Recovery of silver residues from dental amalgam
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Data
2010-03-01
Autores
Barbosa da Silva Pereira, Heloisa Aparecida
Iano, Flavia Godoy
da Silva, Thelma Lopes
de Oliveira, Rodrigo Cardoso
Menezes, Manoel Lima de [UNESP]
Rabelo Buzalaf, Marilia Afonso
Título da Revista
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Editor
Universidade de São Paulo (USP), Faculdade de Odontologia de Bauru
Resumo
D ental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. Objective: The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. Material and Methods: The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5% HNO(3), followed by precipitation with 20% NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO(3) at 90 degrees C, followed by precipitation with 20% NaCl. After washing, the pellet was diluted with concentrated NH(4)OH, water and more NaCl in order to facilitate the reaction with the reducer. Results: Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. Conclusions: The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.
Descrição
Palavras-chave
Dental amalgam, Silver, Solid wastes, Environment
Como citar
Journal of Applied Oral Science. Bauru-sp: Univ São Paulo Fac Odontologia Bauru, v. 18, n. 2, p. 121-126, 2010.