Innovative Air Cleaning System for Healthy Indoor Environments: Characterization of a Novel System Combining MCM-41 Mesoporous Silica and Essential Oils

Essential oils, naturally extracted from various parts of plants, possess remarkable antifungal and antibacterial properties due to their rich composition of bioactive compounds, including terpenes, phenolics, aldehydes, and ketones. This study focuses on their application in the protection of cultural heritage through a preventive approach against biocolonization. Airborne fungal spores and bacteria settle on surfaces, leading to the biodegradation of artworks. To counteract this process, we harness the biocidal properties of tea tree oil, alongside other essential oils, to eliminate microorganisms and prevent their interaction with artistic substrates [1]. However, the high volatility of essential oils and their potential unwanted interactions with delicate surfaces present significant challenges. To address these issues, the bactericidal and fungicidal agents were adsorbed and chemically bonded onto mesoporous silica MCM-41 microparticles, ensuring enhanced stability and a controlled release mechanism [2]. The effectiveness of the essential oils, both in free and supported forms, depends on their chemical composition, making an appropriate analytical protocol essential. While gas chromatography (GC) remains the standard technique for identifying phenolic and terpenic components, its complexity and cost necessitate alternative approaches [3]. In this study, we propose a non-invasive method starting from Near-Infrared Spectroscopy (NIR), which allows for the rapid characterization of functionalized MCM-41 by targeting the harmonic and combination bands of surface OH groups and the distinct spectral features of essential oil compounds [4]. Additionally, Dynamic Light Scattering (DLS) was employed to monitor real-time changes in particle size during functionalization, providing insight into successful modifications. Since these functionalized microparticles are intended for use in air filtration systems to sanitize the air, gas adsorption porosimetry was conducted to examine MCM-41 before and after functionalization. This analysis revealed changes in pore distribution, volume, and structural integrity, offering key insights into MCM-41’s filtration efficiency and its novel post-functionalization interaction with tea tree oil, a process explored here for the first time. This study evaluates the structural and chemical transformations occurring in both the silica support and the essential oil upon adsorption or chemical bonding. These findings are fundamental to optimizing the performance of functionalized MCM-41 in air purification systems, providing an innovative strategy for preventing microbial contamination and safeguarding cultural heritage from biodegradation.