EXPLORING POLYCAPROLACTONE, HALLOYSITE NANOTUBES, DIATOMACEOUS EARTH, AND THEIR COMPOSITES FOR ACETIC ACID MITIGATION IN MUSEUM ENCLOSURES

The long-term preservation of scientific and technological heritage is increasingly threatened by volatile organic compounds (VOCs), particularly low-molecular-weight carboxylic acids such as acetic and formic acids, which accumulate in poorly ventilated museum enclosures and trigger irreversible chemical degradation. Mitigating these pollutants is therefore essential for ensuring the long-term stability of sensitive collections. Nevertheless, the development of reliable, sustainable, and chemically safe adsorbents suitable for deployment in museum environments is still an open challenge, together with the absence of reproducible assessment protocols tailored to museum contexts.This research work addresses these critical gaps by investigating Halloysite nanotubes (HNTs) and Diatomaceous earth (Diat) as green sorbents for reducing gaseous pollutants in museum enclosures, with particular focus on acetic acid. Because of its powdery nature, blends of the biodegradable polymer Polycaprolactone (PCL) were prepared to ensure safety for use in museum contexts. Although these naturally occurring materials have attracted growing interest as sustainable sorbents due to their high surface area, chemical stability, and versatile adsorption properties, their capacity to capture gas-phase carboxylic acids remains largely unexplored.A comprehensive physico-chemical characterisation demonstrated that blending PCL with Diat or HNT is an effective strategy for obtaining biocompatible composites with enhanced viscoelastic, structural, and thermal properties compared with the pure polymer. Their adsorption performance and chemical safety in museum environments were then assessed through a structured evaluation procedure developed during the research period at the Faculty of Chemistry and Chemical Technology (FKKT) of the University of Ljubljana (Slovenia). Within this framework, a systematic quantification of acetic acid uptake and formic/acetic acid release from raw materials and composites, together with assessments of pollutant retention and potential impacts on common heritage materials under museum-relevant conditions, was conducted for the first time.The most effective materials were finally validated through an in situ deployment in an 18th-century historical display case at the Museo della Specola (Palermo). This transition from laboratory settings to a real museum environment represents one of the first practical tests in Italy of newly developed adsorbent materials for mitigating acetic acid in historical enclosures within a scientific collection of astronomical interest. The research further extended to case studies within the Physics and Chemistry collections of the University of Palermo, where visible deterioration in lead-containing components of historical scientific instruments was consistent with corrosion induced by volatile organic acids accumulated in historical wooden enclosures. These investigations provided additional evidence of the broader relevance of VOC-driven degradation in scientific heritage contexts, particularly where original exhibition enclosures remain in use and cannot be replaced.Overall, the results provided an assessment of HNTs, Diat, and their PCL-based hybrids as gas-phase sorbents for carboxylic acids under heritage-relevant conditions and contributed to the standardisation of protocols for the development and comparative assessment of new sustainable sorbents in preventive conservation.