A new adsorbent material for seawater decontamination was studied in order to overcome the issues related to its potential negative effects to the marine ecosystem, revealed through ecotoxicity tests, and more in general to the impacts of its large scale production, evaluated by means of LCA analysis. The adsorbent material was specifically developed and investigated for marine water treatment, which represents an innovative aspect by itself. The demand for effective and cheap heavy metals adsorbents is raising as the presence of these contaminants is pervasive in all aspects of anthropic activities and their adverse effects on human health are attracting growing concern. On the basis of these premises, a nano-structured adsorbent material obtained from a biocompatible and renewable source, cellulose, is studied for optimizing its performances. In this preparation, cellulose undergoes oxidation and subsequent cross-linking with branched polyethyleneimine (bPEI), a polymer largely investigated for its potential applications in medicine, and with citric acid, following a safe-by-design approach. The outcome is a highly performing and eco-safe adsorbent which can compete with other adsorbent materials already in use for water remediation and in particular for heavy metals removal. The scope of this material has been demonstrated on target heavy metal such as Cd2+, Cr3+, Cu2+, Hg2+, Ni2+ and Zn2+, with good to excellent adsorption performances in artificial seawater, depending on the cation and its initial concentration. Furthermore, the possibility of reuse of the adsorbent by means of a regeneration process was successfully investigated, confirming its competitiveness with other commercially available adsorbent materials. The eco-safety of the optimized material was ensured by complying to an eco-design route, which consisted in a step by step evaluation of its potential ecotoxicity towards marine organisms and microorganisms, followed by further modifications in order to reach the final goal. In this context, it was also ensured that the treated waters could be directly released in open sea after heavy metals removal, without requiring further treatments.
È stato sviluppato e ottimizzato un nuovo materiale adsorbente per la decontaminazione delle acque di mare con il fine di risolvere le problematiche legate ai suoi potenziali effetti tossici verso l’ecosistema marino e, più in generale, legate agli impatti della sua produzione su scala industriale, valutati attraverso lo strumento della LCA. Il materiale adsorbente è stato sviluppato e analizzato specificatamente per il trattamento di acque marine, aspetto che già di per sé costituisce un’innovazione rispetto allo stato dell’arte. La domanda per sistemi efficaci e a basso costo per la rimozione dei metalli pesanti da matrici acquose cresce di pari passo con l’attenzione che questi contaminanti attirano a causa dei loro effetti nocivi sulla salute umana e la loro permeazione in tutte le attività antropiche. Sulla base di queste premesse, ci si è concentrati sull’ottimizzazione di un materiale adsorbente nano-strutturato ottenuto a partire da cellulosa, materia prima biocompatibile e rinnovabile. Nel processo di sintesi la cellulosa viene ossidata e successivamente reticolata con polietilenimina ramificata (bPEI), polimero ampiamente studiato per applicazioni in campo biomedico, e con acido citrico, in un approccio definito safe-by-design. Il risultato è un materiale dalle ottime prestazioni adsorbenti ed al contempo sicuro per l’ambiente, in grado di competere con altri materiali e processi per la decontaminazione delle acque da metalli pesanti. Le eccellenti capacità adsorbenti di questo materiale sono state verificate in acqua salata artificiale su un’ampia gamma di metalli pesanti. Inoltre è stata investigata con successo la possibilità di riutilizzo dell’adsorbente attraverso un processo di rigenerazione. L’obiettivo del basso impatto eco-tossicologico del materiale ottimizzato è stato raggiunto attraverso un percorso di eco-design, consistente in graduali valutazioni della sua eco-tossicità nei confronti di organismi marini e successive ulteriori modifiche di processo sintetico, fino al raggiungimento degli obiettivi prefissati. Ciò garantisce che le acque trattate possano essere direttamente rilasciate in mare, senza richiedere ulteriori trattamenti depurativi.
Adsorbent material from renewable sources for marine water remediation : an eco-design route
GRAZIANO, AURORA
2016/2017
Abstract
A new adsorbent material for seawater decontamination was studied in order to overcome the issues related to its potential negative effects to the marine ecosystem, revealed through ecotoxicity tests, and more in general to the impacts of its large scale production, evaluated by means of LCA analysis. The adsorbent material was specifically developed and investigated for marine water treatment, which represents an innovative aspect by itself. The demand for effective and cheap heavy metals adsorbents is raising as the presence of these contaminants is pervasive in all aspects of anthropic activities and their adverse effects on human health are attracting growing concern. On the basis of these premises, a nano-structured adsorbent material obtained from a biocompatible and renewable source, cellulose, is studied for optimizing its performances. In this preparation, cellulose undergoes oxidation and subsequent cross-linking with branched polyethyleneimine (bPEI), a polymer largely investigated for its potential applications in medicine, and with citric acid, following a safe-by-design approach. The outcome is a highly performing and eco-safe adsorbent which can compete with other adsorbent materials already in use for water remediation and in particular for heavy metals removal. The scope of this material has been demonstrated on target heavy metal such as Cd2+, Cr3+, Cu2+, Hg2+, Ni2+ and Zn2+, with good to excellent adsorption performances in artificial seawater, depending on the cation and its initial concentration. Furthermore, the possibility of reuse of the adsorbent by means of a regeneration process was successfully investigated, confirming its competitiveness with other commercially available adsorbent materials. The eco-safety of the optimized material was ensured by complying to an eco-design route, which consisted in a step by step evaluation of its potential ecotoxicity towards marine organisms and microorganisms, followed by further modifications in order to reach the final goal. In this context, it was also ensured that the treated waters could be directly released in open sea after heavy metals removal, without requiring further treatments.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/139776