What is the role of activated carbon in the water purifier?
Source：This site Release time：2018-9-16 14:11:19
1. The water purification effect of activated carbon
Activated carbon removes odor and taste, color, residual chlorine, colloids, organic matter (synthetic detergents, pesticides, herbicides, insecticides, synthetic dyes, trihalomethanes, haloacetic acids, endocrine disruptors such as phthalic acid) Ester PAES, etc., heavy metals (such as mercury, silver, cadmium, chromium, lead, nickel, etc.), radioactive materials, etc., are the earliest and most widely used water purification materials in water purifiers. Not only general activated carbon water purifiers, but also in household reverse osmosis water purifiers, as well as most ultrafiltration, ceramics, KDF, UV and other water purifiers, will use activated carbon.
Both activated carbon and KDF can remove residual chlorine in water, but KDF reacts with chlorine to form zinc ions (Zn2), which may lead to excessive zinc in water. However, there is no such concern when using activated carbon to remove chlorine.
Activated carbon forms a large number of fine pores of various shapes during the activation process, and constitutes a huge surface area with adsorption. The specific surface area is 500-1200 m2/g, and the larger the specific surface area, the better the adsorption effect.
2, the negative impact of activated carbon
(1) Activated carbon adsorbs a large amount of organic matter. These organic substances will become the nutrients of microorganisms such as bacteria. The bacteria will multiply and proliferate in the micropores of activated carbon, and may cause the total number of colonies in the effluent to exceed the standard.
(2) The activated carbon in the water purifier converts the ammonia nitrogen in the water into nitrite nitrogen under the action of microorganisms. It is often found that the nitrite in the water purifier effluent is many times higher than the influent water. Nitrite itself is not a carcinogen, but its nitrosamines formed by reaction with amines in water are strong carcinogens.
(3) Filtration or UV sterilization of effluent plus bromine resin (brominated polystyrene hydantoin) adsorbed by activated carbon is a good method to solve the problem of microbial exceeding in water.
Second, how to improve the water purification effect of activated carbon water purifier
The water purifier manufacturer should purchase good quality activated carbon, and check and test each batch of purchased activated carbon to prevent the purchase of inferior products.
1. Nowadays, many activated carbons on the market are mixed with recycled materials, and some are even all recycled materials. The activated carbon production plant purchases the activated carbon that has been used and scrapped by the user, and then returns it to the furnace for treatment. Some even put the open-air yard in the sun and then sell it or add it to the new activated carbon to reduce the cost and price. . Shanghai CDC has detected strange things in the removal rate of CODMn from activated carbon filter.
In addition, there is water washing, pure water should be used, but the cost is high. Many activated carbon plants do not have pure water equipment. They use river water, well water or even water in the smelly ditch to wash charcoal. Such activated carbon is polluted.
2. Activated carbon plays a role of water purification, and it takes a certain time regardless of physical adsorption or chemical adsorption. Therefore, the water purifier manufacturer should improve the design of the activated carbon filter or activated carbon filter to increase the contact time of water and activated carbon as much as possible. Contact time = length of the carbon column / flow rate of water in the carbon column, increase the length of the carbon column and the amount of activated carbon By reducing the flow rate of water, the contact time between water and activated carbon can be prolonged, and the water purification effect and effluent quality of activated carbon can be improved.
3, the instruction manual of the activated carbon water purifier should inform the user, after opening the water purifier, it is necessary to let off part of the water, drain the water in the water purifier filter and the pipe, and then take the fresh filtered water. . Otherwise, after soaking for a long time, the bacteria in the activated carbon will multiply excessively, and the nitrite may increase. Therefore, the residual water in the water purifier must be drained first.
4, the use of activated carbon water purifier instructions, should warn the user, activated carbon should be changed frequently, usually half a year to replace. In particular, in the south, tap water with surface water as the water source has many colloidal substances and high organic matter content in the water. It is necessary to replace the activated carbon filter element in the water purifier in time. After the activated carbon is saturated with organic matter, it can not only play the role of adsorption and water purification, but will release harmful substances, making the water purifier a "sewage device".