What is alum

Do you know what alum is? Alum is also called white alum and potassium alum. It is a colorless cubic crystal. It is poisonous, so it can be very good at antibacterial. It can also be used to make traditional Chinese medicine, paint, clarifier, papermaking, etc. Many food additives are made of alum. Today we will take a detailed look at the uses of alum.

Alum has many uses. It is also called white alum and can be dissolved in water. Generally, there is a certain amount of alum solution in fire extinguishers. It can also be used as a water purifier. Some Chinese medicines also use alum. Let's take a look at the uses of alum.

Alum as a water purifier

When alum is dissolved in water, it ionizes to produce Al3+. Al3+ combines with OHˉ produced by the ionization of water to form aluminum hydroxide. The aluminum hydroxide colloid particles carry positive charges and meet the negatively charged mud and sand colloid particles, and the charges of each other are neutralized. The colloid particles that have lost their electric charge will quickly gather together, and the particles will become larger and larger until they finally sink to the bottom of the water. In this way, the water becomes clear and clean.

Alum as a fire extinguishing agent

The foam fire extinguisher contains about 1 mol/L of alum solution and about 1 mol/L of NaHCO3 (baking soda) solution (as well as a foaming agent), and the volume ratio of the two solutions is about 11:2. The excess amount of alum is to make the baking soda in the fire extinguisher react fully and release enough carbon dioxide to achieve the purpose of extinguishing the fire.

Alum as a bulking agent

When frying dough sticks (cakes) or puffed foods, if you add baking soda and then alum to the flour, it will speed up the production of carbon dioxide and greatly increase the speed of puffing. In this way, the fried dough sticks (cakes) will puff up in the hot oil pan immediately, and you will get crispy and delicious fried dough sticks (cakes).

Alum as medicine

Alum is cold in nature, sour and astringent in taste, and has a strong astringent effect. Traditional Chinese medicine believes that alum has the effects of detoxification and insecticide, dispelling dampness and relieving itching, stopping bleeding and diarrhea, clearing away heat and eliminating phlegm, and anti-vaginal trichomoniasis. Some Chinese medicine practitioners use alum to treat diseases such as hyperlipidemia, duodenal ulcers, and hemoptysis caused by tuberculosis.

Alum as a buffer

It can be used as a buffer in sulfate zinc plating to stabilize the pH value of the plating solution. Potassium aluminum sulfate is used for sulfate galvanizing, brush galvanizing and chemical oxidation of magnesium alloys. It can also be used as a coagulant for treating sewage. If it is used for galvanizing, attention should be paid to its iron and heavy metal content.

[1] Alum can also be used to prepare aluminum salts, paints, tanning agents, mordants, papermaking, waterproofing agents, etc.

Pharmacological Action

⒈ Antibacterial effect: It has inhibitory effect on Staphylococcus aureus and Proteus (test tube method). It also has obvious inhibitory effect on Escherichia coli, Pseudomonas aeruginosa, Bacillus anthracis, Shigella dysenteriae (French, Shigella), Salmonella typhi, Bacillus paratyphi A, Proteus, as well as Staphylococcus aureus and Candida albicans (paper disc and plate method); it has the strongest effect on viridans streptococci, hemolytic streptococci, pneumococci and diphtheria cortisone; it has the second strongest effect on bovine Brucella, Bordetella pertussis and meningococci, and has no effect on influenza bacilli (paper disc method). High concentration alum solution also has an inhibitory effect on human (H37RV) and bovine tuberculosis bacteria.

⒉ Anti-Trichomonas vaginalis effect: 10% alum solution in a test tube (the ratio of culture medium to drug solution is 1:1) has a significant anti-Trichomonas vaginalis effect.

⒊ The effect of coagulating protein: Alum has a strong effect of coagulating protein. When a few drops of alum water are added to the serum, it can be seen that the substances immediately combine to form insoluble substances and precipitate. Low concentrations have astringent, anti-inflammatory and antiseptic effects, while high concentrations can cause tissue ulceration. Due to its high irritation when taken internally, it is generally only used externally.

⒋ Choleretic effect: Intraduodenal administration of 0.6g/kg alum significantly increased bile flow in anesthetized rats.

I think everyone knows what alum is. We know its many uses and its many pharmacological effects. It can generally be used externally to stop sweating and hemostasis. Also, when we cook porridge, especially mung bean porridge, we can put some alum to make the mung bean porridge easier to cook. I think you don’t know this common sense.