Iron(III) based Metal-Organic Frameworks in cellulose acetate film preservation: Fundamental aspects and first application

• Published in: Journal of cultural heritage 2024-03, Vol.66 (1), p.236-243
• Main Authors: Mohtar, Abeer Al, Severino, Maria Inês, Tignol, Pierre, Ranza, Luigi, Neves, Artur, Nouar, Farid, Pimenta, Vanessa, Lopes, João, Ramos, Ana Maria, Rodrigo, Juan Ignacio Lahoz, Melo, Maria João, Wallaszkovits, Nadja, Pinto, Moisés L., Dupont, Anne-Laurence, Serre, Christian, Lavédrine, Bertrand
• Format: Article
• Language: English
• Subjects: Cellulose acetate movie films; Chemical Sciences; Cultural heritage and museology; Films preservation; Humanities and Social Sciences; Life-cycle assessment; Material chemistry; Metal-Organic Frameworks; MIL-100(Fe)
• ISSN: 1296-2074; 1778-3674
• DOI: 10.1016/j.culher.2023.11.013

•Innovative preservation technology based on MOFs is proposed and validated.•The stability of the MOFs is studied by using accelerated aging in acidic medium.•The compatibility of the MOFs with the artefacts is tested.•Preservation forecast and user recommendation are given using novel model.•The new approach reduces carbon footprint related to film preservation by 50%. Low-temperature storage to slow down degradation is accepted by the film conservation community. Still, this solution prohibits public access, is price-sensitive, has high energy costs, and there are concerns about their effects on the physical stability and material lifetime. In this research, a smart solution is developed based on the selective capture of acetic acid produced by the cellulose acetate polymer. This innovative approach is based on Metal-Organic Frameworks (MOFs) for acetic acid adsorption, specifically a highly selective porous iron(III) based MOF, MIL-100(Fe), which was synthesized using a green approach. The stability of MIL-100(Fe), under acetic acid exposure, was demonstrated by accelerated aging experiments, with no noticeable changes in crystallinity and/or porosity as deduced from powder X-ray diffraction analysis, infrared spectroscopy, thermogravimetric analysis, nitrogen porosimetry, and electron microscopy. Compatibility tests with the artefacts were performed to prove the safety of the MIL-100(Fe) to the artefacts. A field application in a demonstration prototype (smart box) was performed at Institut Valencià de Cultura. A recently developed hybrid model provided recommendations on the quantity of adsorbents to use in the smart box. Good agreement was observed between the model predictions and the in-field experimental results, which validated the model application. The model predicted that the new adsorbent (5% of the film's weight, replaced every 10 years, at 16°C or 22°C) extends the film's lifetime equivalently to cold storage (5°C). Finally, environmental impact assessment and life cycle analysis were performed to compare the two preservation approaches. The new approach based on this Fe-MOF yielded an average reduction of carbon footprint related to movie film preservation of about 50% considering the current European Union (EU) energy mix and about 40% considering the 2030 EU energy mix (where a transition towards renewable energy is expected). The proposed innovative technology represents a robust solution towards efficient and more sustainable film pres