[Environment] Understanding Halogen

When using chemical products, you often hear people mention the word "halogen". Questions such as "Does this product contain halogen?" or "What is the specific content of halogen?" are often asked. Let's learn about halogen here!

Halogen is the English word for halogen. It belongs to Group 17 in the periodic table and contains six elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), arsine (At) and thionium (Ts). The first four are more commonly mentioned, while the last two are extremely radioactive. Since the last two items are less common, we will not explain them in detail here.

About each element

• Fluorine   English name: fluorine   Chemical symbol: F   Atomic number: 9

Fluorine is the lightest element among the halogens and has strong oxidizing properties; in medical terms, small amounts of fluoride can help prevent tooth decay, but high doses can harm health. In adults, exposure to high doses of fluoride increases bone density, but at high enough doses, these bones become more brittle and more prone to fracture, increasing the risk of fractures. Animals exposed to extremely high doses of fluoride have reduced fertility and damage to sperm and testicles. Fluorine and hydrogen fluoride are irritating to the skin, eyes, and respiratory tract. Exposure to high doses of hydrogen fluoride may also be harmful to the heart, which is usually seen in industrial accidents.

• Chlorine   English Name : Chlorine   Chemical Symbol : Cl   Atomic Number : 17

Chlorine is the second lightest halogen between fluorine and bromine, so its non-metallic properties are between them. Chlorine is a yellow-green poisonous gas with a strong pungent odor at room temperature, which turns into a yellow oily liquid after liquefaction. During the chlorination process, chlorine gas may be initially added to the water; however, the chlorine quickly transforms into other chemicals that actually sterilize and disinfect the water. Hypochlorous acid and sodium hypochlorite are two of the chemicals used to detoxify water.

Exposure to low concentrations of chlorine gas can cause irritation of the nose, throat, and eyes; inhalation of higher concentrations of chlorine gas may cause changes in breathing rate, coughing, and damage to the lungs. In general, people with respiratory problems, such as allergies or hay fever, or who are heavy smokers, tend to have more severe effects than healthy people or non-smokers. Hypochlorite solution spilled on the skin can cause skin irritation, the severity of which depends on the concentration of sodium hypochlorite in the bleach.

• Bromine   English Name : Bromine   Chemical Symbol : Br   Atomic Number : 35

Bromine molecules are volatile reddish-brown liquids at standard temperature and pressure, with an activity between that of chlorine and iodine. Bromine vapor is corrosive and poisonous. Bromine and its compounds can be used as flame retardants (brominated flame retardants), water purifiers, pesticides, dyes, etc. Mercurochrome, once a commonly used disinfectant, contains bromine and mercury. In photography, compounds of bromine and iodine with silver act as photosensitizers.

Bromine in its elemental state is toxic and irritating, and its vapor is highly corrosive and can damage rubber. Because bromine is an oxidizing agent and is not stable with most organic or inorganic compounds, it must be transported with caution, usually in lead-lined steel drums supported by sturdy metal racks.

• Iodine   English Name : Iodine   Chemical Symbol : I   Atomic Number : 53

Iodine is the heaviest stable halogen. It is a shiny purple-black solid nonmetal under standard conditions. It melts into a dark purple liquid at 114 °C (237 °F) and vaporizes into a purple gas at 184 °C (363 °F). Iodine occurs naturally in seawater and certain rocks or sediments. Iodine exists in both non-radioactive and radioactive forms. Iodine is used as a disinfectant to clean surfaces or containers. It can also be added to soaps and bandages, and even used to purify water. It is sometimes added to table salt to ensure that people can get enough iodine from their diet.

Iodine has both beneficial and harmful effects on the human body. Our thyroid gland requires an adequate amount of iodine to produce thyroid hormones; however, exposure to unnecessary high doses of non-radioactive or radioactive iodine can damage the thyroid gland, which, if damaged, is likely to affect the function of other organs such as the skin, lungs and reproductive organs. Radioactive iodine can only be used by doctors for medical purposes, such as to treat thyroid cancer.

About Industrial Wastewater Discharge

There are currently no specific regulations directly regulating the discharge of "halogens" in wastewater. However, according to Article 18 of the Water Pollution Prevention and Control Law, public institutions must take water pollution prevention and control measures to ensure that the collection, treatment and discharge of waste (sewage) water comply with relevant standards.