SO2对硫酸雾干扰及其消除研究

针对《固定污染源废气硫酸雾的测定离子色谱法》在污染源测定过程中SO_2引入的正干扰问题,通过实验进行了干扰物确认及消除方式研究。结果表明,在无氧条件下,SO_2不会对硫酸雾产生正干扰,而在有氧气存在条件下标准方法中的碱性吸收液会吸收部分SO_2并最终转化为SO_4~(2-),使硫酸雾测定结果偏高。硫酸生产企业测定结果显示被吸收的SO_2约占其排放量的30%~59%。在原有吸收液中加入1%甲醛作为改进吸收液,可使采集到的SO_2以SO_3~(2-)形式稳定存在,不会对目标化合物SO_4~(2-)产生干扰且稳定时间至少为30 d。采用改进吸收液采集硫酸雾可有效防止SO_2引入正干扰,且对硫酸雾测定结果无影响。

Study on the Interference and Elimination of Sulfur Dioxide to Sulphuric Acid Mist

In order to solve the positive interference problem introduced by SO₂ in the determination process of pollution source in the "Stationary source emission-Determination of sulfuric acid mist-Ion chromatography", the identification and elimination methods of interference were studied through experiments.The experiment concluded that under anaerobic conditions, SO₂ did not cause positive interference to the sulfuric acid mist, while in the presence of oxygen, the alkaline absorption liquid in the original standard method absorbed part of SO₂ and could be converted into sulfate radical, which made the determination result of sulfuric acid mist higher.The results of sulphuric acid production enterprises showed that the absorbed SO₂ accounts for about 30% to 59% of its emissions.Adding 1% formaldehyde to the original absorbent liquid as an improved absorption liquid could keep the collected sulfur dioxide exist stably in the form of SO₃^2-, which did not interfere with the target compound SO₄^2-, and the stable time was at least 30d.The experimental results showed that the method of improving the absorption solution could effectively prevent the positive interference of SO₂ and had no effect on the determination results of sulfuric acid mist.