Federico Galli

Nano and micro-TiO2 for the photodegradation of ethanol: experimental data and kinetic modelling

With TiO2-photocatalysis being an effective alternative to other more expensive Advanced Oxidation Processes (AOPs), the possibility of using micro-sized TiO2 materials rather than the well-known nano-sized powders is an important goal in terms of both handling safety and cost saving. In this work the photodegradation of ethanol, used as a model VOC (Volatile Organic Compound) molecule, was investigated, comparing the efficiency of both commercial nano- and micro- sized TiO2 samples. In all cases the same degradation pathway was observed, namely, a consecutive first-order reaction with acetaldehyde as an intermediate product and CO2 and water as the final products. All photocatalysts were characterized by means of XRD, TEM, IR, BET and XPS analysis. A kinetic model was also developed considering the collected experimental data and a regression of both adsorption and kinetic constants was made using MATLAB software. The optimized parameters were used for simulating the experimental data using an ode15s algorithm.

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.

Preservation of carotenes in the deacidification of crude palm oil

Carotenoids in CPO can be preserved during the deacidification processes performed under mild conditions. The carotenes adsorption on the catalyst surface makes them more stable to air oxidation and to the oil acid content. Satisfactory FFA conversions were obtained and the catalyst showed good performance after 186 hours of work.

Heterogeneous Distillation of the System Water-acetic Acid- P-xylene: Study of Its Fluid Phase Equilibria, Micro-pilot Column Experimental Results and Computer Simulation

The separation of the binary mixture water-acetic acid by direct distillation is not suitable for industrial applications because of the presence of a tangent pinch on the pure water end. The problem is overcome via heterogeneous azeotropic distillation adding a third component, the entrainer, generally immiscible with water. With particular reference to terephthalic acid production process, we selected p-xylene being both a good entrainer and the principal raw material for the terephthalic acid production. The phase equilibria (vapor-liquid and vapor-liquid-liquid) of the ternary system water/acetic acid/p-xylene were analysed in order to choose a right thermodynamic model suitable for the simulation of this system. The simulations obtained by SIMSCI PRO II software adopting the Lyngby modified UNIFAC equation to calculate the activity coefficients and the Hayden-O’Connel correlation to take into account the acetic acid association gave very satisfactory results. As further check, some experimental data were produced by a continuous micro-pilot distillation column, 5 m height with 15 trays. These data, successfully simulated, showed the possibility to use p-xylene as entrainer. A new system based on two operative column for this separation is then proposed. The first column, without entrainer, is used to bring the composition of the distillate near the tangent pinch, while the second one is used to complete the separation.

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.

NOx degradation in a continuous large-scale reactor using full-size industrial photocatalytic tiles

Many reactors were proposed to investigate the efficiency of photocatalytic materials in the degradation of NOx, but the operative conditions are often very far from reality: the parameters and the reactor set-up, which are good for laboratory tests, cannot verify the real efficiency of a photocatalytic material in a real context. To solve this issue, we experimented for the first time with a new kind of gas-flow reactor able to test photocatalytic building materials of large size, optimizing the reaction conditions in order to work both under artificial conditions of irradiation (UV-A lamp) and under direct sunshine.

Robust optimization of the heteroextractive distillation column for the purification of water/acetic acid mixtures using p-xylene as entrainer

Abstract The separation of water and acetic acid mixtures is a challenging task in the terephthalic acid production process. This study addresses the techno-economical optimization of an heteroextractive distillation column that uses p -xylene as entrainer. The optimization of this column is performed by means of robust optimizers belonging to the BzzMath library, coupled with the detailed process simulation of the downstream section performed with the commercial software SimSci PRO/II. A comparison with respect to the commercial simulator optimizer and a quantification of benefits are given. Results show that the BzzMath robust optimizer reaches a lower Total Annual Cost (−3.5%) with respect to the commercial software optimization. Finally, the comparison with other entrainers proposed in literature for the advanced distillation of the water/acetic acid mixtures demonstrates the economical and operational appeal of this process configuration.

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.

Micro-TiO2 coated glass surfaces safely abate drugs in surface water

The ingredients of Pharmaceuticals and Personal Care Products (PPCPs) persist in water and conventional treatment plants are not able to remove them efficiently. Sonochemical treatment is insufficient to mineralize organics such as ibuprofen into CO2 and H2O. TiO2 degrades ibuprofen (IBP) under UV light; however, it does not reach a high grade of conversion. Here, we investigated the mineralization of ibuprofen to CO2 by TiO2 UV-C photocatalysis. We replaced nano-sized P25 (the standard catalyst) with a micro-sized commercial sample of TiO2 to preclude the use of nanoparticles which are dangerous for human health and because typical filtration systems are expensive and inefficient. We deposited micro-TiO2 on glass Raschig rings to ensure an easy recovery and reuse of the photocatalyst and we studied its performance both with a batch and a continuous reactor. Micro-TiO2 mineralized 100% of IBP in 24 h. TiO2-coated glass Raschig rings degraded 87% of IBP in 6 h of UV-C irradiation in a continuous reactor, with a mineralization of 25%. Electronspray ionization mass spectrometer (ESI-MS, positive mode) analyses identified 13 different byproducts and we hypothised a degradration pathway for IBP degradation.

Ultrasound-assisted impregnation for high temperature Fischer-Tropsch catalysts

A fraction of the petroleum extracted from oil reservoirs contains associated natural gas. Rather than building infrastructure to recover low volumes of this natural gas, the industry flares or vents it to the atmosphere, which contributes to atmospheric greenhouse gas emissions but also reduces the air quality locally because it contains gaseous sulphur and nitrogen compounds. Converting the natural gas (NG) to hydrocarbons with a small-scale two-step gas-to-liquids process, is an alternative to flaring and venting. In the first step, NG reacts with oxygen to form syngas (Catalytic Partial Oxidation) and in the second step the syngas reacts over metallic catalysts to form higher paraffins at 210 °C to 300 °C-Fischer Tropsch synthesis (FT). For the first time, we synthesize bimetallic FeCo FT catalysts with ultrasound. An ultrasonic horn agitates the solution during the entire impregnation process. The active phase dispersion of the sonicated catalysts was superior to the catalyst synthesized without ultrasound, while reducing the impregnation time by a factor of three. We tested our catalysts in a lab-scale, fixed-bed reactor at 270 °C and 300 °C, and achieved 80% conversion over 3-days on stream and a 40% yield of C2+.