OZONE DECOMPOSITION OVER ACTIVE COAL ANCHORED Cu(II), Co(II), OR Mn(II) CHLORIDES

Abstract

The known catalyst based on the inorganic support, MnCl2/SiО2, and used in personal respiratory protective devices showed its lack of prospects because of the very heavy load per a protective device and the short time of its protective action. As opposed to it, metal complex compositions based on activated carbons (AC) hold much promise. Since we intended to use activated carbons or compositions based on them in respirators protection against ozone, such an important parameter as the time of protective action was determined for activated carbons of different ranks and for the best one among MCl 2 /AC compositions (M is Cu, Co, or Mn, AC is activated carbon of KAD-iodnii rank) at initial ozone concentrations, СinО 3 , of 1,5 mg/m 3 and 10 mg/m 3 . For selection of the most effective MCl 2 /KAD-iodnii AC composition, the kinetics of ozone decomposition was investigated at СinО 3 = 500 mg/m3. The results of the latter testing showed that activity of the MCl2/KAD-iodnii AC compositions depended not only on the metal and anion nature but also on a degree of the activated carbon surface filling with metal ions. The maximum degree of ozone decomposition in a steady-state mode was demonstrated by MnCl 2 /KAD-iodnii AC. This fact can be explained by MnO 2 formation as a result of MnCl 2 oxidation with ozone. MnO 2 can be a secondary catalyst and stabilize the process of ozone decomposition. The time of protective action for activated carbons significantly depends on their chemical nature and specific micropore and mesopore volumes and increases in the order SKN-K < ART < KAD-iodnii < AG-3 < SKN-2M. MnCl2 anchoring on activated carbon of KAD-iodnii rank resulted in an essential increase in the time of protective action: an ozone outlet concentration was lower than MPCO 3 even in 48 hours. The protective properties of the catalyst for ozone microconcentration decomposition obtained by activated carbon of KADiodnii rank impregnation with MnCl2 are much better than those of the known domestic and foreign analogues and this composition can be used in the devices for protecting environment and human beings against ozone.