Bimetallic Au-Pd and Ag-Pd Clusters Synthesised by

Ag-Pd and Au-Pd (alloyed or core-shell) catalysts were synthesised by radiolytic reduction (gamma rays or electron beam). Selective hydrogenation of buta-1,3-diene was performed with these different nanoparticles deposited on alumina in order to investigate composition and structure effects on catalytic performances. Au-Pd and Ag-Pd nanoparticles exhibit very different catalytic behaviours: whereas only hydrogenation activity is modified on Au-Pd systems without any change in selectivity toward butenes formation, important variations in selectivity into butenes are observed for Ag-Pd nanoparticles deposited on alumina support

Cadmium uptake kinetics and plants factors of shoot Cd concentration

Accumulation of Cd in the shoots of plants grown on Cd contaminated soils shows considerable variation. A previous preliminary experiment established that one major reason for this variation was the rate of Cd influx into the roots (mol Cd cm(-2) root s(-1)). However, this experiment did not distinguish between solubilization of soil Cd on the one hand and difference in Cd uptake kinetics on the other. The main objectives of the present study were thus to characterize Cd uptake kinetics of plants continuously exposed to Cd concentrations similar to those encountered in soils. Furthermore we determined the factors responsible for differences in shoot Cd concentration such as net Cd influx, root area-shoot dry weight ratio, shoot growth rate and proportion of Cd translocated to the shoot. Maize, sunflower, flax and spinach were grown in nutrient solution with five constant Cd concentrations varying from 0 to 1.0 mu mol L-1. Root and shoot parameters as well as Cd uptake were determined at two harvest dates and from these data Cd net influx and shoot growth rates were calculated. Cadmium uptake kinetics, i.e. the net Cd influx vs. Cd solution concentration followed a straight line. Its slope is the root absorbing power, alpha, . The alpha values of spinach and flax were about double that of maize and sunflower (5 x 10(-6) cm s(-1) vs. 2.5 x 10(-6) cm s(-1)). Spinach and flax had a 3-5 times higher shoot Cd concentration than maize and sunflower. The difference in shoot Cd concentration was partly due to the higher Cd influx but also to a higher translocation of Cd from root to shoot and also to a slower shoot growth rate

Determining the fluxes of ions (Pb2+, Cu2+ and Cd2+) at the root surface of wetland plants using the scanning ion-selective electrode technique

Conservation Biolog

Phytoextraction of metals by Erigeron canadensis L. from fly ash landfill of power plant “Kolubara”

The objectives of this study were to determine the concentrations of Pb, Cd, As, Cr, Cu, Co, Ni, Zn, Ba, Fe, Al and Ag in Erigeron canadensis L. growing on fly ash landfill of power plant "Kolubara", Serbia. The content of each element was determined in every part of plant separately (root, stalk and inflorescence) and correlated with the content of elements in each phase of sequential extraction of fly ash. In order to ambiguously select the factors that are able to decidedly characterize the particular part of plant, principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were performed. The bioconcentration factors and translocation factors for each metal were calculated in order to determine the feasibility of the use of plant E. canadensis L. for phytoremediation purpose. There were strong positive correlations between metals in every part of plant samples, and metals from pseudo total form of sequential extraction indicate that the bioavailability of elements in fly ash is similarly correlated with total form. Retained Al, Fe, Cr and Co in the root indicate its suitability for phytostabilization. This plant takes up Cd and Zn from the soil (bioconcentration factors (BCFs) greater than 1), transporting them through the stalk into the inflorescence (translocation factors (TFs) higher than 1). Regarding its dominance in vegetation cover and abundance, E. canadensis L. can be considered adequate for phytoextraction of Cd and Zn from coal ash landfills at Kolubara.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3405