Application background and overview of crystalline sodium carbonate
Sodium carbonate is also known as “soda ash”, “soda”, “alkali surface” and “carbon oxygen”. Chemical formula Na2CO3. Molecular weight 105.99. White powder. It has strong hygroscopicity and can gradually absorb carbon dioxide from humid air to form sodium bicarbonate. The melting point is 851℃ (decomposition), the relative density is 2.53, and the refractive index is 1.535. It begins to decompose and lose carbon dioxide at ℃. It is easily soluble in water and exothermic. It is soluble in glycerin and insoluble in ethanol and ether. The aqueous solution is strongly alkaline, with a pH of 11.6. When the temperature is lower than 32.08℃, the decahydrate is obtained by crystallization from the aqueous solution, when the temperature is between 32.08 and 35.27℃, the heptahydrate is obtained, and when the temperature is higher than 35.27℃, the monohydrate is obtained.
Its decahydrate is also called “crystalline sodium carbonate”, “crystalline soda”, “crystalline alkali”, “ice base” or “washing soda”. It is a colorless and transparent monoclinic columnar crystal that easily erodes in the air. It turns into a monohydrate powder with a relative density of 1.4517 and a refractive index of 1.405, 1.425 and 1.440. It dissolves in its crystal water at 34°C. Its heptahydrate is a colorless orthorhombic crystal that is easily weathered and has a relative density of 1.51. Its monohydrate is a colorless orthorhombic fine-grained crystal, deliquescent, stable at room temperature, relative density 1.562, refractive index 1.506, 1.509. It loses crystal water at 100°C and becomes anhydrous, easily soluble in water. It easily absorbs carbon dioxide in the air and gradually turns into sodium sesquicarbonate. Preparation method: In industry, it is mainly produced by the ammonia-alkali method from sodium chloride, ammonia and carbon dioxide. In the laboratory, it can be produced by heating sodium bicarbonate at 300°C.
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Applications of crystalline sodium carbonate
Sodium carbonate can be used as a detergent, flux, water softener, analytical reference reagent, agricultural culture agent, and is also used in tanning, papermaking, dyes, glass, soap, photography, etc. It is an important basic chemical raw material. Examples of its application are as follows:
1) Prepare a fresh-keeping ice bag, which consists of an outer plastic bag, an inner plastic bag, and a cold storage agent in the packaging bag. The plastic bag contains ammonium nitrate and crystallized sodium carbonate, and is separated by an easily removable partition device outside the bag. The ammonium nitrate and crystalline sodium carbonate are separated within the bag. When in use, remove the separation device, and after the two substances in the bag are fully mixed, the temperature can drop to about zero degrees within 1 minute. This ice pack is convenient for cooling. Fast, easy to use and easy to carry. It is characterized in that the packaging bag has a funnel-shaped water injection port capable of injecting solution into the packaging bag. The fresh-keeping ice bag of the present invention is easy to use and easy to carry and store. The cool storage agent has strong fresh-keeping ability, which is more than twice that of the existing fresh-keeping ice bag cool storage agent. It is also non-toxic, tasteless and odorless, does not contaminate fresh-keeping items, and is easy to separate from the items being kept fresh.
2) Prepare a fruit and vegetable preservative, which is characterized by: it is a composition packed in a paper bag or a cloth bag and composed of the following components and parts by mass: (1) active adsorbent, 0.5 to 5 parts, It is activated carbon, activated clay, attapulgite, or diatomaceous earth adsorbed with potassium permanganate, (2) oxygen absorber, 0.5~5 parts, which is iron powder, (3) ethylene absorber, 0.5~5 parts, it is zeolite or bentonite, (4) carbon dioxide absorber, 0.5~5 parts, it is hydrated lime or coke molecular sieve, (5) antibacterial agent, 1 part, it is sodium benzoate, (6) auxiliary agent, 1~ 10 parts, it is a mixture of equal masses of sodium chloride and crystalline sodium carbonate or a mixture of equal masses of calcium chloride and crystalline sodium carbonate. Using the fruit and vegetable preservative of the present invention, 5 grams of preservative is used for every 500 grams of tomatoes, and the tomatoes can be kept fresh for 60 days without basically deteriorating. The invention discloses a preparation method of a fruit and vegetable preservative.
3) Preparation of ceramic tile adhesive, including the following components, flue gas desulfurization gypsum, crystalline sodium carbonate, borax, kaolin, Portland cement, hydroxypropyl methylcellulose ether, benzyl cyanoethyl cellulose , butadiene-styrene polymer, manganese oxide, redispersible latex powder, glutinous rice pullulan, sustained release agent, waterproofing agent, water; the invention also discloses a specific preparation method of the adhesive. Using flue gas desulfurization gypsum as an adhesive for making ceramic tiles solves the stacking problem of flue gas desulfurization gypsum, reduces the burden on enterprises, and avoids environmental pollution. When combined with other components, the adhesive produced has It has the characteristics of high bonding strength, high bonding stability, stable properties, not easy to age, and non-toxic, and can be bonded multiple times; in addition, the invention also has the advantages of low production cost, simple production process, and does not pollute the environment.
Application and preparation of crystalline sodium carbonate
(1) Dissolve anhydrous sodium carbonate:
Slowly add industrial pure anhydrous sodium carbonate into a stainless steel bucket of distilled water, stir continuously and measure its relative density to be 1.16~1.18g/mL to obtain solution A;
(2) Preparation of crystalline sodium carbonate:
Put analytically pure ethanol into a stainless steel basin, place activated carbon and a low-purity filter sieve on the basin, then slowly pour solution A into the sieve and filter, the filtrate flows into the ethanol basin, stir continuously, and cool naturally until sodium carbonate Precipitate, filter and dry to obtain crystalline sodium carbonate;
