Indoor Air Quality in Museum Display Cases: Volatile Emissions, Materials Contributions, Impacts

Antifungal Hybrid Graphene-Transition-Metal Dichalcogenides Aerogels with an Ionic Liquid Additive as Innovative Absorbers for Preventive Conservation of Cultural Heritage

The use and integration of novel materials are increasingly becoming vital tools in the field of preventive conservation of cultural heritage. Chemical factors, such as volatile organic compounds (VOCs), but also environmental factors such as high relative humidity, can lead to degradation, oxidation, yellowing, and fading of the works of art. To prevent these phenomena, highly porous materials have been developed for the absorption of VOCs and for controlling the relative humidity. In this work, graphene and transition-metal dichalcogenides (TMDs) were combined to create three-dimensional aerogels that absorb certain harmful substances. More specifically, the addition of the TMDs molybdenum disulfide and tungsten disulfide in such macrostructures led to the selective absorption of ammonia. Moreover, the addition of the ionic liquid 1-hexadecyl-3-methylimidazolium chloride promoted higher rates of VOCs absorption and anti-fungal activity against the fungus Aspergillus niger. These two-dimensional materials outperform benchmark porous absorbers in the absorption of all the examined VOCs, such as ammonia, formic acid, acetic acid, formaldehyde, and acetaldehyde. Consequently, they can be used by museums, galleries, or even storage places for the perpetual protection of works of art.

Insight on the deterioration of cultural objects: a multi-analytical approach to characterize degradation products of lead weights from a Steinway & sons piano

The identification of the degradation products in objects of cultural significance, including musical instruments (e.g., a piano), is a key issue for the preservation and valorisation processes of cultural heritage. The aim of this study is to characterize the degradation products of lead weights from an important Steinway & sons piano using a multi-analytical approach that includes ionic chromatography (IC), X-ray diffraction (XRD) and Fourier transform-infrared (FTIR) spectroscopy analyses. These techniques allowed us to identify hydrocerussite as the main degradation product on the superficial layer of lead weights, followed by lead acetate and formate. Moreover, accelerated corrosion experiments in closed environments were performed under acetic and formic acid atmospheres to evaluate the development of lead acetate and formate over time. Exposure of lead weights to formic and acetic acid vapours leads to the prevalent formation of basic lead formate, which promotes the formation of hydrocerussite. These results can help to limit the degradation of these piano components and consequently preserve the sound of the piano itself.

Corrosion Risk to Metal-Based Artefacts in a Scientific and Technical Museum: An Assessment of Environmental and Exhibition Conditions

Materials such as wood, textiles, or plastics that are part of the exhibition system in museums are known to emit pollutants such as organic acids. Scientific and technical objects that include these materials in their composition can themselves be a potential source of emissions, which, together with inappropriate humidity and temperature conditions, can lead to corrosion of the metallic parts. In this work, we have studied the corrosivity of different locations in two venues of the Spanish National Museum of Science and Technology (MUNCYT). Coupons of the most representative metals from the collection were placed in different showcases and rooms for 9 months. The corrosion of the coupons has been evaluated in terms of the rate of mass gain, colour changes and characterisation of the corrosion products. The results were correlated to the relative humidity and concentration of gaseous pollutants to determine which metals are most susceptible to corrosion. The results show that metal artefacts exposed in showcases have a higher risk of corrosion than those exposed directly in the room, and that some pollutants are emitted by the artefacts. The corrosivity of the museum environment is low for copper, brass, and aluminium in most locations; however, some placements present a higher aggressivity for steel and lead, due to the high humidity and the presence of organic acids.

Review of recent advances on the use of mass spectrometry techniques for the study of organic materials in painted artworks

The study of painted artworks using scientific methods is fundamental for understanding the techniques used in their creation and their appropriate conservation. The ethical constraints involved in the handling of, and sampling from, these objects has steered recent developments in the field of Heritage science towards a range of new non-invasive/non-destructive spectroscopic techniques capable of providing important insights into their elemental or bulk chemical compositions. Due to the inherent complexities of heritage artefacts, however, their organic components are especially difficult to study in this way and their identification and degradation pathways are thus often best investigated using mass spectrometric (MS) techniques. The versatility, sensitivity and specificity of MS techniques are constantly increasing, with technological advances pushing the boundaries of their use in this field. The progress in the past ten years in the use of MS techniques for the analysis of paint media are described in the present review. While some historical context is included, the body of the review is structured around the five most widely used or emerging capabilities offered by MS. The first pertains to the use of spatially resolved MS to obtain chemical maps of components in cross-sections, which may yield information on both inorganic and organic materials, while the second area describes the development of novel sample preparation approaches for gas chromatography (GC)-MS to allow simultaneous analysis of a variety of components. The third focuses on thermally assisted analysis (either with direct MS or coupled with GC-MS), a powerful tool for studying macromolecules requiring zero (or minimal) sample pre-treatment. Subsequently, the use of soft ionisation techniques often combined with high-resolution MS for the study of peptides (proteomics) and other macromolecules (such as oligosaccharides and triglycerides) is outlined. The fifth area covers the advances in radiocarbon dating of painting components with accelerator MS (AMS). Lastly, future applications of other MS techniques to the study of paintings are mentioned; such as direct analysis in real time MS (DART-MS) and stable isotope ratio MS (IRMS). The latter, having proven its efficiency for the study of lipids in archaeological artefacts, is envisioned to become a valuable tool for this area, whereas DART-MS is already being utilised to study the surface composition of various museum objects. Rapid technological advances, resulting in increased sensitivity and selectivity of MS techniques, are opening up new approaches for paintings analysis, overcoming the fundamental hurdle of sample size available for destructive analysis. Importantly, while the last decade has seen proteomics applications come to the fore, this review aims to emphasise the wider potential of advanced MS techniques for the study of painting materials and their conservation.

MOFs with Open Metal(III) Sites for the Environmental Capture of Polar Volatile Organic Compounds

Metal-Organic Frameworks (MOFs) with open metal sites (OMS) interact strongly with a range of polar gases/vapors. However, under ambient conditions, their selective adsorption is generally impaired due to a high OMS affinity to water. This led previously to the privilege selection of hydrophobic MOFs for the selective capture/detection of volatile organic compounds (VOCs). Herein, we show that this paradigm is challenged by metal(III) polycarboxylates MOFs, bearing a high concentration of OMS, as MIL-100(Fe), enabling the selective capture of polar VOCs even in the presence of water. With experimental and computational tools, including single-component gravimetric and dynamic mixture adsorption measurements, in situ infrared (IR) spectroscopy and Density Functional Theory calculations we reveal that this adsorption mechanism involves a direct coordination of the VOC on the OMS, associated with an interaction energy that exceeds that of water. Hence, MOFs with OMS are demonstrated to be of interest for air purification purposes.

Indoor Environmental Quality Evaluation Strategy as an Upgrade (Renovation) Measure in a Historic Building Located in the Mediterranean Zone (Athens, Greece)

The assessment of indoor environmental quality in historic buildings converted to museums is a significant tool in deep energy renovation processes, as it provides insights for the microclimatic conditions in the interiors of the building where vast numbers of visitors walk every year and where artifacts that are vulnerable to pollution are exhibited. In this work, aiming to contribute to the development of an energy retrofitting protocol applied in the Mediterranean region (HAPPEN MedZeb protocol) for museums hosted in historic buildings by providing useful data, an experimental campaign to evaluate the indoor environmental quality of a museum housed in a historic building located in Athens took place from February 2019 to April 2021 and was divided into two periods. The findings revealed high concentrations of volatile organic compounds as well as poor thermal comfort levels since the sensors recorded low acceptable percentages of T values within the limits from 7 to 33% for the entire experimental period. Based on the findings, recommendations for retrofitting interventions are made.