What Is Sodium Bicarbonate?

Sodium bicarbonate (CAS 144-55-8) is an inorganic compound that appears as a white powder or fine crystals. It is odorless, has a salty taste, is highly soluble in water, and slightly soluble in ethanol (though some sources state it is insoluble). Its aqueous solution is slightly alkaline. It decomposes readily when heated and slowly decomposes in moist air, producing carbon dioxide. Decomposition begins at approximately 50°C and is complete at 270°C. It decomposes vigorously upon contact with acids, producing carbon dioxide. Sodium bicarbonate is widely used in the chemical, pharmaceutical, food, light industrial, and textile sectors, as well as in everyday life, and plays an important role in the national economy.

How Is Sodium Bicarbonate Made?

Gas-Phase Carbonation Method

A sodium carbonate solution is carbonated with carbon dioxide in a carbonation tower, then separated, dried, and ground to produce the final product.

Gas-Solid Phase Carbonation Method

Sodium carbonate is placed in a reaction bed and mixed with water; carbon dioxide is introduced from the bottom. After carbonation, the material is dried and ground to produce the finished product.

Waste Alkaline Solution Recovery Method

During soda ash production, the furnace gas generated by the soda ash calcination furnace still contains a significant amount of alkali powder after cyclone separation. This furnace gas is used for hot alkali recovery to dissolve the alkali powder in the alkali solution. During the circulation and dissolution process, a portion of the alkali solution is sent to an ammonia stripping tower to strip ammonia from the hot alkali solution, further concentrating the alkali solution to serve as the raw material for sodium bicarbonate production. The mixed gas of ammonia, carbon dioxide, and water discharged from the top of the ammonia stripping tower enters the original furnace gas cooling tower. The mother liquor, separated and dehydrated during sodium bicarbonate production, is used in the hot alkali solution circulation to dissolve and recover the alkali powder from the furnace gas, thereby forming a closed-loop production process.

After recovery, the waste alkali solution undergoes carbonation, centrifugal separation, and drying to produce finished sodium bicarbonate.

Properties

Risk and Safety Statements

What Is Sodium Bicarbonate Used For?

Laboratory Applications

Sodium bicarbonate can be used as an analytical reagent and is also employed in inorganic synthesis. It can be used to prepare sodium carbonate-sodium bicarbonate buffer solutions, which maintain a relatively stable pH in the system by preventing significant changes in hydrogen ion concentration when small amounts of acid or base are added.

Industrial Applications

Sodium bicarbonate is used in the production of acid-base fire extinguishers and foam fire extinguishers. In the rubber industry, it is used in the production of rubber and sponges. In the metallurgical industry, sodium bicarbonate serves as a fluxing agent for casting steel ingots. In the machinery industry, sodium bicarbonate serves as a molding aid for cast steel (sand casting) molds. In the dyeing and printing industry, it functions as a color fixative, an acid-base buffer, and a post-treatment agent for fabric dyeing and finishing; adding baking soda during dyeing prevents color mottling on yarn cones and can also serve as a detergent for wool.

Food Processing Applications

In food processing, sodium bicarbonate is one of the most widely used leavening agents, used in the production of cookies, bread, and other baked goods; however, it leaves sodium carbonate residue after use. Excessive use can make the food overly alkaline, leading to poor flavor and a yellowish-brown color. It serves as a carbon dioxide generator in carbonated soft drinks; It can be combined with alum to form an alkaline leavening agent, or with soda ash to produce household washing soda; it can also be used as a butter preservative. In vegetable processing, it serves as a color retainer for fruits and vegetables. Adding approximately 0.1%–0.2% sodium bicarbonate when washing fruits and vegetables helps stabilize their green color. When used as a fruit and vegetable treatment agent, sodium bicarbonate raises the pH of the produce through blanching, increases the water-holding capacity of proteins, promotes the softening of food tissue cells, and leaches out astringent components. Additionally, it removes the gaminess from goat’s milk; the recommended usage is 0.001%–0.002%.

Agricultural and Livestock Applications

Sodium bicarbonate can be used for seed soaking in agriculture. It can also compensate for insufficient lysine content in feed. Dissolving sodium bicarbonate in a small amount of water or mixing it into concentrate feed for cattle (in appropriate amounts) can promote cattle growth and significantly increase milk production in dairy cows.

Medical Uses

Sodium bicarbonate serves as a raw material in pharmaceutical manufacturing and is used to treat hyperacidity and metabolic acidosis. It can also alkalise urine to prevent uric acid kidney stones. It can also reduce the nephrotoxicity of sulfonamide drugs, prevent haemoglobin deposition in the renal tubules during acute hemolysis, and treat symptoms caused by excessive stomach acid; intravenous infusion has a nonspecific therapeutic effect on poisoning caused by barbiturates, salicylates, methanol, and other drugs. However, it is contraindicated for gastric lavage in cases of poisoning from ingestion of strong acids. Furthermore, when administered in large doses, in patients with renal insufficiency, or during long-term use, it may cause arrhythmias, muscle spasms, pain, abnormal fatigue and weakness, slowed breathing, bad breath, frequent urination, urinary urgency, persistent headaches, loss of appetite, nausea, and vomiting.

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