Electrolysis method: the electrolyte is prepared from ammonium sulfate and sulfuric acid. After removing impurities, it is electrolyzed. HSO4 - discharges at the anode to generate persulfate, and then reacts with ammonium sulfate to generate ammonium persulfate. When the content of ammonium persulfate in the anode solution reaches a certain concentration, the finished product of ammonium persulfate is prepared by filtration, crystallization, centrifugal separation and drying.
The refined electrolyte after removing iron and impurities continuously enters the diaphragm electrolytic cell from the high-level cell. The composition of the electrolyte is as follows: the cathode liquid is sulfuric acid 280 ~ 340kg / m3; Ammonium sulfate 180 ~ 210kg / m3. The anode solution is sulfuric acid 110 ~ 140kg / m3; Ammonium sulfate 300 ~ 340kg / m3. Generally, the current density of anode is 20 ~ 25A / L, the cell voltage is 5.5 ~ 5.8v, and the electrolysis temperature is controlled at 25 ~ 30 ℃. If the tank voltage is too high, it is easy to hydrolyze the generated persulfate into persulfate and reduce the current efficiency; If the tank temperature is too low, it is easy to precipitate ammonium persulfate crystals and block the pipeline. In order to improve the current efficiency, ammonium thiocyanate is usually added, and its amount is about 0.015% ~ 0.03% of the electrolyte. After electrolysis, the content of ammonium persulfate in the anode solution shall reach 220 ~ 260kg / m3. After being collected in the anode solution storage tank, it is filtered and added into the crystallizer. Under stirring, refrigerant is introduced for indirect freezing to crystallize ammonium persulfate. When the temperature drops to - 8 ~ - 12 ℃, stop freezing. After centrifugation and drying, the finished product is obtained. Mother liquor is recycled. The current efficiency of electrolysis is about 84% ~ 85%.
Ammonium persulfate can be prepared by electrolysis of sulfuric acid solution of ammonium sulfate. The electrolysis device is a plain porcelain cylinder with a bottom and a volume of 80 ~ 100ml placed in the beaker. The plain porcelain cylinder is filled with anode liquid, and the cathode liquid is filled between the beaker and the plain porcelain cylinder. The spiral anode made of platinum wire is inserted into the anode liquid, and the cylindrical cathode made of lead plate is placed in the cathode liquid outside the plain porcelain cylinder. Ammonium sulfate is dissolved in dilute sulfuric acid with a concentration of 2mol / L to make a saturated solution, which is used as the anode solution, and the cathode solution is a dilute sulfuric acid solution formed by mixing equal volume of concentrated sulfuric acid with water. The beaker is cooled in cold water, and the temperature of anode liquid is kept in the range of 10 ~ 20 ℃ during electrolysis. After electrolysis at a current of 2 ~ 3A for a period of time, there will be crystallization and precipitation of ammonium persulfate in the plain porcelain cylinder. After 3 ~ 4h, all the crystals in the anode solution are taken out, filtered with a glass sand core funnel, and vacuum dried at a temperature below 40 ℃ to obtain ammonium persulfate product. After the filtrate is saturated with ammonium sulfate, it can be put into a plain porcelain cylinder to continue electrolysis. After 2 ~ 3 repetitions, there is a lot of excess sulfuric acid in the anode solution. Under the condition of cooling, some sulfuric acid can be neutralized with ammonia saturated with ammonium sulfate. After several repetitions, the sulfuric acid concentration in the cathode liquid will be greatly reduced or even become alkaline. At this time, the cathode liquid must be replaced, otherwise the current will weaken rapidly.
制法 將硫酸銨飽和溶液和硫酸混合，濾去不溶物，作為電解液，以鉑作為電極，電解溫度維持在35～45℃為宜，電壓12A 左右，HSO4-子在陽極失電子生成過二硫酸，再與硫酸銨反應生成過硫酸銨，總反應式為：
In the preparation method, the saturated solution of ammonium sulfate and sulfuric acid are mixed, the insoluble matter is filtered out as the electrolyte, platinum is used as the electrode, the electrolysis temperature is appropriate to be maintained at 35 ~ 45 ℃, the voltage is about 12a, HSO4 - loses electrons at the anode to form persulfate, and then reacts with ammonium sulfate to form ammonium persulfate. The general reaction formula is:
When ammonium persulfate in the electrolyte reaches a certain concentration, adjust pH = 7 ~ 8, then filter the electrolyte, cool and crystallize the filtrate, wash the crystallization with a small amount of cold water until it is qualified, shake it dry, and dry it below 40 ℃ to obtain reagent Ammonium persulfate.