Analytical Chemistry of the Citrate Process for Flue Gas Desulfurization

摘要

The citrate process for flue gas desulfurization (FGD) is a product of continuing research by the U.S. Bureau of Mines to meet the goal of minimizing the objectionable effects of minerals industry operations upon the environment. The reduction of SO2 in solution by H2S to produce elemental sulfur by the citrate process is extremely complex and results in solutions that contain at least nine different sulfur species. Process solution analysis is essential to a clear understanding of process chemistry and its safe, efficient operation. The various chemical species, the approximate ranges of their concentrations in citrate process solutions, and the analytical methods evolved to determine them are hydrogen sulfide by specific ion electrode, polysulfides (unknown) by ultraviolet (UV) spectrophotometry, elemental sulfur by UV spectrophotometry, thiosulfate by iodometry or high performance liquid chromatography (HPLC), polythionates by thin layer chromatography (TLC), dithionite (searched for but not detected in process solutions) by polarography or TLC, bisulfite by iodometry, sulfate by a Bureau-developed gravimetric procedure, citric acid by titration or visible colorimetry, glycolic acid HPLC, sodium flame photometry, and chloride by argentometric titration.