Dissertations and Theses
Date of Award
2022
Document Type
Thesis
Department
Engineering
First Advisor
Marco Castaldi
Keywords
Sodium thiosulfate, I2 removal, Waste-to-energy, Combustion, Sulfur dioxide, Atmospheric pollutant
Abstract
The aim of this work was to study the performance of sodium thiosulfate in several systems. Sodium thiosulfate decomposition and SO2 conversion were analyzed using thermogravimetric analysis combined with chromatographic techniques. Thermogravimetric analysis (TGA) measurements determined the decomposition of the acidification reaction of 30% sodium thiosulfate solution in a 14% carbon dioxide (CO2) atmosphere and 1% hydrochloric acid (HCl) solution in the temperature regime of 300 - 750 K. Sodium thiosulfate and sulfur dioxide (SO2) are considered effective methods for removing iodine (I2) from air and flue-gas streams respectively. In acid containing gas-streams where the SO2 content is determined by the incoming feedstock, sodium thiosulfate can be utilized to produce a specific amount of SO2 which is particularly effective in waste-to-energy combustion-gas as a halogen capture agent. The effectiveness of sodium thiosulfate was measured as the rate of iodine removal, defined as the product of SO2 concentration and the moles of iodine absorbed by the thiosulfate. The evolution of SO2 was measured as a result of sodium thiosulfate thermal decomposition to SO2 with a micro-GC, whereby the maximum conversion efficiency was determined to be approximately 37% over a range of temperatures. In addition, the results were verified by experimental data obtained from field studies. A second group of experiments were done to understand the behavior of 30% weight sodium thiosulfate solution in an I2 atmosphere where a mass gain was measured over the range of 11 to 17%. Non-isothermal TGA data in nitrogen (N2) and 14% CO2 atmosphere at different heating rates comprised between 15 and 45 K min−1 were used to obtain the apparent activation energy (Ea) of the thermal degradation process of sodium thiosulfate in all reactions by isoconversional methods. The apparent activation energies for sodium thiosulfate decomposition were found to be 10.95 – 12.34 kJ/mol in CO2 atmosphere, 9.48 – 11.68 kJ/mol in HCl and CO2 atmosphere, and 10.97 – 14.47 kJ/mol in I2 atmosphere. Bunsen reaction parameters were compared to literature data for each experiment, which reveals a good correlation to the overall reaction rate.
Recommended Citation
Arapi, Anjeza, "Investigations of the Therman Treatment of Sodium Thiosulfate in Gas Streams for the Removal of I2" (2022). CUNY Academic Works.
https://academicworks.cuny.edu/cc_etds_theses/1129
Included in
Catalysis and Reaction Engineering Commons, Other Engineering Commons, Thermodynamics Commons