The simultaneous removal of sulfur dioxide and nitrogen dioxide by the limestone slurry with addition of organic acid additives

• Published in: The Korean journal of chemical engineering Vol. 38; no. 10; pp. 2064 - 2071
• Main Authors: Jeong, Ji Eun, Lee, Chang-Yong
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.10.2021; Springer Nature B.V; 한국화학공학회
• Subjects: Absorption; Acetic acid; Acids; Additives; Biotechnology; Catalysis; Chemistry; Chemistry and Materials Science; Efficiency; Environmental Engineering; Formic acid; Hydrophobicity; Industrial Chemistry/Chemical Engineering; Limestone; Materials Science; Nitrogen dioxide; Organic acids; Propionic acid; Slurries; Sulfur dioxide; Sulfur removal; 화학공학; Denitrification; Desulfurization; Simultaneous Removal; Absorption; Organic Acid Additive
• ISSN: 0256-1115; 1975-7220
• DOI: 10.1007/s11814-021-0850-0

This study investigates the effects of organic acid on the simultaneous absorption of SO 2 and NO 2 in the packed column. Organic acids, i.e., formic acid, acetic acid, and propionic acid, were used as additives. In the case of the absence of additives, when SO 2 and NO 2 were simultaneously absorbed into the limestone slurry, both SO 2 and NO 2 contributed to increasing the mutual absorption efficiency. In the simultaneous absorption of SO 2 and NO 2 with addition of additives, the SO 2 removal efficiency appeared in the order of formic acid<no addition<propionic acid<acetic acid. Acetic acid has a superior buffer capacity and intermediate hydrophobic interaction, resulting in the highest SO 2 absorption efficiency. In the slurry with the addition of acetic acid and propionic acid, the reactions of absorbed SO 2 and NO 2 predominantly took place; thus, the SO 4 2− /SO 3 2− ratio was greater than 1. In terms of formic acid, the slurry pH was maintained at approximately 4.0, which departs from the appropriate range, attributed to the small pKa value, showing a negative effect on SO 2 and NO 2 removal. In the slurry with formic acid added, the SO 2 predominantly reacted with formic acid; hence, the SO 4 2− /SO 3 2− ratio was less than 1.