With the intensification of air pollution and the continuous improvement of people's awareness of environmental protection, the haze problem has aroused widespread concern. Ammonia can directly participate in and accelerate the formation of ammonium salts in the atmosphere, which also contributes to the formation of haze particles in the atmosphere. Plays a vital role.

Regarding the formation of ammonium sulfate in the atmosphere, the traditional view is that sulfur trioxide (SO3) first reacts with water to form sulfuric acid, and then further reacts with ammonia gas (NH3) to produce ammonium sulfate. However, the study found that ammonia gas can directly participate in the reaction of sulfur trioxide and water.

In the simulation experiment, the process of spontaneous reaction of ammonia molecules and sulfur trioxide molecules in water clusters to form ammonium bisulfate (NH4HSO4) was directly observed. During the reaction, ammonia gas and sulfur trioxide form a special ring structure with water clusters. The formation of this ring structure greatly promotes the transfer of hydrogen atoms in water molecules to ammonia molecules, thereby forming ammonium ion. At the same time, hydroxide radicals quickly combine with sulfur trioxide molecules to form hydrogen sulfate radicals. Through further reaction transition state search, the reaction path was confirmed. 

They found that the presence of the third water molecule in the three-molecule water cluster helped the formation of the ring structure, and the ring structure could reduce the reaction energy barrier to almost It is zero, which greatly increases the formation rate of ammonium bisulfate in atmospheric water clusters.

At present, in the formation of PM2.5, everyone pays more attention to primary particulate matter, sulfur dioxide, nitrogen oxides, and volatile organic compounds. However, relevant experts pointed out that ammonia gas actually plays an important role in the formation of PM2.5.

Research based on the formation mechanism of ammonia gas in PM2.5 is continuously disclosed. In the future, in the process of smog treatment, measures to carry out large-scale ammonia gas detection to control ammonia gas emissions may receive more and more attention. At present, the main principles adopted by the ammonia gas detector are chemiluminescence method, TDLAS, electrochemical method, infrared method, etc. The related instruments involved will have more demand in the environmental protection industry.