1,720,969 research outputs found
Transesterification of Bis(2-Ethylhexyl) Phthalate for the Recycling of Flexible Polyvinyl Chloride Scraps in the Circular Economy Framework
No full textThe identification of suitable process solutions for the recycling of plastics is nowadays one of the main challenges to reduce their environmental impact and promote their sustainability. In this context, the recycling of flexible polyvinyl chloride (PVC) has severe limitations because this material can contain bis(2-ethylhexyl) phthalate (DEHP), a plasticizing additive recently banned by the European Chemicals Agency (ECHA) due to its endocrine disruptor effect. In this study, we investigated a transesterification process for the possible conversion of DEHP to other less toxic phthalates applicable in the context of PVC mechanical recycling using a selective dissolution process. Different catalytic routes have been tested to find optimal concentrations for pure DEHP conversion and applied under real process conditions. Best results have been obtained at 80 °C with tetrabutyl titanate [Ti(OBu)4], using alcohol/DEHP molar ratios from 10:1 to 5:1, with conversions of more than 90% for pure DEHP in 15 min. However, limitations are related to the final conversion of DEHP in the presence of the PVC phthalate mixture, ranging between 57 and 60% after 90 min for the Ti(OBu)4catalyst. Such results are ascribed to dilution for complete PVC dissolution and the preferential formation of monosubstituted phthalates
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Combined AOPs for formaldehyde degradation using heterogeneous nanostructured catalysts
Get PDFIn this paper we studied the combination of advanced oxidation processes (AOPs), i.e., TiO2‐based photocatalysis and photo‐Fenton process, on the degradation of aqueous solutions containing a low (90 ppm) concentration of formaldehyde. Heterogeneous nanostructured catalysts, supported on polymeric nanofibers, were used; for comparison, some homogeneous or partly heterogeneous systems were also analyzed. Furthermore, to make the process more sustainable (in terms of costs and safety) no hydrogen peroxide was added to the system. The results showed that the combination of AOPs gave a synergy since the presence of iron was beneficial in promoting the photocatalytic activity of TiO2 while TiO2 was beneficial in promoting the photo‐Fenton reaction. Moreover, very good results were obtained using fully heterogeneous nanostructured catalysts (based on TiO2 and FeSO4), without the need to add H2O2
Composting of starch-based bioplastic bags: Small scale test of degradation and size reduction trend
Get PDFIn Italy, the majority of bioplastic bags used in food waste collection is made of starch-based biopolymer. The compostability of this material in a full-scale plant remains to be demonstrated, largely due to the fact that bioplastic bags are screened and removed together with conventional plastic bags during pre-treatment steps. The present research was performed on a small scale to study the degradation of starch-based bioplastics during composting. Evolution of the physical and chemical parameters of the material was evaluated by means of Fourier Transform Infrared (FTIR), experimental mass loss and granulometric trend. The results obtained sug-gested that fragmentation (physical size reduction of the material) occurred mainly during the thermophilic phase, while biodegradation (breakdown by microorganisms of an organic chemical into simpler, innocuous compounds) occurred during the curing phase. Based on the monitored parameters (TS, VS, pH, C/N and RI4), the composting process of the waste matrix ended after 55 days, but the degradation of bioplastics failed to achieve the regulatory standards for assessment of composta-bility (≤ 10% sized > 2 mm). Experimental data revealed a linear trend for the fragmentation process and a duration of 100 days would be required to meet regulatory requirements
Mechanically stable nanofibrous sPEEK/Aquivion®composite membranes for fuel cell applications
No full textVariations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Electrospun active media based on polyvinylidene fluoride (Pvdf)-graphene-tio2 nanocomposite materials for methanol and acetaldehyde gas-phase abatement
No full textThe abatement of organic pollutants by TiO2 photocatalysis has been established as one of the benchmark applications of advanced oxidation processes for both liquid and gas phase purification. Such solution is particularly suitable for indoor air pollution where volatile organic compounds (VOCs) represent a class of chemicals of high concern for their adverse effects on both environment and human health. However, different shortcomings still affects TiO2 photocatalytic performance in terms of weak adsorptivity and fast electron-hole recombination, limiting its applicability. As a result, different strategies have been investigated over the last years in order to promote a higher TiO2 photo-efficiency. In this study we used electrospun (PVDF) nanofibers as a support for the photo catalytic system obtained by coupling graphene based materials and TiO2 during solvothermal synthesis. The resultant nanostructured membranes have been tested for acetaldehyde and methanol degradation under UV light showing an increase in the photocatalytic activity compared to bare TiO2 . Such results may be ascribed to the decrease of band-gap energy and to increased electron mobility in the photocatalytic nanocomposite
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Life Cycle Assessment Framework to Support the Design of Biobased Rigid Polyurethane Foams
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