the inner wall of the kettle grows a thick layer of scale after long use. Generally, scale is mainly caused by & lt; Hard water & quot; We call water containing calcium, magnesium salts and other minerals & lt; Hard water;. Rivers, lakes, wells and springs are all hard water. Tap water is obtained after filtering, so it is also hard water. After the water is boiled, part of the water evaporates and calcium sulfate, which is not easy to dissolve, precipitates. The original dissolved calcium bicarbonate and magnesium bicarbonate decompose in boiling water, giving off carbon dioxide, turning into insoluble calcium carbonate and magnesium carbonate (they are the main components of limestone and dolomite) and settling down. This is the origin of scale. Let’s get to know it with you.
The harm of scale is
scale does great harm to human body. Many people think that scale only affects beauty; If the boiled water precipitates, the scale will not affect the taste; The scale in the thermos can’t be seen anyway, and it won’t have any effect. The scale is the sediment of heavy metals, calcium salts, dust, bacteria, insect eggs and corpses mixed in the water, which is not only unhygienic, but also seriously affects people’s health. According to the chemical analysis, there are a lot of heavy metals in the scale. It has been proved that the scale can not only cause a variety of stone diseases, but also cause diseases of digestive, nervous, urinary, hematopoietic, circulatory and other systems, causing aging. Long term intake will cause heavy metal poisoning in human body, and many heavy metals will cause canceration of human organs.
scaling affects human health, and dental scaling and periodontitis are often caused by scaling; It can kill people. So far, there is no vaccine to prevent Legionella, which is hidden in the scale. In France, 2000 to 3000 people die of this pathogen every year. Scale more hidden dangers, with water containing scale wash face, bath, will form calcium magnesium soap, it is as sticky as gum, stick to the face, skin, so that the dirt is not easy to remove. If the dirt is not cleaned, it will block the opening of skin glands, form embolism, affect the normal metabolism, and make the skin atrophy and aging prematurely.
How to produce scale is mainly related to water quality. If the water quality is hard, the oxygen content in the water is insufficient, and the water molecules are unstable, the solubility of calcium and magnesium ions in the water will be reduced, and the precipitation will be intensified, thus forming scale. As long as the water temperature exceeds 60 ℃, especially in the north where the water quality is relatively hard, there will certainly be scale. Scale will exist in the daily kettle and boiler. The solution is to clean it regularly.
Methods of scale prevention
ion exchange method
ion exchange resin is divided into two categories, one is used to reduce the hardness of water to soft water, used for cleaning, bathing, etc, This kind of ion exchange resin is called sodium ion exchange resin. The second type is used to reduce the hardness of water, so that no scale will be formed after boiling drinking water.
1) cleaning, bathing, etc.: sodium ion resin reacts with calcium and magnesium ions in water to quickly exchange sodium ions into water and absorb calcium and magnesium ions in water, so as to completely soften hard water and turn it into water without calcium and magnesium ions. It is suitable for washing clothes and bathing. The product using this kind of resin is water softener or water softener.
2) drinking: hydrogen ion exchange resin reacts with part of calcium and magnesium ions in water to reduce the hardness appropriately. While retaining the right amount of calcium and magnesium ions in water, scale will not be left in boiling water. Products using this kind of resin, such as special water purification equipment for infants, special filter pot for infants, etc.
physical filtration method
is a kind of membrane separation process, which takes the pressure higher than the osmotic pressure as the driving force, and uses the selective permeability of selective membrane which can only pass through water but not solute to extract fresh water from water. Reverse osmosis is also called reverse osmosis. It is commonly known as pure water machine.
chemical treatment method
chemical agent that can prevent scale formation or inhibit its deposition and growth. Such as silicon phosphorus crystal, trisodium softener (sodium hydroxide, trisodium phosphate, sodium humate). It can be selected according to different use conditions.