Andrea P. Reverberi

Systematical analysis of chemical methods in metal nanoparticles synthesis

We propose a short review paper on the mainly adopted techniques for the production of metal nanoparticles in industrial and laboratory scale. The methods are grouped according to the wellknown classification in bottom-up and top-down schemes, with a particular emphasis on the operating conditions specifically adopted. Namely, some aspects concerning the experimental setup, the choice of precursors and reactants and the relevant technical advantages/limitations of the methods are discussed and compared in light of the most recent issues in matter of metal nanoparticles synthesis.

Preparation and characterization of PbTiO3–epoxy resin compositionally graded thick films

The preparation and properties of compositionally graded PbTiO3 (PT)–epoxy resin (EPR) composite thick films are reported in this study. Various graded specimens were prepared using gravity casting method by embedding PT powders into the EPR matrix. The existence of a graded structure with two distinct phases, a good intermixing, some air pores, and different morphologies, was confirmed by scanning electron microscopy micrographs. The dielectric constants of these composites have values in the range 5–12 at the frequency of ∼104 Hz and about 3–13 at ∼5 × 108 Hz. The composites with permittivity gradient act as a natural impedance match system in the frequency range 2–4 GHz, resulting in very low reflections. Therefore, the compositionally graded PT–EPR composite thick films are suitable as adapting impedance materials for microwave applications.

Biodiesel production via transesterification: Process safety insights from kinetic modeling

Biodiesel is an alternative non-petroleum based fuel, consisting of alkyl esters obtained either by esterification of free fatty acids with low molecular weight alcohols, or by transesterification of triglycerides. The realization of a biodiesel unit can pose several safety issues and inherent safety application opportunities as the production involves the transport, use and storage of hazardous materials, either flammable or toxic. In the experimental phase, we studied, at laboratory scale, different alkali catalysts and the relevant reaction parameters, considering inherent safety opportunities. An accurate kinetic model of the transesterification process was developed and validated, allowing to provide possible minimization and simplification plant options.

A pattern recognition approach to the solution of optimal singular control problems

Abstract A considerable number of algorithms have been proposed in the literature for the optimization of control policies of nonlinear chemical systems. However, most algorithms do not seem to be flexible and robust enough for their application to be a matter of routine. Rather, each of them presents typical shortcomings that restrict applications to special classes of problems. In particular, bang-bang (or on-off) policies are difficult to optimize, due to control discontinuities. In this paper we propose a strategy based on a combination of pattern recognition theory and non-linear mathematical programming for the computation of optimal singular control problems.

Ethylene–air mixtures under flowing conditions: a model-based approach to explosion conditions

Propylene oxide, ethylene oxide (EO), methanol, and phthalic anhydride are examples of versatile, widely applied chemical intermediates, produced at elevated temperature and pressure conditions, demanding rigorous safety considerations. Well-known industrial applications in which ethylene at the vapour phase is oxidized with oxygen are the manufactures of vinyl acetate and of EO. Partial oxidation of ethylene is usually performed at elevated temperature and pressure in multitubular cooled reactors where the application of explosive limits experimentally obtained under stagnant conditions could entail a not justified economical handicap. Bearing in mind these considerations, in this paper, we developed a novel physical–mathematical model to predict the ignition and flame-propagation phenomena in the presence of gaseous explosive mixtures. The explicit formulae for the ignition condition and the transition from local reaction to the fully developed explosion were obtained by exploring a broad range of operative conditions. A fairly good agreement was found between the predictions in this study of the oxygen critical concentration corresponding to the explosion point and the results of previous experimental studies performed by different researchers.

Synthesis of Copper Nanoparticles in Ethylene Glycol by Chemical Reduction with Vanadium (+2) Salts

Copper nanoparticles have been synthesized in ethylene glycol (EG) using copper sulphate as a precursor and vanadium sulfate as an atypical reductant being active at room temperature. We have described a technique for a relatively simple preparation of such a reagent, which has been electrolytically produced without using standard procedures requiring an inert atmosphere and a mercury cathode. Several stabilizing agents have been tested and cationic capping agents have been discarded owing to the formation of complex compounds with copper ions leading to insoluble phases contaminating the metallic nanoparticles. The elemental copper nanoparticles, stabilized with polyvinylpyrrolidone (PVP) and sodium dodecyl sulphate (SDS), have been characterized for composition by energy dispersive X-ray spectroscopy (EDS), and for size by dynamic light scattering (DLS), and transmission electron microscopy (TEM), giving a size distribution in the range of 40–50 nm for both stabilizing agents. From a methodological point of view, the process described here may represent an alternative to other wet-chemical techniques for metal nanoparticle synthesis in non-aqueous media based on conventional organic or inorganic reductants.

An experimental approach for the dynamic investigation on solar assisted direct expansion heat pumps

Federico Scarpaa, Andrea P. Reverberib, Luca A. Tagliaficoa, Bruno Fabiano*,c aUniversity of Genoa, DIME/TEC Thermal Energy and Environmental Conditioning Division, Via Opera Pia 15a, Genoa, Italy bUniversity of Genoa, DCCI Department of Chemistry and Industrial Chemistry, via Dodecaneso 31, Genoa, Italy cUniversity of Genoa, DICCA Department of Civil, Chemical and Environmental Engineering, Via Opera Pia 15, Genoa, Italy bruno.fabiano@unige.it

Nano risk evaluation in laboratory environment by a customized layer of protection analysis approach

Nanotechnologies are widely used in various industrial settings and by the year 2020, it is expected that nearly 20 % of all products manufactured in the world will take a certain amount of nanotechnology. However, there is a substantial imbalance of knowledge between application of nanotechnology and its impact on health and environment, also considering that nanoparticle synthesis by chemical methods assumed a key role for economic, industrial and scale-up issues. The information currently available on nanomaterial risk assessment within the workplace are limited: systematic methods for assessing exposure are not known yet and the number of workers exposed is hardly estimated. This knowledge gap imposes to the scientific community the need to join efforts to provide a shared opinion on safety, health and welfare of workers who use, manipulate, or produce nanomaterials, adopting as well preventive and protective measures proportionated to the risk according to the precautionary principle. We develop a novel framework for Nano Risk Assessment within the laboratory context, by combining LOPA and HazId techniques, assigning credit factors to specific operative procedures and safety training, suitable to mitigate risk exposure and avoid over-conservative evaluations. Conclusions are drawn on applicative results and possible direction for further implementation of the approach, in view of sustainable, healthy and safe production at research and industrial level.

Operational parameter influence on heavy metal removal from metal plating wastewater by electrocoagulation process

Among the different treatment processes available for industrial wastewater treatment, electrocoagulation represents a challenging option due to several features, such as environmental compatibility, inherent safety, energy and cost effectiveness. The effectiveness of electrocoagulation process (ECP) using aluminium and iron electrodes for the removal of heavy metals from industrial wastewater has been investigated, with particular attention to the effects of operating parameters (pH, inter-electrode distance, hydraulic retention time and current density) on removal efficiency. In the first step of the experimental phase, a laboratory-made artificial wastewater containing heavy metals (Cu, Ni and Pb) was adopted in order to identify the optimum conditions that were subsequently applied to treat a metal plating industrial wastewater. Experimental results revealed that under the optimal experimental conditions (actual pH 6.32, current density 0.026 A cm-2), the removal efficiency of heavy metals from artificial wastewater was higher than 95 %.

Nanoscale Topographical Characterization of Orbital Implant Materials

The search for an ideal orbital implant is still ongoing in the field of ocular biomaterials. Major limitations of currently-available porous implants include the high cost along with a non-negligible risk of exposure and postoperative infection due to conjunctival abrasion. In the effort to develop better alternatives to the existing devices, two types of new glass-ceramic porous implants were fabricated by sponge replication, which is a relatively inexpensive method. Then, they were characterized by direct three-dimensional (3D) contact probe mapping in real space by means of atomic force microscopy in order to assess their surface micro- and nano-features, which were quantitatively compared to those of the most commonly-used orbital implants. These silicate glass-ceramic materials exhibit a surface roughness in the range of a few hundred nanometers (Sq within 500–700 nm) and topographical features comparable to those of clinically-used “gold-standard” alumina and polyethylene porous orbital implants. However, it was noted that both experimental and commercial non-porous implants were significantly smoother than all the porous ones. The results achieved in this work reveal that these porous glass-ceramic materials show promise for the intended application and encourage further investigation of their clinical suitability.