MMIJ Annual Meeting

Palladium (Pd) is recognized as an important industrial catalyst which has been used to speed up various chemical reactions. As its demand is growing year by year, it is critical to recover it from Pd(II) containing leachates/wastewaters. This study investigated the utilization of the extremely acidophilic archaeon, Sulfolobus tokodaii, as a support for the bio-Pd(0) nanoparticles production. Owing to microbial enzymatic reaction, Pd(II) ions were effectively removed from solution, forming bio-Pd(0) nanoparticles on the cell surface within 5 hours (with 10 mM sodium formate). Fine and well-dispersed bio-Pd(0) nanoparticles were produced only in the presence of active cells. Those were not formed in the absence of cells (control), in the presence of enzyme inhibitor or inactivated enzyme (heat-killed cells). Catalytic activities of bio-Pd(0) nanoparticles were evaluated using Cr(VI) reduction reaction in the presence of electron donor (formate or hydrogen gas) in the acidic condition. Highly toxic Cr(VI) anions were completely reduced to less toxic Cr(III)　anions within 12 hours in the presence of 0.025 mg/ml bio-Pd(0) nanoparticles (weight including dried cell mass) and 10 mM sodium formate. The results suggest the potential of microorganisms to produce highly catalytic bio-Pd(0) nanoparticles using an environmental friendly approach. （若手ポスターに発表）