Carlo Dossi - Academia.edu (original) (raw)
Papers by Carlo Dossi
Annali Di Chimica, 2006
A chemometric approach based on Principal Component Analysis (PCA) has been proposed, in order to... more A chemometric approach based on Principal Component Analysis (PCA) has been proposed, in order to study chemical features (major and minor ions, total alkalinity, dissolved silica) of surface and deep waters of Lake Como (Northern Italy). The method allowed us to investigate the correlations between the analyzed ions in an easy-to-see way, using bi-dimensional graphs. In wintertime, the ionic composition of Lake Como waters seems to be mainly related to the geological composition of the lake basin, with a crystalline bedrock on the northern side and a sedimentary cover in the southern part. The presence of contaminants such as bromide and nitrite in water columns is also evidenced and discussed.
Journal of Catalysis, 1996
A Pt/HL model catalyst has been obtained by chemical vapor deposition of platinum hexafluoracetyl... more A Pt/HL model catalyst has been obtained by chemical vapor deposition of platinum hexafluoracetylacetonate and structurally characterized by EXAFS. In the conversion of methylcyclopentane at 350 • C, the selectivity is consistent with the typical bifunctional nature of the active sites. EXAFS results show that agglomeration of metal particles is greatly inhibited under catalytic conditions, i.e., it is not responsible for the observed catalyst deactivation. Temperature-programmed oxidation profiles, in agreement with EXAFS results obtained from the used catalyst, indicate that carbon deposits are preferentially located on the protonic acidic sites of the HL structure.
Journal of The Chemical Society, Faraday Transactions, 1994
... 1 I , 80333 Miinchen, Germany Horacio Treviiio, 2. Conrad Zhangt and WMH Sachtler V. N. lpati... more ... 1 I , 80333 Miinchen, Germany Horacio Treviiio, 2. Conrad Zhangt and WMH Sachtler V. N. lpatieff Laboratory, Center for Catalysis and Surface Science, Departments ... t Present address : Catalytic System Division, Johnson Matthey, 456 Devon Park Drive, Wayne, PA 19087, USA ...
Analytica Chimica Acta, 2007
A new automated batch method for the determination of ultratrace metals (nanogram per liter level... more A new automated batch method for the determination of ultratrace metals (nanogram per liter level) was developed and validated. Instrumental and chemical parameters affecting the performance of the method were carefully assessed and optimized. A wide range of voltammetric methods under different chemical conditions were tested. Cadmium, lead and copper were determined by anodic stripping voltammetry (ASV), while nickel, cobalt, rhodium and uranium by adsorptive cathodic stripping voltammetry (AdCSV). The figures of merit of all of these methods were determined: very good precision and accuracy were achieved, e.g. relative percentage standard deviation in the 4-13% for ASV and 2-5% for AdCSV.
![Research paper thumbnail of A molecular approach to heterogeneous catalysis. Ethylene hydroformylation catalysed by silica-supported [Rh 12(CO) 30] 2− cluster anion: influence of the countercations Li +, Na +, K +, Zn 2](https://attachments.academia-assets.com/48549116/thumbnails/1.jpg)
](Journal of Molecular Catalysis A-chemical, 1996
The title reaction has been investigated at 115°C using HOs3(CO)t0(OSi~) as catalyst or catalyst ... more The title reaction has been investigated at 115°C using HOs3(CO)t0(OSi~) as catalyst or catalyst precursor. By FTIR and XP spectroscopy and by TPDE, evidence exists for the in situ formation of molecular oxidized osmium moieties, covalently anchored to the surface, which are the active catalytic species. The intermediate formation of an olefin adduct during the in situ decomposition of the cluster precursor is supported by chemical extraction of the surface species and further FTIR and ~H NMR characterization. The reversible poisoning effect of CO and the beneficial influence of H2 on the catalytic activity and selectivity are also reported and discussed. The catalytic behavior of preformed oxidized osmium surface species has been found to be markedly dependent on the preparation method. The highest activity was obtained when they are formed in situ in the presence of l-butene. Silica-supported metallic osmium catalysts displayed different activity and selectivity, thus confirming the molecular nature of the catalytic process.
Journal of Molecular Catalysis A-chemical, 2002
Hydrodechlorination of carbon tetrachloride was performed at atmospheric pressure over Pd and Pt ... more Hydrodechlorination of carbon tetrachloride was performed at atmospheric pressure over Pd and Pt catalysts supported on various inorganic oxides (Al 2 O 3 , MgO, CeO 2 ) and obtained from different organometallic precursors (Pd(acac) 2 , [Pd(C 3 H 5 )Cl] 2 , Pt(acac) 2 and Pt(CH 3 CN) 2 Cl 2 . Generally, Pd-based catalysts show low conversion levels and high selectivity to C 1 -C 7+ hydrocarbons with a distribution that fits a typical Schulz-Flory mechanism for alkyl polymerization.
Microchemical Journal, 2010
A low cost, high performance ultraviolet digester was developed and tested in our laboratory. Its... more A low cost, high performance ultraviolet digester was developed and tested in our laboratory. Its main features include limited costs (around 600 € for all the parts) and high efficiency toward total organic carbon (TOC) abatement. As a result the TOC of typical natural waters is reduced to less than 10% of its initial value with half an hour treatment. Easiness of use, temperature control and flexibility in sample size (up to 25 mL) and number (up to twelve 12 mL test tube) are other important characteristics of the developed UV digester. This apparatus was tested as a pretreatment method for the determination of the total content of trace elements such as copper, uranium and platinum in natural waters by cathodic adsorptive stripping voltammetry. The voltammetric technique was chosen because it is strongly interfered by the presence of even low levels of natural organic complexing molecules. As a result, a 30 minute UV treatment yielded results non distinguishable from ICP-MS data.
Fresenius Journal of Analytical Chemistry, 2000
A simple computerized potentiometric titrator is described for performing automated analyses of c... more A simple computerized potentiometric titrator is described for performing automated analyses of chloride ions on solid materials as well as the continuous determination of HCl in effluent gas streams. This versatility has been obtained by a dedicated instrumental design, which offers easy interfacing to catalytic reactors and flexibility in software programs, including Gran’s plot determination of end-points. The validation of the analytical methodology for quantitative determination of chloride ions in solid matrices required the definition and the preparation of suitable reference materials of known chloride content.
Applied Catalysis B-environmental, 1999
We prepared H-ZSM-5 (Si/Al80), amorphous mesoporous silica±alumina (MSA, Si/Al90), and Silicalite... more We prepared H-ZSM-5 (Si/Al80), amorphous mesoporous silica±alumina (MSA, Si/Al90), and Silicalite-1 (S-1) according to the methods described by Bellussi and co-workers, and compared their ion-exchange capacity for copper ions. The Cu-ZSM-5, Cu±MSA and Cu±S-1 samples thus obtained have been investigated as catalysts for the NO decomposition reaction at 773 K.
Marine and Freshwater Research, 2007
... Eastern Alps, Italy) Carlo DossiA,C, Elena CiceriA, Barbara GiussaniA, Andrea PozziA, Antonio... more ... Eastern Alps, Italy) Carlo DossiA,C, Elena CiceriA, Barbara GiussaniA, Andrea PozziA, Antonio GalgaroB, Alessia VieroB and Alfio ViganòA ADepartment of Chemical and Environmental Sciences, Insubria University, Via Valleggio 11, Como 22100, Italy. ...
Catalysis Today, 1993
ABSTRACT
Mikrochimica Acta, 2009
An empirical approach is presented for validating trace metal profiles in tree rings for use as e... more An empirical approach is presented for validating trace metal profiles in tree rings for use as environmental archives. Concentration profiles of Zn, Cd, Cu, Pb and U in tree rings and lake sediments are compared for assessing the reliability of the former as an environmental proxy. Laser ablation sampling in conjunction with inductively coupled plasma mass spectrometry (LA–ICP–MS) is used for the direct analysis of tree rings. An optimised analytical protocol is devised with particular emphasis on sample preparation and quantification strategy. Significant correlations in the two environmental archives were found for zinc, copper and uranium, while cadmium and lead temporal trends, although showing enrichment in recent years, do not agree with the concentration profiles in lacustrine sediment cores. A chemical model based on metal affinity for hard type ligands present in wood is proposed to explain these results. Moreover, spring and winter wood are analysed separately thanks to the high spatial resolution of laser ablation sampling. As a result, enhanced metal loadings are shown to lead to intraring differences in trace metal concentrations.
Journal of Molecular Catalysis A-chemical, 2003
... Journal of Molecular Catalysis A: Chemical Volumes 204-205, 15 September 2003, Pages 465-472 ... more ... Journal of Molecular Catalysis A: Chemical Volumes 204-205, 15 September 2003, Pages 465-472 In honour of Prof. R. Ugo on the occasion of his 65th. Birthday. ... Dedicated to Professor Renato Ugo on the occasion of his 65th birthday. ...
Fresenius Journal of Analytical Chemistry, 2001
The development of an analytical method for the determination of platinum in MgO based Pt/Sn cata... more The development of an analytical method for the determination of platinum in MgO based Pt/Sn catalysts is described. Electrothermal atomic absorption spectroscopy (ETAAS) was chosen because of its high sensitivity and robustness against spectral interferences. All the sources of chemical interferences were statistically analyzed and corrections were adopted for the presence of magnesium oxide support. The effectiveness of different mineralization procedures was critically evaluated as a function of the chemical of the solid catalyst. Microwave digestion allowed recovery of metal of 100% for all the catalysts analyzed and exhibited significant better precision values than other digestion methods, which could nevertheless be utilized under proper conditions in selected cases.
Journal of Catalysis, 1999
Magnesia-supported Sn-Pt catalysts were prepared by reaction between preformed platinum metal par... more Magnesia-supported Sn-Pt catalysts were prepared by reaction between preformed platinum metal particles and Sn(n-C 4 H 9 ) 4 . HRTEM and H 2 -chemisorption data confirm the synthesis of very small tin-decorated platinum particles (∼1.0 nm mean diameter). Preliminary studies on catalytic hydrogenation of citral in a tricklebed reactor reveal that 97% selectivity to unsaturated alcohols at 100% conversion can be easily achieved. The electronic ligand effect produced by the basic support is supposed to be fundamental to enhance the selectivity to unsaturated alcohols and to stabilise the bimetallic particles.
Thermochimica Acta, 1998
... a Dipartimento di Chimica Inorganica, Metallorganica e Analitica, University of Milano Milan ... more ... a Dipartimento di Chimica Inorganica, Metallorganica e Analitica, University of Milano Milan Italy. b CNR Center 'CSSCMTBSO' Via Venezian, 21 20133 Milan Italy. Received 2 September 1997; revised 5 May 1998; accepted 11 May 1998. Available online 2 September 1998. ...
Talanta, 2008
Poor recoveries are obtained if the BCR three-step sequential extraction is applied to 100 mg spe... more Poor recoveries are obtained if the BCR three-step sequential extraction is applied to 100 mg specimens rather than to 1 g. It is observed that analytes are lost during each phase separation which is carried out via centrifugation and can be hardly quantitatively performed on 100 mg sediment specimens. An alternative procedure, which is carried out on a single empty SPE column and involves separation by filtration, is developed to solve this problem. The proposed method is validated on 100 mg samples of certified sediment (BCR-701), but could be potentially used for even lower sediment specimens. Problems related to pH stability during step 2 and its influence on recoveries is also reported.
Journal of Physical Chemistry B, 2002
... Dipartimento di Scienze CC, FF, MM, Università degli Studi dell'Insubria, Via Valleggio 1... more ... Dipartimento di Scienze CC, FF, MM, Università degli Studi dell'Insubria, Via Valleggio 11, 22100 Como, Italy. Rinaldo Psaro, Achille Fusi, and Renato ... the active sites are probably formed by two copper centers with a favorable geometric arrangement for the N−N bond formation ...
Environmental Science and Pollution Research, 2011
Background, aim and scope A new approach towards monuments, considering them as a passive sampler... more Background, aim and scope A new approach towards monuments, considering them as a passive sampler of pollution, is presented. Cultural Heritage objects suffer daily the damages of environmental pollution, especially in those areas interested by heavy traffic. Since monuments undergo only periodic conservation or maintenance works, surfaces are able to accumulate atmospheric deposit and to record changes in its composition. An optimised analytical protocol was developed in order to quantify platinum and rhodium at trace level on surfaces. The two elements have become tracers of automobile emissions in recent years, since the introduction of catalytic converters, and could have catalytic effects on the decay reactions of natural and artificial stone materials. As a first case study, the cement mortar surfaces of a twentieth century monument, the Camerlata Fountain, in Como (Italy) were investigated. Materials and methods The surfaces of the monument were scraped in areas both exposed to atmosphere and sheltered by the architectural elements of the building. The powders were dissolved by microwave-assisted mineralisation with a solution of HCl and HNO3. The solution was filtered, irradiated and analysed by adsorptive cathodic stripping voltammetry. The powders were also analysed by infrared spectroscopy and X-ray diffraction in order to determine the chemical and mineralogical composition. Results and discussion An analysis protocol was set up considering the matrix effect and the expected low concentrations of the two metals. The results enlightened variable concentration values and distribution areas of platinum (0.013–45 μg/kg) and rhodium (0.55–274.4 μg/kg), suggesting the ability of artificial stone surfaces to accumulate the two elements. The sample chemical and mineralogical composition was consistent with a typical cement plaster interested by decay phenomena. Conclusions This work investigated the relation between Cultural Heritage and pollution by another point of view. The analytical protocol presented in this paper was effective in determining platinum and rhodium in traces on the investigated stone surfaces with negligible matrix effects. Recommendation and perspectives The presence of platinum and rhodium on monument surfaces should be of significant interest when planning Cultural Heritage conservation. A better knowledge of the role of the two metals in decay phenomena could impact in a positive way artwork conservation.
Annali Di Chimica, 2006
A chemometric approach based on Principal Component Analysis (PCA) has been proposed, in order to... more A chemometric approach based on Principal Component Analysis (PCA) has been proposed, in order to study chemical features (major and minor ions, total alkalinity, dissolved silica) of surface and deep waters of Lake Como (Northern Italy). The method allowed us to investigate the correlations between the analyzed ions in an easy-to-see way, using bi-dimensional graphs. In wintertime, the ionic composition of Lake Como waters seems to be mainly related to the geological composition of the lake basin, with a crystalline bedrock on the northern side and a sedimentary cover in the southern part. The presence of contaminants such as bromide and nitrite in water columns is also evidenced and discussed.
Journal of Catalysis, 1996
A Pt/HL model catalyst has been obtained by chemical vapor deposition of platinum hexafluoracetyl... more A Pt/HL model catalyst has been obtained by chemical vapor deposition of platinum hexafluoracetylacetonate and structurally characterized by EXAFS. In the conversion of methylcyclopentane at 350 • C, the selectivity is consistent with the typical bifunctional nature of the active sites. EXAFS results show that agglomeration of metal particles is greatly inhibited under catalytic conditions, i.e., it is not responsible for the observed catalyst deactivation. Temperature-programmed oxidation profiles, in agreement with EXAFS results obtained from the used catalyst, indicate that carbon deposits are preferentially located on the protonic acidic sites of the HL structure.
Journal of The Chemical Society, Faraday Transactions, 1994
... 1 I , 80333 Miinchen, Germany Horacio Treviiio, 2. Conrad Zhangt and WMH Sachtler V. N. lpati... more ... 1 I , 80333 Miinchen, Germany Horacio Treviiio, 2. Conrad Zhangt and WMH Sachtler V. N. lpatieff Laboratory, Center for Catalysis and Surface Science, Departments ... t Present address : Catalytic System Division, Johnson Matthey, 456 Devon Park Drive, Wayne, PA 19087, USA ...
Analytica Chimica Acta, 2007
A new automated batch method for the determination of ultratrace metals (nanogram per liter level... more A new automated batch method for the determination of ultratrace metals (nanogram per liter level) was developed and validated. Instrumental and chemical parameters affecting the performance of the method were carefully assessed and optimized. A wide range of voltammetric methods under different chemical conditions were tested. Cadmium, lead and copper were determined by anodic stripping voltammetry (ASV), while nickel, cobalt, rhodium and uranium by adsorptive cathodic stripping voltammetry (AdCSV). The figures of merit of all of these methods were determined: very good precision and accuracy were achieved, e.g. relative percentage standard deviation in the 4-13% for ASV and 2-5% for AdCSV.
Journal of Molecular Catalysis A-chemical, 1996
The title reaction has been investigated at 115°C using HOs3(CO)t0(OSi~) as catalyst or catalyst ... more The title reaction has been investigated at 115°C using HOs3(CO)t0(OSi~) as catalyst or catalyst precursor. By FTIR and XP spectroscopy and by TPDE, evidence exists for the in situ formation of molecular oxidized osmium moieties, covalently anchored to the surface, which are the active catalytic species. The intermediate formation of an olefin adduct during the in situ decomposition of the cluster precursor is supported by chemical extraction of the surface species and further FTIR and ~H NMR characterization. The reversible poisoning effect of CO and the beneficial influence of H2 on the catalytic activity and selectivity are also reported and discussed. The catalytic behavior of preformed oxidized osmium surface species has been found to be markedly dependent on the preparation method. The highest activity was obtained when they are formed in situ in the presence of l-butene. Silica-supported metallic osmium catalysts displayed different activity and selectivity, thus confirming the molecular nature of the catalytic process.
Journal of Molecular Catalysis A-chemical, 2002
Hydrodechlorination of carbon tetrachloride was performed at atmospheric pressure over Pd and Pt ... more Hydrodechlorination of carbon tetrachloride was performed at atmospheric pressure over Pd and Pt catalysts supported on various inorganic oxides (Al 2 O 3 , MgO, CeO 2 ) and obtained from different organometallic precursors (Pd(acac) 2 , [Pd(C 3 H 5 )Cl] 2 , Pt(acac) 2 and Pt(CH 3 CN) 2 Cl 2 . Generally, Pd-based catalysts show low conversion levels and high selectivity to C 1 -C 7+ hydrocarbons with a distribution that fits a typical Schulz-Flory mechanism for alkyl polymerization.
Microchemical Journal, 2010
A low cost, high performance ultraviolet digester was developed and tested in our laboratory. Its... more A low cost, high performance ultraviolet digester was developed and tested in our laboratory. Its main features include limited costs (around 600 € for all the parts) and high efficiency toward total organic carbon (TOC) abatement. As a result the TOC of typical natural waters is reduced to less than 10% of its initial value with half an hour treatment. Easiness of use, temperature control and flexibility in sample size (up to 25 mL) and number (up to twelve 12 mL test tube) are other important characteristics of the developed UV digester. This apparatus was tested as a pretreatment method for the determination of the total content of trace elements such as copper, uranium and platinum in natural waters by cathodic adsorptive stripping voltammetry. The voltammetric technique was chosen because it is strongly interfered by the presence of even low levels of natural organic complexing molecules. As a result, a 30 minute UV treatment yielded results non distinguishable from ICP-MS data.
Fresenius Journal of Analytical Chemistry, 2000
A simple computerized potentiometric titrator is described for performing automated analyses of c... more A simple computerized potentiometric titrator is described for performing automated analyses of chloride ions on solid materials as well as the continuous determination of HCl in effluent gas streams. This versatility has been obtained by a dedicated instrumental design, which offers easy interfacing to catalytic reactors and flexibility in software programs, including Gran’s plot determination of end-points. The validation of the analytical methodology for quantitative determination of chloride ions in solid matrices required the definition and the preparation of suitable reference materials of known chloride content.
Applied Catalysis B-environmental, 1999
We prepared H-ZSM-5 (Si/Al80), amorphous mesoporous silica±alumina (MSA, Si/Al90), and Silicalite... more We prepared H-ZSM-5 (Si/Al80), amorphous mesoporous silica±alumina (MSA, Si/Al90), and Silicalite-1 (S-1) according to the methods described by Bellussi and co-workers, and compared their ion-exchange capacity for copper ions. The Cu-ZSM-5, Cu±MSA and Cu±S-1 samples thus obtained have been investigated as catalysts for the NO decomposition reaction at 773 K.
Marine and Freshwater Research, 2007
... Eastern Alps, Italy) Carlo DossiA,C, Elena CiceriA, Barbara GiussaniA, Andrea PozziA, Antonio... more ... Eastern Alps, Italy) Carlo DossiA,C, Elena CiceriA, Barbara GiussaniA, Andrea PozziA, Antonio GalgaroB, Alessia VieroB and Alfio ViganòA ADepartment of Chemical and Environmental Sciences, Insubria University, Via Valleggio 11, Como 22100, Italy. ...
Catalysis Today, 1993
ABSTRACT
Mikrochimica Acta, 2009
An empirical approach is presented for validating trace metal profiles in tree rings for use as e... more An empirical approach is presented for validating trace metal profiles in tree rings for use as environmental archives. Concentration profiles of Zn, Cd, Cu, Pb and U in tree rings and lake sediments are compared for assessing the reliability of the former as an environmental proxy. Laser ablation sampling in conjunction with inductively coupled plasma mass spectrometry (LA–ICP–MS) is used for the direct analysis of tree rings. An optimised analytical protocol is devised with particular emphasis on sample preparation and quantification strategy. Significant correlations in the two environmental archives were found for zinc, copper and uranium, while cadmium and lead temporal trends, although showing enrichment in recent years, do not agree with the concentration profiles in lacustrine sediment cores. A chemical model based on metal affinity for hard type ligands present in wood is proposed to explain these results. Moreover, spring and winter wood are analysed separately thanks to the high spatial resolution of laser ablation sampling. As a result, enhanced metal loadings are shown to lead to intraring differences in trace metal concentrations.
Journal of Molecular Catalysis A-chemical, 2003
... Journal of Molecular Catalysis A: Chemical Volumes 204-205, 15 September 2003, Pages 465-472 ... more ... Journal of Molecular Catalysis A: Chemical Volumes 204-205, 15 September 2003, Pages 465-472 In honour of Prof. R. Ugo on the occasion of his 65th. Birthday. ... Dedicated to Professor Renato Ugo on the occasion of his 65th birthday. ...
Fresenius Journal of Analytical Chemistry, 2001
The development of an analytical method for the determination of platinum in MgO based Pt/Sn cata... more The development of an analytical method for the determination of platinum in MgO based Pt/Sn catalysts is described. Electrothermal atomic absorption spectroscopy (ETAAS) was chosen because of its high sensitivity and robustness against spectral interferences. All the sources of chemical interferences were statistically analyzed and corrections were adopted for the presence of magnesium oxide support. The effectiveness of different mineralization procedures was critically evaluated as a function of the chemical of the solid catalyst. Microwave digestion allowed recovery of metal of 100% for all the catalysts analyzed and exhibited significant better precision values than other digestion methods, which could nevertheless be utilized under proper conditions in selected cases.
Journal of Catalysis, 1999
Magnesia-supported Sn-Pt catalysts were prepared by reaction between preformed platinum metal par... more Magnesia-supported Sn-Pt catalysts were prepared by reaction between preformed platinum metal particles and Sn(n-C 4 H 9 ) 4 . HRTEM and H 2 -chemisorption data confirm the synthesis of very small tin-decorated platinum particles (∼1.0 nm mean diameter). Preliminary studies on catalytic hydrogenation of citral in a tricklebed reactor reveal that 97% selectivity to unsaturated alcohols at 100% conversion can be easily achieved. The electronic ligand effect produced by the basic support is supposed to be fundamental to enhance the selectivity to unsaturated alcohols and to stabilise the bimetallic particles.
Thermochimica Acta, 1998
... a Dipartimento di Chimica Inorganica, Metallorganica e Analitica, University of Milano Milan ... more ... a Dipartimento di Chimica Inorganica, Metallorganica e Analitica, University of Milano Milan Italy. b CNR Center 'CSSCMTBSO' Via Venezian, 21 20133 Milan Italy. Received 2 September 1997; revised 5 May 1998; accepted 11 May 1998. Available online 2 September 1998. ...
Talanta, 2008
Poor recoveries are obtained if the BCR three-step sequential extraction is applied to 100 mg spe... more Poor recoveries are obtained if the BCR three-step sequential extraction is applied to 100 mg specimens rather than to 1 g. It is observed that analytes are lost during each phase separation which is carried out via centrifugation and can be hardly quantitatively performed on 100 mg sediment specimens. An alternative procedure, which is carried out on a single empty SPE column and involves separation by filtration, is developed to solve this problem. The proposed method is validated on 100 mg samples of certified sediment (BCR-701), but could be potentially used for even lower sediment specimens. Problems related to pH stability during step 2 and its influence on recoveries is also reported.
Journal of Physical Chemistry B, 2002
... Dipartimento di Scienze CC, FF, MM, Università degli Studi dell'Insubria, Via Valleggio 1... more ... Dipartimento di Scienze CC, FF, MM, Università degli Studi dell'Insubria, Via Valleggio 11, 22100 Como, Italy. Rinaldo Psaro, Achille Fusi, and Renato ... the active sites are probably formed by two copper centers with a favorable geometric arrangement for the N−N bond formation ...
Environmental Science and Pollution Research, 2011
Background, aim and scope A new approach towards monuments, considering them as a passive sampler... more Background, aim and scope A new approach towards monuments, considering them as a passive sampler of pollution, is presented. Cultural Heritage objects suffer daily the damages of environmental pollution, especially in those areas interested by heavy traffic. Since monuments undergo only periodic conservation or maintenance works, surfaces are able to accumulate atmospheric deposit and to record changes in its composition. An optimised analytical protocol was developed in order to quantify platinum and rhodium at trace level on surfaces. The two elements have become tracers of automobile emissions in recent years, since the introduction of catalytic converters, and could have catalytic effects on the decay reactions of natural and artificial stone materials. As a first case study, the cement mortar surfaces of a twentieth century monument, the Camerlata Fountain, in Como (Italy) were investigated. Materials and methods The surfaces of the monument were scraped in areas both exposed to atmosphere and sheltered by the architectural elements of the building. The powders were dissolved by microwave-assisted mineralisation with a solution of HCl and HNO3. The solution was filtered, irradiated and analysed by adsorptive cathodic stripping voltammetry. The powders were also analysed by infrared spectroscopy and X-ray diffraction in order to determine the chemical and mineralogical composition. Results and discussion An analysis protocol was set up considering the matrix effect and the expected low concentrations of the two metals. The results enlightened variable concentration values and distribution areas of platinum (0.013–45 μg/kg) and rhodium (0.55–274.4 μg/kg), suggesting the ability of artificial stone surfaces to accumulate the two elements. The sample chemical and mineralogical composition was consistent with a typical cement plaster interested by decay phenomena. Conclusions This work investigated the relation between Cultural Heritage and pollution by another point of view. The analytical protocol presented in this paper was effective in determining platinum and rhodium in traces on the investigated stone surfaces with negligible matrix effects. Recommendation and perspectives The presence of platinum and rhodium on monument surfaces should be of significant interest when planning Cultural Heritage conservation. A better knowledge of the role of the two metals in decay phenomena could impact in a positive way artwork conservation.