Hydrothermal synthesis reactor, also known as high-pressure digestion tank, is mainly used for sample pretreatment to digest heavy metals, agricultural residues, food, sludge, rare earth, aquatic products, organic matter, etc,
It is a powerful assistant for digestion of samples in the determination of trace elements and trace elements. It consists of stainless steel shell, kettle cover, PTFE lining (para polystyrene lining)
It is composed of a booster rod and a stainless steel gasket (two pieces)~
一、Working principle of hydrothermal synthesis reactor
Hydrothermal synthesis reactor is to use high-temperature and high-pressure aqueous solution under certain temperature and pressure to dissolve those insoluble or insoluble substances under atmospheric conditions, or react to produce the dissolved products of the substances. By controlling the temperature difference of the solution, convection is generated to form a supersaturated state and precipitate growth crystals. It can be used for the preparation of nano materials, compound synthesis, crystal growth, etc. it can also be used for low-dose synthetic reaction. It is a small reaction kettle commonly used in Colleges and universities.
二、Precautions for use of hydrothermal synthesis reactor
1.Pour the reactant into the PTFE bushing or ppl bushing and ensure that the feeding coefficient is less than 80%.
2.Make sure the position of the lower gasket of the kettle body is correct (the protrusion faces down), then put in the PTFE bushing or ppl bushing and the upper gasket, tighten the kettle cover first, and then screw down the kettle cover with the force adding rod.
3.Place the hydrothermal synthesis reactor in the heater and raise the temperature to the required reaction temperature according to the specified heating rate（ Less than the specified safe use temperature).
4.After confirming that the temperature in the kettle is lower than the boiling point of the reactant system solvent, the kettle cover can be opened for subsequent operations. When it is cooled down after the reaction, it shall also be operated in strict accordance with the specified cooling rate, so as to facilitate safety and the service life of the reactor.
5.After confirming that the temperature in the kettle is lower than the boiling point of the reactant solvent, loosen the kettle cover with a screw, and then open the kettle cover.
6.The hydrothermal synthesis reactor shall be cleaned in time after each use to avoid corrosion. Pay special attention to cleaning the sealing parts of kettle body and kettle cover line, and strictly prevent them from being damaged.
三、Specific cleaning methods for the lining of hydrothermal kettle
1、Different cleaning methods are selected according to different reaction media of hydrothermal kettle
（1）The catalyst of the hydrothermal kettle is a silicon system. After use, add an appropriate amount of hydrofluoric acid or alkali to heat and wash;
（2）Silicon metal system is different from the acid dissolved during the reaction. For example, aqua regia (concentrated nitric acid) is required for hydrochloric acid
And concentrated hydrochloric acid (3:1 ratio).
For example, dissolve potassium permanganate in water after use, then add 3-5ml of concentrated hydrochloric acid and put it into a hydrothermal kettle
After sealing, it can be cleaned after hydrothermal reaction at 180 ℃ for 5-10 hours.
2、Cleaning methods of hydrothermal kettle lining commonly used in laboratory
（1）Wash with aqua regia (aqua regia: concentrated nitric acid and concentrated hydrochloric acid in the ratio of three to one).
（2）After the experimental reaction, add about 1:5 mixed solution of nitric acid and water into the inner tank (hydrothermal kettle accessories), and then heat it to 180 ℃ for about 12 hours. These data are only for reference. The proportion and temperature of the mixed solution in the actual operation can be determined according to the specific situation of the experimental reaction. But the disadvantage of this method is that it will make the repeatability of the experiment worse.
（3）Cook the oxalic acid solution for about 6 hours.
（4）Use hydrofluoric acid or ethanol to heat reaction cleaning, or use other strong acids.
Precautions: the low boiling point system that is easy to explode is strictly prohibited for the hydrothermal kettle. When the hydrothermal kettle is used up, the lining and jacket are separated and dried at 50 ℃.