INNOVATIVE SYSTEMS FOR THE MITIGATION OF RISKS: CATALYSTS AND SMART MATERIALS FOR DETECTION AND DECONTAMINATION OF HAZARDOUS CHEMICAL, BIOLOGICAL AND EXPLOSIVE SUBSTANCES
Tesi di Dottorato
Data di Pubblicazione:
2024
Citazione:
INNOVATIVE SYSTEMS FOR THE MITIGATION OF RISKS: CATALYSTS AND SMART MATERIALS FOR DETECTION AND DECONTAMINATION OF HAZARDOUS CHEMICAL, BIOLOGICAL AND EXPLOSIVE SUBSTANCES / S. Econdi ; tutor: A. Caselli ; co-tutor: M. Guidotti ; coordinatore: D. Roberto. Dipartimento di Chimica, 2024 Feb 27. 36. ciclo, Anno Accademico 2022/2023.
Abstract:
Incidents involving Chemical, Biological, Radiological, Nuclear and explosive agents (CBRNe), whether intentional or accidental, pose significant threats in the modern international scenario. The use of these substances, not only endangers human life, but also represents a threat to national defence, the economy and, above all, the environment due to their strong harmfulness, persistence and recalcitrance. Consequently, there is a critical need for the development of innovative systems to mitigate the risks associated with these hazardous agents. This research spans several areas related to the mitigation of chemical, and biological risks. The broad aim of this Ph.D. thesis was to overcome the problems and limitations currently present in some conventional decontamination and detection methods concerning these hazardous agents.
Decontamination of Hazardous Biological Agents - In this field, it is a priority to focus on substances that are both environmentally and economically sustainable, as well as safe from a toxicity point of view, aiming to avoid the extensive use of chlorine-based solutions or to minimise the release of VOCs into the environment. In response to the COVID-19 pandemic, hydrogen peroxide has emerged as a sustainable alternative for inactivating SARS-CoV-2 in the liquid phase. A diluted 3% w/w H2O2 solution acidified to pH 2.5 by adding citric acid inactivated SARS-CoV-2 virus by more than 4 orders of magnitude in 5 min. Conversely, H2O2 solutions with no additives displayed a scarce virucidal activity, confirming that a pH-modifying ingredient is necessary to have a H2O2-based disinfectant active against this virus. Furthermore, recognizing that an acid and an oxidizing functionality are important for the inactivation of many pathogens, efforts were made to heterogenize and immobilize these functionalities within a system based on sulfonic acid cation exchange resins. After a simple contact treatment with an aqueous H2O2 solution, these resins demonstrated the ability to store oxidising species and release them over time. These systems exhibited potent biocidal efficacy against bacteria, resulting in a reduction of 9 and 5 orders of magnitude in Escherichia coli (Gram -) and Staphilococcus aureus (Gram +) viability, respectively, even after 1 min. Additionally, they showed effectiveness against viruses, with a complete absence of viral replication for SARS-CoV-2 (RNA virus), Herpes simplex (DNA virus), and Monkeypox (DNA virus) after 2 min. This drastic biocidal action is therefore attributable to the synergistic effect between the strong Brønsted acidity of the resins and the oxidising capacity due to the presence of H2O2 and in-situ formed peroxosulfonic species.
Decontamination and abatement of hazardous chemicals - The transition from stoichiometric to catalytic methods is crucial for the effective and sustainable decontamination of hazardous chemicals. In this study, nanostructured porous materials, including commercial non-ordered aluminosilicates (SiO2-Al2O3), niobium oxide (Nb2O5), and modified synthetic saponites clays (NbSAP, Na-SAP, H-SAP), were selected and tested as heterogeneous catalysts for the liquid-phase degradation of two organophosphorus obsolete agrochemicals and CWAs simulants, namely paraoxon-ethyl and parathion-ethyl. Regarding synthetic saponite clays, they represent a class of hydrated smectite-type phyllosilicate materials, consisting of a 2:1 trioctahedral structure of alternating tetrahedral (T) and octahedral (O) sheets, typically composed of Si(IV), Al(III), Mg(II) and O2- sites, organised to form T-O-T layers alternating with an interlamellar space containing exchangeable cations and water molecules. Thanks to the ability to modulate the physico-chemical features of saponites
Tipologia IRIS:
Tesi di dottorato
Elenco autori:
S. Econdi
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