Abstract
Zeolites are micro- and mesoporous aluminosilicate minerals (both natural and industrially produced) widely used as catalysts and sorbents in domestic and commercial water purification and separation technologies. Their ability to selectively adsorb gases (i.e., water vapor, carbon dioxide, and sulfur dioxide removal) from an air stream makes them suitable for applications in odor reducing media used in filtering facepiece respirators (FFRs). FFRs are multilayer products in which the most important role is played by high-performance melt-blown electret nonwovens modified with activated carbon to adsorb malodorous compounds. Replacing carbon sorbents with zeolites could increase the efficiency of odor abatement, thus alleviating work-related hazards for individuals exposed to malodorous substances with adverse effects on human well-being. The objective of the present work was to analyze the influence of the textural parameters of zeolite and mesoporous silica materials on the protective and functional properties of polymeric nonwoven composites containing them. In our experiments, the longest breakthrough time against ammonia vapor was found for a nonwoven composite containing the inorganic mesoporous silica material type MCM-41. It was also characterized by high filtration efficiency against aerosols with solid and liquid dispersed phases (97% and 99% for sodium chloride and paraffin oil mist, respectively) at an airflow resistance of approximately 330 Pa. In turn, the composites containing the molecular sieve (SM-zeolite ZSM-5) exhibited the longest breakthrough time for acetone and cyclohexane vapors at the maximum allowable concentrations of 235 ppm and 81 ppm, respectively. Basic filtration tests showed that the composite was 97% effective against both test aerosols at an airflow resistance of 283.5 Pa.
Highlights
At a time of increasing public awareness, migration of urban dwellers to rural areas, spatial development of cities bringing residential areas closer to industrial facilities, and rapid economic growth the presence of noxious odors has often been reported to environmental law monitoring and enforcement agencies
The studied composites were made with unmodified mesoporous silica materials and zeolites synthesized from fly ash by the classical hydrothermal method, as well as zeolite and silica materials modified with hexadecyltrimethylammonium (HDTMA) bromide supplied by the Lublin University of Technology
Zeolite Na-A impregnated with HDTMA is shown in Figure 2c; its crystals are covered with a thin layer of HDTMA
Summary
At a time of increasing public awareness, migration of urban dwellers to rural areas, spatial development of cities bringing residential areas closer to industrial facilities, and rapid economic growth the presence of noxious odors has often been reported to environmental law monitoring and enforcement agencies. Irrespective of their origin, malodorous compounds may lead to psychological discomfort or, in extreme cases, to pathological symptoms, including headaches, vomiting, diarrhea, upper airway and eye irritation, and even depression [1,2]. The available literature mostly concerns industrial applications, with no data on the sorption of volatile compounds by the flat filtration/adsorption media used in respiratory protective devices
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