Daria C. Boffito

Ultrasound and microwave assisted synthesis of high loading Fe-supported Fischer–Tropsch catalysts

Supported iron-based Fischer-Tropsch (FT) catalysts with high loading of active metal have been prepared using both traditional and innovative methods. In these latter the impregnation of silica support has been performed by adding a step involving an ultrasound (US) or a microwave (MW) treatment to improve the metal deposition and to increase the catalyst activity. FT results have indicated the catalysts prepared by US as the most efficient, particularly when sonication is performed in argon atmosphere. MW prepared samples have given results very similar to those obtained with the traditional method. In order to explain the different catalytic activity, all the samples have been characterized by BET, TPR, SEM, TEM, XRD and micro-Raman analyses.

Ultrasonic free fatty acids esterification in tobacco and canola oil

Ultrasound accelerates the free fatty acids esterification rate by reducing the mass transfer resistance between methanol in the liquid phase and absorbed organic species on Amberlyst®46 catalyst. The reaction rates of canola oil is three times greater than for tobacco seed oil but half the reaction rate of pure oleic acid as measured in a batch reactor. The beneficial effects of ultrasound vs. the conventional approach are more pronounced at lower temperatures (20°C and 40°C vs. 63°C): at 20°C, the free fatty acids conversion reaches 68% vs. 23% with conventional mechanical stirring. The increased conversion is attributed to acoustic cavitation that increases mass transfer in the vicinity of the active sites. The Eley-Rideal kinetic model in which the concentration of the reacting species is expressed taking into account the mass transfer between the phases is in excellent agreement with the experimental data. Ultrasound increases the mass transfer coefficient in the tobacco oil 6 and 4.1 fold at 20°C and 40°C, respectively.

Photocatalytic coatings for building industry: study of 1 year of activity in the NOx degradation

Nitrogen oxides (NOx) play a key role in the atmospheric reactions that create ground-level ozone and acid rain. The exploitation of building coatings acting as catalysts for NOx degradation under the effect of solar radiation represents a feasible way of wide applicability to lower NOx concentration in air. A crucial issue for the practical application of photocatalytic coatings is the actual lifetime of the active material. To investigate this aspect, two paints and two plasters (silicate and siloxane resins based) commercially available were formulated with 2% TiO2 Aeroxide P25 and tested in the photocatalytic removal of NOx in air. The results collected over 1 year show how the photoactivity lifetime of these products always decreases with their curing age, being strictly correlated to the formulation of the materials.

Ultrasound assisted synthesis of Ag-decorated TiO2 active in visible light

Titanium dioxide is the most popular photocatalyst to degrade organic pollutants in air, as well as in water. The principal drawback preventing its commercial application lies in its limited absorption of the visible light (400-700nm), while it is active under UV irradiation (≤387nm). Supporting noble metals in the form of nanoparticles on TiO2 increases its activity in the visible range. However, both the synthesis of noble metal nanoparticles and their deposition on TiO2 are multi-step processes that often require organic solvents. Here, we deposit Ag nanoparticles from AgNO3 on the surface of micrometric TiO2 with H2O as a solvent and under ultrasound irradiation at 30Wcm-2. Ultrasound increases the surface amount of Ag on TiO2 with heterogeneous size distribution of Ag nanoparticles, which are bigger and overlaid (1-20nm vs. 0.5-3nm) compared to the sample obtained in traditional conditions (TEM images). While this change in morphology had no effect on acetone photodegradation under UV light, the 5%, 10%, and 20% Ag-TiO2 degraded 17%, 20% and 24% acetone under visible light, respectively. The 10% by weight Ag-TiO2 sample obtained in absence of ultrasound only degraded 14% acetone in 6h, while the bare TiO2 was not active.

Non Edible Oils: Raw Materials for Sustainable Biodiesel

In EU directive 2003/30/EC biodiesel is defined as “methyl ester produced from vegetable or animal oil, of diesel quality, to be used as biofuel”. The more recent EU directive 2009/28/EC has set the targets of achieving, by 2020, a 20% share of energy from renewable energy sources in the EU’s overall energy consumption and a 10% share of energy from renewable sources in each member State’s transport energy consumption. In this context special consideration is paid to the role played by the development of a sustainable and responsible biofuels production, with no impact on food chain. Nowadays most biodiesel is produced through triglycerides transesterification of edible oils with methanol, in the presence of an alkaline catalyst (Lotero et al., 2005). The so obtained product has low viscosity and is a biofuel (fatty methyl ester) that can replace petroleum-based diesel fuel with no need of engine modifications (Suwannakarn et al., 2005). Furthermore, if compared to fossil fuel, the formed ester fuels are non-toxic, safe to handle, and biodegradable (Krawczyk, 1996). Glycerine is also obtained as by-product as shown in Fig. 1.

Intellectual contributions meriting authorship: Survey results from the top cited authors across all science categories

Authorship is the currency of an academic career for which the number of papers researchers publish demonstrates creativity, productivity, and impact. To discourage coercive authorship practices and inflated publication records, journals require authors to affirm and detail their intellectual contributions but this strategy has been unsuccessful as authorship lists continue to grow. Here, we surveyed close to 6000 of the top cited authors in all science categories with a list of 25 research activities that we adapted from the National Institutes of Health (NIH) authorship guidelines. Responses varied widely from individuals in the same discipline, same level of experience, and the same geographic region. Most researchers agreed with the NIH criteria and grant authorship to individuals that draft the manuscript, analyze and interpret data, and propose ideas. However, thousands of the researchers also value supervision and contributing comments to the manuscript whereas the NIH recommends discounting these activities when attributing authorship. People value the minutiae of research beyond writing and data reduction: researchers in the humanities value it less than those in pure and applied sciences; individuals from Far East Asia and Middle East and Northern Africa value these activities more than anglophones and northern Europeans. While developing national and international collaborations, researchers must recognize differences in peoples values while assigning authorship.

Water treatment: Mn-TiO 2 synthesized by ultrasound with increased aromatics adsorption

Pharma-products are mostly single or multiple cyclic compounds. They pollute surface water and are persistent in the aquatic ecosystem. When irradiated by UV light, TiO2 catalysts cleave or degrade organic contaminants in water. Removal of organics by photocatalysis results from a synergistic effect of adsorption and photocatalysis. Synthesis of catalysts by ultrasound (US) produces high surface area and porous solids. Here, we synthesized Mn-doped TiO2 with a US-assisted sol-gel method. Compared to the classical synthesis, US increased the BET surface area from 83 m2 g-1 to 90 m2 g-1 in the Mn-TiO2 sample and from 9.0 m2 g-1 to 53 m2 g-1 in the control TiO2. Accordingly, acetaminophen and amoxicillin adsorption increased from 44% to 52%, and from 34% to 94% for the Mn-TiO2 obtained in absence and presence of US, respectively. When in a mixture, the two drugs strongly compete for adsorption on TiO2.

Batch and Continuous Ultrasonic Reactors for the Production of Methyl Esters from Vegetable Oils

Mass transfer is a rate limiting step in biodiesel production. Ultrasound can accelerate tremendously the mass transfer in both triglycerides transesterification and free fatty acid esterification by finely emulsifying reagents that are poorly miscible. We describe reactor configurations for both transesterification and esterification, with emphasis on the work published by the authors. Ultrasound in the esterification increases the mass transfer in raw oils at temperatures below 40 °C. The Eley–Rideal kinetic model of the esterification including the mass transfer resistance between the phases is in excellent agreement with the experimental data. The Rosett cell reactor combines acoustic cavitation and turbulence and transesterifies 90 % of the feedstock in 5 min, whereas it takes 90 min in a conventional batch reactor. Continuous and semi-continuous tubular reactors irradiated at a power density of 40 kW/cm3 converts 90 % of the oil in 10 min. A Sonitube® (Synetude) converts 90 % of the oil after a single passage in a continuous reactor. This corresponds to 18 s and a rate 300 times faster than the conventional process. Sonitube ® improves mass transfer substantially and is worthy of scaling up.

Transesterification of triglycerides in a new ultrasonic-assisted mixing device

We adapted a media mill to house an ultrasonic horn to transesterify triglycerides to biodiesel. This configuration combines enhanced mass transfer from the acoustic cavitation of the ultrasonic probe with nonconventional mixing from the media mill. It ensures oil and methanol circulates in the vicinity of the ultrasonic tip. We tested methanol, ethanol and isopropanol as alcohols and KOH as a catalyst to transesterify canola oil. The branched isopropanol lowers the biodiesel cloud point by 10 °C compared to biodiesel produced with methanol (fatty acid methyl ester). We withdrew samples at regular intervals and analysed them in a GC according to EN14103-2011. The ultrasonic-assisted mixing device that we designed converts most of the triglycerides with methanol within one minute of pulsed ultrasonic irradiation. The reaction with ethanol and isopropanol is faster than in classical batch reactors.

Soybean Oil De-Acidification as a First Step Towards Biodiesel Production

According to the predictive studies of the World Energy Outlook 2009, the global demand of energy is expected to increase till 2030 of about 1.5 percentage points per year. Fossil fuels are expected to remain the main energy source in the world, but in the meantime renewable energy sources (wind, solar, geothermal, bioenergy) will be characterized by a rapid growing rate. Their use and development is strongly encouraged by most of the recent regulations. For instance, as reported by the European Environment Agency Transport (EEA), 2009, the European Union required in the same year to achieve by 2020 at least 10% of mixture of hydrocarbons from renewable and conventional sources for what concerns the energy employed for the transports. In addition, the increase in oil price and the growing interest in environmental issues have recently given a considerable impetus to the research for cleaner and renewable energy sources, in order to ensure a sustainable future. Biodiesel (BD) is a renewable energy source in liquid form that has many advantages over normal diesel, including lower emissions of gases harmful to humans and environment. The UE directive 2003/30/EC, defines the Biodiesel as “a methyl ester produced from vegetable or animal oil, of diesel quality, to be used as biofuel”. Moreover, the National Biodiesel Board (NBB), 1996, responsable for biodiesel ASTM standards, define biodiesel as “the mono alkyl esters of long chain fatty acids derived from renewable lipid feedstock’s, such as vegetable oils or animal fats, for use in compression ignition (diesel) engines.” The processes for BD production are well known. According to the NBB, 2007, there are three main routes to BD production from oils and fats: Basecatalyzed transesterification; Direct acidcatalyzed transesterification; Conversion of the oil into fatty acids and then into biodiesel. At the present BD is mainly produced through the base-catalyzed transesterification for many different reasons: Mild reaction conditions, i.e. low temperature and pressure may be adopted; High conversions (up to 98.5%) are usually achieved in short times with minimization of side reactions; The conversion into BD is direct and no intermediate steps are required;