Fluorine and hydrogen fluoride are very reactive and they are very corrosive. Many fluorine compounds are toxic, so for a long time, some people are afraid of elemental fluorine and fluorine products. However, in modern society, fluorine products make a great contribution to humans. PTFE has excellent performance and is known as the plastic king. It is widely used in special industries with stable fluorine rubber. The special physical and chemical properties of Freon make it widely used in compression cycle refrigeration machinery. As a refrigerant; cryolite is an indispensable raw material for the electrolytic aluminum industry. Only the above three items have benefited mankind. However, when using fluorine and fluorine products, we must pay attention to the harmful aspects of the prevention of fluorine.
Human understanding of fluorine should be counted from 1768. In that year, the German mineralogist Maglaf used hydrogen sulfate and fluorite to obtain hydrogen fluoride. In 1771, the Swedish chemist Scheler also conducted a detailed study of this highly corrosive acid. In the early 19th century, when chemists determined that there was no oxygen in hydrochloric acid, the famous French physicist A.M. Ampere proposed to David that hydrofluoric acid is an acid formed by hydrogen and another element. . He suggested that the element be named "Fluorine", which is "fluorine" and the element symbol is "F". Its original Latin meaning is fluorite.
From the early 19th century, chemists from various countries began to conduct research on the release of elemental fluorine. The research work was extremely difficult, and the chemists made great sacrifices: the British chemist David, the French chemists Gay Lussac and Tyner were both poisoned by inhaling a small amount of hydrogen fluoride; Thomas, a member of the Royal Irish Academy of Sciences Thomas Knox was almost poisoned and his brother George Knox was cured after three years of healing; the Belgian chemist P. Louyet was martyr for scientific research for a long time. . The chemist who sacrificed for this research is Professor J. Nickles. When we use fluorine products, we must not forget the sacrifices made by our ancestors to study fluoride.
1813 David intends to take fluoride electrolytic method, he found that not only hydrogen fluoride glass corrosion, but also corrosion of metal silver. He first used platinum and angular silver (AgCl) to make hydrogen fluoride-containing vessels, and later used fluorite to make hydrogen fluoride-containing vessels for electrolyzing hydrofluoric acid. However, in the electrolysis, no fluorine is obtained at the anode, only oxygen is obtained, and water in the hydrofluoric acid is decomposed during the electrolysis. The research on the electrolysis of Guy Lussac did not receive fluorine.
The Knox brothers made a set of fluorite vessels containing dry mercury fluoride with a fluorite receiver placed on it, and the receiver's recess was lined with gold foil. He heats the mercury fluoride while introducing dry chlorine. He obtained crystals of mercury chloride in the receiver and found that the gold foil in the receiver was corroded. He moved the corroded gold foil into a glass bottle and treated the gold foil with sulfuric acid, and the glass was corroded. Knox's experimental phenomenon indicates that mercury fluoride is decomposed by chlorine during heating to obtain volatile mercuric chloride and fluorine gas, which corrodes the gold foil in the receptacle. However, the Knox brothers did not get free fluorine.
In 1850, E. Fremy, the curator of the French Museum of Nature and a professor of chemistry at the French Institute of Technology, electrolyzed anhydrous calcium fluoride, silver fluoride, potassium fluoride and other substances. He saw bubbles on the anode and the corresponding metal precipitated on the cathode. The electrolysis did occur. However, the gas generated on the anode immediately reacts with the substance constituting the anode to form other compounds, and no free fluorine is obtained. In 1884, he gave his unfinished desire to produce free fluorine to his student H. Moissan.
Mowasan, an apprentice from a pharmaceutical store, has been a teacher since the age of 20 years. He is hard-working and smart. After summarizing the failure lessons of the predecessors who made free fluorine for more than 70 years, he believes that the key to failure is that the activity of elemental fluorine is too high. In the past, the electrolysis of fluorine was caused by the fact that the melting point temperature of the electrolyte was too high, so that the temperature during electrolysis was high, resulting in failure of electrolysis, and even the use of a platinum anode during electrolysis was not helpful. He distilled a mixture of arsenic oxide, fluorite and sulfuric acid to prepare arsenic fluoride having a melting point of only -8.5 ° C, and then electrolyzing arsenic fluoride. Although after four poisonings and multiple failures, arsenic powder was finally obtained from the cathode during electrolysis, and bubbles were also escaping on the anode. However, this bubble is absorbed by arsenic fluoride during the ascending process, and free fluorine is not obtained.
Mowasang was not discouraged by the failure of the experiment. He dissolved potassium fluorohydride (KHF2) in hydrogen fluoride as an electrolyte, and sealed the electrode made of platinum- rhodium alloy with a fluorite spiral cap in a platinum U-tube as an electrolysis device, and then used methyl chloride to electrolyze the entire electrolysis device. Cold to -23 ° C. On August 26, 1886, electrolysis was carried out using this specific electrolysis apparatus, and free gaseous fluorine was produced on the anode. Contacting this gas with this gas immediately ignited a violent chemical reaction. Two days later, he asked the Academy of Sciences scholar J.H. Debrary to read a report on the preparation of free fluorine to the French Academy of Sciences.
The French Academy of Sciences appointed a group of three people, Deborah, P.E.M.Berthelot and Fleet, to validate this newly separated element. Unexpectedly, on the first day, the experimental device failed, and Movasan did not get a bubble during electrolysis. The next day, he replaced all the medicines, re-electrolyzed, and smoothly obtained the gas fluorine. The three professors were very satisfied with the results of the experiment and warmly congratulated Movasan on his success. Frye's long-cherished wish was fulfilled, and excitedly said: Seeing that his students are blue and blue is better than being a teacher.
From David and Guy Lussac, experiments have begun to produce elemental fluorine by electrolysis, and it has been more than 70 years since Movasan successfully electrolyzed elemental fluorine at low temperatures. The chemical industry has paid a heavy price for this. Mowasang himself was unable to effectively control the poisoning of gases due to the limitation of his understanding. He had been in contact with harmful fluorine-containing gases for a long time and his body was damaged. At the age of 54, he died.
Carbon Ring Seal,Tm170 Sealing Series,Carbon Graphite Fiber Seal Ring,Carbon Ring Mechanical Seal
Dandong Huarui Fluid Machinery Co., Ltd , https://www.ddhrseal.com