS2) and\ud arsenopyrite (FeAsS). Also for the surface of mineral sulfides, terminal S atoms and central S atoms in the\ud polysulfide chains can successfully be identified

An extensive investigation on the noble metal (NM) content in different classes of waste printed circuit boards (WPCBs: random access memories, RAMs; network interface controllers, NICs; motherboards; TV, DVD/CD player, hard-drive, and mobile phone PCBs) has been performed to define the most appropriate case study and provide a robust database useful for workers in the waste valorization field. Following accurate selection, mechanical comminution, representative sampling, quantitative digestion, and analytical characterization (ICP-AES), RAMs and mobile phone PCBs confirmed to be the “richest” source, while TV PCBs are the “poorest” one in term of NM content. Accordingly, the RAM case study has been employed for the application of a new NMs recovery method, previously set up on finely comminuted waste electric and electronic equipment underwent materials enrichment by mechanical separation. Despite the very large amount of vitreous-plastic and metallic materials present in the mixture, satisfactory NM recovery yields (Cu 70%, Ag 92%, Au 64%) with limited byproduct formation have been obtained using safe and recyclable reagents in mild conditions: citric acid for base metal leaching, ammonia in oxidizing environment for Cu and Ag separation and recovery, triiodide aqueous solution for gold recovery, at room pressure, and 25–100 °C. The reported results provide useful quantitative parameters for assessing the profitability of an industrial scale-up of the new sustainable NMs recovery method.

The peculiar properties of iodine and safe lixiviants for sustainable and effective noble-metal recovery from shredded WEEE.