Maria Michela Dell’Anna

A Recyclable Nanoparticle-Supported Rhodium Catalyst for Hydrogenation Reactions

Catalytic hydrogenation under mild conditions of olefins, unsaturated aldeydes and ketones, nitriles and nitroarenes was investigated, using a supported rhodium complex obtained by copolymerization of Rh(cod)(aaema) [cod: 1,5-cyclooctadiene, aaema–: deprotonated form of 2-(acetoacetoxy)ethyl methacrylate] with acrylamides. In particular, the hydrogenation reaction of halonitroarenes was carried out under 20 bar hydrogen pressure with ethanol as solvent at room temperature, in order to minimize hydro-dehalogenation. The yields in haloanilines ranged from 85% (bromoaniline) to 98% (chloroaniline).

Polymer Supported Catalysts Obtained from Metal-Containing Monomers

This review summarizes the progress made in the last eight years on the synthesis and use in catalysis of polymer supported metal complexes obtained by co-polymerization of metal-containing monomers (MCMs) with suitable co-monomers and cross-linkers. These materials are divided into four important classes: microporous organic polymers, molecularly imprinted polymers (MIPs), macro- pouros organic polymers, polymers obtained by ring opening metathesis polymerization (ROMP). Although the MIPs have essentially a macroporous structure, they constitute a separate group of catalysts for their peculiar way of synthesis. The discussion focuses on the ef- ficiency and reusability of all these potentially recoverable catalysts.

Asymmetric allylic alkylation using a polymer-supported palladium catalyst in the presence of chiral ligands

Abstract Polymer-supported Pd(AAEMA)2 (Pd-pol) [AAEMA−: deprotonated form of 2-(acetoacetoxy)ethyl methacrylate] in the presence of chiral ligands catalyses the asymmetric substitution of rac-1,3-diphenyl-2-propenyl acetate with dimethyl malonate. A series of conventional ligands were tested: the enantioselectivities (up to 93% ee) were similar to those observed employing the analogous homogeneous catalyst or a classical soluble palladium complex. In some case the supported catalyst was used in two subsequent runs with only a slight loss of activity and selectivity.

Are conventional statistical techniques exhaustive for defining metal background concentrations in harbour sediments? A case study: The Coastal Area of Bari (Southeast Italy)

Sediment contamination by metals poses significant risks to coastal ecosystems and is considered to be problematic for dredging operations. The determination of the background values of metal and metalloid distribution based on site-specific variability is fundamental in assessing pollution levels in harbour sediments. The novelty of the present work consists of addressing the scope and limitation of analysing port sediments through the use of conventional statistical techniques (such as: linear regression analysis, construction of cumulative frequency curves and the iterative 2σ technique), that are commonly employed for assessing Regional Geochemical Background (RGB) values in coastal sediments. This study ascertained that although the tout court use of such techniques in determining the RGB values in harbour sediments seems appropriate (the chemical-physical parameters of port sediments fit well with statistical equations), it should nevertheless be avoided because it may be misleading and can mask key aspects of the study area that can only be revealed by further investigations, such as mineralogical and multivariate statistical analyses.

Iron(II) modified natural zeolites for hexavalent chromium removal from contaminated water

Abstract Three different types of Fe(II)-modified natural zeolites were tested as supports in continuous-flow columns for the treatment of Cr(VI) contaminated water. The natural zeolites chosen as support were commercially available Zeosand (80% clinoptilolite), ATZ (79% phillipsite/chabazite), and ZS-55RW (90% Chabazite). All the examined modified zeolites turned out active for hexavalent chromium abatement, lowering its concentration below the European regulation level, even at relatively high flow rates (40 mL/h, linear velocity 15 cm/h). Zeosand, having a broader pH range of stability, was found to be the best one in terms of both Fe(II) uptake (0.54 wt%) and Cr removal (90 mg Cr/Kg zeolite).

Influence of hydrodynamic features in the transport and fate of hazard contaminants within touristic ports. Case study: Torre a Mare (Italy)

The environmental quality of Torre a Mare port (Italy) was assessed evaluating on one side, the chemical concentration of nine metals and metalloids within bottom sediments and on the other one, by exploring the impact of hydrodynamic conditions in contaminant’s transport within the most polluted basins. The investigated port was selected as case study because it resulted much more polluted than it was expected based on the touristic port activities and related stressors loading on it. In order to determine the origin and fate of contaminants in the port basin, 2D numerical simulations were carried out by MIKE21 software. The hydrodynamic module (HD) based on a rectangular grid was initially used to characterize the flow field into two domains that cover the inner and offshore harbor area. Then, advection–dispersion (AD) and water quality (WQ) modules were coupled in order to simulate the simultaneous processes of transport and dispersion of hypothetical pollutant sources. The dissolved/suspended sediment particulates (DSS) were selected as contaminant tracers. The comparative analysis between simulation responses and the real metal contaminant distribution showed high agreement, suggesting that contaminants mainly come from outside port and tend to accumulate in the inner basin. In fact, hydrodynamic circulations cause inflowing streams toward the harbor entrance and the particular port morphology hampers the exit of fine sediments from the inner basin, enhancing thus the accumulation of sediment-associated contaminants within the port area. The study confirms that the quality of touristic port areas strongly depends on both pollution sources located within and outside the port domain and it is controlled mainly by the hydrodynamic-driven processes.