Direct and quinone-mediated palladium reduction by Geobacter sulfurreducens: mechanisms and modeling.
Palladium(II) reduction to Pd(0) nanoparticles by Geobacter sulfurreducens was explored under conditions of neutral pH, 30 °C and concentrations of 25, 50, and 100 mg of Pd(II)/L aiming to investigate the effect of solid species of palladium on their microbial reduction. The influence of anthraquinone-2,6-disulfonate was reported to enhance the palladium reaction rate in an average of 1.7-fold and its addition is determining to achieve the reduction of solid species of palladium. Based on the obtained results two mechanisms are proposed: (1) direct, which is fully described considering interactions of amide, sulfur, and phosphoryl groups associated to proteins from bacteria on palladium reduction reaction, and (2) quinone-mediated, which implies multiheme c-type cytochromes participation. Speciation analysis and kinetic results were considered and integrated into a model to fit the experimental data that explain both mechanisms. This work provides elements for a better understanding of direct and quinone-mediated palladium reduction by G. sulfurreducens, which could facilitate metal recovery with concomitant formation of valuable palladium nanoparticles in industrial processes.
División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), Camino a la Presa San José 2055, Col. Lomas 4a. Sección, C. P. 78216, San Luis Potosí, SLP, Mexico.
Aurora M
AM
Pat-Espadas
Elías
E
Razo-Flores
J Rene
JR
Rangel-Mendez
Francisco J
FJ
Cervantes
D000880:Anthraquinones; D045302:Geobacter / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D011809:Quinones / Q000737:chemistry*
D000880:Anthraquinones; D011809:Quinones; C408124:anthraquinone-2,6-disulfonate; D010165:Palladium