Preparation background and overview of sodium perborate monohydrate
Sodium perborate, also known as “sodium perborate”, is stable in cold and dry places, releases oxygen in hot and humid air, and decomposes above 60°C. Soluble in glycerol, soluble in 40 parts of water, its aqueous solution is alkaline. Can decompose and release hydrogen peroxide. The pH of the aqueous solution is 10 to 10.3, and the available oxygen is 10%.
Sodium perborate (PBS) has three hydrates: NaBO3.H2O monohydrate, NaBO3.4H tetrahydrate 2O and NaBO3.3H2O. Among them, sodium perborate monohydrate and sodium perborate trihydrate are more important in industry. They are High-efficiency oxygen-based bleach also has functions such as sterilization and fabric color preservation. It is widely used in daily materials such as bleaching powder, washing powder, and detergents. Sodium perborate monohydrate can be used for fabric bleaching, electroplating, sterilization, etc.
There are two main methods for preparing sodium perborate monohydrate: one is a dry production process, that is, sodium metaborate solution and hydrogen peroxide solution are sprayed on the crystals of sodium percarbonate monohydrate and evaporated at the same time. The moisture is obtained by sodium perborate. Although this method can obtain better product quality, firstly, the concentration of hydrogen peroxide required is relatively high (≥50%). Secondly, the production equipment is relatively complex and the equipment investment is large. The other is a wet production process, that is, hydrogen peroxide solution is added dropwise to sodium metaborate solution for reaction and crystallization, and sodium perborate monohydrate is obtained after drying. This method is affected by the selection of crystal habit improver, the dripping method, etc. , making the sodium perborate monohydrate produced have a lighter specific gravity, poor particle appearance and wet stability.
Preparation structure of sodium perborate monohydrate
Indications for the preparation of sodium perborate monohydrate
For intramedullary cavity bleaching.
Preparation specifications of sodium perborate monohydrate
Sodium perborate is in powder form and contains 93% perboric acid, which is equivalent to 9.9% available oxygen. Stable under dry conditions, it degrades into sodium perborate, hydrogen peroxide and nascent oxygen in acidic, hot air or water.
Preparation, usage and dosage of sodium perborate monohydrate
After the root canal filling is completed, the rubber dam isolates the treated tooth, removes the filling gutta-percha and paste in the pulp cavity, and lowers the root filling to the level below the gingival margin (2mm below the root of the clinical crown). Glass ionomer cement or other cement pads with a protective base of more than 2mm. Mix sodium perborate and 35% hydrogen peroxide into a uniform paste. Use a filler to put the paste into the medullary cavity and compress it tightly. Use a cotton ball to suck out the excess water, and use a temporary sealing material such as zinc oxide clove. Oil paste seals the medullary cavity. Follow up after 3 to 5 days and replace the paste; if sodium borate has been used alone, follow up after 2 weeks. After 1 to 3 treatments, observe the bleaching effect and decide whether you need to repeat the treatment until you are satisfied.
Preparation and pharmacological effects of sodium perborate monohydrate
Sodium perborate is a weak oxidant. It forms perboric acid and hydrogen peroxide after degradation. The oxidation reaction lasts for a long time.
Precautions for the preparation of sodium perborate monohydrate
In order to avoid damage to the periodontal ligament tissue, a protective base must be prepared before placing the drug to prevent oxidants from penetrating into the periodontal ligament through dentinal tubules.
Preparation of sodium perborate monohydrate and other applications
Sodium perborate monohydrate is also used as a bleaching agent in detergents and washing powders, so that detergents and washing powders have sterilization, disinfection and other effects; it can also be used in toothpaste production and as oxidants, mordants, and dyes in the printing and dyeing industry. Bleach degreaser, etc.
For example, a dishwashing agent is prepared, including sodium polyacrylate, citric acid, salicylic acid, triethanolamine, sodium perborate monohydrate, dodecyldimethylamine betaine, sodium tripolyphosphate, and water, The mass parts of each component are: sodium polyacrylate 20-30, citric acid 20-28, salicylic acid 13-18, triethanolamine 8-15, sodium perborate monohydrate 5-9, dodecyl dimethyl Betaine 4-9, sodium tripolyphosphate 10-15, water 50-60. The invention has no harm to human skin, no residue, and no pollution to food and the environment; the cleaning agent contains no foaming agent, is convenient for rinsing, saves water consumption, and is widely applicable.
Preparation of sodium perborate monohydrate
The preparation method of sodium perborate monohydrate uses sodium metaborate solution and hydrogen peroxide solution as raw materials, and is characterized in that the sodium metaborate solution and hydrogen peroxide solution are added dropwise into the reaction kettle to produce four crystal waters. sodium perborate crystals. After the reaction is completed, the sodium perborate tetrahydrate crystals are dried to obtain sodium perborate monohydrate. Phosphate can also be added to the sodium metaborate solution as a crystal habit improver.
The phosphate can be any one or a mixture of more than one of sodium hexametaphosphate, sodium pyrophosphate, sodium phosphate, potassium phosphate, etc., and the amount added is 0.05 of the weight of sodium metaborate based on effective P2O5. ~0.5%, preferably 0.1~0.4%. The concentration of the sodium metaborate solution may be 25-40%. Polycarboxylic acid and its salts can also be added to the hydrogen peroxide solution as stabilizers. The polycarboxylic acid and its salt can be any one or a mixture of more than one of polyacrylic acid, polymaleic acid, sodium polyacrylate, polymaleic acid, etc., and its addition amount is 0.05-0.05-by weight of sodium metaborate. 0.5%, priority can be 0.08-0.2%. The concentration of hydrogen peroxide may be 25-50%.
The reaction described is hydrogen peroxide and parabensThe molar ratio of sodium phosphate can be 1:0.95-1.12. The reaction temperature during the reaction may be 25-40°C, and the reaction time may be 45-60 min. This method innovatively improves the existing production process of sodium perborate monohydrate. The sodium metaborate solution and the hydrogen peroxide solution are dropped into the reaction kettle at the same time, and polycarboxylic acid and its salt are added to the hydrogen peroxide as a stabilizer. Phosphate is added to the sodium solution as a crystal habit modifier, which effectively improves the bulk specific gravity range and particle appearance of sodium perborate, and improves the wet stability of the product.
Dimethylaminopyridine
Overcoming the existing wet production of sodium perborate, the product has a light specific gravity (generally 0.35-0.55g/cm3), poor particle appearance, only 10-20% of fine powder below 100 mesh, and poor wet stability. Good to wait for defects. After practical application, the bulk specific gravity of the present invention can generally be adjusted within the range of 0.45-1.0g/cm3, the fine powder below 100 mesh in the product is less than 5.0%, the wet stability is greater than 85%, and its production process is relatively simple, using hydrogen peroxide The concentration is low and suitable for large-scale production.
