Ultrafine metal oxides dismantle chlorinated organics
Researchers at Kansas State University (Manhattan) have developed a low-temperature, noncatalytic process that destroys chlorinated organic compounds without creating harmful byproducts. The process, dubbed destructive adsorption, uses ultrafine particles of several common metal oxides to convert chlorocarbon molecules into metal chlorides and carbon oxides. To date, the process has only been demonstrated for the bench-scale decomposition of carbon tetrachloride (CCl{sub 4}). However, Colorado-based NanTech has recently been awarded a grant to develop the process for commercialization. Certain metal oxides, such as CaO and MgO, react favorably with many of the chlorinated organics commonly found in industrial exhaust streams, and in the organics-laden vapors commonly recovered during soil and groundwater remediation. In the presence of chlorinated compounds such as carbon tetrachloride (CCl{sub 4}), chloroform (CHCl{sub 3}), tetrachloroethylene (C{sub 2}Cl{sub 4}) and chlorobenzene (C{sub 6}H{sub 5}Cl), these metal oxides adsorb chlorine atoms to form metal chlorides (MgCl{sub 2} or CaCl{sub 2}), and their oxygen atoms combine with carbon in the organics to form CO and CO{sub 2}. While these reactions are favorable from a thermodynamic standpoint (all are mildly exothermic), reaction rates are kinetically limited, because they involve solid-gas or solid-liquid reactions. As the metal chloride forms on the surface of the metal oxide, the resulting salt buildup gradually impedes--and eventually prevents--the reaction between the metal oxide and the chlorocarbon compound. To overcome this obstacle, the Kansas State researchers experimented with extremely small particles of metal oxides--less than 25 nanometers dia.--to maximize overall surface area. This increased the reactivity and the capacity of the metal oxide particles.
- OSTI ID:
- 87582
- Journal Information:
- Environmental Engineering World, Journal Name: Environmental Engineering World Journal Issue: 4 Vol. 1; ISSN EEWOFR; ISSN 1079-3186
- Country of Publication:
- United States
- Language:
- English
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