Preparation, Characterization, and Application of Modified Chitosan Sorbents for Elemental Mercury Removal

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• 作者：Anchao Zhang ; Jun Xiang ; Lushi Sun ; Song Hu ; Peisheng Li ; Jinming Shi ; Peng Fu ; Sheng Su
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2009
• 出版时间：May 20, 2009
• 年：2009
• 卷：48
• 期：10
• 页码：4980-4989
• 全文大小：369K
• 年卷期：v.48,no.10(May 20, 2009)
• ISSN：1520-5045

文摘

A series of raw, iodine (bromide) or/and sulfuric acid-modified chitosan sorbents were synthesized and comprehensively characterized by N₂ isotherm adsorption/desorption method, TGA, FTIR, XRD, and XPS et al. Adsorption experiments of vapor-phase elemental mercury (Hg⁰) were studied using the sorbents in a laboratory-scale fixed-bed reactor. The results revealed that porosities and specific surface areas of the sorbents decreased after modification. The sorbents operated stably at flue-gas temperature below 140 °C. The chemical reactions of iodine and sulfate ion with the amide of chitosan occurred, and the I₂ was found in the sorbents due to the presence of H₂SO₄. Fixed-bed adsorber tests showed that compared to raw chitosan, the bromide or iodine-modified chitosan could promote the efficiency of Hg⁰ capture more or less. Mercury removal efficiency could be significantly promoted when an appropriate content of H₂SO₄ was added, and the iodine and H₂SO₄ modified sorbents almost had a mercury removal efficiency of 100% for 3 h. The presence of moisture can increase the sorbent’s capacity for mercury uptake due to the existence of active sites, such as sulfonate and amino group. The mercury breakthrough of modified chitosan sorbents decreased with increasing temperature. A reaction scheme that could explain the experimental results was presumed based on the characterizations and adsorption study.