Abstract:

The resource recycling of flue gas pollution is the developing direction of exhaust pollutant treatment. In order to explore the feasibility of the direct electrolysis process for resource recycling of the absorption solution from the ammonia-based wet desulfurization and denitrification, the effect of electrolyte compositions and concentrations, temperature, current densities, flow rate, electrolytic time and impurities of absorption on current efficiency of persulfate production were investigated in a two-compartment electrolytic cell under batch recirculation. The experimental results indicated that urea and ammonia has inhibitory effect on current efficiency, while ammonium sulfite and nitrite existing in anode chamber showed no significant influence on current efficiency. The current efficiency of simulated absorbent solution decreased to 69.88%, which was much lower than 86.98% by the pure ammonium sulfate electrolysis process under the optimal condition. Therefore, necessary pretreatments for the absorption solution, which contained the removal of heavy metal ions and urea, the oxidation of sulfite and the adjustment of pH, must be adopted before entering the electrolysis system. Using the pretreated absorption solution, the current efficiency could reach to 85.12%. The electrolytic reactor could effectively produce persulfate in anodic chamber and hydrogen by-product in cathodic chamber at the same time. Furthermore, the remainder solution after crystallization could be coupled with circulation absorption solution, and thus improving the denitrification efficiency. Therefore, it is a novel environmentally effective technology for flue gas cleaning with great prospects for development.

Key words: resource recycling, ammonium persulfate, desulfurization and denitrification, electrolysis, hydrogen

摘要：

燃煤烟气污染物资源循环利用是烟气污染治理的发展方向，为探究直接电解氨基湿法脱硫脱硝吸收液制备过硫酸铵进行资源化回收的可行性，在板框式隔膜流动电解槽中考察了硫酸铵浓度、硫氰酸铵浓度、硫酸浓度、温度、电流密度、流速、电解时间以及吸收液中杂质成分等工艺参数对电解制备过硫酸铵的影响特性。结果表明，吸收液中的尿素和氨水对电流效率有抑制作用，而SO₃^2-和NO₃^-对电流效率几乎没有影响，模拟吸收液的电流效率仅为69.88%，远低于单一电解硫酸铵溶液86.98%的电流效率。对吸收液采取去除尿素、亚硫酸根氧化和吸收液pH调节（pH=2.2）预处理后，其电流效率达到85.12%。氨基湿法脱硫脱硝吸收液电解工艺不仅可高效制备过硫酸铵，阴极还可副产氢气，电解结晶后余液进一步与氨基湿法脱硫脱硝循环吸收液耦合，还可较大提升烟气脱硝效率，是一种新型的绿色高效的烟气净化技术路线，具有极大的发展前景。

关键词: 资源化, 过硫酸铵, 脱硫脱硝, 电解, 氢气