大気汚染物質除去に関する研究 : (6) EDTA・Fe (II) 添加 MgSO_3 スラリーによる希薄 NO, SO_2 の単一および同時吸収

Abstract

The absorption rates of (1) NO in aqueous solutions of (Fe)^<II>-EDTA, (2) NO in aqueous solutions or slurries of MgSO_3 with added (Fe)^<II>-EDTA, and (3) NO in the presence of SO_2 in aqueous slurries of MgSO_3 with added (Fe)^<II>-EDTA were measured using a stirred vessel with a plane gas-liquid interface at 25℃ and 1atm. The forward rate constant of the complexing reaction, NO+(Fe)^<II>-EDTA &rlarr; (Fe)^<II> (EDTA)(NO), at various pH's was derived from the enhancement factor for absorption of NO in aqueous solutions of (Fe)^<II>-EDTA. The reduction of NO coordinated to (Fe)^<II>-EDTA with SO_3^<2-> is found to be very slow as compared with the above complexing reaction. Coexisting SO_2 can promote the absorption rate of NO by aqueous slurries of MgSO_3 with (Fe)^<II>-EDTA. It is believed that coexisting SO_2 plays a part of releasing SO_3^<2-> from the complex (Fe)^<II> (EDTA)(SO_3^<2->)(NO) and that the presence of SO_2 in the gas phase effectively improves the pH of the solution at the interface toward favorable values for the reaction of NO with (Fe)^<II>-EDTA.