Destructive Adsorption of Chlorinated Hydrocarbons on Ultrafine (Nanoscale) Particles of Calcium Oxide. 3. Chloroform, Trichloroethene, and Tetrachloroethene

As a one-step approach to the safe destruction of chlorocarbons, the reactions of trichloroethene, chloroform, and tetrachloroethene with ultrafine particles of calcium oxide have been studied. Calcium oxide prepared by an aerogel/hypercritical drying method (AP-CaO) is generally superior to conventionally prepared (CP-CaO) and vastly superior to commercially available (CM-CaO) samples, although in higher temperature reactions with C 2 Cl 4 CP-CaO exhibited higher capacity but slower reaction kinetics. The main reaction products of CaO with C 2 HCl 3 were CaCl 2, H 2 O, CO and C; with CHCl 3 were CaCl 2, H 2 O and CO and with C 2 Cl 4 were CaCl 2, CaCO 3, and C. Reaction temperatures were 300−500 °C, and optimum temperatures were found. If temperatures were too low, reaction efficiencies were low and if too high, efficiencies could also go down due to graphite formation which could block reactive sites.