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The general aim of this study is the valorisation of Automotive Shredder Residue (ASR) via pyrolysis. Tar, the condensable gases obtained in the pyrolysis process, is an interesting alternative fuel. Thus, the pyrolysis process was investigated in order to maximize the tar yield. The design of experiment approach was used to plan a series of experiments and to identify which operating variables influence the yield of the process. Temperature and carrier gas flow proved to be significant factors affecting the yield, while the influence of ASR light fraction amount pyrolysed was negligible. In the experimental domain, the maximum response was obtained at 500 °C and 100 mL/min

The general aim of this study is the recovery of Automotive Shredder Residue (ASR). The ASR light fraction, or car fluff, that was collected at an Italian shredding plant was pyrolysed at various temperatures (500–800 °C) in a lab-scale reactor. The condensable gases (tar) and solid residue yields increased with decreasing temperature, and these products were characterized to suggest a potential use to reclaim them. The higher heating value (HHV) of tar was 34–37 MJ/kg, which is comparable with those of fossil fuels. Furthermore, the ash content was low (0.06–4.98%). Thus, tar can be used as an alternative fuel. With this prospect, the concentrations of polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in tar were determined. The toxicity of tar changes with temperature (1–5 ng I-TEQ/g), and the PCDFs significantly contribute to tar toxicity, which was 75–100% with a maximum of 99.6% at 700 °C. Regarding the characterization of the solid residue, the low HHV (2.4–3.3 MJ/kg) does not make it suitable for energy recovery. Regarding material recovery, we considered its use as a filler in construction materials or a secondary source for metals. It shows a high metal concentration (280,000–395,000 mg/kg), which is similar at different pyrolysis temperatures. At 500 °C, polycyclic aromatic hydrocarbons (PAHs) were not detected in the solid residue, whereas the maximum total PAH concentration (19.41 ng/g, 700 °C) was lower than that in fly ash from MSWI. In conclusion, 500 °C is a suitable pyrolysis temperature to obtain valuable tar and solid residue.

We developed a phenomenological approach to explain the kinetic experimental data of PCDD/F formation/destruction based on a reaction mechanism model at the congener group level. In the present work, we investigated the formation and destruction of PCDD/F on fly ash as a function of time at 280 °C, chlorine mass balance, evolution of the total equivalent toxicity and kinetic modelling. We determined that the volatilization process is negligible and that the reactive processes at short reaction times only become important above 300 °C. The results provide a substantial improvement on existing studies. We experimentally demonstrated, for the first time, that there is a correlation between the oxidative breakdown of native carbon and PCDD/F de novo synthesis. Data processing by our kinetic model showed that the formation of oxygen complexes C(O) was the determining step for de novo synthesis of PCDD/F. Indeed, the calculated reaction time at which the PCDD/F concentration was at a maximum (850 min) was greater than that calculated for the oxygen complexes C(O) (435 min). Moreover, the experimental carbon conversion efficiency for PCDD/F production (0.0032% at 600 min maximum) was in a very good agreement with the theoretical conversion (0.0041%).

1,1,3,3-Tetramethylguanidine (TMG), methanol and carbon dioxide were investigated as switchable polarity solvents (SPS) in the simultaneous derivatization and extraction of triacylglycerols for the gas chromatographic (GC) characterization of olive oil. Three commercial olive oils were used as test samples. Results of the developed method did not differ statistically from those provided by reference derivatization procedures. The transesterification reaction was carried out under a very mild condition, one step and in situ, and no particular matrix interferences were evidenced. The method represented the first example of the use of a switchable polarity mixture for the preparation of methyl ester derivatives of fatty acids (FAME).

In the recent past we reported the investigation of different devulcanization processes of a ground tire rubber (GTR) such as supercritical fluid, ultrasonic and biological technologies. Each of these techniques had been previously optimized, focusing on the experimental combination of parameters providing the best devulcanization conditions. The present study aims to extensively compare the optimal conditions of these three different techniques for the devulcanization of a GTR. In particular the GTR and the devulcanizates by each technique were blended into raw natural rubber at a concentration of 10 phr. The rheological and mechanical properties of their vulcanizates were investigated and compared to find out the rubber providing the highest compatibility for compounding and revulcanization. In addition, a comparison of these results was made with the ones of raw natural rubber compound and vulcanizate.

tIn this study a 24factorial design was employed to investigate the supercritical CO2devulcanization pro-cess of ground tire rubber from end of life tires performed using diphenyl disulfide (DD) as devulcanizingreagent.The aim of the experimental design was to investigate the influence on the process of temperature,pressure, amount of devulcanizing reagent, treatment time and their interactions.The crosslink density, sol fraction, gel fraction and sulfur content were chosen as experimentalresponses. Multiple linear regression was used for modeling the relationship between each responseand the process variables. Reduced regression models were obtained for each response, considering onlythe significant variables and interactions. The predicted results from these reduced models showed goodagreement with the experimental values.Temperature, amount of DD and DD–temperature interaction resulted the relevant parameters for theprocess. On the contrary, the influence of treatment time, pressure and all other interactions proved tobe negligible.These results have an important outcome since this devulcanization process can be carried out in ashort time and at relatively low pressure, with subsequent energy saving.

Ground truck-tire rubber (GTR) was characterized and subsequently devulcanized in supercritical CO2 (scCO2) in the presence of Diphenyl Disulfide (DD) as devulcanizing agent. Temperature and pressure were kept respectively at 180 C and 15 MPa and the ratio between rubber and DD was 10 wt %. The treatment effect on the properties of GTR was widely studied. The reached degree of devulcanization was about 50% with a low amount of sol fraction. The results display that the treatment with the DD in presence of scCO2 reduces the crosslink density of the GTR, increasing the property of the gel fraction and the compatibility of this material with the raw rubber. The suitability of the devulcanized GTR to be reemployed in new tire blends was investigated through the final mechanical properties. The unreacted DD can strongly affect the revulcanization process and the mechanical properties of the blends containing devulcanized rubber, resulting the only limiting factor for the application of this devulcanization process. © 2014 Elsevier Ltd. All rights reserved.

The use of residential wood combustion represents an important renewable energy source, but it contributes in a considerable way to atmospheric particulate matter (PM) concentration in urban as well as in rural sites. Moreover, recent studies pointed out wood burning as an important source of PAH.In the present work, the influence of wood combustion on PM was studied, investigating its contribution to the carbonaceous PM fraction and to benzo(a)pyrene (B[a]P) and polychlorodibenzo-p-dioxins and polychlorodibenzofurans (PCDD/F) concentrations, using levoglucosan as a marker. PM10 samples were collected daily for six months in two sites located in Piemonte (Northern Italy): Torino and Susa. Composite monthly samples were chemically characterized, analyzing the concentrations of levoglucosan, B[a]P, PCDD/Fs, organic carbon (OC), elemental carbon, major anions and cations, and metals.PM and OC concentrations were almost twice in Torino with respect to Susa, while levoglucosan and B[a]P concentrations were almost comparable at the two sites. Therefore, wood combustion affects more Susa than Torino. Concentrations of B[a]P and levoglucosan were highly correlated in both sites. Using the macro tracer method and the emission factors reported in literature, the wood combustion percentage contribution to B[a]P concentration was estimated and resulted as the main source in both sites. The levoglucosan to soluble potassium ratio was higher in Torino with respect to Susa, indicating that combustion plants with different efficiency are used at the two sites. PCDD/F concentrations were higher in Torino than in Susa. © 2012 Elsevier Ltd.

Car Fluff samples collected from a shredding plant in Italy were classified based on particle size, and three different size fractions were obtained in this way. A comparison between these size fractions and the original light fluff was made from two different points of view: (i) the properties of each size fraction as a fuel were evaluated and (ii) the pollutants evolved when each size fraction was subjected to combustion were studied. The aim was to establish which size fraction would be the most suitable for the purposes of energy recovery. The light fluff analyzed contained up to 50. wt.% fines (particle size. <. 20. mm). However, its low calorific value and high emissions of polychlorinated dioxins and furans (PCDD/Fs), generated during combustion, make the fines fraction inappropriate for energy recovery, and therefore, landfilling would be the best option. The 50-100. mm fraction exhibited a high calorific value and low PCDD/F emissions were generated when the sample was combusted, making it the most suitable fraction for use as refuse-derived fuel (RDF). Results obtained suggest that removing fines from the original ASR sample would lead to a material product that is more suitable for use as RDF. © 2013 Elsevier B.V.

The kinetics for the oxidative breakdown of native carbon in raw fly ash samples (RFA) and for the formation and destruction of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF), abbreviated PCDD/F, were investigated using a flow-over solid system in which the RFA samples were thermally treated at 300 C under synthetic air. This study investigated the correlation between the disappearance of the reagent and the formation of the products to gain insight into the underlying mechanisms that govern these reactions at congener groups level.The detailed analyses of the experimental concentration-time data revealed significant differences in the behavior between the 2,3,7,8-substituted PCDD and the 2,3,7,8-substituted PCDF, non-2,3,7,8-substituted PCDD and PCDF. The chlorine balance for the former was always negative, that is, chlorine was released regardless of reaction time and primarily resulted from the dechlorination of the hepta- and octa-homologues. However, for the others, the balance was substantially positive up to approximately 240 min and became negative at longer intervals when the dechlorination reactions took over.The processes involving PCDD and PCDF in which the thermal destruction was only partial were found to increase the total equivalent toxicity (TEQ) levels rather than reduce them. © 2013 American Chemical Society.

The aim of the research was to develop new products and processes from a manufacturing waste from an Italian metallurgic company. The company produced thin silver metallic films and the production scraps were silver flakes. The possibility to use the silver flakes in water disinfection processes was studied. The antimicrobial activity of the flakes was investigated in batch using Escherichia coli as Gram-negative microorganism model. The flakes did not show any antimicrobial activity, so they were activated with two different processes: thermal activation in reducing atmosphere and chemical activation, obtaining, respectively, reduced flakes (RF) and chemical flakes (CF). The flakes, activated with either treatment, showed antimicrobial activity against E. coli. The kill rate was dependent on the type of activated flakes. The chemical flakes were more efficient than reduced flakes. The kill rate determined for 1 g of CF, 1.0 ± 0.2 min -1, was greater than the kill rate determined for 1 g of RF, 0.069 ± 0.004 min -1. This was confirmed also by the minimum inhibitory concentration values. It was demonstrated that the antimicrobial capability was dependent on flakes amount and on the type of aqueous medium. Furthermore, the flakes maintained their properties also when used a second time. Finally, the antimicrobial activities of flakes were tested in an effluent of a wastewater treatment plant where a variety of heterotrophic bacteria were present. © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences.