Mild treatment with hydrogen peroxide solutions (3-30%) efficiently decomposes adsorbed chemical warfare agents (CWAs) on microporous activated carbons used in protective garments and air filters. Better than 95% decomposition of adsorbed sulfur mustard (HD), sarin, and VX was achieved at ambient temperatures within 1-24 h, depending on the H2O2 concentration. HD was oxidized to the nontoxic HD-sulfoxide. The nerve agents were perhydrolyzed to the respective nontoxic methylphosphonic acids. The relative rapidity of the oxidation and perhydrolysis under these conditions is attributed to the microenvironment of the micropores. Apparently, the reactions are favored due to basic sites on the carbon surface. Our findings suggest a potential environmentally friendly route for decontamination of adsorbed CWAs, using H2O2 without the need of cosolvents or activators.
The chromia-based catalysts have been reported to combine the high activity and resistance to deactivation in oxidative removal of chlorinated VOC. However, their activity is limited by the low amount of chromia that can be deposited on supports maintaining the optimal state of surface species and high surface area. The pure nanostructured chromia was used as a catalytically active support for noble metals and transition-metal oxide oxidation catalysts. High efficiency of Pt-promoted CrOOH aerogel with surface area of 500 m2*g(-1) was demonstrated in full combustion of 1,2-dichloroethane (DCE) and chlorobenzene (CB). At gas hour space velocity (GHSV) of 46 000 h(-1), the total conversion to CO2/H2O/HCl was achieved at 330 degrees C (DCE) and 380 degrees C (CB). The combustion rate constants measured at standard conditions with 0.5% Pt/CrOOH catalyst were 1 or 2 orders of magnitude higher than measured with 15%Cr2O3/Al2O3 or 0.5%Pt/Al2O3, respectively. The effects of Pt, Au, Mn, and Ce additives on the performance of CrOOH aerogel in combustion of chlorinated VOC were analyzed related to the materials structure.
Low permeability and self-decontamination are extremely desired features for protective equipment against chemical warfare agents (CWAs). ∼4 nm TiO 2 nanoparticles were synthesized in the porous matrix of MCM-41 (45 wt%) as a novel reactive adsorbent for the degradation of sarin and VX. TiO 2 /MCM-41 (∼520 m 2 /g) was embedded in a polydimethylsiloxane (PDMS) sheet. PDMS was chosen as a model for an air-impermeable barrier with high permeability to CWAs. The incorporation of the reactive adsorbent decreased the diffusion coefficients, increased the breakthrough time, and dramatically decreased the desorption of sarin and VX vapors. The adsorbed CWAs in the hybrid matrix decompose (≥99%) to the nontoxic corresponding acids after 1 and 3 days for VX and sarin, respectively. This study demonstrates, for the first time, the potential of TiO 2 / MCM-41 as a reactive adsorbent embedded in polymeric matrices to improve the protection level and safety of protective equipment via combined adsorption and self-decontamination.
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