Papers by Maurizio Caselli
Annali di Chimica, 2004
In this report we have studied the extraction of a series of heavy metals ions (Cu2+, Ni2+, Fe3+,... more In this report we have studied the extraction of a series of heavy metals ions (Cu2+, Ni2+, Fe3+, Cr3+, CrO4(2-)) from water bulk solutions by means of reverse micelles. The parameters explored are the nature and concentration of the accompanying electrolyte, as well as the surfactant nature and its concentration. The extracted metals can be recovered and eventually concentrated in a new water solution carrying out a back extraction. The extracted amount of metal is strongly dependent on the charge of the metal to be extracted. Therefore the extracted water solution is enriched in higher charge metal. Anions of amphoteric metals, like the chromate ions, can be quantitatively separated from their positive cations, like Cr3+ by properly choosing the cationic or the anionic surfactants. The transfer of the metal is essentially controlled by electrostatic forces. A model based on the Poisson-Boltzmann distribution allow us to get the potential profile inside the water pool by determining the concentrations of the surfactant counter ions. From the potential profile and mass balance it is possible calculate the extraction percentage.
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Biotechnology and Bioengineering, 1991
alpha-chymotrypsin is taken as a model protein to investigate three aspects of the protein extrac... more alpha-chymotrypsin is taken as a model protein to investigate three aspects of the protein extraction by reverse micelles: (1) the comparison between the two forward transfer techniques, i.e., the liquid-liquid and the solid state-liquid transfer; (2)the back-transfer, i.e., the capability of the protein to be recovered from the micellar solution; and (3) the maintainance of the enzyme activity at the end of the extraction cycle. Concerning the forward transfer from the liquid phase, we study first the effect of salt initially present in the aqueous phase on the equilibrium concentration of the extracted species; further, we study the forward protein extraction from the solid state, and the effect of pH, salt, and protein concentration on the transfer efficiency. Concerning the back transfer, we find the somewhat surprising result, that the percentage of protein back-extraction depends on the type and concentration of salt used for the forward transfer. Preliminary data concerning an alternative method for the back-transfer using silica gel to liberate the protein from the micellar environment, are presented. Finally, it is found that the enzyme activity depends again on the type and concentration of salt used for the forward transfer.
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Nucleation and Atmospheric Aerosols, 2007
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In this paper an application of new procedures for atmospheric particulate analysis is illustrate... more In this paper an application of new procedures for atmospheric particulate analysis is illustrated. PM10, PAHs (benzo[a]anthracene (BaA), benzo[b]fluoranthene (BbF), benzo[j]fluoranthene (BjF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1, 2, 3-cd]pyrene (Ip), dibenzo[a, h]anthracene (DbA)) and heavy metals (Cu, Ni, Zn, Co, Mn, Cd, Fe and Pb) were investigated. PM10 determination was performed by gravimetric method, PAHs were measured by GC-MS, and heavy metals by HPIC. An air quality monitoring campaign on the territory of Bari municipality has been organised, and its results are shown.
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Atmospheric Research, 2008
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Electrochimica Acta, 1980
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Biotechnology Progress, 1988
A short time ago a simplified model for inclusion of protein molecules in reverse micelles (r.m.)... more A short time ago a simplified model for inclusion of protein molecules in reverse micelles (r.m.) was presented [1]. The model was originally worked out in order to rationalize the protein extraction process [2, 3], but it has subsequently adapted [4] for dealing with systems obtained by injection technique [3].The results concerning the ultracentrifugation double-dye experiments by Zampieri, et al. [5] have been used as a test for the model. The calculated values for the observables show a very good agreement with the experiments.
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Current Analytical Chemistry, 2010
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Journal of Atmospheric Chemistry, 2006
Atmospheric concentrations of benzene and toluene were assessed during three different seasons in... more Atmospheric concentrations of benzene and toluene were assessed during three different seasons in the city of Taranto, using Radiello® diffusive samplers, in order to detect the most critical areas and to point out the sources contributing to pollution (vehicular traffic or industrial activities). High spatial resolution maps were built using a grid of 30 meshes drawn on the urban area of the city. For each mesh a monitoring site as representative as possible was chosen. Besides, in order to describe the highest levels of pollutants to which people is exposed, other 10 sampling sites were detected near high vehicular traffic crossroads or in particular critical zones of the city. The measurements of the concentration of these pollutants were carried out with Radiello® diffusive samplers for thermal desorption. The analysis of the results and the comparison between the map of vehicular traffic flows and the map of the concentrations of benzene suggested that in urban area the main benzene source is the traffic and the most significant pollution phenomena happens in zones characterized by narrow roads. Moreover it was possible to observe that high concentrations of benzene found in the NE zone of Taranto could be assigned to the industrial activities. This hypothesis was confirmed considering the diagnostic ratio between the toluene and benzene concentrations.
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Water Air and Soil Pollution, 2008
Volatile organic compounds (VOC) have been monitored in 12 sites of Canosa di Puglia, a city loca... more Volatile organic compounds (VOC) have been monitored in 12 sites of Canosa di Puglia, a city located in the Southern of Italy, in order to identify the main VOC source—vehicular traffic or industrial—and to evaluate the critical situations in the city. Monitoring, carried out by using Radiello® diffusive samplers, has been planned taking into account the traffic density and the architecture of the city. From the study of the data it has been emerged that, among all considered VOC, benzene, toluene, ethylbenzene and xylenes (BTEX) are the pollutants at higher concentration. However no critical situation has appared from the present monitoring. Maps of daily benzene and toluene concentrations have shown that the most significant pollution phenomena happens in the center of the urban area which is in a valley with narrow roads and high buildings that do not allow an efficient dispersion of pollutants. The study of the diagnostic ratios between the toluene and benzene concentrations in the several areas (average T/B = 3.4) and the high Pearson’s coefficient among the pollutants, and in particular between benzene and toluene concentrations (r = 0.9505), have suggested that in urban area these pollutants are emitted from the same source: the vehicular traffic.
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Environmetrics, 2006
Two frequently used factor analysis (FA) methods, Absolute Principal Components Scores (APCS) and... more Two frequently used factor analysis (FA) methods, Absolute Principal Components Scores (APCS) and Target Transformation Factor Analysis (TTFA), are compared by examining two cases with different complexity on sources and parameters. The effect of the noise contribution on the data is evaluated.By applying the methods to simulated data matrices, it has been found that the APCS method characterizes the source matrix better than TTFA method. APCS method also reconstructs the sample better than TTFA. In addition both methods are applied to real data collected during a monitoring campaign in Taranto city (South Italy). Copyright © 2006 John Wiley & Sons, Ltd.
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Current Analytical Chemistry, 2010
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Journal of Atmospheric Chemistry, 2006
Atmospheric concentrations of benzene and toluene were assessed during three different seasons in... more Atmospheric concentrations of benzene and toluene were assessed during three different seasons in the city of Taranto, using Radiello® diffusive samplers, in order to detect the most critical areas and to point out the sources contributing to pollution (vehicular traffic or industrial activities). High spatial resolution maps were built using a grid of 30 meshes drawn on the urban area of the city. For each mesh a monitoring site as representative as possible was chosen. Besides, in order to describe the highest levels of pollutants to which people is exposed, other 10 sampling sites were detected near high vehicular traffic crossroads or in particular critical zones of the city. The measurements of the concentration of these pollutants were carried out with Radiello® diffusive samplers for thermal desorption. The analysis of the results and the comparison between the map of vehicular traffic flows and the map of the concentrations of benzene suggested that in urban area the main benzene source is the traffic and the most significant pollution phenomena happens in zones characterized by narrow roads. Moreover it was possible to observe that high concentrations of benzene found in the NE zone of Taranto could be assigned to the industrial activities. This hypothesis was confirmed considering the diagnostic ratio between the toluene and benzene concentrations.
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Water Air and Soil Pollution, 2008
Volatile organic compounds (VOC) have been monitored in 12 sites of Canosa di Puglia, a city loca... more Volatile organic compounds (VOC) have been monitored in 12 sites of Canosa di Puglia, a city located in the Southern of Italy, in order to identify the main VOC source—vehicular traffic or industrial—and to evaluate the critical situations in the city. Monitoring, carried out by using Radiello® diffusive samplers, has been planned taking into account the traffic density and the architecture of the city. From the study of the data it has been emerged that, among all considered VOC, benzene, toluene, ethylbenzene and xylenes (BTEX) are the pollutants at higher concentration. However no critical situation has appared from the present monitoring. Maps of daily benzene and toluene concentrations have shown that the most significant pollution phenomena happens in the center of the urban area which is in a valley with narrow roads and high buildings that do not allow an efficient dispersion of pollutants. The study of the diagnostic ratios between the toluene and benzene concentrations in the several areas (average T/B = 3.4) and the high Pearson’s coefficient among the pollutants, and in particular between benzene and toluene concentrations (r = 0.9505), have suggested that in urban area these pollutants are emitted from the same source: the vehicular traffic.
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Environmetrics, 2006
Two frequently used factor analysis (FA) methods, Absolute Principal Components Scores (APCS) and... more Two frequently used factor analysis (FA) methods, Absolute Principal Components Scores (APCS) and Target Transformation Factor Analysis (TTFA), are compared by examining two cases with different complexity on sources and parameters. The effect of the noise contribution on the data is evaluated.By applying the methods to simulated data matrices, it has been found that the APCS method characterizes the source matrix better than TTFA method. APCS method also reconstructs the sample better than TTFA. In addition both methods are applied to real data collected during a monitoring campaign in Taranto city (South Italy). Copyright © 2006 John Wiley & Sons, Ltd.
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Microchemical Journal, 2008
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Atmospheric Research, 2008
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Atmospheric Research, 2010
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Atmospheric Environment, 2008
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Papers by Maurizio Caselli