stefano salvestrini | Università della Campania Luigi Vanvitelli (original) (raw)
Papers by stefano salvestrini
Microporous and Mesoporous Materials, 2007
The sorption of humic acids (HA) by phillipsite-and chabazite-rich Neapolitan Yellow Tuff (NYT) a... more The sorption of humic acids (HA) by phillipsite-and chabazite-rich Neapolitan Yellow Tuff (NYT) and a clinoptilolite-rich tuff from Turkey (CLT), both in the native and in Ca-enriched forms, have been investigated. Experimental data showed that the sorption capacity of the Ca-enriched forms was higher than that of the native forms. NYT, in particular, was very effective in removing humic acids from water. Its sorption capacity was higher than that of CLT, although the latter material had a higher zeolite content (CLT: 79% clinoptilolite; NYT: 37% phillipsite + 17% chabazite). HA sorption by Ca-enriched NYT readily attained a pseudo steady-state, after which the tuff/HA-solution system evolved in a few months to a final equilibrium state characterized by a much higher sorption capability. Desorption experiments at high pH levels resulted in a HA recovery >80%. The UV-vis spectrum and the gel permeation chromatogram of the recovered HA solution were indistinguishable from those obtained for a freshly prepared HA solution.
Journal of Porous Materials, 2007
Within a research program aimed to utilize natural zeolites for pedotechnical purposes, such as t... more Within a research program aimed to utilize natural zeolites for pedotechnical purposes, such as to rebuild degraded soils, to improve soil fertility and to remove soil pollutants, the adsorption process of humic acids (HAs) on untreated Neapolitan Yellow Tuff and on Ca2+-enriched samples was investigated in the temperature range 1–45°C. Experimental data showed a negligible temperature effect indicating that ΔH ≈ 0. Moreover, Scatchard-like plots suggested the occurrence of more than one adsorption sites for both samples. A good fit of the adsorption isotherms was obtained by two-site Langmuir equation. For both sites the HAs affinity was not modified by Ca2+-enrichment and ΔS° was >0. The adsorption of HAs on tuff is an entropy-driven process.
Applied Clay Science, 2010
Two different acid-activated zeolite-rich tuffs were evaluated as potential adsorbents for atrazi... more Two different acid-activated zeolite-rich tuffs were evaluated as potential adsorbents for atrazine removal from water. The materials investigated were: Neapolitan yellow tuff (NYT, containing 37% phillipsite and 17% chabazite) and a clinoptilolitic tuff from Eskişehir (Turkey) (T-CPL, 79% clinoptilolite). The T-CPL tuff exhibited the highest adsorption capacity. Atrazine adsorption, estimated by batch method, was likely to involve electrostatic interactions obeying
Annali Di Chimica, 2007
Background atmospheric levels of aldehydes, BTEX and PM10 pollutants were measured in the suburb ... more Background atmospheric levels of aldehydes, BTEX and PM10 pollutants were measured in the suburb of Caserta (Italy), 75 thousands inhabitants, 41° 04' N, on rainless weekdays and weekends during 2005. On weekdays the average daily concentrations (μg m-3) were 41.6 PM10, 8.6 benzene, 25.2 toluene, 6.3 ethylbenzene, 14.0 (m+p)-xylene, 11.7 o-xylene, 6.5 formaldehyde, 3.3 acetaldehyde. All the pollutant concentrations were strictly correlated (mean correlation coefficients = 0.90). At weekends the concentrations were lower by about 1.6 times. Both on weekdays and at weekends the PM10 and benzene levels exceeded the limits set by the EU Directive 30/1999 and 69/2000, respectively.
Journal of The Chemical Society-perkin Transactions 2, 2002
ABSTRACT
Pest Management Science, 2008
BACKGROUND:Although biodegradation seems to be the main cause of herbicide degradation, abiotic d... more BACKGROUND:Although biodegradation seems to be the main cause of herbicide degradation, abiotic degradation can also be important for chemicals such as phenylureas, which are subject to catalysed soil reactions. The aim of this work is to investigate the effect of dissolved humic acids (HAs), normally present in natural waters, on the hydrolysis of phenylurea herbicides, and it presents a kinetic model that takes into account the role of adsorption.RESULTS:The linearity of the adsorption isotherms indicates that phenylurea–humic acid interaction can be considered in terms of a repartition-like equilibrium of phenylurea between water and HAs. Kinetic experiments show that the degradation rates of phenylureas increase with HA concentration.CONCLUSION:The kinetic equation adopted adequately describes the experimental data trend, allowing the evaluation of the catalytic effect of HAs on the chemical degradation of phenylureas. Carboxyl groups of HAs seem to play a leading role in the catalysis. The kinetic equation derived in this work could be helpful in predicting the persistence of phenylureas and of related compounds in natural water. Copyright © 2008 Society of Chemical Industry
Environmental Monitoring and Assessment, 2009
Atmospheric BTEX [benzene, toluene, ethylbenzene, o-xylene and (m + p)-xylene] concentrations hav... more Atmospheric BTEX [benzene, toluene, ethylbenzene, o-xylene and (m + p)-xylene] concentrations have been determined in the Naples metropolitan area (NMA) and in two suburban areas located on the north within about 25 km, during 2006. The pollutants were collected by passive samplers (24-h samplings), and analysed by GC-MS. In all the areas analysed the average atmospheric benzene concentrations were higher than the limit value fixed by the European Union for 2010 and in NMA the average concentration (9.8 μg m-) also exceeded the limit fixed for 2006. High linear correlation coefficients between the average daily concentrations of the different BTEX are indicative of a single major source, most likely the vehicular traffic. The temporal and spatial distribution of BTEX relative concentrations suggest that massive emissions in NMA negatively affect the quality of the air in northern suburban areas, prevalently during the hottest months of the year, probably due to transport by local seasonal winds. The ratios between BTEX daily concentrations showed a clear dependence on the intensity of solar actinic flow, indicating a major role of photochemical processes in the air cleaning from these volatile organic pollutants.
Chemosphere, 2004
A kinetic equation for the analysis of the degradation reaction of xenobiotic molecules in the so... more A kinetic equation for the analysis of the degradation reaction of xenobiotic molecules in the soil/water mixture has been derived. By means of this equation we have evaluated the microscopic rate constant for the abiotic hydrolysis of the herbicide diuron in the water phase of a soil/water mixture assuming that the reaction occurs only in the water phase and that diuron is reversibly adsorbed by the soil with a higher rate. The soil catalytic capacity on the hydrolysis of diuron was evaluated.
Applied Clay Science, 2005
... years ago) tuffaceous formations of the Phlegraean Fields (Naples, Italy), covering an area o... more ... years ago) tuffaceous formations of the Phlegraean Fields (Naples, Italy), covering an area of about 13 km 2 (de' Gennaro and Langella ... spectrophotometry at 450 nm (Perkin Elmer Lambda 40), using the extinction coefficient =0.0005157 mg −1 l cm −1 (Atkins, 1999), previously ...
Journal of The Chemical Society-perkin Transactions 2, 2002
An elementary analysis of recently published experimental kinetic data evidences some aspects tha... more An elementary analysis of recently published experimental kinetic data evidences some aspects that should have been considered before proposing the kinetic mechanisms.
International Journal of Environmental Health Research, 2004
The relation between the prevalence of doctor-diagnosed asthma in children and the presence of ai... more The relation between the prevalence of doctor-diagnosed asthma in children and the presence of air-proof doors and windows (doors and windows with rubber gaskets) in their homes was investigated by a cross-sectional survey in the area of Campania Plain, South Italy. Information on the occurrence of asthma and home/family characteristics, including parental smoking habit and level of education, was obtained by a questionnaire given to school children, aged 8-14 years, and their parents. After possible confounders were controlled, the risk of developing asthma was found to be significantly higher in children living in houses equipped with air-proof doors and windows (Odds ratio = 1.30, 95% Confidence interval = 1.1-1.5). By reducing the air exchange, these fixtures are likely to produce increased levels of indoor pollutants. No interaction was found between the two variables 'air-proof doors and windows' and 'parental smoking habit'.
Chemosphere, 2002
The influence of pH and buffer concentration on the chemical degradation of diuron in water has b... more The influence of pH and buffer concentration on the chemical degradation of diuron in water has been analysed over a wide temperature range. The process irreversibly gives 3,4-dichloroaniline as the only product containing the phenyl ring. H þ , OH À and phosphate buffer are efficient catalysts of the reaction. The rate constant first increases rapidly at low buffer concentrations and then gradually levels off at higher ones. At 40°C and high phosphate concentration (>0.01 M), or in the extreme pH regions, the half-life is approximately 4 months and the activation energy is 127 AE 2 kJ mol À1 . Ó
Chemosphere, 2008
The atmospheric concentrations of benzene, toluene, ethylbenzene and isomeric xylenes (BTEX) in a... more The atmospheric concentrations of benzene, toluene, ethylbenzene and isomeric xylenes (BTEX) in a medium-sized town (S. Maria Capua Vetere, about 32000 inhabitants, Southern Italy) have been determined during working days and weekends in 2006. The procedure used was 24h passive adsorption by samplers distributed throughout the town followed by GC/MS analysis. On a yearly base, the arithmetic mean benzene concentrations were above the limit required by the 2000/69/CE European Directive. The Pearson correlation coefficients of the 24h geometric mean BTEX concentrations were indicative of stationary sources of toluene located in a well circumscribed area of the urban territory, active only during the working days and not officially recognized. The results highlight the effectiveness of the statistical approach used in this study for the identification of pollutant sources.
Microporous and Mesoporous Materials, 2007
The sorption of humic acids (HA) by phillipsite-and chabazite-rich Neapolitan Yellow Tuff (NYT) a... more The sorption of humic acids (HA) by phillipsite-and chabazite-rich Neapolitan Yellow Tuff (NYT) and a clinoptilolite-rich tuff from Turkey (CLT), both in the native and in Ca-enriched forms, have been investigated. Experimental data showed that the sorption capacity of the Ca-enriched forms was higher than that of the native forms. NYT, in particular, was very effective in removing humic acids from water. Its sorption capacity was higher than that of CLT, although the latter material had a higher zeolite content (CLT: 79% clinoptilolite; NYT: 37% phillipsite + 17% chabazite). HA sorption by Ca-enriched NYT readily attained a pseudo steady-state, after which the tuff/HA-solution system evolved in a few months to a final equilibrium state characterized by a much higher sorption capability. Desorption experiments at high pH levels resulted in a HA recovery >80%. The UV-vis spectrum and the gel permeation chromatogram of the recovered HA solution were indistinguishable from those obtained for a freshly prepared HA solution.
Journal of Porous Materials, 2007
Within a research program aimed to utilize natural zeolites for pedotechnical purposes, such as t... more Within a research program aimed to utilize natural zeolites for pedotechnical purposes, such as to rebuild degraded soils, to improve soil fertility and to remove soil pollutants, the adsorption process of humic acids (HAs) on untreated Neapolitan Yellow Tuff and on Ca2+-enriched samples was investigated in the temperature range 1–45°C. Experimental data showed a negligible temperature effect indicating that ΔH ≈ 0. Moreover, Scatchard-like plots suggested the occurrence of more than one adsorption sites for both samples. A good fit of the adsorption isotherms was obtained by two-site Langmuir equation. For both sites the HAs affinity was not modified by Ca2+-enrichment and ΔS° was >0. The adsorption of HAs on tuff is an entropy-driven process.
Applied Clay Science, 2010
Two different acid-activated zeolite-rich tuffs were evaluated as potential adsorbents for atrazi... more Two different acid-activated zeolite-rich tuffs were evaluated as potential adsorbents for atrazine removal from water. The materials investigated were: Neapolitan yellow tuff (NYT, containing 37% phillipsite and 17% chabazite) and a clinoptilolitic tuff from Eskişehir (Turkey) (T-CPL, 79% clinoptilolite). The T-CPL tuff exhibited the highest adsorption capacity. Atrazine adsorption, estimated by batch method, was likely to involve electrostatic interactions obeying
Annali Di Chimica, 2007
Background atmospheric levels of aldehydes, BTEX and PM10 pollutants were measured in the suburb ... more Background atmospheric levels of aldehydes, BTEX and PM10 pollutants were measured in the suburb of Caserta (Italy), 75 thousands inhabitants, 41° 04' N, on rainless weekdays and weekends during 2005. On weekdays the average daily concentrations (μg m-3) were 41.6 PM10, 8.6 benzene, 25.2 toluene, 6.3 ethylbenzene, 14.0 (m+p)-xylene, 11.7 o-xylene, 6.5 formaldehyde, 3.3 acetaldehyde. All the pollutant concentrations were strictly correlated (mean correlation coefficients = 0.90). At weekends the concentrations were lower by about 1.6 times. Both on weekdays and at weekends the PM10 and benzene levels exceeded the limits set by the EU Directive 30/1999 and 69/2000, respectively.
Journal of The Chemical Society-perkin Transactions 2, 2002
ABSTRACT
Pest Management Science, 2008
BACKGROUND:Although biodegradation seems to be the main cause of herbicide degradation, abiotic d... more BACKGROUND:Although biodegradation seems to be the main cause of herbicide degradation, abiotic degradation can also be important for chemicals such as phenylureas, which are subject to catalysed soil reactions. The aim of this work is to investigate the effect of dissolved humic acids (HAs), normally present in natural waters, on the hydrolysis of phenylurea herbicides, and it presents a kinetic model that takes into account the role of adsorption.RESULTS:The linearity of the adsorption isotherms indicates that phenylurea–humic acid interaction can be considered in terms of a repartition-like equilibrium of phenylurea between water and HAs. Kinetic experiments show that the degradation rates of phenylureas increase with HA concentration.CONCLUSION:The kinetic equation adopted adequately describes the experimental data trend, allowing the evaluation of the catalytic effect of HAs on the chemical degradation of phenylureas. Carboxyl groups of HAs seem to play a leading role in the catalysis. The kinetic equation derived in this work could be helpful in predicting the persistence of phenylureas and of related compounds in natural water. Copyright © 2008 Society of Chemical Industry
Environmental Monitoring and Assessment, 2009
Atmospheric BTEX [benzene, toluene, ethylbenzene, o-xylene and (m + p)-xylene] concentrations hav... more Atmospheric BTEX [benzene, toluene, ethylbenzene, o-xylene and (m + p)-xylene] concentrations have been determined in the Naples metropolitan area (NMA) and in two suburban areas located on the north within about 25 km, during 2006. The pollutants were collected by passive samplers (24-h samplings), and analysed by GC-MS. In all the areas analysed the average atmospheric benzene concentrations were higher than the limit value fixed by the European Union for 2010 and in NMA the average concentration (9.8 μg m-) also exceeded the limit fixed for 2006. High linear correlation coefficients between the average daily concentrations of the different BTEX are indicative of a single major source, most likely the vehicular traffic. The temporal and spatial distribution of BTEX relative concentrations suggest that massive emissions in NMA negatively affect the quality of the air in northern suburban areas, prevalently during the hottest months of the year, probably due to transport by local seasonal winds. The ratios between BTEX daily concentrations showed a clear dependence on the intensity of solar actinic flow, indicating a major role of photochemical processes in the air cleaning from these volatile organic pollutants.
Chemosphere, 2004
A kinetic equation for the analysis of the degradation reaction of xenobiotic molecules in the so... more A kinetic equation for the analysis of the degradation reaction of xenobiotic molecules in the soil/water mixture has been derived. By means of this equation we have evaluated the microscopic rate constant for the abiotic hydrolysis of the herbicide diuron in the water phase of a soil/water mixture assuming that the reaction occurs only in the water phase and that diuron is reversibly adsorbed by the soil with a higher rate. The soil catalytic capacity on the hydrolysis of diuron was evaluated.
Applied Clay Science, 2005
... years ago) tuffaceous formations of the Phlegraean Fields (Naples, Italy), covering an area o... more ... years ago) tuffaceous formations of the Phlegraean Fields (Naples, Italy), covering an area of about 13 km 2 (de' Gennaro and Langella ... spectrophotometry at 450 nm (Perkin Elmer Lambda 40), using the extinction coefficient =0.0005157 mg −1 l cm −1 (Atkins, 1999), previously ...
Journal of The Chemical Society-perkin Transactions 2, 2002
An elementary analysis of recently published experimental kinetic data evidences some aspects tha... more An elementary analysis of recently published experimental kinetic data evidences some aspects that should have been considered before proposing the kinetic mechanisms.
International Journal of Environmental Health Research, 2004
The relation between the prevalence of doctor-diagnosed asthma in children and the presence of ai... more The relation between the prevalence of doctor-diagnosed asthma in children and the presence of air-proof doors and windows (doors and windows with rubber gaskets) in their homes was investigated by a cross-sectional survey in the area of Campania Plain, South Italy. Information on the occurrence of asthma and home/family characteristics, including parental smoking habit and level of education, was obtained by a questionnaire given to school children, aged 8-14 years, and their parents. After possible confounders were controlled, the risk of developing asthma was found to be significantly higher in children living in houses equipped with air-proof doors and windows (Odds ratio = 1.30, 95% Confidence interval = 1.1-1.5). By reducing the air exchange, these fixtures are likely to produce increased levels of indoor pollutants. No interaction was found between the two variables 'air-proof doors and windows' and 'parental smoking habit'.
Chemosphere, 2002
The influence of pH and buffer concentration on the chemical degradation of diuron in water has b... more The influence of pH and buffer concentration on the chemical degradation of diuron in water has been analysed over a wide temperature range. The process irreversibly gives 3,4-dichloroaniline as the only product containing the phenyl ring. H þ , OH À and phosphate buffer are efficient catalysts of the reaction. The rate constant first increases rapidly at low buffer concentrations and then gradually levels off at higher ones. At 40°C and high phosphate concentration (>0.01 M), or in the extreme pH regions, the half-life is approximately 4 months and the activation energy is 127 AE 2 kJ mol À1 . Ó
Chemosphere, 2008
The atmospheric concentrations of benzene, toluene, ethylbenzene and isomeric xylenes (BTEX) in a... more The atmospheric concentrations of benzene, toluene, ethylbenzene and isomeric xylenes (BTEX) in a medium-sized town (S. Maria Capua Vetere, about 32000 inhabitants, Southern Italy) have been determined during working days and weekends in 2006. The procedure used was 24h passive adsorption by samplers distributed throughout the town followed by GC/MS analysis. On a yearly base, the arithmetic mean benzene concentrations were above the limit required by the 2000/69/CE European Directive. The Pearson correlation coefficients of the 24h geometric mean BTEX concentrations were indicative of stationary sources of toluene located in a well circumscribed area of the urban territory, active only during the working days and not officially recognized. The results highlight the effectiveness of the statistical approach used in this study for the identification of pollutant sources.