The hazards of nitrogen oxides

Nitrogen oxides are made up of different compounds, nitrogen dioxide being the most important. Nitrogen oxides have many harmful effects and may cause cancer. It can have very serious effects on the human body, and the key is that it can also produce ozone. Ozone is a kind of destruction to nature. Various substances react to form nitrogen oxides, which eventually form acid rain, which is corrosive.

1. NO will combine with hemoglobin in the blood, reducing the blood's oxygen transport capacity and causing hypoxia;

2. NO is carcinogenic and can have adverse effects on cell division and genetic information;

3. In the atmosphere, NO will be slowly oxidized into N02 under the action of 02. The generated N02 enters the human respiratory system and causes lung and bronchial diseases;

4. NO2 is the precursor of nitric acid and nitrous acid in acid. Under ultraviolet light, NO2 will react with carbon oxides in the atmosphere to generate photochemical smog and ozone.

5. The acid rain and photochemical smog generated will cause large-scale death of crops and forests. Acid rain will also corrode buildings and equipment. Photochemical smog has obvious carcinogenic effects. Ozone in the near-ground atmosphere will cause great damage to the central nervous system.

Nitrogen oxide pollution to the environment has become an increasingly serious global problem. Its impact on the atmosphere mainly includes acid rain and higher ground ozone concentration, and it also participates in the formation of suspended dust in the air. Nitrogen oxides are one of the important pollutants in the atmosphere, including N20, NO, N202, N203, N02, N204 and N205. Among them, NO and N02 are the main pollutants to the atmosphere, among which NO accounts for 95% of the NOx in typical coal-fired flue gas, and the rest is mainly N0216l.

In addition, NOx can form nitric acid and nitrate fine particles in the atmosphere, which, together with sulfuric acid and sulfate fine particles, are transported over long distances, thereby accelerating the deterioration of regional acid rain. Studies have shown that the contribution of HN03 to acid rain is on the rise, and the ratio of N037S042' in precipitation is gradually increasing across the country. At present, SO2 emissions have been comprehensively controlled in combination with the division of the two control zones. However, the rapid growth of total NOx emissions and the increase in its atmospheric concentration and oxidizability may offset the control effect on SO2, making it impossible to fundamentally control the worsening trend of acid rain. The increase in NOx emissions will make the already severe acid rain pollution even worse. Moreover, some surveys have shown that NOx tends to replace SO2 as the main cause of acid rain. For a long time, acid rain has caused great harm to crops, forests, groundwater and buildings. In China alone, the area of ​​farmland polluted by acid rain has reached 40 million mu, and the annual agricultural economic losses are more than 1.5 billion yuan.

NOx can also react with stratospheric ozone through reactions (1-1) and (1-2), causing stratospheric ozone depletion and resulting in an ozone hole. In addition, NOx also contributes to the formation of suspended dust. In short, nitrogen oxides can cause serious damage to human health, the ecological environment and the national economy. The Science and Technology Policy Research Institute of the Science and Technology Agency of Japan conducted a forecast survey on the development of science and technology before 2020. The survey results announced in 1993 were: technology for removing nitrogen oxides that pollute the atmosphere was listed as the first of 12 major technological topics in the next 30 years. The National Environmental Science and Technology Development "15th Five-Year Plan" proposed to "vigorously promote the research of low nitrogen oxide emission technology, carry out flue gas nitrogen oxide purification technology and its industrial demonstration research 1121". It can be seen that the elimination of NOx has also become the hottest issue in the field of air pollution control.