2017 Volume 64 Issue 5 Pages 222-229
Although conventional chemical or thermal recycling techniques are often the most appropriate means of recovering precious and rare metals, biological methods provide an attractive and eco-friendly alternative strategy in which metal ion-reducing microorganisms, Shewanella bacteria are applied to separate and concentrate precious and rare metals from aqueous solutions. We have developed a new biomineralization system to reduce soluble palladium(II), rhodium(III), platinum(IV), and gold(III) into insoluble metal nanoparticles at room temperature within 120 min. Biogenic palladium nanoparticles on the cell surface were found to exhibit better catalytic properties than those of commercial palladium catalysts. When processing the aqua regia leachate of spent automotive catalysts by adjusting its pH, Shewanella bacteria were able to rapidly and selectively collect platinum group metals. We also proposed a new biosorption system to separate soluble indium(III) or dysprosium(III) into microbial cells. We achieved selective adsorption of indium(III) ions in Shewanella bacteria from the leachate of spent liquid crystal displays by adjusting its pH. Our proposed microbial methods enable the rapid and highly efficient recovery of precious and rare metals by using Shewanella bacteria.
