title: Evaluation of gold and silver leaching from printed circuit board of cellphones.
abstract: Electronic waste has been increasing proportionally with the technology. So, nowadays, it is necessary to consider the useful life, recycling, and final disposal of these equipment. Metals, such as Au, Ag, Cu, Sn and Ni can be found in the printed circuit boards (PCB). According to this, the aims of this work is to characterize the PCBs of mobile phones with aqua regia; obtaining "reference" values of leaching, to gold and silver, with cyanide and nitric acid, respectively; and study the process of leaching of these metals in alternative leaching with sodium thiosulfate and ammonium thiosulfate. The metals were characterized by digesting the sample with aqua regia for 1 and 2h at 60°C and 80°C. The leaching of Au with a commercial reagent (cyanide) and the Ag with HNO3were made. The leaching of Au and Ag with alternative reagents: Na2S2O3, and (NH4)2S2O3 in 0.1M concentration with the addition of CuSO4, NH4OH, and H2O2, was also studied. The results show that the digestion with aqua regia was efficient to characterize the metals present in the PCBs of mobile phones. However, the best method to solubilize silver was by digesting the sample with nitric acid. The leaching process using sodium thiosulfate was more efficient when an additional concentration of 0.015 and 0.030 M of the CuSO4 was added.
authors: LACOR, PPGE3M, Universidade Federal do Rio Grande do Sul, Campus do Vale, Setor 4, Prédio 74, Av. Bento Gonçalves 9500, CEP 91501-970 Porto Alegre, RS, Brazil. Electronic address: patymhp@yahoo.com.br.
authors: P M H
authors: PM
authors: Petter
authors: LACOR, PPGE3M, Universidade Federal do Rio Grande do Sul, Campus do Vale, Setor 4, Prédio 74, Av. Bento Gonçalves 9500, CEP 91501-970 Porto Alegre, RS, Brazil.
authors: H M
authors: HM
authors: Veit
authors: LACOR, PPGE3M, Universidade Federal do Rio Grande do Sul, Campus do Vale, Setor 4, Prédio 74, Av. Bento Gonçalves 9500, CEP 91501-970 Porto Alegre, RS, Brazil.
authors: A M
authors: AM
authors: Bernardes
mesh_terms: D040421:Cell Phone; D059029:Electronic Waste / Q000706:statistics & numerical data*; D006046:Gold / Q000032:analysis* / Q000302:isolation & purification; D006851:Hydrochloric Acid; D017942:Nitric Acid; D059027:Recycling / Q000379:methods*; D012037:Refuse Disposal / Q000379:methods*; D012834:Silver / Q000032:analysis* / Q000302:isolation & purification; D013885:Thiosulfates
chemical_list: D013885:Thiosulfates; D012834:Silver; D017942:Nitric Acid; D006046:Gold; C035309:ammonium thiosulfate; C017717:sodium thiosulfate; D006851:Hydrochloric Acid; C022102:aqua regia
keywords: Leaching; Mobile-phones; Precious metals; Printed circuit boards; Recycling