Monica Puccini

The sustainable management of municipal solid waste (MSW) remains a pressing challenge, particularly for the under-sieve fraction generated during mechanical treatment (MT), which is currently landfilled. This study proposes an integrated valorization route involving hydrothermal carbonization (HTC), followed by potassium hydroxide (KOH) activation to convert MT-MSW into activated hydrochar (AHC). Response surface methodology (RSM) was employed to systematically investigate the synergistic effects of activation temperature (500–700 °C) and KOH/hydrochar impregnation ratio (0.5–1.5) on specific surface area and BTEX (benzene, toluene, ethylbenzene, and xylenes) removal efficiency from water. Results demonstrate that moderate activation severity (600 °C, KOH/HC = 1.0) promotes the formation of a predominantly microporous structure (BET surface area: 440.7 m2/g; micropore area: 363.9 m2/g), achieving a total BTEX removal of 84.7%. RSM analysis showed that both activation temperature and KOH/hydrochar ratio significantly affected AHC yield and surface area, whereas activation temperature was the main statistically significant factor governing BTEX removal. Overall, the developed models provide a predictive framework for tailoring AHC properties by optimizing the activation conditions. These findings establish a viable circular solution for the upcycling of urban waste streams into engineered adsorbents for environmental remediation.

High-temperature adsorption using regenerable solid sorbents is a promising technology for post-combustion CO2 capture. However, reactor-scale models for ceramic sorbents, such as doped lithium orthosilicate (Li4SiO4), remain limited. In this work, a two-dimensional axisymmetric model of a fixed-bed reactor packed with K2CO3-doped Li4SiO4 pellets was developed, coupling momentum, mass, and energy balances in COMSOL Multiphysics®. The carbonation reaction was described by a modified shrinking-core model accounting for a molten Li2CO3/K2CO3 phase and initial reaction product nucleation. A dedicated mass-transfer study, by varying the carrier-gas flow rate, showed that external gas-film resistance has a limited but measurable influence during the early reaction-controlled stage. External mass transfer was therefore incorporated into the pellet model to distinguish its contribution from intrinsic reaction kinetics and product-layer diffusion. The simulated breakthrough curves demonstrated good fitting with experimental data obtained from CO2 adsorption tests in a lab-scale fixed bed reactor at different temperatures, gas velocities, and low CO2 concentration (4 vol%). The transition from reaction- to diffusion-controlled adsorption was identified as the mechanism governing breakthrough, predicting breakthrough time with a mean absolute relative deviation of 8.8 %. Sensitivity analysis identified the kinetic parameters exerting the greatest influence on breakthrough behavior. Therefore, the proposed multiscale framework could provide a validated tool for the design and optimization of high-temperature fixed-bed CO2 capture reactors.

The increasing deployment of lithium-ion batteries (LIBs) requires effective recycling strategies to reduce environmental impacts and dependence on critical raw materials. In this study, a comparative life cycle assessment (LCA) of two LIB recycling routes, a pyrometallurgical process (Pyro) and a hydrometallurgical process with co-precipitation (Hydro), was performed using a Python-based process modeling framework. The LCA was carried out using an attributional approach, with impacts referred to 1 kg of spent LIBs treated at the recycling facility inlet, considering a representative mix of battery formats and cathode chemistries. Results showed that, when normalized per kilogram of treated batteries, the Hydro route is more impactful than the Pyro one, particularly in terms of global warming potential. The Pyro process does not enable direct cathode regeneration but allows the recovery of high-purity metal salts, whereas the Hydro route enables the production of re-formed NMC-111 cathode material that exhibits lower environmental impacts than virgin cathode production. Overall, the study highlights how rigorous process modeling integrated with LCA enables a detailed and non-trivial assessment of LIB recycling sustainability, revealing trade-offs that are not evident from simplified or purely qualitative analyses.

Fast charging of Li‐ion batteries remains a critical barrier for electric vehicle adoption due to parasitic reactions at the negative electrode, which irreversibly reduce lithium inventory, closely linked to graphite phase separation dynamics. This study presents a physics‐based fast‐charge protocol derived from a pseudo‐two‐dimensional phase‐field electrochemical model that was rigorously calibrated and validated through teardown characterisation, galvanostatic cycling, and impedance spectroscopy on a commercial cylindrical battery. The model‐informed protocol achieves charging from 20% to 80% state‐of‐charge within 15 min, outperforming both the manufacturer specification (18 min) and a commercial electric vehicle profile (25 min), while limiting capacity loss below 5% over 500 cycles. System‐level simulations of a charging station demonstrate compatibility with current electric infrastructure and show significant improvements in throughput and users waiting time under realistic usage scenarios. The work demonstrates that exploiting internal cell physics through model‐informed control can unlock high‐rate charging without hardware modification, offering a viable path toward low‐degradation fast charging.

The invasive aquatic plant Myriophyllum aquaticum represents both an ecological threat and a wet biomass disposal challenge. This study investigates hydrothermal carbonization (HTC) as a strategy for its valorisation into energy-dense hydrochar. A Design of Experiments–Response Surface Methodology (DoE-RSM) approach was applied to elucidate the combined influence of temperature (200–260 °C), residence time (30–210 min), and solid load (5–25 wt%) on hydrochar yield and properties. Hydrochar yields ranged from 48.8% to 65.6%, with the highest yields achieved at 200 °C, 30 min, and 25 wt% solids. Higher heating values of hydrochars spanned from 12.14 to 14.53 MJ/kg, corresponding up to +19% energy densification at higher process severity. Carbon and energy yields reached 69.7% and 68.6%, respectively, with maximum values attained under low-severity, high-solid-load conditions. The predictive models exhibited strong agreement with experimental data, enabling optimisation of HTC parameters for targeted hydrochar applications. Two hydrochars, “peat-like” and “lignite-like”, were further characterised for their potential use as soil amendments. The lignite-like hydrochar complied with EU contaminant limits and showed no phytotoxicity, confirming its suitability for agronomic use. Overall, HTC of M. aquaticum provides an effective waste-to-resource pathway, transforming wet invasive biomass into value-added carbon materials.

The development of environmentally friendly pretreatment processes for spent lithium-ion batteries (LIBs) is crucial for optimizing direct recycling methods. This study explores alternative approaches for recovering active cathode materials from end-of-life LIBs, focusing on environmentally safer options compared to the usually employed toxic solvent N-methyl-pyrrolidone (NMP), using disassembled batteries as test subjects. Various pretreatment methods, including thermal treatment, selective aluminum foil dissolution with a NaOH solution, and the use of eco-friendly solvents such as triethyl phosphate (TEP), are examined on the cathode sheets. The results show that thermal pretreatment combined with TEP provides the most effective approach, achieving a recovery efficiency of 95% while maintaining the morphology and purity of the recovered materials, making them suitable for direct recycling. These methods are further tested on complete battery cells, simulating industrial-scale operations. The TEP treatment proves particularly promising, ensuring high recovery efficiency and preserving the structural integrity of the materials, with a mean particle diameter of approximately 8 µm. Additionally, when applied to cycled batteries, this pretreatment successfully recovers active materials without contamination. This study provides valuable insights into various pretreatment strategies, contributing to the development of a greener, more efficient direct recycling pretreatment process for spent LIBs.

Electrochemical impedance spectroscopy is a non-destructive technique that provides useful information on the status of a lithium-ion battery, including its state-of-health. However, conventional harmonic perturbation methods are too sophisticated for applications in operating environments. This study systematically investigates the system requirements for reconstructing impedance via the Fourier transform of voltage and current signals obtained upon current interruption. Using a calibrated equivalent circuit model, key parameters such as the minimum sampling interval ∆ t s , the initial time collected during relaxation t i , and the current removal duration t f , are correlated with the frequency range [ f min , f max ] in which impedance is reconstructed within 1% error. A Gaussian window, whose width is modulated with frequency, effectively mitigates noise up to 0.1 mV. The resulting general relations, f min = 4 / t f and f max = 0.07 / ∆ t s (or f max = 0.07 / t i for t i > ∆ t s ), are valid within 10⁻²–10⁴ Hz, that is sufficient to cover ohmic, polarisation, and diffusion impedance features. Experimental tests on a commercial lithium-ion cell corroborate the generality of these system requirements. With a sampling interval of 70 μs for f max = 10 3 Hz and a waiting time of 40 s for f min = 10 − 1 Hz, the current interruption technique appears compatible with commercial instrumentation, making it potentially applicable for real-time impedance monitoring in operating lithium-ion batteries.