The Pr.O.F. project: orienting late High School students to University methodology in Chemistry and other Sciences

The P.r.O.F. project has been presented at the ECTN meeting and positively evaluated. The project aims to help high school students in the transition to University. It covers the areas of Chemistry, Physics, Biology and Mathematics. In the Chemistry section, methodological issues were emphasized. The specific subject, selected jointly by University and School teachers, was Solutions and Solubility. Short and long-time tests were performed to check the effectiveness of the intervention

Sustainable Synthesis of Epoxidized Cynara C. Seed Oil

The use of non-edible vegetable oils to produce oleochemicals has been attracting more attention in recent years. Cardoon seed oil, derived from the Cynara C. plant, growing in marginal and contaminated lands, represents a non-edible alternative to soybean oil to obtain plasticizers through epoxidation reaction. The use of hydrogen peroxide as oxidant and in the presence of a heterogeneous catalyst allows overcoming the limits of epoxidation with peracids. γ-alumina has been shown to have an active catalyst epoxidation reaction with hydrogen peroxide, mainly using acetonitrile as solvent. However, the use of acetonitrile as solvent is widely debated due to its hazardous character and health issues. For these reasons, the influence of solvent on the reaction was studied in this work to find a more environmentally friendly and stable solvent. The study showed that the epoxidation reaction takes place also in the absence of solvent although with lower selectivity. The type of solvent influences both the epoxidation and decomposition reactions of hydrogen peroxide. γ-valerolactone was found to be the most promising solvent for cardoon oil epoxidation reaction. This finding represents a noteworthy novelty in the field of epoxidation of vegetable oils with hydrogen peroxide, opening the way to greener and cleaner process. Finally, an optimization study showed that the most effective molar ratio between hydrogen peroxide and double bonds for better selectivity was 4.5 and the need to use the highest possible initial concentration of hydrogen peroxide (approximately 60 wt. %)

chemical reaction engineering as a bridge between nano and macro world

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Kinetic Modeling of Solketal Synthesis from Glycerol and Acetone Catalyzed by an Iron(III) Complex

In the last few years, the depletion of the fossil sources and their negative effect on the environment has led to find new alternatives; among these, biodiesel is considered one of the most promising for this purpose. Biodiesel can be produced from the transesterification of vegetable oils or animal fats, obtaining glycerol as a by-product. Glycerol can be used in different processes and one of the most interesting is the condensation with acetone to produce solketal. Among its applications, plasticizers, solvents, and pharmaceutical formulations are the most common. In this work, the attention was focused on the reaction between glycerol and acetone to give solketal promoted by an iron(III) complex. The reaction mechanism was hypothesized, and the kinetics was studied in a batch reactor. Finally, the thermodynamic and kinetic parameters were determined with a reliable model investigating the phenomena that occurred in the reaction network. Keywords

A general kinetic and mass transfer model to simulate the baker's yeast growth in bioreactors

In this paper a general cybernetic model has been developed to describe the growth of baker's yeast in every type of reactor (batch, fed-batch, continuous). The model, which takes into account also the mass-transfer oxygen limitation, has been tested on literature continuous runs performed at different aerating gas composition. The results obtained show that the model can describe the growth of S. cerevisiae also under conditions of inefficient aeration, so it should be useful to optimise and modeling industrial bioreactors

In vivo and Post-synthesis Strategies to Enhance the Properties of PHB-Based Materials: A Review

The transition toward “green” alternatives to petroleum-based plastics is driven by the need for “drop-in” replacement materials able to combine characteristics of existing plastics with biodegradability and renewability features. Promising alternatives are the polyhydroxyalkanoates (PHAs), microbial biodegradable polyesters produced by a wide range of microorganisms as carbon, energy, and redox storage material, displaying properties very close to fossil-fuel-derived polyolefins. Among PHAs, polyhydroxybutyrate (PHB) is by far the most well-studied polymer. PHB is a thermoplastic polyester, with very narrow processability window, due to very low resistance to thermal degradation. Since the melting temperature of PHB is around 170–180°C, the processing temperature should be at least 180–190°C. The thermal degradation of PHB at these temperatures proceeds very quickly, causing a rapid decrease in its molecular weight. Moreover, due to its high crystallinity, PHB is stiff and brittle resulting in very poor mechanical properties with low extension at break, which limits its range of application. A further limit to the effective exploitation of these polymers is related to their production costs, which is mostly affected by the costs of the starting feedstocks. Since the first identification of PHB, researchers have faced these issues, and several strategies to improve the processability and reduce brittleness of this polymer have been developed. These approaches range from the in vivo synthesis of PHA copolymers, to the enhancement of post-synthesis PHB-based material performances, thus the addition of additives and plasticizers, acting on the crystallization process as well as on polymer glass transition temperature. In addition, reactive polymer blending with other bio-based polymers represents a versatile approach to modulate polymer properties while preserving its biodegradability. This review examines the state of the art of PHA processing, shedding light on the green and cost-effective tailored strategies aimed at modulating and optimizing polymer performances. Pioneering examples in this field will be examined, and prospects and challenges for their exploitation will be presented. Furthermore, since the establishment of a PHA-based industry passes through the designing of cost-competitive production processes, this review will inspect reported examples assessing this economic aspect, examining the most recent progresses toward process sustainability

Understanding Marine Biodegradation of Bio-Based Oligoesters and Plasticizers

The study reports the enzymatic synthesis of bio-based oligoesters and chemo-enzymatic processes for obtaining epoxidized bioplasticizers and biolubricants starting from cardoon seed oil. All of the molecules had MW below 1000 g mol-1 and were analyzed in terms of marine biodegradation. The data shed light on the effects of the chemical structure, chemical bond lability, thermal behavior, and water solubility on biodegradation. Moreover, the analysis of the biodegradation of the building blocks that constituted the different bio-based products allowed us to distinguish between different chemical and physicochemical factors. These hints are of major importance for the rational eco-design of new benign bio-based products. Overall, the high lability of ester bonds was confirmed, along with the negligible effect of the presence of epoxy rings on triglyceride structures. The biodegradation data clearly indicated that the monomers/building blocks undergo a much slower process of abiotic or biotic transformations, potentially leading to accumulation. Therefore, the simple analysis of the erosion, hydrolysis, or visual/chemical disappearance of the chemical products or plastic is not sufficient, but ecotoxicity studies on the effects of such small molecules are of major importance. The use of natural feedstocks, such as vegetable seed oils and their derivatives, allows the minimization of these risks, because microorganisms have evolved enzymes and metabolic pathways for processing such natural molecules

An Environmentally Friendly Nb–P–Si Solid Catalyst for Acid-Demanding Reactions

Here, we report the structural characteristics, the surface properties, and the catalytic performances of a Nb–P–Si ternary oxide material (2.5Nb2O5·2.5P2O5·95SiO2, 2.5NbP) in two reactions of importance for biomass valorisation and green industrial production: hydrolysis of inulin and esterification of oleic acid with polyalcohol for biolubricant production. High dispersion of the Nb centers, ascertained by UV–vis–DRS, 29Si, 31P, and 1H solid-state NMR spectroscopy, is the key point for the successful activity of 2.5NbP. Intrinsic and effective acidities of the sample were studied by FT-IR of adsorbed pyridine in the absence and presence of water and by volumetric titrations of the acid sites in cyclohexane and in water, to enlighten the nature and amount of acid sites in different environments. For both studied reactions, 2.5NbP catalyst exhibits water-tolerant acidic sites, mainly Brønsted ones, giving higher activity and better stability in the reaction medium than well-known niobium oxophosphate catalyst, which is considered one of the best water-tolerant acid catalysts

Poly (Lactic Acid)/Thermoplastic Starch Films: Effect of Cardoon Seed Epoxidized Oil on Their Chemicophysical, Mechanical, and Barrier Properties

In this work, biodegradable films based on poly (lactic acid) (PLA) and corn thermoplastic starch (TPS), additivated with epoxidized cardoon oil plasticizer (ECO) at 3% by weight with respect to PLA mass fraction, were prepared by melt extrusion process and compression molding. The effect of ECO on structural, thermal, mechanical, barrier, and spectral optical properties of the films was investigated. Spectroscopic analysis evidenced the development of physical interaction between oil and polymers, mainly PLA. In addition, no oil migration occurrence was detected after six months of film preparation, as evidenced by oil mass evaluation by precipitation as well as by 1H-NMR methods, thus highlighting the good inclusion of oil inside the polymeric network. The plasticizing action of the oil induced a lean improvement of the interfacial adhesion between hydrophobic PLA and hydrophilic TPS, particularly accentuated in PLA80_ECO composition, as evidenced by morphological analysis of blend fracture surfaces. TGA data underlined that, differently from TPS-based films, PLA-based systems followed one degradative thermal profile suggesting a slight compatibilization effect of epoxidized oil in these films. The shifting of Tg values, by differential scanning calorimetry (DSC) analysis, indicated a weak miscibility at molecular level. Generally, in the investigated blends, the phase separation between PLA and TPS polymers was responsible for the mechanical properties failing; in particular, the tensile strength evidenced a negative deviation from the rule of mixtures, particularly marked in TPS-based blends, where no physical entanglements occurred between the polymers since their immiscibility even in presence of ECO. The epoxidized oil strongly improved the barrier properties (water vapor permeability (WVP) and oxygen permeability (O2P)) of all the films, likely developing a physical barrier to water and oxygen diffusion and solubilization. With respect to neat PLA, PL80 and PL80_ECO films evidenced the improvement of surface wettability, due to the presence of polar groups both in TPS (hydroxyl residues) and in epoxidized oil (oxirane rings). Finally, following to the conditioning in climatic chamber at T = 25 °C and RH = 50%, PLA80 film became opaque due to TPS water absorption, causing a light transmittance decreasing, as evidenced by spectral optical analysis