A New Concept of Desulfurization: The Electrochemically Driven and Green Conversion of SO2 to NaHSO4 in Aqueous Solution

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• 作者：Chuan Wang ; Hong Liu ; Xiang-Zhong Li ; Jianying Shi ; Gangfeng Ouyang ; Min Peng ; Chengchun Jiang ; Hua’ ; nan Cui
• 刊名：Environmental Science & Technology
• 出版年：2008
• 出版时间：November 15, 2008
• 年：2008
• 卷：42
• 期：22
• 页码：8585-8590
• 全文大小：217K
• 年卷期：v.42,no.22(November 15, 2008)
• ISSN：1520-5851

文摘

A new concept of desulfurization was developed by designing a series of electrochemical reactions to drive an SO₂ absorption-and-conversion process in aqueous solution, hence the SO₂ in gas was eventually converted to a valuable chemical of NaHSO₄. A model experiment of chemically substantiating this concept includes two steps: (I) absorption of SO₂ gas by aqueous solution and oxidation of the absorbed SO₂ to SO₄²⁻ by air and (II) transformation of the SO₄²⁻ to NaHSO₄. The experiment demonstrated that in Step I, the cathodic reduction of O₂ from ambient air scavenged the H⁺ released due to the SO₂ absorption and its further oxidation, which thereby were accelerated. Meanwhile H₂O₂ as a cathodic product further enhanced the SO₂ oxidation. In Step II, the anodic oxidation of H₂O supplied H⁺ and allowed the NaHSO₄ formation through balances of electrons and mass. Thereafter, a pH range of 5.0−6.0 for the SO₂ oxidation was optimized, and an electrochemically driven process for the SO₂ conversion to NaHSO₄ was proposed. Sustainability evaluation indicated that this concept complies with the principles of green chemistry and potentially enables the SO₂ conversion from flue gas to NaHSO₄ as a value-added process.