NATURAL CLINOPTILOLITE ANCHORED CHLORIDES OF 3D METALS IN THE REACTION OF LOW-TEMPERATURE SULFUR DIOXIDE OXIDATION WITH AIR OXYGEN

Such adsorbents as natural aluminosilicates and activated coal and such chemisorbents as transition metal oxides are commonly used for cleaning gas emissions from sulfur dioxide. The main disadvantage of the latters except for manganese oxides is that high temperatures (up to 800 °C) are needed for the reaction proceeding. However sulfur dioxide can be oxidized to H2SO4 in conformity with complicated mechanisms in aqueous solutions of coordination compounds of copper(II,III), iron(II,III), manganese(II) and cobalt(II) at ambient temperature. Three types of mechanisms of interaction between sulfur dioxide and air oxygen can be considered as most probable: the chain-radical mechanism with single-electron transfer, the non-radical mechanism with two-electron transfer, and the combined mechanism having some elements of two above-mentioned mechanisms. We studied the reaction of sulfur dioxide oxidation by air oxygen over natural clinoptilolite anchored chlorides of 3d metals (MCl2/NCLI where М = Cu2+, Co2+, Mn2+, and Cd2+). It has been found that the amounts of sulfur dioxide reacted (Qexp) at all CMCl2 are far more, than Qexp in the case of pure N-CLI. That is 3d metal chlorides can affect the reaction of sulfur dioxide oxidation with air oxygen. However the mechanisms of their action depend on the nature of the metal ion and its concentration. This phenomenon can be seen from the values of Qexp, tMPC (a time of protective action, i.e. a period of time from experiment beginning up to the moment when C fSO2 achieves its maximum permissible concentration (MPC), 10 mg/m3), and t1/2 (a half-conversion time, i.e.a period of time from experiment beginning up to the moment when C fSO2b ecame equal to 0.5C in SO2 ) . For instance, at CMCl2 = 2.9×10-5 mol/g, Qexp, tMPC and t1/2 decrease in the order Mn(ІІ)> Cu(ІІ) > Cd(ІІ) > Co(ІІ), whereas at CMCl2 = 11.7 ∙10-5 mol/g, the order changes as follows: Cu(ІІ) > Co(ІІ) > Cd(ІІ) > Mn(ІІ). Thus, comparing the results of our experiments and the data for resolved 3d metal chlorides reported in literature, a certain similarity can be traced