Reciclagem de discos compactos: um estudo sobre a recuperação de metais encontrados nos discos por meio de processos químicos.

Abstract

Compact discs (CDs, CD-Rs, CD-ROMs, and CD-RWs) are magneto-optical supports on which sound or information is recorded. Currently, the incorrect disposal of these materials has increased significantly, due to its rapid obsolescence and replacement by other media, generating several environmental problems. The discs have in their composition metals such as silver, aluminum, gold or titanium that can be released into the environment during the deposition of these products in landfills and dumps. In addition, the CDs also have Polycarbonate in their composition, a polymeric compound that can release bisphenol A when degraded. The present work discusses the environmental impacts resulting from the incorrect disposal of CDs and suggests a method for recovering metals found on the discs. The constitution of the discs and recycling methods used by companies and organizations were studied. The Brazilian environmental legislation with respect to electrical and electronic waste was also analyzed. In the elaboration of the chemical method for metal recovery, several reactants were tested for removal of the existing layers on the discs. The results indicate that sodium hydroxide is effective in removing the printable layer, the acrylic lacquer and also the reflective layer on CDs. The removal of the reflective metal layer on CD-Rs was achieved with commercial sodium hypochlorite 2.0% w/v. Ethanol 90% v/v proved to be efficient for the dissolution of Phthalocyanine found in CD-Rs. Aiming at a lower environmental impact of the method, the suggested procedure was also analyzed based on the principles of Green Chemistry.