Simultaneous Removal of NO_x and SO₂ through a Simple Process Using a Composite Absorbent

• Main Authors: Ping Fang, Zijun Tang, Xiongbo Chen, Peiyi Zhong, Jianhang Huang, Zhixiong Tang, Chaoping Cen
• Format: Article
• Language: English
• Published: MDPI AG 2018-11-01
• Series: Sustainability
• Subjects: NO_x; SO₂; NaClO₂; Na₂S₂O₈; wet scrubbing
• Online Access: https://www.mdpi.com/2071-1050/10/12/4350

In this work, the feasibility of the simultaneous removal of NO_x and SO₂ through a simple process using a composite absorbent (NaClO₂/Na₂S₂O₈) was evaluated. Factors affecting the removal of NO_x and SO₂, such as NaClO₂ and Na₂S₂O₈ concentrations, solution temperature, the initial pH of solution, gas flow rate, and SO₂, NO, and O₂ concentrations were studied, with a special attention to NO_x removal. Results indicate that a synergistic effect on NO_x removal has been obtained through combination of NaClO₂ and Na₂S₂O₈. NaClO₂ in the solution played a more important role than did Na₂S₂O₈ for the removal of NO_x. The above factors had an important impact on the removal of NO_x, especially the solution temperature, the initial pH of the solution, and the oxidant concentrations. The optimum experimental conditions were established, and a highest efficiency of NO_x removal of more than 80% was obtained. Meanwhile, tandem double column absorption experiments were conducted, and a NO_x removal efficiency of more than 90% was reached, using NaOH solution as an absorbant in the second reactor. A preliminary reaction mechanism for NO_x and SO₂ removal was deduced, based on experimental results. The composite absorbent has the potential to be used in the wet desulfurization and denitration process, to realize the synergistic removal of multi-pollutants.