A.A. 2023-24
Research activity in the Academic Year 2023-24 of PhD students is below briefly summarized.
As regards to the first year students (39th cycle) activity:
The research “Ecological and digital transition in the requalification of polluted sites: development of guidelines and vademecum for public administration” focuses on the preparation of guidelines and documents that can be adopted, in public administration and by practitioners, in the management of remediation procedures. The main issues related to requalification are identified, in addition, the ecological innovation and the use of digital technologies, for the development of more sustainable interventions, are explored. In the first year, as part of the experimental activity, the experimentation begun during the master's thesis work was continued, which allowed the exploration of a combined adsorption and bioremediation process, defining its applicability, using materials from the valorization of waste from other supply chains, with a view to the ecological transition itself: in particular, biomass enriched in Polyhydroxyalkanoates, obtained from the fermentation of FORSU, and Pine Wood BioCHar (PWB-BC) produced from the gasification of pine wood scraps. From the second year, relations with the PA will be undertaken more, for the collection of information and drafting of the above-mentioned useful documents
The first year of “Chemical-physical characterization and electrochemical study of stratified oxides rich in lithium and nickel for applications in aprotic lithium ion batteries” focused on the development and characterization of layered oxides with electrochemical applications as positive electrodes for aprotic lithium-ion batteries, as well as the analysis of separators and electrolytes for 3rd b generation batteries. Both research topics are framed in the European SIGNE project (Horizon Europe), which funds the research grant. Specifically, the characterization of electrolytes for next-generation batteries and ultra-thin cellulose fiber separators (~10 μm) provided by SIGNE project partners was carried out, along with an extensive theoretical and experimental study of oxides containing nickel, manganese, and cobalt (NMC cathode materials). In parallel, an original research aimed at the synthesis and study of a new class of compounds termed “Lithium-Nickel rich (LN-r)” was developed.
The aim of the research “ Project and optimization of a prototype system operating in continuous mode for the re-synthesis of cathode materials of lithium-ion batteries” from leachates of spent electrodes of end-of-life batteries” is to develop an apparatus synthesising in continuous cathodic materials (NMC811, made of nickel, cobalt and manganese) for lithiumion batteries using leachates of spent electrodes as raw materials. The synthesis proceeds by a precipitation reaction. The work done in the first year can be divided in three main activities: (i) Literature analysis: to study and for the drifting of a review . (ii) Preliminary synthesis of cathodic materials: the experiments were devoted to the identification of the best operative conditions. The outcomes collected were used for the dimensioning of the first prototype assembled. (iii) Study of the nucleation and growth phenomena.
In the framework of the thesis: Experimental and study activities of the catalytic conversion processes of CO2 into e-fuels, the activities conducted in the first year of the PhD program included various experimental studies and process simulations. At the ENEA Casaccia research center, a pilot plant for CH₄ synthesis (1 Nm³/h) from H₂ and CO₂ was studied, using a PFR reactor loaded with a Ni-based pellet catalyst. The dynamic behavior of the system, plant characteristics, and operational parameters were analyzed. Simultaneously, in the BASF laboratories at the Rome site, a Ru-based pellet catalyst on γ-alumina was developed, intended for use in the ENEA reactor. Production was successfully scaled up from laboratory scale (300 g) to pilot scale (3 kg). Additionally, the synthesis of an innovative Ru-based catalyst with a steel honeycomb structure was initiated. Process simulations (Aspen) enabled both steady-state and dynamic analysis of e-fuel technology on an industrial scale.
The activities carried out this year in the framework of the thesis: “Li electrochemical extraction and direct synthesis of new-generation electrode materials from end-of-life lithium-ion batteries” focused on the synthesis and characterization of anode and cathode materials from end-of-life Li-ion batteries, and the study of the electrochemical process for Li extraction from black mass. Initially, literature studies were conducted to identify optimal process conditions. The black mass was treated with Hummers’ method to obtain graphene oxide, which was then reduced for the synthesis of anode material. The Hummers’ solution, rich in metals, underwent a co-precipitation process to produce cathode materials, later tested electrochemically in a button cell. A new two-compartment cell configuration was tested for Li recovery. The initial phase was dedicated to optimizing the setup, overcoming several challenges by modifying cell characteristics. Lithium extraction trials on the optimized setup have now started.
During this first year of the thesis “Innovative applications of biochar, obtained from agro-industrial wastes”, bibliographic research and experimental activities have been carried out. Bibliographic research had the aim to learn the most important features of biochar and characterization procedures. Concerning laboratory activities, different biochars were synthetized and characterized, starting from vegetable waste biomass. Different feedstock biomass and pyrolysis temperature have been tested, in order to obtain materials with different properties. I have used licorice roots, grape peel and seeds, tomato plants and spent coffee ground as feedstock biomass, that have been pyrolyzed in a temperature range between 300 and 900 °C. All of these materials have been characterized: mass yield (%) and pH of zero charge have been measured and different techniques have been considered (e.g. FTIR, Raman and Atomic Absorption spectroscopy, SEM-EDS, ICP and IC) to find a relationship between biochar characteristics and synthesis parameters.
The research “Evaluating Multi-salt Electrolytes and “Anode-less” Supports for Lithium Metal Batteries“ focused on the development of liquid electrolytes and nanostructured metal substrates for lithium metal batteries in “Anode-less/Zero-Excess” configuration.
The electrolytes under investigation were obtained by mixing equimolar combinations of lithium salts (LiFSI(1), LiTFSI(2), LiNO3 (3) e LiBOB(4)) in organic solvents (DME(5) e DMC(6)). To evaluate the reversibility of the battery processes and the dependence on salt composition, the formulated electrolytes were tested in half-cells consisting of smooth copper| electrolyte (soaked on Cellgard) lithium, under galvanostatic conditions. Initially, a methodology was established to calculate the number of reversible cycles and the average coulombic efficiency for comparing the performance of different electrolytes. Additionally, Raman spectroscopy was used to reveal the different solvation spheres of Li+ ions in the various tested electrolytes. Finally, in collaboration with the company Standex, a preliminary study was conducted on the fabrication of nanostructured substrates using the “Laser Induced Periodic Surface Structures” technique. The morphology of the resulting structures was analyzed using electron microscopy and post-imaging techniques, assessing the influence of two fabrication parameters.
In the first year of the thesis “Extraction and characterization of bioactive compounds: a comprehensive study”, a research of related literature and experimental activities have been performed. Literature review provided extraction and characterization techniques, optimization of process parameters, and potential applications of extracted bioactive compounds. Laboratory activities for the first semester involved setting up extraction workflows, exploring diHerent biomass sources, assessing appropriate extraction methods, quantifying phytochemical content, and testing for antioxidant activities. The main raw material currently used are seaweeds, which were prepared through different drying methods (oven drying, freeze drying), extracted using diHerent solvents (methanol, deep eutectic solvents) and extraction methods (microwave-assisted, maceration), and characterized by FTIR and antioxidant assays (DPPH, ABTS, FRAP). Consequently, the extraction process will be optimized to obtain increased yields of bioactive compounds and to utilize techniques to identify these compounds (LCMS/MS, metabolomics). In the subsequent years, potential applications of these bioactive compounds will be explored.
During the first year of the PhD program of the PNRR grant entitled: “Synthesis of nanostructured electrodes for the electrochemical reduction of carbon dioxide”, literature studies were carried out to synthesize electrodes with a high surface area. Based on these studies, it was decided to utilize the bubbling electrodeposition process. Specifically, the application of a cathodic potential generates hydrogen bubbles that, while moving away from the surface during metal deposition, act as a template for foam formation. This process enabled the creation of porous structures (foam) and was applied to electrodes made of zinc and copper. A study of the electrodeposition process was conducted under galvanostatic and potentiostatic conditions. For each of these electrodeposition strategies, the effects of operating parameters (potential/current, amount of charge) on the morphology and structure of the synthesized electrodes were analyzed. To achieve this, SEM and XRD characterizations were carried out. The synthesized electrodes were utilized as cathodes in electrochemical reduction experiments of CO2 in H cells, allowing us to evaluate how catalytic activity is influenced by morphology and structure.
The activities carried out this year on the “Development of multicomponent lipid nanocarriers via microfluidics for the delivery of genetic material and drugs: characterization and optimization”, focused on the synthesis of multicomponent lipid systems for the delivery of genetic material and drugs using microfluidic techniques. Various lipid compositions were investigated based on the molar ratio between the different components. These were then analyzed using DLS to evaluate the sizes obtained. Preliminary tests were also conducted by varying the operating conditions, such as the flow ratios and the concentration of phospholipids in the organic phase, to observe how they affected the size of the nanoparticles. Additionally, initial samples were tested on cell lines to assess the effectiveness of the system in terms of transport and encapsulation of genetic material and drugs.
During the first year of the PhD thesis in "Carbon dioxide sequestration from cement plant fumes and other hard-to-abate industry sectors using reversible molten carbonate fuel cells: development of the simulation model and implementation in the process cycle," the research activities focused primarily on an in-depth analysis and critical review of the literature regarding the operation of molten carbonate cells, with particular attention to works on CO2 capture and utilization, especially in hard-to-abate industries. Additionally, the principles governing the operation of a cement plant were examined in terms of energy requirements and CO2 emission sources. The laboratory setup required for testing and characterizing the performance of molten carbonate cells in reversible mode was studied, and the first experimental campaign was initiated, with an article planned for submission by the end of 2024. Furthermore, I contributed to the development of a study on methodologies for gas composition analysis using TDLAS-NDIR equipment, applied to fuel cells and electrolyzers.
In the first-year doctoral research on “Innovative and eco-sustainable materials, for aprotic sodium ion batteries” aimed at the synthesis and study of nanostructured carbon materials for use as anodes in sodium-ion batteries”, the theorized synthesis involved the use of two pure, inexpensive, and naturally abundant organic precursors: glucose and lignin. The nanostructure was generated using an inorganic ceramic compound, β-zeolite, as a template, through a process of precursor absorption within the zeolite followed by pyrolysis. The template was subsequently removed by basic washing of the sample. Thermogravimetric results showed incomplete removal of the template. The collected diffractograms, on the other hand, show a transition of the zeolite from crystalline to amorphous. The obtained carbons have high surface areas of around 400-600 m2/g and good electrochemical performance, delivering capacities of about 180 mAh/g under galvanostatic conditions.
In the thesis “Decarbonization of the cement and iron-steel production sectors and enhancement of CO2 through green hydrogen and/or mineralization”, after completing an in-depth bibliographic study on the state of the art of carbon dioxide capture technologies via chemical absorption and process intensification technologies, the design of the laboratory plant was undertaken. During this phase, purchases of an IR analyzer and three flow meters were initiated, which are essential tools for analyzing a synthetic gas like that produced by a cement plant, composed of CO₂, N₂, and O₂ (with a CO₂ percentage of 15%). Reagents for the preparation of nanofluids (the selected process absorbent), a thermostatic bath for solvent regeneration, and the necessary glassware to define the experimental setup for benchmarking were also purchased. The benchmark will be conducted using a 25% by mass aqueous solution of potassium carbonate (K₂CO₃). Additionally, materials for 3D printers will be purchased, useful for creating a static mixer and a rotor stator-spinning disk reactor (RS-SDR), which will be used to intensify the absorption process with K₂CO₃-based nanofluids or with the aqueous solvent containing only K₂CO₃. After defining the most suitable final experimental setup for reactive CO₂ absorption tests, the experimental campaign was started, using a batch process in which CO₂ is captured using a K₂CO₃ solution. Later, the solution was enriched with titanium oxide nanoparticles to study the intensification of mass transfer due to the nanoparticles. Subsequently, the intensification of heat transfer during the absorbent regeneration phase will also be analyzed.
The research activities conducted during the first year of the thesis, titled "Microbial Electrochemical Technologies for Cheese Whey Valorization in a Circular Bio-Economy Perspective," focused on the valorization of cheese whey through dark fermentation and bio-electrochemical processes. Literature research, on cheese whey (CW) dark fermentation, was conducted to identify optimal fermentation parameters as temperature, pH, rpm, dilution, and pretreatment. Various dilutions of CW were tested: 1:2, 1:4, 1:8, and undiluted, to determine the best conditions for maximizing hydrogen (H₂) and volatile fatty acid (VFA) production. The potential enhancement of the dark fermentation process by different electro-conductive materials (ECMs) such as biochar, magnetite, and graphite was also investigated. Microcosms containing these materials were prepared and monitored for H₂, lactose, VFA, and total carbohydrate production. All three materials improved VFA and H₂ production compared to the control (CW without conductive materials). The next step will focus on treating the fermentation effluent, which is rich in VFAs, using a bio-electrochemical cell to further increase hydrogen production.
As regards to the thesis: “Analisi teorica e sperimentale di processi termochimici innovativi alimentati da impianti solari termici a concentrazione” the work focuses in the first year on four primary areas related to innovative approaches to harnessing solar energy as part of ongoing national and European projects:
1. Methane/biogas pyrolysis: a preliminary investigation aiming at determining materials for molten baths and the most promising operating conditions, as well as building an experimental setup for laboratory-scale research on the process (PTR 2022-2024 LA1.5).
2. Perovskites synthesized using various techniques for thermochemical water splitting (TWS): morphological and structural characterization. (“Piano Operativo della Ricerca sull’Idrogeno” PNRR 2022-2025-M12).
3. Development and characterization of a spinel structure mixed oxide, produced through several techniques, intended for use in thermochemical storage. (“Integrated Project on electrochemical and thermal storage” PTR 2022-2024-O1-P.1.2-WP4).
4. Producing sulfur has the potential to be a viable substitute for hydrogen since it is easily transportable and stored in a solid state. A crucial phase in the sulfur production cycle is the study of SO2 disproportionation processes into sulfur and sulfuric acid, which is a part of my research (Sulfurreal, European collaborative project).
In the framework of the thesis: “Combined chemical-physical and biological processes for the remediation of contaminated groundwater” a continuous BES process for the reduction of trichloroethylene and the removal of its degradation byproducts was studied and optimized. The system consisted of two column reactors: one for the reduction of chlorinated compounds and the other for the oxidation of byproducts such as vinyl chloride and ethylene. Fluid dynamics, chemical, and electrochemical characterisations were performed to optimize system performance. Oxidative reactor to study the oxidation processes of chlorinated compounds better was also studied.
The research activity carried out during the first year of the Ph.D. “Development of a Sustainable Biotechnological Process in an Urban Biorefinery Perspective” focused on the optimization of an anaerobic conversion process of municipal organic waste into medium-chain fatty acids (MCFAs), specifically caproic acid, by acidogenic co-fermentation and chain elongation in a single-stage reactor. The study focused on the mixture ratio of the waste used as substrates, namely food waste (FW) and waste activated sludge (WAS), and on thermal pre-treatment of the mixture. Preliminary batch tests were conducted on untreated and pre-treated mixtures, at two different FW/WAS mixing ratios: 60/40 and 70/30, on a volatile solids (VS) basis. Since the best caproate (C6) yield (190.7 mgCOD/gVSfed) was obtained with the pre-treated feed and the 60/40 mixing ratio, the semi-continuous test was conducted for 60 days with the above conditions, resulting in a C6 conversion of total and soluble organic matter of 11.5% and 36%, respectively.
The first-year activity on Innovative technology for producing clean H2 comprised of a combination of literature studies and experimental research. The study focused on systems utilising plasma technology for the production of H2 from methane, whether in its pure or mixed form. The principal emphasis was on systems utilising microwaves to ignite a plasma maintained at atmospheric or slightly reduced pressure. Additionally, catalysts may be employed in this type of system. The literature review concentrated on Ni-based catalysts due to their catalytic activity. The initial focus was on Ni catalysts with carbonaceous support. The experimental work comprised the preparation and characterisation of carbon supports and catalysts. The supports were prepared from pulverised hazelnut shells with the objective of obtaining a carbonaceous material recovered and recycled in accordance with the principles of the circular economy. The catalysts were prepared by impregnation of the substrate and subsequent calcination/reduction of suitable metal salts.
The study on “Electrochemical storage sytems” examined the thermal behavior and safety aspects of lithium-ion (Li-ion) batteries, focusing on conditions that can lead to thermal runaway. A coupled electrochemical-thermal model was developed using COMSOL Multiphysics and validated against experimental data from the literature, showing a strong correlation between the simulated and experimental results. The study focused on commercial 18650 NCM cells and conducted two sets of simulations: one for a single cell and another for a module containing 20 cells. The single-cell analysis identified key parameters that influence thermal runaway during high-current charging. For the battery pack, the study analyzed the effects of overcharged cell positioning, charging rates, and cooling fluid flow rates. ANOVA analysis was conducted using Minitab software to assess these factors. Also, a predictive model using a GRU (Gated Recurrent Unit) structure was developed to forecast the future behavior of Li-ion cells. And the results showed a good agreement between predicted and measured values. Future work aims to refine this model and further improve data-driven approaches for better prediction and management of thermal events in Li-ion batteries.
As regards to the activity of students at their second year (38th cycle):
In the framework of the thesis “Valorisation of waste biomasses via thermochemical processes: optimization of yield and quality of the biocrude obtained from Hydrothermal Liquefaction for the production of an advanced biofuel” the research focused on energy recovery and material valorization from secondary sludge derived from the treatment of municipal and industrial wastewater, processed through hydrothermal liquefaction (HTL). The first experimental campaign focused on studying the evolution of HTL product yields from secondary sludge (from papermill and municipal facilities) under varying temperatures and reaction times, which led to the participation in the IConBM2024 conference and the subsequent publication in CET. This conference marked the inclusion of my research in the NEST project. A second experimental campaign, conducted in collaboration with ENEA, focused on comparing the HTL and pyrolysis processes applied to digested municipal secondary sludge, with particular emphasis on the quality of the produced bio-oil, in terms of H/C, O/C and N/C molar ratio, and the obtained biochar. Furthermore, upgrading solutions for the bio-oils obtained from both pyrolysis and HTL were explored under hydrothermal conditions, using heterogeneous hydrogen donors (zero-valent metals) and catalysts.
Throughout the year, as regards to the thesis: Cracking del metano: studio sperimentale e cinetico, methane pyrolysis experiments were conducted to study the process of carbon formation in a quartz tubular reactor (d = 1 cm, Q=25 ml/min) at atmospheric pressure, with temperatures ranging from 900 to 1000 ÅãC. The tests were performed in two configurations: one with an empty reactor and one with the reactor filled with ceramic spheres (average diameter 5 mm). The main objective was to evaluate the effects of temperature and surface on carbon formation. The primary measurements focused on methane conversion and the nature of the carbon products formed. The composition of the gas phase at the reactor outlet was analyzed by mass spectrometry, allowing for the determination of methane conversion and the formation of gaseous intermediates (C2H6, C2H4, and C2H2). In addition to the analysis of the gas phase, the various carbon products obtained were collected and characterized. Carbon was collected both on the hot surfaces (reactor walls and ceramic spheres) and in the cooler zone at the reactor outlet, where a trap was used to capture carbon particles carried along with the gas phase. The characterization of the carbon was carried out using scanning electron microscopy (SEM) and Raman spectroscopy, providing information on the morphology and structural properties of the deposits. The results showed that temperature played a significant role in methane conversion, which reached 4% at 1000 ÅãC, and in the total carbon yield (0.22 g after 60 minutes of operation), promoting carbon formation in the gas phase. The addition of ceramic spheres had a notable effect on the composition of the measured C2 species and on the distribution of carbon products. In particular, the presence of the spheres favored carbon formation on the surfaces, indicating that the interaction between deposited carbon and nucleated carbon in the gas phase plays a key role in determining the morphology and structural order of the carbon products obtained.
During the second year of the thesis: “Calcium batteries: a “New challenge”, activties were focused on the synthesis and characterization of the salt Ca[B((CF3)4C2O2)2]2 (Ca-FPB). We optimized its synthesis and, through electrochemical characterization, demonstrated its effectiveness in calcium plating/stripping. In tests with asymmetric cells Ca| Ca-FPB 0.25M in DME | steel (SS)/ poly-anthraquinone (PAQ), Ca-FPB showed the ability to work with organic cathodes and nucleate calcium metal on inert substrates. A scientific letter has been written and is currently under internal review. However, the complex and scarcely scalable synthesis led us to explore calcium-zinc alloys as negative electrodes, testing their compatibility with commercial electrolytes like Ca(TFSI)2. Various synthetic approaches were explored, with arc-melting proving to be the most efficient method for producing Ca-Zn alloys. The synthesized alloys were characterized by XRD, SEM/EDX, and electrochemically studied through cyclic voltammetry and galvanostatic tests. Preliminary results show that alloys with lower calcium content offer greater reversibility and stability over time. In the coming months, we plan to further optimize the synthesis and deepen our understanding of the electrochemical mechanisms.
During the second year of the thesis: “Processi di risanamento chimico-fisici e biologici combinati con sistemi di manipolazione idraulica della falda”, activities were carried out in parallel on basic research at the laboratories of Prof. Petrangeli's research group while collaborating with the company IEG Technologie GmbH (co-funder of my PhD grant). The research carried out at La Sapienza has as its objective the production of a colloidal suspension of biochar (waste from energy production processes) that can be used as an alternative adsorbent for injection into polluted aquifers to stop the migration of contaminants. The activities carried out in collaboration with IEG involve the design, monitoring and optimization of remediation operations of contaminated groundwater at various sites in Italy and abroad. Also with IEG, I have been abroad in Taiwan for installation, start-up and monitoring activities for the remediation of a contaminated aquifer.
During the second year of the thesis “Polymeric cryogels and extrusion-based 3D bioprinting”, in continuity with the laboratory activity carried out in the previous year, further studies on the release of vitamin B12 from cryogels were carried out, using different loading methodologies. Following the acquired data, a mathematical model, which consider the presence of a hierarchical porous structure within the specimens, was developed. This particular porous conformation, due to the phenomenon of cryoconcentration, is responsible for the anomalous behaviour observed in the release data. In addition, since the porous structure of cryogels can be used effectively in bioseparations, a modelling/computational study on chromatographic separations based on cryogel-like structures has been initiated.
As regards to the thesis: A study of an innovative process for the valorization of cellulose from agro-food waste”, during the first year of activities, a bibliographical research focused on microencapsulation, and cellulose and protein extraction techniques was carried out, which informed the direction of the experimental work. Cellulose was successfully extracted from bamboo and various agro-food waste materials, including spent coffee grounds, banana peels, potato peels, and pomegranate peels. The extracted cellulose was characterized using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) to assess its structural and chemical properties. Microencapsulation and controlled release methodologies as potential valorization strategies for cellulose were also explored, though these techniques were not applied to the extracted cellulose during this phase. Additionally, protein extraction from seaweeds was studied. In parallel, the antioxidant activity of different honey samples was determined using DPPH, ABTS, FRAP, and Total Phenolic Content (TPC) assays to quantify their antioxidant capacities.
During the second year of the PhD project on: “Stochastic modeling of intracellular biochemical processes with applications to lipid nanoparticles' transport and reaction”, the following activities were carried out: (i) Experimental work in the laboratory of Prof. Guido Bolognesi (UCL) (January-May 2024) aimed at analyzing the motion of fluorescent nanoparticles in physically crosslinked alginate hydrogels.; (ii) Analytical and simulation-based modeling activities aimed at describing anomalous transport in complex media, integrating the hydromechanical properties of the medium.
For the doctoral project aimed at the "Development of a continuous process for the production of polyhydroxyalkanoates with mixed microbial cultures" the following activities were carried out: (i) Integration of the accumulation phase in the continuous line of the process, resulting in optimization of the process parameters for this last phase (and related patent development). (ii) Optimization of the downstream process, in particular by replacing the more conventional extraction methods with chlorinated solvents with an oxidative treatment involving the use of sodium hydroxide (NaOH) and hydrogen peroxide (H2O2). In particular, 75 g of PHBV copolymer were produced as part of the European AGRILOOP project of which this project belongs. (iii) Development of preliminary tests for the upgrading of carbon dioxide (CO2) to biopolymers, using bioelectrochemical systems. A bacterial strain (Kyrpidia Spormannii) was purchased, capable of storing polyhydroxybutyrate (PHB) starting from hydrogen (H2) and carbon dioxide (CO2). Preliminary tests were therefore carried out in bioelectrochemical systems, the main objective of which was the production of PHB starting from CO2, supplied externally and H2, produced electrochemically directly in the system.
As regards to the third year (37th cycle) student activity:
The experimental work in the third year of the PhD thesis on: “Characterization of different synthetic and natural surfactants for applications in contaminated aquifers remediation using SEAR (Surfactant Enhanced Aquifer Remediation) technology”, involved the evaluation of the ability of two anionic surfactants, belonging to the alkyl-sulfosuccinate family, to mobilize hydrophobic organic contaminants in the form of pure residual phase trapped by capillarity in the porosities of a porous system, exploiting the mechanism of microemulsion formation between the aqueous and organic phases. The study began with a preliminary characterization of surfactants to measure their critical micellar concentration (CMC). Then, using toluene and trichloroethylene (TCE) as reference organic contaminants, a study was conducted in a batch configuration to evaluate the optimal conditions in terms of solution salinity (by varying the NaCl concentration) required for the formation of microemulsions between t surfactant and organic contaminant. After determining the optimal salinity for each surfactant-contaminant system, the surfactant + NaClOPTIMAL formulations were used in a continuous experiment for the mobilization of toluene and TCE in the pure residual phase by simulating at bench scale a soil flushing process aimed at attacking secondary sources of contamination that characterize almost all sites polluted by hydrophobic organic compounds.
During the second year of the PhD project focused on the “Development of a bioelectrochemical process for the conversion of CO2 into acetate”, the possibility of using a pure culture of an extremophilic halophilic bacterial species, which requires high salinity as a growth condition (NaCl 150 g/L) was explored. This strategy aims to prevent contamination by competing bacteria, such as methanogens, which currently represent the main limitation in the development of this technology, with the only long-term solution being the use of chemical inhibitors. The halophile *Acetohalobium arabaticum* was used and tested under hydrogenophilic conditions in serum bottles, both in autotrophic mode (H2 and CO2 as the only substrates) and mixotrophic mode (H2, CO2, and an organic substrate), based on the positive results obtained from the work carried out at TU Delft during the second year. Furthermore, to demonstrate its effectiveness in suppressing methanogens, tests were conducted using anaerobic digestion sludge in the same halophilic growth medium. The pure culture was then used for the first time in bioelectrochemical conditions in a state-of-the-art laboratory-scale reactor with a cathodic potential of -0.9 V vs SHE, with continuous gas recirculation consisting of 30% CO2 and 70% N2 v/v. In parallel, a modeling work using Matlab to describe acetate production in batch mode in relation to the competition with methane production was carried out.
As regards to the third year (37th cycle) student activity:
- The experimental work in the third year of the PhD thesis on: “Characterization of different synthetic and natural surfactants for applications in contaminated aquifers remediation using SEAR (Surfactant Enhanced Aquifer Remediation) technology”, involved the evaluation of the ability of two anionic surfactants, belonging to the alkyl-sulfosuccinate family, to mobilize hydrophobic organic contaminants in the form of pure residual phase trapped by capillarity in the porosities of a porous system, exploiting the mechanism of microemulsion formation between the aqueous and organic phases. The study began with a preliminary characterization of surfactants to measure their critical micellar concentration (CMC). Then, using toluene and trichloroethylene (TCE) as reference organic contaminants, a study was conducted in a batch configuration to evaluate the optimal conditions in terms of solution salinity (by varying the NaCl concentration) required for the formation of microemulsions between t surfactant and organic contaminant. After determining the optimal salinity for each surfactant-contaminant system, the surfactant + NaClOPTIMAL formulations were used in a continuous experiment for the mobilization of toluene and TCE in the pure residual phase by simulating at bench scale a soil flushing process aimed at attacking secondary sources of contamination that characterize almost all sites polluted by hydrophobic organic compounds.
- During the second year of the PhD project focused on the “Development of a bioelectrochemical process for the conversion of CO2 into acetate”, the possibility of using a pure culture of an extremophilic halophilic bacterial species, which requires high salinity as a growth condition (NaCl 150 g/L) was explored. This strategy aims to prevent contamination by competing bacteria, such as methanogens, which currently represent the main limitation in the development of this technology, with the only long-term solution being the use of chemical inhibitors. The halophile *Acetohalobium arabaticum* was used and tested under hydrogenophilic conditions in serum bottles, both in autotrophic mode (H2 and CO2 as the only substrates) and mixotrophic mode (H2, CO2, and an organic substrate), based on the positive results obtained from the work carried out at TU Delft during the second year. Furthermore, to demonstrate its effectiveness in suppressing methanogens, tests were conducted using anaerobic digestion sludge in the same halophilic growth medium. The pure culture was then used for the first time in bioelectrochemical conditions in a state-of-the-art laboratory-scale reactor with a cathodic potential of -0.9 V vs SHE, with continuous gas recirculation consisting of 30% CO2 and 70% N2 v/v. In parallel, a modeling work using Matlab to describe acetate production in batch mode in relation to the competition with methane production was carried out.
- During the 3rd year of the PhD project “Bimetallic Nanomaterials using Spinning disc reactor for enviromental and energy applications”, the Spinning Disc Reactor for producing inorganic composite nanostructured oxides was used, particularly for environmental applications and energy applications such as organic dye degradation and green hydrogen production via solar water splitting process. The research article with title “Room temperature oxidation of gaseous formaldehyde over silver-doped manganese oxide catalyst” has been published (online) in a SCI journal.
- In the framework of the thesis: “Green hydrogen production through molten carbonate electrolysis” during the first months of the third year, experimental activities at were carried out at the Royal Institute of Technology (KTH) in Stockholm. The goal was to assess the feasibility of fuel-assisted electrolysis in MCECs by feeding methane to the electrode where oxygen is produced. This strategy prevents the formation of gaseous oxygen and reduces the operating potential of the cell. Galvanostatic tests and impedance spectra confirmed the feasibility of operating the cells in this mode, although they also highlighted the low reactivity of methane under the tested conditions. It is important to note that, as this is an innovative approach, no references on the subject were found in the literature.
Subsequently, the data collected at ENEA last year were analyzed, delving deeper into the impedance spectra using the DRT technique to clarify the hydrogen production mechanism at the anode. The gas analysis results from the planar cell (100 cm²) were also analzyed, thus quantitatively evaluating the contribution of the reverse water gas shift reaction and water electrolysis, and how these are influenced by both inlet composition and temperature.
The use of two different experimental setups, combined with the application of numerical tools such as the DRT technique, allowed for insights from multiple perspectives on MCEC behavior. These integrated approaches provided valuable insights for improving cell performance, both in terms of understanding electrochemical mechanisms and optimizing operating conditions.
- The experimental activity carried out as part of the 3rd year of the PhD thesis on “Development and characterisation of a bioelectrochemical reactor for the simultaneous treatment of oxidisable and reducible contaminants from contaminated groundwater” was mainly conducted (from January to September 2024) at the Chemical and Environmental Engineering Laboratory (LEQUIA) of the University of Girona (UdG), under the supervision of Prof. Sebastià Puig. In line with the themes and objectives of the work carried out during the first two years, an innovative approach combining the electrobioremediation of nitrate-contaminated waters with membrane ultrafiltration technology was studied during this period. The aim of this research was to develop a system in which conductive membranes act as both electrodes and filter media, enabling the simultaneous filtration of water and biodegradation of contaminants directly on the membrane surface. In principle, this configuration improves treatment efficiency by reducing membrane fouling and allowing the co-localization of contaminants and microorganisms, facilitating more effective degradation. The dual functionality of the system allows nitrate reduction via an electrical potential while filtering suspended particles and other contaminants. The results demonstrated significant efficiency in nitrate removal, highlighting the potential of this approach for advanced water remediation.
- The research activity conducted on “Decarbonization of hard-to-abate sectors: testing, simulation and CFD analysis of pre- and post-combustion CO2 reduction and sequestration methods” was focused on studying solutions to decarbonize "hard to abate" sectors. In particular, innovative process schemes have been analyzed from an energy, economic, and environmental perspective, with the aim of producing alternative steel using green methods. A model of a direct reduction furnace for the production of iron sponge has been developed. The model is based on a kinetic approach and has been validated with plant data. The model allows for the assessment of the impact of using reducing agents obtained from different sources and the integration of a CO2 capture plant into the process. In detail, the use of syngas from methane reforming, syngas and hydrogen from municipal solid waste gasification, and hydrogen from water electrolysis have been analyzed. Furthermore, in collaboration with the Max Planck Institute, an experimental study on steel production through hydrometallurgical process has been initiated.
- During the 3rd year of the PhD work on “Innovative electrochemical processes for methane upgrading”, the research activity focused on the development of a bioelectrochemical continuous-flow planar reactor, referred to as a microbial electrolysis cell (MEC) consisting of two-chamber (anode and cathode) separated by a proton-exchange membrane. The innovation of this study was the utilization of real feedstocks as anode feeding: a fermentate, the liquid effluent of acidogenic fermentator and then, a digestate, the liquid effluent of anaerobic digestion. Digestate was provided by a company, InnovEn srl (involved in the project activity). The aims of the study were the investigation of anode biofilm performance oxidizing COD (Chemical Oxygen Demand) contained in the organic matrices and the generation of electric current. The amount of removed COD converted into current represent the coulombic efficiency (%CE). The generated current with a small surplus of external energy, provided the reducing cathode power to reduce H+ to H2. When the cathode is inoculated with methanogens and flushed with CO2, CH4 formation occurs according to the following reaction: 4H2 + CO2 CH4 + 2H2O. Cathode performances were evaluated in terms of bio- H2, bio-CH4 production rate and cathode capture efficiency (%CCE) that represent the amount of current converted into reduced products of interest (i.e. bio- H2, bio-CH4).
- With reference to the project “Conversion of plastic waste into biopolymers”, the properties of materials consisting of a biodegradable polymer (PHBV) and mixed plastic waste (Plasmix) developed the previous year in collaboration with the Instituto de Agroquímica y Tecnología de Alimentos (IATA) were investigated. In particular, the biodegradability of these materials in film form was studied by testing them for their ability to biodegrade in anaerobic environments. Specifically, two conditions were evaluated: one for the production of methane and the other for the production of organic acids (such as acetic and propionic acid), ideal substrates for the production of bio-based and biodegradable biopolymers (PHAs). The results showed excellent biodegradability of the materials, with a conversion to methane higher than that of pure PHBV, which reached 100% for all samples, and no inhibiting effects on the used mixed microbial culture were observed. Additionally, in collaboration with the company NextChem s.p.a. (involved in the project), the economic aspect was analyzed, proposing a process to treat Plasmix through physicochemical pre-treatment, with the aim of transforming it into a resource for the production of new biopolymers. Preliminary calculations were made on capital (CAPEX) and operating (OPEX) costs for an industrial scale plant.
- In the third year of the project “Sustainable green process to extract bioactive compounds from food byproducts and whole cells with natural atoxic solvents”, using previously screened and tested methodologies, the work focused on optimizing the extraction of high-value biomolecules from selected microalgal biomasses: Arthrospira platensis and Haematococcus pluvialis. The approach leveraged Switchable Hydrophilicity Solvents (SHS) for efficient extraction and separation of the target fractions. Key process parameters—such as energy density during ultrasound pretreatment, biomass concentration, and extraction time—were optimized to maximize the yield and recovery of each desired fraction.
- In the context of the work on “Immobilization of industrial lipases on graphene oxide nanosheets for biodiesel production”, the work focused on the development and optimization of an innovative system for the immobilization of Candida rugosa lipase (CRL) on aminated graphene oxide (GO-NH₂), aimed at improving the stability and catalytic efficiency of the enzyme for biodiesel production applications. The functionalization of GO with amino groups was carried out through a controlled amination process, promoting the formation of covalent bonds between the support and the carboxylic groups of the enzyme, ensuring stable anchoring. The immobilization significantly improved the performance of the lipase compared to its free form, increasing the enzyme's thermal and chemical stability. The analyses conducted (TGA, FTIR) confirmed the formation of covalent bonds and enhanced resistance to high temperatures and pH variations. Additionally, the immobilized lipase demonstrated good tolerance to alcohols such as methanol, a crucial aspect for biodiesel synthesis. The results highlight the potential of the CRL@GO-NH₂ complex for industrial applications, offering a reusable and stable biocatalyst with high catalytic efficiency even under challenging operating conditions.
- The research activity conducted during the third year of the Ph.D. program on “Simulation, CFD modelling and advanced control of innovative waste-to-chemicals plants in the circular economy: Gasification of Refuse Derived Fuel” focused on advanced modeling of thermochemical processes for waste and biomass treatment, with particular emphasis on gasification. The three-dimensional CFD model for the homogeneous section of the gasifier was completed, integrating homogeneous and heterogeneous reactions to analyze system behavior, validating reactive simulations, and identifying critical parameters. Additionally, the study of the thermal properties of ashes highlighted their role in the operational conditions of the gasifier and their potential recovery as a resource. Variations in melting temperature were analyzed as a function of composition, providing insights to prevent slagging and optimize system operation. Finally, a simulation model was developed for the treatment of landfill waste and leachate, assessing energy efficiency, sustainability, and the reactor's flexibility in handling varying feedstock characteristics. These studies represent a significant contribution to enhancing waste-to-chemicals technologies within the framework of a circular economy.
- In the context of the thesis on: “Development of in situ treatment processes for the sustainable remediation of groundwater contaminated by PFAS”, during the first months of the third PhD year, adsorption tests were carried out using a continuous flow-through configuration for various PFAS compounds (both short-chain and long-chain), using different types of pine wood biochar, differing by sieving and pyrolysis temperature (850° <200, >200; 1000°). Moreover, the adsorbent-adsorbate behavior was studied by batch tests with date seed biochar functionalized with CTAB, evidencing unsatisfactory preliminary data. Thus, the same functionalization protocol was applied to pinewood biochar (850°), showing better performance compared to non-functionalized biochar and date seed biochar. As a result, the functionalized biochar was also studied by continuous flow tests. The research continued with adsorption tests on PFAS using functionalized pinewood biochar, revealing results similar to those obtained with activated carbon. Finally, the most efficient biochars (850° functionalized, 1000°), with performance comparable to activated carbon, were also applied to mixtures of long-chain (PFOA, PFOS) and medium-short chain (PFBA, PFBS, PFHxA, PFHxS) PFAS solutions using the same experimental setup.
- In the framework of the thesis: “Eco-sustainable processes for the production of monomers for synthesis of innovative biodegradable polyesters, with particular reference to PBS (polybutylene succinate)”, on this year the research focused on the hydrothermal liquefaction (HTL) of oakwood, emphasizing the catalytic effects of red mud (RM) modified through calcination and acid washing. Key parameters, including surface area and morphology, were analyzed to evaluate their influence on HTL yields. During a research period at Aalborg University, hydrotreating experiments using metallic catalysts for HTL biocrudes achieved from Cedrous waste wood were carried out. Upgrading experiments explored conditions such as temperature, reaction time, and catalyst-to-biocrude ratio, utilizing NiMo sulfided and zeolite catalysts. Comprehensive analyses, including elemental analysis, GC-MS, SEM, BET, FTIR and XRD, were conducted on hydrotreated biocrudes and spent catalysts. A paper on technoeconomic analysis (TEA) and life cycle assessment (LCA) of HTL, published in Energy Conversion and Management was finalized, and a manuscript on oakwood HTL using modified RM was submitted. Also, research at Conser in Rome on bio-based maleic anhydride (MAN) production using furfural and biobutanol was carried out, supported by a comprehensive literature review and experiments on HTL of cellulose to produce MAN precursors.
- In the context of the thesis “Development of methodologies for the remediation of contaminated sites following accidental events, including significant ones, relating to lithium batteries“, at the beginning of the third year of the PhD, the preparation and writing of a paper to be submitted for publication and participation in the CISAP 11 Conference (AIDIC) was carried out, regarding the data elaboration of chemical analyses on the organic and inorganic compounds in solid, liquid and gaseous residues after the extinction of lithium batteries fires (experimental tests). Metals were also analysed in the aforementioned post-extinction residues, with the aim of setting up the subsequent work on the remediation techniques of heavy metals contaminated soil (carried out in collaboration with the company Romana Ambiente). Data elaboration and writing of the experimental work carried out during the period abroad at the DTU in Copenhagen (which took place in the second year of the PhD) was performed. The work was aimed at testing the thermal behaviour of lithium batteries (in particular the measurement of the Heat Release Rate) and the extinction efficiency using different water-based agents. A study on the extinction phenomenology evidenced during the experimental tests held in previous years was performed. The PhD Thesis draft was written.
In the year 2023-24, students participated in seminars, conferences and workshops on topics related to their research activity, obtaining the training credits according to their training plan.
All PhD students also participated in the training activities proposed by the Board in the academic year. 2023-24, as it follows:
Seminars for students 37-38 and 39th cycle:
8-02-2024 M. Bracconi (Politecnico di Milano) - Advanced reactor analysis and design through reactive Computational Fluid Dynamics and hierarchical approach
3-04-2024 Gregory S.Patience - New Zero Dreaming: Fossil Fuels or Darkness and Hunger
3-04-2024 J. F. Borges Puna (Instituto Superior de Engenharia de Lisboa) - The reduction of GHG emissions to the atmosphere
Courses 37th cycle
J. F. Borges Puna (Instituto Superior de Engenharia de Lisboa)
- State-of-the-art related with the sustainable technologies applied for biofuels and hydrogen production.
- Electrochemical and thermochemical processes: bio-oil and syngas production and process applications.
- Heterogeneous catalysts for bioproducts and biofuels: biomass and biorefinery.
Courses 38th cycle
J. F. Borges Puna (Instituto Superior de Engenharia de Lisboa)
- State-of-the-art related with the sustainable technologies applied for biofuels and hydrogen production.
- Electrochemical and thermochemical processes: bio-oil and syngas production and process applications.
- Heterogeneous catalysts for bioproducts and biofuels: biomass and biorefinery.
Perspectives and challenges in liquid chromatography (S. Cerbelli, Sapienza)
Tecniche di caratterizzazione avanzata (G. Greco, ENEA)
Experimental Design and data analysis (F. Pagnanelli, Sapienza)
Courses 39th cycle
J. F. Borges Puna (Instituto Superior de Engenharia de Lisboa)
- State-of-the-art related with the sustainable technologies applied for biofuels and hydrogen production.
- Electrochemical and thermochemical processes: bio-oil and syngas production and process applications.
- Heterogeneous catalysts for bioproducts and biofuels: biomass and biorefinery.
From Stokesian dynamics to microfluidic applications (M. Gona, G, Procopio, Sapienza)
Electrochemical storage of Energy (Prof. A. Celeste, Sapienza)
Tecniche di caratterizzazione avanzata (G. Greco, ENEA)
Experimental Research Planning and Model Development (R. Lavecchia, A. Zuorro, Sapienza)