Nano-Scale Metal Oxide Particles as Reagents for Destruction and Immobilization of Hazardous Substances

Principal Investigators
K.J. Klabunde, Kansas State University

Abstract

Goal: Investigators are attempting to develop a new technology for one-step destruction of hazardous substances, including chlorocarbons, chlorofluorocarbons, organophosphorus, nitrogen, and sulfur compounds. This new technology is based on ultrahigh surface area metal oxides with reactive surfaces that behave as "destructive adsorbents" (surfaces that adsorb and break chemical bonds in the hazardous adsorbate). Research objectives are (1) to develop the best ways of synthesizing destructive adsorbents, (2) to understand the surface chemistry going on during the adsorption/destruction process, and (3) to develop a second generation of better destructive adsorbents based on multilayer oxide/oxide composites. Destructive adsorbent technology has promise as an alternative to incineration and for air purification systems.

Rationale: Organic compounds containing halogens can be complet ely destroyed under mild conditions using metal oxides. Destructive adsorbent technology has promise as an alternative to incineration and for air purification systems. Further research is needed to develop this technology so that it can be used in field applications.

Approach: Research work on the production of magnesium oxide, ferric oxide on magnesium oxide, and calcium oxide in nano-scale particle size and reactivity studies are being carried out. Adsorption and transformation of chlorinated hydrocarbons, phenols, and phosphorous compounds are being investigated.

Status: Work has been done with nanoscale calcium oxide (CaO) including Fourier Transform Infrared (FTIR) studies of the CCl4 + CaO reaction. In work on decomposition of trichloroethylene on CaO, trichloroethylene was adsorbed on calcium oxide at various temperatures under the pressure of 50 Torr of chlorocarbon. The amount of adsorbed TCE is determined by the gain in the weight of the oxide. The solid product is a black powder, CaOCl2 based on the powder XRD. Experiments related to surface area and OH groups on CaO revealed that autoclave prepared CaO has a larger number of OH groups compared to conventionally prepared CaO. Studies at lower temperatures are necessary to finish the comparison. A bench-scale fixed bed reactor has been built and is working well. Work on second generation destructive adsorbents has shown that [Mn2O3]MgO, [V2O3]MgO, [Fe2O3]MgO, and [Fe2O3]CaO are the most efficient for destructive adsorption. The [V2O3]MgO is the very best sample for the AP-MgO series. Experiments have been conducted with zero-valent met als to destroy chlorocarbons in water. Results from work with Znº + Cl2C = CHCl indicate that nanoparticle Znº is most reactive. Current work is aimed at determining products and material balance. This project is in its third year.

Clients/Users: Results of this research are of interest to other researchers and to those in private industry. Representatives from several government agencies have expressed interest in the research.

Key words: magnesium oxide, carbon tetrachloride, adsorption, calcium oxide.

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