What Is the Connection Between Acid Rain and Sulfuric Acid?

Acid rain is wet deposition in acid precipitation. Acid precipitation can be divided into two categories: "wet deposition" and "dry deposition". The former refers to all gaseous or granular pollutants. With rain, snow, fog or hail Those who fall to the ground in the form of precipitation, the latter refers to the acidic substances carried by the falling dust from the air on days when it does not rain. Acid rain is divided into nitric acid rain and sulfuric acid rain.

Acid rain refers to rain or snow or other forms of precipitation with a pH less than 5.6. ^[1]

A sample of acid rain collected somewhere is not yet considered

Acid rain

The anions in acid rain are mainly nitrate and sulfate ions. According to the concentrations of the two in acid rain samples, it can be determined whether the main factor affecting precipitation is sulfur dioxide or nitrogen oxides. Sulfur dioxide mainly comes from

Acid rain can cause

1. Discharge and conversion conditions of acidic pollutants. Generally speaking, the more serious the SO2 pollution in a certain place, the

China began to observe and investigate acid rain pollution in the 1980s. In the 1980s, acid rain in China mainly occurred in Chongqing, southwestern regions represented by Guiyang and Liuzhou. The area of acid rain was about 1.7 million square kilometers. By the mid-1990s, acid rain had developed to the south of the Yangtze River, east of the Qinghai-Tibet Plateau and a large area of the Sichuan Basin. The area of acid rain had expanded by more than 1 million square kilometers. The acid rain areas in Central China represented by Changsha, Ganzhou, Nanchang, and Huaihua have become the areas with the most severe acid rain pollution in the country. The average precipitation pH in the central area is lower than 4.0, and the frequency of acid rain is as high as 90% or more. Must be sour ". The coastal areas of East China represented by Nanjing, Shanghai, Hangzhou, Fuzhou and Xiamen have also become the main acid rain areas in China. It is worth noting that acid precipitation occurs frequently in Beijing and Tianjin in North China, Dandong in Northeast, and Tumen. The area with an average annual pH value below 5.6 already accounts for about 40% of China's land area. The chemical characteristics of acid rain in China are low pH, and the concentrations of sulfate (SO42-), ammonium (NH4 +), and calcium (Ca2 +) ions are much higher than those in Europe and America, while the concentration of nitrate (NO3-) is lower than in Europe and America. Studies have shown that the molar ratio of sulfate to nitrate in acidic precipitation in China is about 6.4: 1. Therefore, acid rain in China is sulfuric acid type, which is mainly caused by man-made SO2 emissions. Therefore, controlling SO2 emissions in China has a decisive effect on the management of acid rain in China.

1. Develop new energy sources, such as hydrogen, solar, hydro, tidal, and geothermal energy.

2. Use coal-fired desulfurization technology to reduce sulfur dioxide emissions.

3. Discharge the industrial production exhaust gas after treatment.

4. Drive less and travel more by public transport.

5. Use cleaner energy such as natural gas and less coal ^[2]

Acid Rain International Response

Many countries in Europe and North America, where the acid rain is the worst in the world, have suffered from acid rain for many years, and finally realized that the atmosphere has no borders. The prevention and control of acid rain is an international environmental problem. It cannot be solved by one country alone. We must take countermeasures together. Reduce emissions of sulfur oxides and nitrogen oxides. After several consultations, the "Convention for the Control of Long-Range Transboundary Air Pollution" was adopted at the United Nations Economic Commission for Europe's Environment Ministers' Meeting in Geneva in November 1979, and entered into force in 1983. The Convention stipulates that by the end of 1993, the State party must reduce its sulfur dioxide emissions to 70% of its 1980 emissions. 32 countries including Europe and North America (including the United States and Canada) have signed the convention. In order to fulfill their promises, most countries have adopted active countermeasures and formulated regulations to reduce acid emissions. For example, the "Acid Rain Act" of the United States stipulates that the sulfur dioxide emissions from the east of the Mississippi River must be reduced from 20 million tons / year in 1983 to 10 million tons / year after 10 years; the sulfur dioxide emissions in Canada have been reduced from 470 in 1983 10,000 tons / year, reduced to 2.3 million tons / year by 1994, etc. ^[5]

Acid rain specific measures

At present, the main measures to reduce sulfur dioxide emissions in the world are:

1. Raw coal desulfurization technology can remove about 40% to 60% of inorganic sulfur in coal combustion.

2. Prioritize the use of low-sulfur fuels, such as low-sulfur low-sulfur coal and natural gas.

3. Improve coal combustion technology and reduce emissions of sulfur dioxide and nitrogen oxides during coal combustion. For example, liquefied coal combustion technology is one of the new technologies welcomed by countries. It mainly uses limestone and dolomite, reacts with sulfur dioxide, and generates calcium sulfate to be discharged with ash.

4. The flue gas formed after the combustion of coal is subjected to flue gas desulfurization before being discharged into the atmosphere. At present, the lime method is mainly used to remove 85% to 90% of sulfur dioxide gas in the flue gas. However, the desulfurization effect is good but expensive. For example, the cost of installing a flue gas desulfurization device in a thermal power plant can reach as much as 25% of the total investment in the power plant. This is also one of the main difficulties in controlling acid rain.

5. Develop new energy sources, such as solar energy, wind energy, nuclear energy, and combustible ice.

6. Biological control: At the "International Conference on the Application of Environmentally Sound Biotechnology," held in India in 1993, experts proposed the use of biotechnology to prevent, prevent and reverse environmental degradation, enhance the sustainable development and application of natural resources, and maintain the environment Measures of integrity and ecological balance. At present, scientists have found that microorganisms that can remove sulfur in pyrite include Thiobacillus ferrooxidans and Thiobacillus oxidans. A new technology developed by the Japan Electric Power Central Research Institute using microbial glue sulfur can remove 70% of inorganic sulfur and reduce dust by 60%. This technical principle is simple and the equipment is inexpensive, and it is especially suitable for developing countries that cannot afford expensive desulfurization equipment. Biotechnology desulfurization is in line with the principles of "source management" and "clean production", so it is a very promising management method, and it is increasingly valued by countries around the world. ^[2]