Shih Ger Chang

Effects of metal chelates on wet flue gas scrubbing chemistry

Addition of metal chelates in a wet stack gas scrubber to improve removal efficiency of both NO and SO/sub 2/ could provide a major new dimension to environmental control technology without requiring major capital modification to existing power plants. Criteria for an effective metal chelate additive include large absorption capacity and rapid binding rate of NO, and rapid regeneration rate of metal chelates from nitrosyl metal chelates by reaction with absorbed SO/sub 2/ in aqueous solutions. The thermodynamics and kinetics of chemical reactions involved are discussed. Laser Raman spectroscopy, gas chromatography, and mass spectrometry have been employed to directly and unambiguously identify some reaction intermediates and products.

Identification of species in a wet flue gas desulfurization and denitrification system by laser Raman spectroscopy

Raman spectra have been obtained for a number of intermediates and products of the reaction of nitrite iron with bisulphite ion. This is the first direct observation of all stable species in this reaction system. The dynamics of the species have been investigated at several nitrite and bisulphite concentrations that resemble those found in realistic power plant flue gas wet scrubbers.

Effect of simple anions and metal ions on the hydrolysis of disulfate ion

This paper reports on the influence of anions and cations commonly found in flue gas scrubber systems on the hydrolysis rate of disulfate ion (S{sub 2}O{sub 7}{sup 2{minus}}) that has been studied. The cations studied include Na{sup +}, K{sup +} Ca{sup 2+}, Mg{sup 2+}, and Mn{sup 2+}. The anions studied include SO{sub 3}{sup 2{minus}}, SO{sub 4}{sup 2{minus}}, S{sub 2}O{sub 3}{sup 2{minus}}, S{sub 2}O{sub 6}{sup 2{minus}}, HSO{sub 3}{sup {minus}}, Cl{sup {minus}}, H{sub 2}PO{sub 4}{sup {minus}}, and HPO{sub 4}{sup 2{minus}}. Of the ions studied, Ca{sup 2+}, Mg{sup 2+}, SO{sub 3}{sup 2{minus}}, and S{sub 2}O{sub 6}{sup 2{minus}} were found to approximately double the rate of S{sub 2}O{sub 7}{sup 2{minus}} hydrolysis. Adipic acid was found to have no effect on S{sub 2}O{sub 7}{sup 2{minus}} hydrolysis. Activation energies for the S{sub 2}O{sub 7}{sup 2{minus}} hydrolysis rate accelerated by Ca{sup 2+}, Mg{sup 2+}, and SO{sub 3}{sup 2{minus}}, as well as for the unenhanced rate, were found to be in the range of 9-12 kcal/mol.