Search results for "CHIMICA"
showing 10 items of 4450 documents
Effect of Organic Amendments on the Evolution of Soil Organic Matter in Soils Stressed by Intensive Agricultural Practices
2013
Losses of soil organic carbon often occur because of intensive agricultural practices that lead to removal of organic carbon following harvest production and to insufficient inputs. Organic amendments can be a very appropriate matrix for enhancing organic carbon content in very stressed agricultural soils. In general, they, enhancing soil organic matter, play an important role in environmental matrices due, for example, to their capacity in retaining water, in interacting with organic and inorganic pollutants, and in enhancing nutrient availability to plants. For this reason, the understanding of the mechanisms with which organic amendments interact with other chemicals in the environment i…
Case study: inorganic pollutants associated with particulate matter from an area near a petrochemical plant.
2004
The area of Gela (Sicily, Italy) contains one of the largest petroleum refineries in Europe and also has several oil fields both on land and offshore. This paper discusses how the oil refinery and traffic-related air pollution affect the chemical composition of airborne particulate matter over the town of Gela, using pine needles and urban road dust as the means of survey. Forty-one samples of pine needles from Pinus halepensis (Mill.) and two composite samples of roadway dust, each subdivided into six size fractions, were analyzed for major and trace elements. Information on the natural or anthropogenic origin of the observed heavy metals was deduced from factor analysis and element distri…
Dust, Metals and Metalloids in the Environment: From Air to Hair .
2013
Billions tons of particulate matter, made up of inorganic and organic compounds, are released every year into the atmosphere, from both anthropogenic and natural sources. The latter, which include geogenic material from erosion, agriculture, sea spray and volcanic activity, account for about 97% of the total mass of particles. The contribution of anthropogenic sources, about 3%, is more pronounced in industrialised and also in urban areas, where vehicular traffic is one of the most important sources. When examining the health impact, in addition to mass level and size, two other main characteristics of particulate matter need to be considered: its nature and chemical composition. These para…
Voltammetric Analysis of Platinum in Environmental Matrices
2014
This article will summarize measurement data for Pt in different environmental samples obtained by the authors using a recently developed approach by voltammetric analysis. A fast accumulation of platinum and rhodium in the environmental and biological matrices has been observed in the last few years and concern has arisen about potential environmental and health risks. Voltammetry was used for the determination of Pt and Rh in airborne particulate collected in Palermo, Italy. Possible interferences by other environmental metals have also been evaluated. All samples show concentrations of Pt and Rh above average upper crust values. The Pt and Rh concentrations in particulate samples collect…
Anodizing and post-anodizing processes to enhance corrosion resistance of Al alloys
2021
In this work the dependence of corrosion resistance of Al alloys AA 2024-T3 on sealing treatments was studied. AA 2024-T3 samples were anodized at 14 V in a bath containing sulfuric and tartaric acids. Anodized samples were sealed with four different treatments: hot water, vapour, hot water with salts and stirred hot water. Electrochemical Impedance Spectroscopy measurements were performed to estimate samples' corrosion resistance in a solution simulating sea water environment. Samples sealed in hot water showed the highest corrosion resistance.
Effect of TiO2 and Al2O3 Addition on the Performance of Chitosan/Phosphotungstic Composite Membranes for Direct Methanol Fuel Cells
2023
Composite chitosan/phosphotungstic acid (CS/PTA) with the addition of TiO2 and Al2O3 particles were synthesized to be used as proton exchange membranes in direct methanol fuel cells (DMFCs). The influence of fillers was assessed through X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, liquid uptake, ion exchange capacity and methanol permeability measurements. The addition of TiO2 particles into proton exchange membranes led to an increase in crystallinity and a decrease in liquid uptake and methanol permeability with respect to pristine CS/PTA membranes, whilst the effect of the introduction of Al2O3 particles on the characteristics of membranes is almost the op…
Tuning The Selectivity To Aldehyde Via Ph Regulation In The Photocatalytic Oxidation Of 4-Methoxybenzyl Alcohol And Vanillyl Alcohol By Tio2 Catalysts
2021
Abstract The influence of pH on the photocatalytic partial oxidation of 4-methoxybenzyl alcohol (MBA) and vanillyl alcohol (VA) to their corresponding aldehydes in aqueous suspension under UVA irradiation was investigated by using poorly crystalline home-prepared and crystalline commercial TiO2 (BDH, Merck and Degussa P25) photocatalysts. The results clearly show as tuning pH can strongly impart selectivity and activity to photocatalytic processes which are often quite unselective in aqueous suspensions. It was found that pH effect on reaction rate and product selectivity strongly depended on TiO2 crystallinity and substrate type. In the case of MBA oxidation, photoreactivity and selectivit…
Synthesis, characterization of diorganotin(IV) complexes of N-(2-hydroxyarylidene)aminoacetic acid and antitumour screening in vivo in ehrlich ascite…
2001
Some new diorganotin(IV) complexes have been prepared by reacting potassium N-(2-hydroxyarylidene)aminoacetate with R2SnCl2(R = Me,nBu,Ph). The complexes have been characterized by 1H,13C,119Sn NMR, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analysis. In the solid state, the complexes possess penta- and hexa-coordinated tin centres. The hexa-coordinated tin complexes were found to dissociate in solution, giving rise to penta-coordinated species as revealed by 119Sn NMR spectroscopy. Antitumour screening in vivo of the complexes L4snPh2,L4SnPh2· Ph3SnCl and L4SntBU2·t Bu2SnCl2 (L4 = N-(2-hydroxyacetophenone)aminoacetate) is also reported. Copyright © 2001 …