1. After water is boiled, part of the water evaporates, and insoluble calcium sulfate (CaSO4, gypsum is calcium sulfate containing crystal water) is precipitated. The original dissolved calcium bicarbonate (Ca(HCO3)2) and magnesium bicarbonate (Mg(HCO3)2) are decomposed in boiling water, releasing carbon dioxide (CO2), which becomes insoluble calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2) and precipitates, and sometimes MgCO3 is generated. This forms a scale.
2. According to the causes and forms of scale, scale can be roughly divided into hard scale and soft scale. When water contains impurities such as carbonate colloid, bacteria and organic matter, carbonate is similar to sand in cement mortar, while colloid, bacteria and organic matter are equivalent to cement in cement mortar. Viscous substances such as colloid, bacteria and organic matter in water interact with carbonate to form hard scale attached to the container (or pipeline surface) when boiling at high temperature. Once the viscous substances such as colloid, bacteria and organic matter are removed (for example, by ultrafiltration), even if the concentration of calcium, magnesium ions and carbonate ions in water is high, it will become white and loose carbonate soft scale, which is easy to remove and will not produce hard scale.
3. Exclusion method (methods 6 and 7 can be used if the water heater is used for a long time)
(1) Boil sweet potatoes (sweet potatoes, sweet potatoes) in a kettle, put more than half a pot of sweet potatoes, fill them with water, cook them, and then boil the water, so that scale will not accumulate. However, it should be noted that do not scrub the inner wall of the kettle after cooking the sweet potato, otherwise it will lose the descaling effect. For the old kettle that has been covered with scale, after being boiled once or twice by the above method, not only the original scale will gradually fall off, but also it can prevent the scale from accumulating again.
(2) Baking soda descaling When boiling water in an aluminum pot with scale, add 1 teaspoon baking soda and boil for a few minutes, and the scale will be removed.
3 Boil the eggs and scale the boiling pot. After a long time, it will be difficult to scale. If you use it to cook eggs twice, you will get the ideal effect.
(4) Scale removal of potato skin After being used in aluminum pot or aluminum pot for a period of time, there will be a thin layer of scale. Put the potato skin into it, add appropriate amount of water, boil it, and take it out for about 10 minutes.
⑤ Thermal expansion and cold contraction remove scale. Put the empty kettle on the stove to dry the water in the scale. When the bottom of the kettle cracks or there is a "bang", take off the kettle and quickly inject cold water, or wrap the handle and spout with a rag, hold it with both hands, and quickly sit the dried kettle in the cold water (don't let water inject into the kettle). Repeat for 2 to 3 times, and the scale at the bottom of the pot will fall off due to thermal expansion and cold contraction.
⑥ Remove the scale from the lemon and put the lemon slices into the kettle (the thinner the better, the purpose is to release citric acid as much as possible). Boil water for about 5 minutes, then soak lemon in water for 2 minutes to remove water.
7 vinegar descaling If the kettle has scale, you can put a few spoonfuls of vinegar in the water and burn it for an hour or two, and the scale will be removed. If the main component of the scale is calcium sulfate, the soda solution can be poured into the kettle for cooking to remove the scale. White vinegar removes scale.
8 mask scale prevention put a clean mask in the kettle. When boiling water, the scale will be absorbed by the mask.
⑨ Magnetization Putting a magnet in the pot can not only prevent fouling, but also magnetize boiling water, and also prevent constipation and pharyngitis.
Attending ion exchange descaling method: replacing calcium and magnesium ions in water with sodium ions with specific cation exchange resin. Due to the high solubility of sodium salt, scaling with the increase of temperature is avoided.
Methods of membrane separation and scale removal: Both nanofiltration membrane (NF) and reverse osmosis membrane (RO) can intercept calcium and magnesium ions in water, thus fundamentally reducing the hardness of water. The characteristics of membrane separation scale removal method are obvious and stable effect, and the treated water has a wide range of applications; However, the requirement for water inlet pressure is high, and the equipment investment and operation cost are high.
To remove the scale of water used by the whole family, you can install a water softener to remove the scale of water used by the whole family, so that everyone can save the trouble of scale. For the descaling of drinking water quality, water purification equipment with hydrogen ion resin can be used, such as baby love the water baby filter kettle.
Supermarkets and tea shops sell scale cleaners, the main component of which is hydroxypropionic acid. The raw materials are safe, non-toxic and environmentally friendly. This scale remover is convenient to use and has good effect. Suitable for home users, with appropriate dosage and detailed instructions.