Treatment of gaseous streams polluted with H 2 S: Comparison of electrolytic and electro-Fenton assisted absorption processes.

H ₂ S is a gaseous compound that contributes to air pollution. In this work, the electrochemical oxidation treatment of gaseous streams polluted with H ₂ S is evaluated using a jet mixer and electrochemical cell device, in which the performance of electrolytic and electro-Fenton assisted absorption processes are compared. Results demonstrate the feasibility of both processes to remove H ₂ S, reaching coulombic efficiencies of nearly 100% in the electrolytic assisted absorption, and 70-80% in the electro-Fenton assisted absorption. Aqueous solutions containing phosphate salts as electrolyte were found to be suitable as absorbents for the process. Efficiency in the cathodic production of H ₂ O ₂ in these solutions using the experimental device was found to be as high as 32.8% (1.184 mgH ₂ O ₂ /min) at 12 °C and atmospheric pressure. Sequential formation of SO ₂ and SO ₃ is obtained by the oxidation of H ₂ S contained in the gas. These species are hydrolysed, and a part remained in the absorbent as SO ₃ ^2- and SO ₄ ^2- , while the rest is dragged in the outlet gas. SO ₃ production is promoted by electrolytic assisted absorption and polysulphides by the electro-Fenton technology. Low concentrations of elemental sulphur are detected in the solid suspensions formed during the process.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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