Zeolite Fibers Research Articles

Fabrication of Hollow Zeolite Fibers through Layer-by-Layer Adsorption Method

Abstract Hollow fibers with nanozeolite walls are firstly fabricated through layer-by-layer (LbL) technique, using carbon fibers as templates, coupled with removal of the templates by calcination. The thickness and the composition of the walls can be readily controlled by varying the number of the deposition cycles and the zeolite types used, respectively.

Formation of ZSM-5 (MFI) Zeolite Fiber

Zeolite fiber was manufactured from the nanosized ZSM-5 crystals. In this process, it was found that the size of zeolite particles (≤200nm) play critical role in the fiber formation. To obtain nanosized zeolite crystals, ZSM-5 zeolite was crystallized at the temperature of 80°C and the atmospheric pressure. The size of zeolite was observed to be dependent on Si/Al ratio. Si/Al ratio of 33 was optimum for the synthesis of 200-nm sized zeolites. The formation of zeolite fiber was also affected by the interaction between particles and solvent. High adhesion energy of zeolite particles seems to be required to form the fiber. ZSM-5 zeolite fiber was transparent because the size of zeolite particles is below the wavelength of visible light (400-700nm). The particle size of ZSM-5 fiber was found to be larger than that of TS-1 zeolite fiber (80nm).

Fluorescence imaging of reactive oxygen metabolites generated in single macrophage cells (NR8383) upon phagocytosis of natural zeolite (erionite) fibers.

In this paper we address the phenomenon of reactive oxygen metabolite generation subsequent to phagocytosis of mineral fibers by macrophages. Natural erionite fibers were chosen because of their established toxicity. Macrophages (cell line NR8383) were loaded with the dye 5-(and 6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate and exposed to erionite particles by centrifuging cells and fibers together to effect adherence. Reactive oxygen metabolite generation was examined by monitoring the fluorescence of oxidized dye formed via the reaction with oxygen species produced during phagocytosis. Individual cells were repeatedly scanned for up to 2 hr to monitor the evolution of this fluorescence. It was found that erionite-exposed cells had a mean total fluorescence of three times that of controls during the first 35 min, declining to two times that of controls at 35-60 min and about the same level as that of controls at 60-80 min. Ultrastructural studies of similarly treated aliquots of cells showed marked variation in size and numbers of the phagocytized particles. This study demonstrates that intracellular oxidation can be monitored on a single cell basis over a period of time. Quantitative studies are in progress to establish the relationship between the phagocytized particulate load and the extent of fluorescence.

Fluorescence Imaging of Reactive Oxygen Metabolites Generated in Single Macrophage Cells (NR8383) upon Phagocytosis of Natural Zeolite (Erionite) Fibers

In this paper we address the phenomenon of reactive oxygen metabolite generation subsequent to phagocytosis of mineral fibers by macrophages. Natural erionite fibers were chosen because of their established toxicity. Macrophages (cell line NR8383) were loaded with the dye 5-(and 6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate and exposed to erionite particles by centrifuging cells and fibers together to effect adherence. Reactive oxygen metabolite generation was examined by monitoring the fluorescence of oxidized dye formed via the reaction with oxygen species produced during phagocytosis. Individual cells were repeatedly scanned for up to 2 hr to monitor the evolution of this fluorescence. It was found that erionite-exposed cells had a mean total fluorescence of three times that of controls during the first 35 min, declining to two times that of controls at 35-60 min and about the same level as that of controls at 60-80 min. Ultrastructural studies of similarly treated aliquots of cells showed marked variation in size and numbers of the phagocytized particles. This study demonstrates that intracellular oxidation can be monitored on a single cell basis over a period of time. Quantitative studies are in progress to establish the relationship between the phagocytized particulate load and the extent of fluorescence.

Nanoparticle synthesis of titanium silicalite for fiber, film, and monolith formation

Zeolite fiber, film, and monolith were prepared by using nanosize titanium silicalite (TS-1) crystals. Films and fibers of TS-1 zeolite were optically transparent, which might be important for advanced optozeolitic materials. A permeation result of gases on monolith indicates that the gas permeation is governed by the Knudsen mechanism. All types of TS-I zeolites manufactured in this work are observed to be MFI structure with an orthorhombic symmetry. These results suggest that nanosize zeolites have potential to allow morphological design with applications for advanced functional materials.

In vitro interaction of zeolite fibers with individual cells (macrophages NR8383): measurement of intracellular oxidative burst.

Inhalation of fibrous minerals such as asbestos and erionite can cause various lung diseases, including cancer. The mechanism by which these fibers induce disease is an area of active research. Interaction of fibers with lung macrophages leads to release of many substances. Among these, reactive oxygen metabolites (which include hydrogen peroxide, superoxide, and possibly hydroxyl radicals) are proposed to cause cellular damage. In this paper, we report a method for observing intracellular hydrogen peroxide release as rat lung-derived macrophages (NR-8383) phagocytize erionite fibers. This is possible by observing the fluorescence of 2',7'-dichlorofluorescein-the intracellular, oxidized form of 5 (and 6)-carboxy-2', 7'-dichlorodihydrofluorescin formed in the presence of newly released hydrogen peroxide. We are able to image the fluorescence within a single cell, thereby allowing us to get information on the spatial distribution of the metabolites.

Natural fibrous zeolites and their carcinogenicity — a review

More than 50 cases of pleural mesothelioma have been reported during the period 1974–1978 in a relatively small area of Turkey, centered in and around the villages of Karain and Tuzköy, in the province of Cappadocia. The area of Karain and Tuzköy is covered with volcanic tuffs, in which asbestos, glass and zeolite fibers were detected. The inhaled dusts of these fibrous materials might be the cause of the high mesothelioma rate. The most important publications on this problem are reviewed and the results of our own examinations are discussed.

Characterization of Zeolite Fiber Sizes Using Scanning Electron Microscopy

A synthetic zeolite and four natural zeolites from the western United States were examined for fibers using a scanning electron microscope. The distributions of fiber sizes were compared to distributions of fiber sizes of erionite and fibrous glass to determine if the fiber sizes were similar to those associated with mesothelioma in humans and animals. Fibers were abundant in two samples of natural erionite, rare in two samples of natural mordenite, and not present in the sample of synthetic mordenite. Although the majority of the erionite fibers were short (less than 8 mu long) and thicker than the tumorigenic erionite (greater than 0.25 mu wide), 6% and 11% of the fibers corresponded to fiber size categories of fibrous glass that have correlated with pleural mesothelioma production in rats. Even a single species of zeolite (erionite) is not uniform in its distribution of fiber sizes. On the basis of fiber size, these natural zeolites should be evaluated because of their potential carcinogenic risk.