RESUMEN
Transition-metal-catalyzed copolymerization of ethylene with carbon monoxide affords polyketones materials with excellent mechanical strength, photodegradability, surface and barrier properties. Unlike the widely used and rather expensive Pd catalysts, Ni-catalyzed carbonylative polymerization is very difficult since the strong binding affinity of CO to Ni deactivates the highly electrophilic metal center easily. In this study, various cationic P,O-coordinated Ni complexes were synthesized using the electronic modulation strategy, and the catalyst with strong electron-donating substituents exhibits an excellent productivity of 104 â g polymer (g Ni)-1 , which represents a rare discovery that a Ni complex could operate with such exceptional efficiency in comparison with Pd catalysts. Notably, those Ni catalysts were also efficient for terpolymerization of ethylene, propylene with CO for producing commercial polyketone materials with low melting temperatures and easy processibility.
RESUMEN
An anthraquinone-2-sulfonate and reduced graphene oxide nanocomposite (AQS@rGO) was prepared and the improvement on the biotic reduction of a pollutant, i.e., azo dye, was demonstrated. Electron paramagnetic resonance signal of the semi-quinone radical in the well-dispersed solid AQS@rGO solution was detected. Although the as-prepared AQS@rGO has a negligible adsorption capacity toward methyl orange (MO) dye, the decolorization efficiencies in both flask experiments and sequencing operation reactors in the presence of AQS@rGO were increased by more than 1.5 times as compared to that with graphene oxide, and an efficient and continuable catalytic effect on the decolorization of azo dyes in seven operation periods was maintained. The catalytic effect on reduction was caused by the formation of a space-charge layer, which facilitates the efficient e- transfer from the conductive rGO sheets to the C=O of the AQS molecule. The results suggested that the AQS@rGO may act as an efficient insoluble redox mediator, which is important for the pollution control by accelerating the extracellular electron transfer.
RESUMEN
Biogenic nanoparticles are promising materials for their green synthesis method and good performance in stimulation on reduction of environmental contaminants. In this study, Pd(0) nanoparticles (bio-Pd) were generated by Klebsiella oxytoca GS-4-08 in fermentative condition and in-situ improved the azo dye reduction. The bio-Pd was mainly located on cell membrane with a size range of 5-20â¯nm by TEM and XRD data analyses. Anthraquinone-2-disulfonate (AQS) greatly increased the reduction rate of Pd(II) with a reduction efficiency as high as 96.54⯱â¯0.23% in 24â¯h. The quinone respiration theory, glucose metabolism and the biohydrogen pathway were used to explain the enhancement mechanism of the in-situ generated bio-Pd on azo dye reduction. These results indicate that the in-situ generated bio-Pd by K. oxytoca strain is efficient for azo dye reduction without complex preparation processes, which is of great significance for the removal and subsequent safe disposal of hazardous environmental compounds.
