Сорбція сульфур (IV) оксиду деякими видами сухої рослинності

Abstract

Sulfur dioxide is one of the most dangerous pollutants in the air. The leaves of plants perform a filtering function and absorb SO2 from the atmosphere. As a result - spots appear on the leaves - necrosis. Dry vegetation has a porous structure, so it absorbs dust and toxic gases more intensively. Absorbed Sulfur dioxide re-enters the air during seasonal burning of dry leaves and grass, creating dangerous to human health local excess concentrations. Leaves of common in the Transcarpathian region and Ukraine field plants plantain, meadow fescue, nettle and burdock were used for the study. Sulfur dioxide, formed by the interaction of concentrated sulfuric acid and crystalline sodium sulfite, was pumped through series-connected absorption containers with dry leaves and a solution of potassium chlorate, which oxidized excess of sulfur dioxide to sulfate ions. The concentration of sulfate ions was determined titrimetrically. Gas transmission was carried out at temperatures of 22oC and 0oC. The obtained results have been shown decreasing of specific sorption with a temperature decreasing. Probably, this is due to the narrowing of pores and reducing of dry leaf fibers permeability. Measurement of the total and specific surface area of plants made it possible to estimate their total surface area, formed by smooth sections, protrusions and cracks. The specific surface area increases in a number of plantain-burdock-nettle-meadow fescue. At a temperature of 22oC, a direct relationship between the specific surface area and the sorption capacity has not been established. It indicates the participation in the process of gas absorption not only of the surface , but also internal pores. Therefore, to approximate the porosity of the studied samples of dry leaves, the bulk density of crushed and sifted through calibrated sieves of dry biomass was measured. The obtained results make it possible to conclude that at 22 ° C burdock leaves absorb the largest amount of sulfur dioxide among the studied plant species. At 0ºС the largest amount of SO2 is sorbed by meadow fescue. The mass of sorbed gas is from 18 to 34% of the mass of dry leaves (in terms of green biomass - from 4 to 9%).

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