2015年10月27日星期二

Bioleaching of gallium from gallium arsenide by Cellulosimicrobium funkei and its application to semiconductor/electronic wastes

Abstract

The aim of this work was to screen and characterize heterotrophic bacteria for gallium arsenide (GaAs) leaching. Ga in the form of GaAs has been extensively used as a semiconductor substrate material. The advantage of using microbes for gallium recovery is the fact that this method is a safer, environment–friendly and includes energy–saving processes, which can leach metals at relatively low concentrations. Eight bacterial isolates were isolated from cadmium–, and arsenic–contaminated soil in the presence of GaAs. Pad I and NKS III showed the highest efficiency in Ga leaching at approximately 63–81% after 15 and 30 days, respectively, under neutral pH conditions. The analysis of 16S rDNA sequences indicated that strain Pad I was close to strain NKS III; it was characterized and identified as Cellulosimicrobium funkei (C. funkei). Further investigation revealed that the ability of Ga leaching from GaAs by this bacterium involved amino acids. This process occurred in a weak base pH range. The results show a potential application of C. funkei to leach Ga from semiconductors or electronic wastes. The in–depth mechanism of bacterial leaching of Ga from GaAs was also investigated.

Keywords

  • Cellulosimicrobium funkei
  • Gallium arsenide
  • Semiconductor
  • Bioleaching
  • Electronic waste