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Composite materials comprising themetal–organic framework CuBTC (HKUST-1 or Cu3(BTC)2) and zirconium hydroxide were made to develop a materialcapable of broad spectrum toxic chemical removal. Materials were physicallymixed at varying percentages, followed by pressing into pellets toset the structure. Mixtures were confirmed using powder X-ray diffraction,attenuated total reflectance–Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy, and scanning electron microscopy.Nitrogen isotherm data were collected on the composite media, followedby breakthrough testing against ammonia, cyanogen chloride, and sulfurdioxide. All samples exhibited substantial porosity. As the percentageof CuBTC increased, ammonia performance increased while sulfur dioxideremoval generally decreased. Cyanogen chloride removal increased withincreased CuBTC percentage under dry conditions, but failed to provideany significant removal under humid conditions. Adding triethylenediamineto the composites resulted in a substantial increase in cyanogen chlorideremoval capacity under humid conditions. In all, the composite structuresresulted in some synergistic effects for ammonia and cyanogen chloride,with removal capacities higher than weighted averages based on performanceof pure components. Data indicate that composites comprising CuBTCand zirconium hydroxide may be viable for broad spectrum toxic chemicalfiltration. [ABSTRACT FROM AUTHOR]

A novel microporous sorbent consisting of zirconium hydroxide impregnated with triethylenediamine (TEDA) was evaluated for the removal of cyanogen chloride. Breakthrough data were collected on packed beds, illustrating the efficacious nature of TEDA and the enhanced cyanogen chloride removal from the basic zirconium hydroxide structure. NMR and XPS analyses revealed the fate of cyanogen chloride, with inorganic chloride byproducts deposited on the surface of the material and polymerized urea condensates physically adsorbed in the pore structure. The zirconium hydroxide media were found to provide significantly enhanced removal capabilities as compared to traditionally impregnated activated carbons, allowing for the development of respirators with reduced encumbrance. [ABSTRACT FROM AUTHOR]

Zirconium hydroxide [Zr(OH)4], with a surface area of 365 m2/g, was evaluated for its ability to remove SO2from streams of air at room temperature. The SO2removal capacity of Zr(OH)4was ∼90 mg SO2removed per cm3bed volume, which is almost an order of magnitude greater than the value achieved for activated carbon and is more than twice the value achieved for activated carbon impregnated with 10% CuO. Temperature-programmed desorption results indicate that SO2is strongly retained by Zr(OH)4. X-ray photoelectron spectroscopy results reveals the presence of sulfite (SO32−) species following reaction exposure, which suggests the formation of zirconium sulfite. Although the SO2removal capacity (volume basis) of Zr(OH)4is high, relative to that of impregnated activated carbon, only 10% of the stoichiometric hydroxyl groups are able to contribute to the removal of SO2. [ABSTRACT FROM AUTHOR]

Zeolite H−ZSM-5 with a SiO2/Al2O3ratio of 25 was evaluated for its ability to remove ethylene oxide (EtO) from streams of air at 25 °C and between 15 and 90% relative humidity (RH). The primary mechanism for the removal of ethylene oxide using H−ZSM-5 involves a catalyzed hydrolysis reaction initiated by the adsorption of EtO onto a Brønsted acid site. Secondary addition reactions leading to the formation of polyglycols are also occurring. The reaction is poisoned by the accumulation of reaction products within the pores of the zeolite, which ultimately leads to elution of EtO from the filter bed. The ability of H−ZSM-5 to remove EtO decreased significantly as the relative humidity increased from 50 to 90%. For example, the EtO breakthrough time decreases from 220 min at 50% RH to 57 min at 90% RH. The decrease in the EtO breakthrough time over the stated RH range is attributed to the increased hydration of the Brønsted acid site. As the extent of Brønsted acid site hydration increases, the reactivity of the site is reduced, leading to a reduction in the EtO breakthrough time. [ABSTRACT FROM AUTHOR]