WashU researchers develop porous titanium-dioxide-coated zeolite particles for enhanced safety and protection
New research from Xinhua Liang’s lab seeks to enhance performance of gas mask filters
Gas masks are essential to protect individuals exposed to hazardous environments in different scenarios, ranging from industrial sites to emergencies involving toxic gases. The function of a gas mask depends on several key factors, including the type of filter, filtration efficiency and airflow mechanism. Each part has a critical role to ensure the safety of individuals.
Typically, gas masks comprise a flexible face covering, transparent eye lenses and one or two filter cartridges. These filter cartridges are the core of a gas mask’s protective capability, trapping harmful gases, dust and bacteria. Activated carbon is commonly used as the primary material in the filter cartridge to absorb harmful chemicals because of its high surface area and strong adsorption properties. However, these gas masks have limitations when protecting individuals against small volatile molecules, such as carbon monoxide (CO) and ammonia (NH3), which can lead to respiratory, skin irritation and lung damage, even at low concentrations.
To address this limitation, new research from Washington University in St. Louis’ Department of Energy, Environmental & Chemical Engineering has examined the potential of advanced composite materials to enhance the performance of gas mask filters. The research was published in Chemical Engineering Journal on Dec.15, 2024.
The research, led by Xinhua Liang, professor of energy, environmental & chemical engineering in WashU’s McKelvey School of Engineering, addresses the limitations of traditional activated carbon by using zeolite 13X particles as a base material, coated with a layer of porous titanium dioxide (TiO2) and decorated with silver oxide (Ag2O) nanoparticles.
Zeolite 13X is a crystalline, microporous material with a large surface area and an optimal pore size that can adsorb a variety of molecules, including both small gases and volatile organic compounds. However, zeolite 13X alone faces challenges in efficiently adsorbing small volatile molecules like ammonia due to its relatively large pore size of about 1 nanometer, which is not ideal to capture certain toxic gases. To address this, the researchers turned to TiO2, which acts as an efficient Lewis acid, a chemical species that can accept a pair of electrons to form a covalent bond, to capture ammonia. By coating the zeolite particles with a thin layer of porous TiO2 film, they reduced the pore size of the zeolite particles at the pore mouth of zeolite due to pore misalignment of two porous materials and to enhance their adsorption performance.
Liang highlighted the broader impact of this innovation under different scenarios, emphasizing its potential to enhance safety in various situations.
“Gas masks with such filler materials are expected to provide protection against chemical weapons attack and avoid the disease diffusion for soldiers, health workers, patients and the remaining population,” Liang said. “The research outcomes are addressing the most critical issues of gas masks for the Army and other Department of Defense personnel working in similar threatening environments, and the research results are also beneficial for health providers, first responders, and even the general public facing similar needs.”
The next step for Liang’s team is testing new prototypes of gas masks with higher quantities of advanced zeolite-composite adsorbents.
Su W, Wang K, Yu H, Fayyazbakhsh F, Watts J, Huang Y, Wang J, Liang X. Zeolite 13X particles with porous TiO2 coating and Ag2O nanoparticles as multi-functional filler materials for face masks. Chemical Engineering Journal, Dec.15, 2024. https://doi.org/10.1016/j.cej.2024.157937
Funding for this research was provided by the Army Research Laboratory under Cooperative Agreement Number W911NF-21-2-0262.
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