Observation of the Curie Transition in Palladium Bionanomaterial Using Muon Spin Rotation Spectroscopy

Palladium bionanomaterial was manufactured using the sulfate-reducing bacterium, Desulfovibrio desulfuricans, to reduce soluble Pd(II) ions to cell-bound Pd(0). The material was examined using a Superconducting Quantum Interference Device (SQUID) to observe bulk magnetisation over the temperature range 10 – 300 K and by Muon Spin Rotation (μSR), which is a probe of the local magnetic environment inside the sample, over the temperature range 200 – 700 K. Results from SQUID were used to model the temperature dependence of ferromagnetic and paramagnetic components of the bulk magnetisation and, by extrapolation, to predict the Curie transition temperature. Results from μSR confirmed the accuracy of the prediction to within 20 K. The Curie transition, which started at 528 K, was shown to be spread over a wide ( 100 K) range. This was attributed to dependence of the transition on particle size and the range of particle sizes in the population. A competing contribution to the overall magnetisation was observed due to partial thermal decomposition of the organic component of the material. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3533

Nanoparticles of palladium supported on bacterial biomass : new re-usable heterogeneous catalyst with comparable activity to homogeneous colloidal Pd in the Heck reaction

AbstractThe Heck coupling of iodobenzene with ethyl acrylate or styrene was used to assess the catalytic properties of biogenic nanoparticles of palladium supported upon the surface of bacterial biomass (bioPd), this approach combining advantages of both homogeneous and heterogeneous catalysts. The biomaterial was comparably active or superior to colloidal Pd in the Heck reaction, giving a final conversion of 85% halide and initial rate of 0.17mmol/min for the coupling of styrene and iodobenzene compared to a final conversion of 70% and initial rate of 0.15mmol/min for a colloidal Pd catalyst under the same reaction conditions at 0.5mol.% catalyst loading. It was easily separated from the products under gravity or by filtration for reuse with low loss or agglomeration. When compared to two alternative palladium catalysts, commercial 5% Pd/C and tetraalkylammonium-stabilised palladium clusters, the bioPd was successfully reused in six sequential alkylations with only slight decreases in the rate of reaction as compared to virgin catalyst (initial rate normalised for g Pd decreased by 5% by the 6th run with bioPd catalyst cf. a decrease of 95% for Pd/C). A re-usable Pd-catalyst made cheaply from bacteria left over from other processes would impact on both conservation of primary sources via reduced metal losses in industrial application and the large environmental demand of primary processing from ores

Catalytic activity of biomass-supported Pd nanoparticles : influence of the biological component in catalytic efficacy and potential application in ‘green’ synthesis of fine chemicals and pharmaceuticals

AbstractFive gram negative and two gram positive bacterial strains known for their heavy metal tolerance or ability to reduce metal ions were coated with Pd(0) nanoparticles (NPs) via reduction of soluble Pd(II) ions under H2 following an initial uptake of PdCl42- without added electron donor ('biosorption'), where the gram negative strains had a ~5-fold greater capacity for Pd(II). Cupriavidis metallidurans accumulated Pd(II) exceptionally; the possibility of reduction to Pd(0) via an endogenous electron donor was not discounted. The initial rate of subsequent H2-mediated Pd(II) reduction correlated with the Pd(II) removed during biosorption (r2=0.9). TEM showed strain-specific variations of Pd-NPs. At a 1:3 loading of Pd:biomass the cell surfaces of Escherichia coli and Desulfovibrio desulfuricans showed uniform coverage with small NPs with the other strains showing larger aggregates. NPs made by the gram positive cells appeared larger than their gram negative counterparts. At a loading of 1:19 all were active catalysts in Cr(VI) reduction and in two Heck coupling reactions. BioPdE. coli and bioPdD. desulfuricans and bioPdA. oxydans were consistently the best and worst catalysts respectively. BioPdE. coli was further tested as a process catalyst according to industrial protocols in Heck and Suzuki coupling reactions. Laboratory and industrial tests (coupling of phenyl iodide and ethyl acrylate) gave 75% and 78% conversion to ethyl cinnamate, respectively. The biomaterial catalysed Heck and Suzuki reactions using bromoacetophenone and 4-bromoanisole (Heck) and 4-chloroanisole (Suzuki) but not 3-chlorotoluene. In accordance with known chemical catalysis the catalytic efficacy was related to electron-withdrawing substituents on the phenyl ring, with more than 90% conversion (Suzuki) using 4-bromobenzotrifluoride

Direct solid state NMR observation of the 105Pd nucleus in inorganic compounds and palladium metal systems

The ability to clearly relate local structure to function is desirable for many catalytically relevant Pd-containing systems. This report represents the first direct 105Pd solid state NMR measurements of diamagnetic inorganic (K2Pd(iv)Cl6, (NH4)2Pd(iv)Cl6 and K2Pd(iv)Br6) complexes, and micron- and nano-sized Pd metal particles at room temperature, thereby introducing effective 105Pd chemical shift and Knight shift ranges in the solid state. The very large 105Pd quadrupole moment (Q) makes the quadrupole parameters (CQ, ηQ) extremely sensitive to small structural distortions. Despite the well-defined high symmetry octahedral positions describing the immediate Pd coordination environment, 105Pd NMR measurements can detect longer range disorder and anisotropic motion in the interstitial positions. The approach adopted here combines high resolution X-ray pair distribution function (PDF) analyses with 105Pd, 39K and 35Cl MAS NMR, and shows solid state NMR to be a very sensitive probe of short range structural perturbations. Solid state 105Pd NMR observations of ∼44-149 μm Pd sponge, ∼20-150 nm Pd black nanoparticles, highly monodisperse 16 ± 3 nm PVP-stabilised Pd nanoparticles, and highly polydisperse ∼2-1100 nm biomineralized Pd nanoparticles (bio-Pd) on pyrolysed amorphous carbon detect physical differences between these systems based on relative bulk:surface ratios and monodispersity/size homogeneity. This introduces the possibility of utilizing solid state NMR to help elucidate the structure-function properties of commercial Pd-based catalyst systems. © 2018 the Owner Societies

Applications of bacterial hydrogenases in waste decontamination, manufacture of novel bionanocatalysts and in sustainable energy

Bacterial hydrogenases have been harnessed to the removal of heavy metals from solution by reduction to less soluble metal species. For Pd(II), its bioreduction results in the deposition of cell-bound Pd(0)-nanoparticles that are ferromagnetic and have a high catalytic activity. Hydrogenases can also be used synthetically in the production of hydrogen from sugary wastes through breakdown of formate produced by fermentation. The Bio-H2 produced can be used to power an electrical device using a fuel cell to provide clean electricity. Production of hydrogen from confectionery wastes by one organism (Escherichia coli) can be used as the electron donor for the production of Bio-Pd0 from soluble Pd(II) by a second organism. The resulting Bio-Pd0 can then be used as a bioinorganic catalyst in the remediation of Cr(VI)-contaminated solutions or polychlorinated biphenyls at the expense of Bio-H2, as a hydrogenation catalyst for industry or as a component of a fuel cell electrode