Measurement of the carbonaceous component in the Milan urban particulate matter

The carbonaceous component in the Milan urban particulate matter, i.e. the two components black carbon (BC) and organic carbon (OC), has been measured by means of a thermogravimetric analyzer combined with an infrared spectrophotometer (TGA/FT-IR). While black carbon may be considered a primary pollutant, organic carbon includes both primary emissions and secondary organic aerosols. Since carbonaceous aerosol (including a small quantity of inorganic carbon, too) makes up roughly from 25% to 50% of the average annual PM 2.5 mass concentration, a deeper understanding of this component is required. The TGA/FT-IR technique, employed for the first time to our knowledge for the quantification of the particulate matter carbonaceous component, allows, thought the results here presented are preliminary, to assess the two components BC and OC in a simple way especially if compared with the methods reported in the literature. The total carbon (TC) determinations performed by TGA/FT-IR on Milan urban particulate matter are in good agreement with the results obtained by a total organic carbon (TOC) analyzer operating directly on the solid sample.     

Measurement of carbonaceous aerosols: validation and comparison of a solvent extraction-gas chromatographic method and a thermal optical transmittance method

A solvent extraction-gas chromatographic method was developed for the measurement of four classes of solvent-extractable organic compounds (SEOC), viz., aliphatic hydrocarbons, polynuclear aromatic hydrocarbons, fatty acids and alkanols, in ambient carbonaceous aerosols. The selectivity and recovery of the method using different solvents commonly used in the analysis of SEOC was evaluated. The composition of SEOC in aerosol and urban dust samples was found to vary with the choice of solvent. Such variation was not observed in filters spiked with standards of SEOC. The developed method was validated by the analysis of reference urban dust SRM 1649a from the National Institute of Standards and Technology. The concentrations of selected polynuclear aromatic hydrocarbons in the reference dust were found to fall within the certified and reference concentrations. The thermal characteristics of aerosol samples collected in an urban area of Hong Kong and the four classes of identified SEOC were also studied using a thermal optical transmittance (TOT) method as specified in NIOSH Method 5040. Correlations were made to compare the method-dependent SEOC content obtained by the solvent extraction method and the results for total carbon, organic carbon and elemental carbon obtained by the TOT method.     

表面改性纳米SiO2复合聚合物电解质的制备及性能

通过化学方法将具有增塑效果的环状碳酸酯基团引入纳米SiO2表面,并用FTIR与TGA对改性纳米SiO2进行了表征.将改性纳米SiO2添加到以聚氧化乙烯(PEO)为基体的聚合物电解质中,制备了复合聚合物电解质.通过DSC和交流阻抗等方法对该聚合物电解质膜的热力学和电化学性能进行了研究.结果表明,掺杂改性纳米SiO2的聚合物电解质具有更高的离子电导率,室温最高离子电导率可达到1.84×10-5 S/cm;具有较高的锂离子迁移数,最高可达到0.49,且具有更好的界面稳定性.     

A new sorbent for uranium extraction: ethylenediamino tris(methylenephosphonic) acid grafted on polystyrene resin

A new chelating polymeric sorbent has been developed using polystyrene resin grafted with ethylenediamino tris(methylenephosphonic) acid. After characterisation by FTIR and elementary analysis, the new grafted resin has been investigated in liquid–solid extraction of uranium(VI). The influence of analytical parameters including pH, amount of resin, metal ion concentration, sample volume and ionic strength were investigated on the recovery of U(VI). Adsorption kinetic and isotherm studies were also carried out to understand the nature of the sorption of uranium(VI) by the resin. The total sorption capacity was found to be 41.76 mg/g under optimum conditions. The total desorption of the sorbed uranium ions was successfully performed with 0.1 M ammonium carbonate. Further, the effect of temperature was realized and the thermodynamic parameters were calculated.     

CO2 adsorption studies on hydroxy metal carbonates M(CO3)x(OH)y (M = Zn, Zn-Mg, Mg, Mg-Cu, Cu, Ni, and Pb) at high pressures up to 175 bar

Carbon dioxide (CO(2)) adsorption capacities of several hydroxy metal carbonates have been studied using the state-of-the-art Rubotherm sorption apparatus to obtain adsorption and desorption isotherms of these compounds up to 175 bar. The carbonate compounds were prepared by simply reacting a carbonate (CO(3)(2-)) solution with solutions of Zn(2+), Zn(2+)/Mg(2+), Mg(2+), Cu(2+)/Mg(2+), Cu(2+), Pb(2+), and Ni(2+) metal ions, resulting in hydroxyzincite, hydromagnesite, mcguinnessite, malachite, nullaginite, and hydrocerussite, respectively. Mineral compositions are calculated by using a combination of powder XRD, TGA, FTIR, and ICP-OES analysis. Adsorption capacities of hydroxy nickel carbonate compound observed from Rubotherm magnetic suspension sorption apparatus has shown highest performance among the other components that were investigated in this work (1.72 mmol CO(2)/g adsorbent at 175 bar and 316 K).     

Enlightening the influence of mordant, dyeing technique and photodegradation on the colour hue of textiles dyed with madder - A chromatographic and spectrometric approach

Wool samples were dyed with madder and alum, copper, and iron salts at different concentration by pre-mordanting (MD) and simultaneous mordanting (M + D) procedures. Samples were artificially aged to identify the influence of the mordant on the madder chromophores photodegradation. A set of analytical techniques was used for complete characterisation of the dyed fibres before and after light exposure, which included colour and chromophore analysis (colourimetry and LC-ESI-MS/MS analysis), determination of mordant ions amounts in the fibres (FAAS and ICP-OES analysis), morphological characterisation of the fibres and punctual chemical analysis (SEM-EDS studies).Fibre colour hue was found to be dependent on the mordant ion nature, mordant bath concentration and dyeing procedure. Mordant ion quantification showed that the uptake of metal ion by the fibres is relatively small, with the Cu ion presenting the highest affinity for the fibre. MD method yields fibres with higher amounts of metal ions and larger chromophore chromatographic peak areas corresponding, in general, to stronger colour hues. Photodegradation was more severe in alum mordant samples and in the first 480 h of light exposure. Chromophore degradation rates are unequal and dependent on the mordant nature, contributing for colour changes observed after light exposure.     

Development of a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and saccharidic compounds in atmospheric aerosols. Application to urban aerosols

We developed and validated a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and the related monosaccharide anhydrides, mannosan, galactosan and 1,6-anhydro-beta-D-glucofuranose in urban atmospheric aerosols collected on quartz fiber filters. The method is based on extraction with dichloromethane-methanol (80 : 20, v/v), trimethylsilylation, multiple reaction monitoring in the tandem mass spectrometric mode using the ion at m/z 217, and the use of an internal standard calibration procedure with the structurally related compound methyl beta-L-arabinopyranoside. In addition, the method allows the quantification of other saccharidic compounds, arabitol, mannitol, glucose, fructose, inositol and sucrose, which were found to be important in summer aerosols. The recovery of levoglucosan was estimated by spiking blank filters and was better than 90%. The precision evaluated by analyzing parts of the same filters was about 2% for the monosaccharide anhydrides and 7% for the other saccharidic compounds in the case of a winter aerosol sample, and the corresponding values for a summer aerosol sample were 5% and 8%. The method was applied to urban PM(10) (particulate matter of <10 microm aerodynamic diameter) aerosols collected at Ghent, Belgium, during a 2000-2001 winter and a 2001 summer episode and revealed interesting seasonal variations. While monosaccharide anhydrides were relatively more important during the winter season owing to wood burning, the other saccharidic compounds were more prevalent during the summer season, with some of them, if not all, originating from the vegetation.     

Precise and Sensitive Water Soluble Ion Extraction Method for Aerosol Samples Collected on Polytetrafluoroethylene Filters

Abstract

The widely used aerosol collection filters composed of polytetrafluoroethylene (Teflon) present a problem in the extraction of water soluble ions from the collection surface due to the hydrophobic nature of the Teflon. A method is presented for the extraction and analysis of water soluble ions from Teflon aerosol filters which is efficient and sensitive. This method uses a direct application of ethanol to the filter surface to decrease the surface tension of the filter and allow a dilute HC10, solution to contact the collection surface and extract any water soluble ions. This study compares this extraction method with other extraction methods currently being used. The results obtained from the extraction of water soluble ions from the Teflon filters were also compared to the results obtained from quartz filters collected on a colocated high volume sampler. From these studies, it is concluded that the hydrophobic nature of the Teflon filters makes the complete dissolution of water soluble ions exceptionally difficult and that the prewetting of the Teflon filters with ethanol minimizes dissolution and extraction problems.     

Measurement of carbonaceous aerosols: validation of a thermal gravimetric method and its comparison with a thermal optical transmittance method

A high throughput thermal gravimetric method was developed to measure the carbonaceous aerosols and particulates collected on filters. Representative portions or the whole piece of a loaded or blank filter was sampled and conditioned at 105±5 °C for 4 h to drive away water moisture. The sample was then treated at 550±10 °C for 4 h. After each of the heat treatment steps, the sample was conditioned in a humidity and temperature-controlled cabinet for 12 h till constant weight. The weight of the filter before and after the heated treatment was measured and the weight difference between the treatment at 550 and 105 °C was calculated as the weight of the carbon containing substances (CCS). Reference chemical standards and certified reference materials SRM 1649a and 1650a were used to validate the method. CCS concentrations of real aerosol samples collected in the city of Hong Kong during the summer of 2001 were also measured, compared and correlated with the concentrations of total carbon (TC), elemental carbon (EC) and organic carbon (OC) of the samples determined using a thermal optical transmittance (TOT) method as specified in NIOSH method 5040. The weight of organic compounds in airborne particulate matters is usually estimated by multiplying the weight of TC, which is determined by thermal/thermal optical methods, by a factor of 1.2 or 1.4. To this end, a correction factor of approximately 1.6 was found to relate TC to the measured values of CCS in aerosol samples collected in the urban atmosphere of Hong Kong. The proposed procedure for measurement of CCS is simple, easy to follow and requires simple laboratory instrumentation. Typically, the analysis of more than 100 filter samples can be completed within three working days with minimal attention.     

Search criteria and rules for comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry analysis of airborne particulate matter

Direct thermal desorption-gas chromatography-time-of-flight mass spectrometry (DTD-GC-TOFMS) and comprehensive two-dimensional (2D) gas chromatography-time-of-flight mass spectrometry (GC x GC-TOFMS) was applied for characterisation of semi-volatile organic compounds (SVOC) in fine particulate matter (PM), with a diameter of up to 2.5 microm (PM2.5), from ambient air in Augsburg, Germany. DTD-GC-TOFMS measurements on the SVOC in PM2.5 are done on a daily basis (time series over several years). The data will be used in an epidemiological study questioning the influence of SVOC in PM2.5 on ambient aerosol related health effects. The outcome of the first measurements periods is that the organic inventory in the ambient aerosol can undergo drastic fluctuations, e.g. due to meteorological influences or specific emission sources. This includes also the large fraction of chromatographically not resolved peaks (unresolved carbonaceous matter (UCM)). The UCM fraction contains about 70% of the SVOC mass in PM2.5. GC x GC-TOFMS is a suited technique to study the nature of the yet unidentified compounds forming the UCM. The considerably increased chromatographic resolution in GC x GC allows separation of many UCM compounds while the TOFMS supplies mass spectral data of all separated compounds. However, the data sets are getting enormously complex. In a typical PM2.5 sample from Augsburg more than 15,000 peaks can be detected. Thus, it is important to classify the observed GC x GC peaks by rational means. A classification procedure based on GC x GC retention times and the fragmentation patterns is suggested. With a preliminary classification procedure it is already possible to group compounds with some certainty into substance classes. After some further development, this approach can be used for classifying GC x GC data, e.g. for environmental and epidemiological studies.     

Pyrolysis-FTIR and TGA techniques as tools in the characterization of blends of natural rubber and SBR

The employment of used tyres as a new source of raw materials for different applications can be a partial solution to the great environmental problems generated by these products concerning their disposal at waste depots. In this study, high-resolution thermogravimetric analysis (Hi-Res TGA) is used to quantify the elastomer composition of SBR/NR in tyre formulations. This technique provides the ability to generate TGA derivative profiles (DTGA), which can be used to distinguish different formulations from appropriate calibration curves. Infrared spectroscopy (FTIR) is also employed for composition quantification of used tyres and the results are compared to those obtained by Hi-Res TGA. Both analysis methods give satisfactory results when applied to elastomer mixtures of known composition and to tyre rubbers of unknown composition. The study confirms the accuracy of high-resolution TGA-DTGA technique for rapid quantitative determination of elastomer blends in used tyres.     

Pyrolysis of waste materials using TGA-MS and TGA-FTIR as complementary characterisation techniques

Pyrolysis of waste materials, biomass wood waste, waste tyre, refuse derived fuel (RDF) and waste plastic was performed using two thermogravimetric analysers (TGA). One TGA was coupled to a mass spectrometer (MS) and the other to an infrared spectrometer (FTIR). The kinetic parameters of the pyrolysed waste materials obtained for TGA-MS and TGA-FTIR were compared using a model based on first-order reactions with a distribution of the activation energies. A further comparison of the volatile species evolved by thermal degradation (TGA) and the subsequent characterisation by the MS and FTIR spectra was performed. The first-order reaction pathways and subsequent activation energies calculated from the differential TGA data presented good repeatability between the TGA-MS and TGA-FTIR. The TGA-MS and TGA-FTIR produced a broad spectrum of qualitative data characterising the volatile gaseous fraction of the waste materials pyrolysed. TGA-MS and TGA-FTIR are shown to be valuable techniques in corroborating the respective thermograms and spectrograms of the volatile species evolved during the pyrolysis of waste materials. However both techniques are prone to interference and careful interpretation of the spectra produced is required.     

Size-exclusion chromatography with organic carbon detection using a mass spectrometer

A novel organic carbon detector for size-exclusion chromatography (SEC) is described. The instrument uses the conventional UV-persulfate oxidation method to convert organic carbon to CO(2), which is then detected using a mass spectrometer. This system, using the mass spectrometer, had lower limits of detection (LOD) and limits of quantification (LOQ) than a previously described system using a Fourier transform infrared (FTIR) spectroscopy 'lightpipe' detector (i.e. when quantification was based on calibration using phthalate standards). When used to analyse natural organic matter (NOM) in water, it also had a superior signal-to-noise ratio to the previously described system. The use of a mass spectrometer to detect organic carbon (as CO(2)) enables the possibility of further characterisation of NOM by measuring the stable carbon isotope ratios of the various molecular size fractions of organic carbon, as obtained by SEC.     

Depth-resolved speciation of nitrogen compounds in environmental solids

Dynamic SIMS has been applied to the analysis of inorganic and organic nitrogen compounds. A depth-resolved speciation of nitrogen, based on the intensities of small ionic clusters, has been developed. An evaluation method is outlined to distinguish inorganic and organic nitrogen compounds. Furthermore, several organic compound families can be recognised including detailed nitrogen speciation. Because this method is suitable even for characterisation of complex mixtures, urban outdoor aerosol particles have been analysed with Dynamic SIMS.     

Synthesis of a cellulose derivative for enhanced sorption and selectivity of uranium from phosphate rocks prior to its fluorometric determination

In this research work, the separation of Uranium from phosphate medium via adsorption prior to its fluorometric determination was carried out onto a newly synthesised adsorbent made via impregnation of urea onto cellulose (UIC). The full characterisation of the synthetic extractant (UIC) was carried out by various instrumental techniques such as elemental analysis, FTIR, TGA, XRD and SEM analysis. Various factors that may affect the quality of adsorbing U (VI) ions using synthesised Urea-impregnated cellulose had been investigated. The maximum adsorption capacity (82 mg/g) for U (VI) has been verified by the Langmuir isotherm model. The thermodynamics and kinetics of the adsorption process indicated that the uranium sorption onto synthesised Urea-impregnated cellulose was an exothermic and pseudo-second-order process. The tolerance limits for the common cations which are actually found with uranium in the phosphate solutions and may show sorption behaviour on the synthesised UIC resin were calculated and gave a high tolerance limit. Contrary to previously reported studies, several ameliorations have resulted including an elevated selectivity and adsorption capacity of uranium from phosphate medium. The optimised method was applied with good accuracy results for determination of uranium in reference and different phosphate rock types bearing uranium.     

Speciation of arsenic in coarse and fine urban aerosols using sequential extraction combined with liquid chromatography and atomic fluorescence detection

An analytical procedure for speciation of As in urban aerosol samples was developed. The aerosols were collected by sequential filtration through membrane filters. Part of each filter was investigated by INAA for the total amount of As. Another part of the filters was treated by a sequential extraction procedure to differentiate between water-extractable, phosphate-extractable and refractory chemical forms. Water-extractable forms were further differentiated into anionic As species by HPLC-HGAFS. Extractability of As into water exhibited a clear dependency on the aerosol size fraction (12% in coarse fraction and 50% in fine fraction). Dependency of the phosphate extractable As on the aerosol size fraction seems not to be significant (10–15% in both size fractions). The remaining amount, i.e., about 78% of the coarse As and about 40% of the fine As was considered to be refractory or environmentally immobile As. Water-extractable As forms could only be attributed to arsenate.     

Speciation of arsenic in coarse and fine urban aerosols using sequential extraction combined with liquid chromatography and atomic fluorescence detection

An analytical procedure for speciation of As in urban aerosol samples was developed. The aerosols were collected by sequential filtration through membrane filters. Part of each filter was investigated by INAA for the total amount of As. Another part of the filters was treated by a sequential extraction procedure to differentiate between water-extractable, phosphate-extractable and refractory chemical forms. Water-extractable forms were further differentiated into anionic As species by HPLC-HGAFS. Extractability of As into water exhibited a clear dependency on the aerosol size fraction (12% in coarse fraction and 50% in fine fraction). Dependency of the phosphate extractable As on the aerosol size fraction seems not to be significant (10-15% in both size fractions). The remaining amount, i.e., about 78% of the coarse As and about 40% of the fine As was considered to be refractory or environmentally immobile As. Water-extractable As forms could only be attributed to arsenate.     

Removal of phosphate using copper-loaded polymeric ligand exchanger prepared by radiation grafting of polypropylene/polyethylene (PP/PE) nonwoven fabric

A novel polymeric ligand exchanger (PLE) was prepared for the removal of phosphate ions from water. 2,2′-dipyridylamine (DPA), a bidentate ligand forming compound with high coordination capacity with a variety of metal ions was bound to glycidyl methacrylate (GMA) grafted polypropylene/polyethylene (PP/PE) nonwoven fabric synthesized by radiation-induced grafting technique. DPA attachment on epoxy ring of GMA units was tested in different solvents, i.e. methanol, ethanol, dioxane and dimethylsulfoxide (DMSO). The highest amount of modification was achieved in dioxane. In order to prepare the corresponding PLE for the removal of phosphate, DPA-immobilized fabric was loaded with Cu(II) ions. Phosphate adsorption experiments were performed in batch mode at different pH (5–9) and phosphate concentrations. The fabric was found to be effective for the removal of phosphate ions. At every stage of preparation and use, the nonwoven fabric was characterized by thermal (i.e. DSC and TGA) and spectroscopic (FTIR) methods. Competitive adsorption experiments were also carried out using two solutions with different concentration levels at pH 7 to see the effect of competing ions. Phosphate adsorption was found to be effective and selective from solutions having trace amounts of competitive anions. It is expected that the novel PLE synthesized can be used for the removal of phosphate ions in low concentrations over a large range of pH.     

Surface Complexation Modeling and FTIR Study of Carbonate Adsorption to Goethite

Experimental data for carbonate adsorption onto synthetic goethite, spanning 3 orders of magnitude in carbonate concentrations, were simulated using the triple-layer surface complexation model (TLM). A single set of TLM parameters successfully described the adsorption behavior versus pH over the concentration range obtained from closed and open CO(2) conditions. An optimization analysis was performed for all possible interfacial charge configurations using FITEQL3.2. The results yielded an optimum charge allocation of 0 and -1 in the 0- and beta-planes, respectively, which suggests a monodentate complex most probably in an inner-sphere configuration (SOCOO(-beta)). Fourier transform infrared (FTIR) spectroscopic measurements on open systems at atmospheric P(CO(2)) confirmed this result by showing a clear peak split (155 cm(-1)) of the nu(3) C-O asymmetric stretching frequency of surface-bound carbonate, consistent with that reported for monodentate Co(III)-carbonato inner-sphere solution complexes. An additional Na(+)-ternary complex (SOCOONa) was invoked in the TLM construct to improve simulations of the enhanced carbonate adsorption occurring at high ionic strength and high pH. The model was successful in predicting carbonate adsorption behavior under diffferent conditions than it was calibrated for. Projections for equilibration at higher P(CO(2))'s (1-10%) than those used in this work show the potential for carbonate sorption densities of up to 2.5-3 μmol/m(2). Copyright 2001 Academic Press.