http://elea.unisa.it/xmlui/handle/10556/47 2026-04-14T13:09:16Z 2026-04-14T13:09:16Z Montone, Angela Michela Immacolata http://elea.unisa.it/xmlui/handle/10556/7280 2025-04-30T17:36:47Z 2023-05-08T00:00:00Z

Development of edible coating functionalized with hydroxyapatite, complexed with bioactive compounds for the shelf-life extension of food products Montone, Angela Michela Immacolata The main goal of food packaging is to protect the food from physical, chemical and biological contaminations. The environmental impact of conventional food packaging directed research towards new packaging strategies based on environmentally friendly and biodegradablenatural polymers. The nature of biopolymers influences the physicochemical and mechanical properties of films and coatingssuch as mechanical stability, transparency, moisture and gas barrier. Generally, polysaccharides are employed to avoid gas permeability, lipids limit water vapour transmission, and proteins improve the mechanical stability of the structure. Anovel way to preserve the safety of food products and prolong their shelf life is represented by the incorporationinto edible coatingsof active compounds, such as nutrients, antioxidants, antimicrobials, colorants, and flavorings, which are mainly used to improve the functional properties of coatings. However, the poor stability of these bioactive compoundsunder processing conditions and during storage makes it necessary to use a carrier system for the release of the compound from the coating to the product surface. Among severalcarriersystems adopted to protect active compounds, hydroxyapatite crystals seem to be attractive candidates for this application. Hydroxyapatiteis a calcium phosphate similar to that present in the human hard tissues as regard morphology and composition. It is used especially for the fabrication of inorganic scaffolds for bone replacement and tissue engineering.Thanks to its structure and composition, this mineral is able to chemically interact with different organic molecules such as proteins and antimicrobial peptides, representing a potential carrier for the delivery of bioactive compounds in the development of active systems. On the basis of the above considerations, my research project has been focused on the development and optimization of an alginate-based edible coating enriched with hydroxyapatite crystals complexed with active compounds, for the shelf life extension of food products. Among active compounds, the flavonoid quercetinhas been already used in different active systems mainly for its antioxidant capacity; However, my interest was also focused on its potential antimicrobial activity.The results on antimicrobial activity of quercetin glycoside compounds against Pseudomonas fluorescens, one of the most abundant Gram negative bacteria responsible for meat and meat products spoilageon obtained, showed a total bacterial reduction at 1000 mg/L and 500 mg/L of quercetin,Similar results were obtained when quercetin was loaded into hydroxyapatite structure, at the same quercetin amount. [...] [edited by Author] 2021 - 2022

2023-05-08T00:00:00Z Meloni, Eugenio http://elea.unisa.it/xmlui/handle/10556/7278 2025-04-30T17:37:02Z 2023-02-27T00:00:00Z

Innovative structured catalysts susceptible to microwaves for the intensification of chemical processes Meloni, Eugenio Since the late 1980s, the scientific community has been attracted to microwave (MW) energy as an alternative method of heating, due to its peculiarity to be a volumetric process in which heat is generated within the material itself, and, consequently, it can be very rapid and selective. Application of the MW heating technique to a chemical process can lead to both a reduction in processing time as well as an increase in the production rate due to chemical reactions enhancing, so resulting in energy saving. The synthesis and sintering of materials by means of MW radiation has been used for more than 20 years, while future challenges will be, among others, the intensification of existing chemical processes aiming at achieving lower greenhouse gas (e.g., CO2) emissions. A natural choice in such efforts would be the combination of catalysis and MW radiation, but the selection of the proper material is fundamental for having a successful MW-assisted heterogeneous catalytic reaction/process. In this Ph.D. thesis the feasibility to intensify chemical processes by using MWs has been investigated. As a reference case for the endothermic reactions, the methane steam reforming (MSR) process has been studied. The main critical issue of the methane reforming reactions is represented by the enormous thermal duty required for the feed heating and for the reaction endothermicity, so involving a very high temperature heating medium (T > 1100°C) as well as special steels for the heat transfer to the catalyst. Nevertheless, the heat transfer process is the rate limiting step, corresponding to very large reactor volume and very slow transient behavior. In addition, the thermal constrains of this system limit the maximum temperature achievable in the catalytic bed, and consequently the hydrocarbons conversion is usually lower than 85%. This complexity results in high fixed and operative costs, and, in turn, in a reduction of the overall process efficiency. In order to overcome the previously discussed critical issues of the reforming reactor, the application of a structured catalyst susceptible to microwaves aims to realize the direct heating of the catalyst due to microwave radiation. In this way, it could be possible to remove the rate limiting step of the heat transfer and the related negative drawbacks. The possibility to fast and directly provide the heat inside the catalytic volume allows to realize a simpler reactor design, a dramatic reduction of the reaction volume, shorter start-up times and the use of cheaper materials. In particular, by selecting the catalyst’s carrier with the right chemical-physical XII properties, in terms of MW-loss factor and thermal conductivity, a very uniform temperature profile could be achieved, resulting in a more effective and selective exploiting of catalyst surface, minimizing the catalyst mass, making the system more attractive in terms of cost and compactness. In this Ph.D. thesis the material constituting the carrier selected for the preparation of the structured catalysts has been silicon carbide (SiC), due to its well- known dielectric properties. Two reactor configurations ((i) a simple cylindrical reator, and (ii) an optimized configuration with a restriction of the middle section (where the structured catalyst could be placed) with respect to the inlet and outlet sections, in order to intensify the microwaves electric field in that zone) for performing the MW-assisted reactions have been designed and set up, as well as a dedicated lab plant has been implemented. The first experimental tests have been devoted to verifying the effective heating of the bare SiC monoliths when exposed to MWs. The results of the tests, performed at various flow rates by feeding N2 at the fixed power supplied by the microwave generator of 600W and 400 W in the classical and optimized reactor, respectively, evidenced the beneficial effect of the new reactor configuration. In fact, the same monolith can be heated up to the reaction temperature (about 800 °C) with a lower MW power in all the investigated flow rate values. The optimized reactor configuration was also modelled by using the COMSOL Multyphics software (release 5.6) in order to predict the distribution of the electric field and the temperatures inside the monoliths when the microwave’s heating system is on. The developed model was validate by means of properly designed experimental tests. The comparison among the modelled and experimental data evidenced the very good agreement among the former and the latter, mainly in terms of temperature distribution inside the SiC monolith. Regarding the catalytic activity tests, starting from previous studies, in which SiC was used as catalyst carrier both in endothermic reactions for its high thermal conductivity and in MW-assisted soot oxidation for its good dielectric properties, the structured catalysts were prepared by depositing a CeO2-Al2O3 washcoat and Ni as active species on commercial SiC monoliths. In particular, two different Ni-based catalysts, differing from each other by the Ni loading (7 and 15 wt% with respect to the washcoat) were prepared, characterized and tested in the MW-assisted methane steam reforming reaction by using the two reactor configurations. The catalytic activity tests were performed by supplying a feeding stream with a Steam/Carbon ratio of 3 and Nitrogen/Carbon ratio of 3, at gas hourly space XIII velocities (GHSV) of 3300 and 5000 h-1 (calculated as the ratio between the volumetric flow rate and the overall volume, included the monolith). The results highlighted how the optimized reactor configuration positively influenced the system performance: higher both CH4 conversion and H2 yield may be obtained. In fact, with the new reactor configuration, the catalyst with the lower Ni loading approaches the CH4 conversion thermodynamic equilibrium at about 750°C, showing, in whatever case, a CH4 conversion higher than 80% for temperature higher than 700°C. The same catalyst has shown a significantly lower both CH4 conversion and H2 yield in the tests performed in the old reactor configuration. In particular, this catalyst was not able to approach the thermodynamic equilibrium values in all the investigated temperature range. Moreover, the energy efficiency of the MW-assisted MSR performed in the new reactor was of about 73% with an energy consumption of 2.5 kWh/Nm3 of produced H2. The same data obtained by using the old reactor configuration were 50% and 3.8 kWh/Nm3 of produced H2. In particular, it is very important to note that, besides the intrinsic energy efficiency of the magnetron (about 50-60%), the developed MW-assisted high efficiency catalytic reactor is able to allow an energy consumption (2.5 kWh/Nm3H2) very close to the one of the best resistive MSR (2 kWh/Nm3H2). This result is noteworthy since the latter process is not affected by any intrinsic energy losses (the catalyst is directly heated through Joule effect, without any other devices for energy generation). Therefore, when driven by renewable electricity, the proposed reactor configuration promises a high potential to address the decarbonization challenge in the near-term future. [edited by Author] 2021 - 2022

2023-02-27T00:00:00Z Casa, Marcello http://elea.unisa.it/xmlui/handle/10556/7236 2025-04-30T17:32:43Z 2022-11-22T00:00:00Z

Valorization of tomato industrial by-products in Campania region for sustainable recovery of active compounds and biogenic fuels Casa, Marcello Italy is the 2nd country in the world for tomato transformation after USA, due to 5 million tons of processed fresh fruits every year [1]. The Campania Region, due to its long-standing experience, is the main and biggest production pool regarding the transformation of tomato in Europe; it is reported [2], [3] that companies, operating in this region, process almost half of the Italian tomatoes for industry, namely 2.2 Mton of fresh fruits transformed every year. The transformation of tomato leads to a huge amount of residues, namely peels, seeds and tomato pomace. These residues can represent even the 10% in weight of the processed tomato, with a high moisture content in the range 69-90 % by weight. Considering these data, it is estimated that 64 kton of tomato by-products are produced every year in Campania. However, their generation concentrates in only two months, according to the seasonality of the tomato supply chain. Tomato pomace is composed by a mixture of pulp, skin, and seeds, carrying an enormous content of high-value compounds as carotenoids in the extractive, pectin and cutin (mainly in the peels), and glycerides (mainly in the seeds). These by-products are classifiable as a lignocellulosic biomass. Unfortunately, these residues are disposed of without any income for the tomato transformation companies, that is as animal feed or in the worst case sent to landfill, thus wasting high-value compounds and contributing to earth pollution. In principle, tomato processing by-products could be exploited through thermochemical, biological and chemical conversion to obtain biogenic fuels and then electricity and heat. Anyway, it is undoubtedly convenient to extract and recover, before conversion, the high-value compounds present in the pomace. A literature study carried out revealed 3 main components of interest: i. Lycopene, which is the most abundant carotenoid in peels and is well known to be the most a powerful antioxidant with beneficial effect on cancer and cardiovascular disease [4], [5]; ii. cutin, which is the main building block of the plant cuticles and it can be used as starting material for biopolymers; iii. pectin, which is another building block of the cuticle of fruits and can be used in food processing. As a side work, a careful study on funded European projects regarding the management of tomato wastes was carried out, assessing and reporting about their scientific and technical results. Moreover, the interconnection among them was highlighted by focusing on the contribution that they gave to the European know-how, the management of these by- products and the progress they reached on waste minimization and valorization. Finally, the industrial and environmental outcomes of these projects have been reported by highlighting issues and problems that are still to be overcome Considering this background, this work focused on the valorization of tomato by-products of Campania industries for the recovery of both added-value compounds and energy by making recourse to the “biorefinery cascade approach”, namely a set of integrated unit operations that, while extracting the most valuable components from biomass first, leads to sustainable co-production of energy, fuel and high-value chemical compounds, with minimal generation of waste. As show in figure, a first outcome of this work was a brief block diagram for a multi-products biorefinery based on tomato by- products. In the first instance, a brief economic evaluation was carried out in order to demonstrate the importance that tomato residues could have in Campania economy and to estimate the added value that every year is wasted. The multi-product biorefinery scheme was divided in operating blocks, like tomato pomace separation, lycopene extraction, biodiesel production and so on. For each operating block two alternatives were selected from literature, one typical and commercially available, and the other one less studied and ‘green’. Then, each alternative was studied, modelled and optimized to check the tecno-economic feasibility. Microsoft Excel ® and when possible Aspen Plus ® was used to evaluate mass and energy balances of the different operative blocks. Economic indexes, as gross profit and return of investment, were used to assess the economic feasibility of each biorefinery section and to compare different alternatives. In general, results show that valorizing tomato by-products with cascade approach is technically feasible; moreover, the economic sustainability is always guaranteed, both for the commercial and the ‘green’ alternatives. Finally, the Life Cycle Assessment was carried out to quantitatively assess the environmental impacts of two alternative biorefinery schemes, one based on the conventional techniques and another one on the ‘green’ alternatives. Then, two different scenarios were modeled for comparing the actual situation, namely how tomato pomace is disposed of, with the two developed biorefineries. LCA results shows that both biorefineries perform better than the actual scenario in all categories except in the ozone depletion and slightly in ionizing radiation. Conventional biorefinery performs worse than the actual scenario also in cancer effects, climate change and marine eutrophication. In general, the average reduction is 15.4% for conventional biorefinery and 39.7% for alternative biorefinery. This result suggests that, from an environmental perspective, processing tomato pomace in an alternative biorefinery is better than the actual situation. Chosing a conventional strategy would be less effective, even if it is worth noticing that products output is higher in this case. [edited by Author] 2020 - 2021

2022-11-22T00:00:00Z Scarpa, Davide http://elea.unisa.it/xmlui/handle/10556/7204 2025-04-30T17:30:28Z 2022-12-06T00:00:00Z

Electrochemical syntheses Assisted by new nano-structured Catalysts Scarpa, Davide Nowadays, the necessity of a full transition towards green chemistry has become of fundamental importance. In order to guarantee such transition, an increasing reduction of fossil-based sources and, consequently, a growing shift towards recycled and renewable resources would be the most feasible and desirable idea. Among renewables, molecular hydrogen gas (H2) is one of the most promising energy carriers for the future. Although 95% of the global hydrogen is currently produced from fossil fuels, turning to the so-called sustainable “green hydrogen” is of such fundamental relevance for the development of a carbon-neutral economy. Water electrolysis enables the generation of H2 at its highest level of purity and at the lowest temperatures when compared to all the other hydrogen generation processes, starting from an easily available and abundant source such as water, and with the possibility of receiving as input energy the one from renewables, hence overcoming also the issues related with them. Platinum (Pt)-based electrocatalysts and their derivatives are by no means the most efficient catalysts towards the cathodic hydrogen evolution reaction (HER) in acid electrolyte solutions. However, their industrial-scale production and application have been significantly limited by the scarce availability and high price of Pt. In view of all this, as well as by considering that platinum is anyhow indispensable in the formulation of an efficient HER electro-catalysts, the primary objective of the following PhD research project has been to design, with the help of nanotechnology, new nano-structured catalysts for the hydrogen evolution reaction (HER) with the purpose of (i) using reduced amount of platinum and (ii) studying new combinations of small quantities of other metals with platinum, as well as by adopting more economic and, at the same time, highly efficient supports. Therefore, two new nano-electrocatalysts were synthesized, PtRh and PtRh/MoS2, with a scalable, simple, and cost-effective bottom-up wet chemistry synthesis approach. Subsequently, the samples were extensively characterized and their electrocatalytic properties for HER were evaluated, proving to be more efficient than most of the current HER catalysts reported in literature. Throughout this study, carried out during the first year of the PhD course, another important issue emerged: distilled water adopted in the electrolytic cell is obtained only after a series of expensive and complex purification steps, followed by the addition of either acid or basic electrolytes, which obviously increase the total costs of the process. Considering this, an interesting and attractive alternative is represented by the electrochemical generation of H2 directly from seawater, about which, however, a mature scientific literature background is still missing. Furthermore, in the unpurified seawater there are hundreds of different impurities which might lead to catalyst poisoning, especially with platinum-based catalysts. That is why the catalysts prepared for the “traditional” HER could not be adopted for seawater electrolysis. Therefore, throughout the second year of the following PhD project, efforts have been devoted to design two new and efficient nano-structured catalysts for HER in seawater, such as a trimetallic alloy (NiRuIr_G) and a quaternary nanostructure (RuOs_G), both supported on graphene and exhibiting high stability in the new electrolytic environment. Once again, they were synthesized through a wet-chemistry, easily reproducible and scalable synthesis approach, and after being broadly characterized, they were tested in an electrolytic cell with seawater, showing remarkable performance when compared to literature and Pt itself. Eventually, during the third year, a further step forward towards sustainability has been taken, based on the following rationale: combining water and renewable sources to produce clean and pure hydrogen in a green perspective is appealing, but it would be even more fascinating if also a detrimental greenhouse gas, such as carbon dioxide (CO2), could be employed in the same process along with the same reactant with the double purpose of reducing the carbon footprint and obtaining a valuable chemical, such as a ”greener” syngas, with a tunable CO/H2 ratio, enabling the integration of a sustainable process into production lines of different chemicals. From an accurate search and evaluation of the available scientific literature on the most efficient catalysts thus far proposed for the simultaneous HER and carbon dioxide reduction reaction to carbon monoxide (CO2RR to CO), it emerged that catalytic activity and stability can be significantly increased by turning from metal-based nano-sized catalysts to metal single atom catalysts (SACs) in the M-N-C form. However, literature on this cutting-edge topic is still limited and there are still many routes to explore such as, for instance, regulating the H2 and CO production by preparing two metals on the same carbonaceous support with dual N-M active sites. Following this idea, throughout the last period of PhD research, a novel dual-active sites single atom catalyst for the syngas electro- production has been prepared through a simple pyrolysis method, adopting nontoxic glucose as carbon precursor and very small quantities of two economic metals, i.e. zinc (Zn) and cobalt (Co). The as-prepared catalyst, named as ZnCo-NC, showed higher performance than most of the current catalysts reported in literature. [edited by Author] 2020 - 2021

2022-12-06T00:00:00Z