The Synthesis of Nanophase, High Surface Area CaO and MgO for DAT Application

Nanoscale, highly reactive metal oxide powders with very high surface areas are required as destructive adsorbents to treat hazardous substances. Destructive Absorption Technology (DAT) is a non-polluting treatment process that has demonstrated the capability of treating hazardous substances and allows for reclamation of valuable byproducts. But currently, DAT performance is dependent upon the synthesis and use of ultrafine (nanoscale), highly reactive metal oxides such as CaO and MgO. A supercritical CO(2) process is proposed for the synthesis of nanoscale CaO and MgO powders that have very high surface areas. Supercritical CO(2) is a novel solvent that enable precise control of primary crystallite size, aggregate size and distribution, and particle surface area. The process will operate in a closed-loop configuration; CO(2) is abundant, environmentally benign, inexpensive ($ 0.05/lb.), and has reasonable critical parameters that enable this process to be economically scaled to produce large quantities of powder. Commercial CaO or MgO will be solubolized in CO(2). Nucleation, particle growth, and surface area will be determined by controlled expansion of the CO(2) solution. Powder surface area will be correlated with destructive capacity using various stimulants and chlorinated solvents as substrates. Nanophase Technologies Corporation is a commercial producer of nanoscale powders by the GPC process and is developing a range of catalytic applications for our powders. During Phase II a prototype DAT reactor will be built and tested for a range of hazardous substances.