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How to identify the advantages and disadvantages of purified water activated carbon and methods for screening activated carbon and primary activated carbon
- Dec 28, 2018 -

"Activated carbon is one of the most widely used adsorbent materials in the water purification industry. It is characterized by strong adsorption capacity, stable performance and high cost performance. However, China's activated carbon started late and the industry standard is missing, so the current activated carbon on the market is mixed. The advantages and disadvantages are difficult to distinguish, this article will share some simple and easy to distinguish methods."


Classification of purified water activated carbon


Purified water activated carbon is divided into coal and wood (coconut and shell). Coal-based activated carbon is mainly used in large-scale water purification facilities (such as waterworks and sewage treatment plants) and part of filter making, and wood activated carbon in water purifiers. It is widely used, especially coconut shell activated carbon. The above several kinds of activated carbon have their own advantages and disadvantages. The coal-based activated carbon is low in price and large in output. The one-time purchase quantity in the movable one is extremely dominant in the hundreds of thousands or even thousands of tons of tap water projects, but the ash content is high and the heavy metal content is high. Block short plates are not obvious in large-scale water treatment projects, but the drawbacks are highlighted in the terminal clean water, because the terminal clean water is deep purification of drinking water based on the use of tap water as the base water, and removes heavy metals and Other impurities harmful to the human body, coal-based activated carbon obviously cannot achieve this effect.


The wood activated carbon is divided into shell activated carbon and coconut shell activated carbon. The plant area of the shell activated carbon is mainly concentrated in Hebei, Shandong, Ningxia and other places. The local walnut shell, apricot kernel and jujube core are used as raw materials. The advantage of this kind of activated carbon is the price ratio. The coconut shell activated carbon is relatively low, and the quality is higher than that of coal-based activated carbon. The disadvantage is that the adsorption capacity is low, the iodine adsorption value is mostly between 600-900, the strength is poor, and it is easy to be broken, especially when the iodine value After more than 800, there may be a phenomenon in which activated carbon fine powder flows out during use.


Coconut shell activated carbon is the highest grade in the final clean water, and it is also the most commonly used. Its advantages are strong adsorption capacity, low ash, high strength and good mouthfeel. The disadvantage is that the price is high. At present, there are not many enterprises that actually produce high-grade coconut shell water-purifying activated carbon. The raw materials are basically from Southeast Asian countries such as the Philippines, Malaysia, Indonesia, etc. The production process is basically based on converter activation, the original Slep furnace and The grate furnace is basically being phased out.


How to identify the pros and cons of activated carbon


The first function of activated carbon is its adsorption capacity. The size of its adsorption capacity depends on the development of its pore diameter and the distribution of different pore sizes. Generally, pores with pore diameter less than 2 nm are regarded as micropores, and the range of 2--50 nm is considered. For mesopores, larger pores larger than 50nm, pores with different pore sizes play different roles in the adsorption process. Macropores account for a small proportion of specific surface area, and tend to become channels of adsorbate molecules during adsorption of activated carbon. The pore is not only the channel of adsorption, but also the capillary condensation occurs under a certain pressure, which plays an important role in adsorbing macromolecules, and the adsorption of micropores is the largest, which plays a dominant role in the adsorption amount of activated carbon, to a large extent. Determine the size of the adsorption capacity of activated carbon. So what method should we choose in the actual test? There are usually two indicators for detecting the adsorption capacity of activated carbon. One is the iodine adsorption value, the other is the methylene blue adsorption value. The size of the iodine adsorption value reflects the development degree of the micropores. The size of the methylene blue adsorption value corresponds to the mesopores. The degree of development, a very important indicator in water treatment is heavy metals, the adsorption of heavy metals mainly depends on micropores, so usually in the selection of purified water activated carbon, the size of the iodine adsorption value to distinguish its adsorption capacity (some Enterprises use COD removal rate to select activated carbon. This method is very practical, but this indicator is greatly affected by its raw water quality and cannot be explained by uniform standards, so we will not communicate here.) Generally, it is preferred to use an iodine adsorption value between 1000 and 1200 for end water treatment. There are many manufacturers, especially those with relatively small scale and incomplete testing equipment. When distinguishing the adsorption capacity of activated carbon, it is determined by the more or less bubbles in the water. In fact, this method is intuitive but very unscientific, affecting There are many factors such as the number of bubbles, such as the level of water, etc., can not completely reflect the adsorption capacity of activated carbon, it is recommended to use professional methods and means to detect activated carbon.


Another important indicator of clean water activated carbon is strength. The quality of this indicator will be related to whether the customer will produce black fine powder during use, and also the service life of the water purifier using the filled activated carbon process. Select activated carbon with a strength greater than 98, and try not to use less than 95.


Regarding the choice of PH value, if the activated carbon or activated carbon filter is post-mounted, it is recommended to choose PH between 7 and 8.5. The pH of this range is better, which is beneficial to human health.


How to distinguish between recycled activated carbon and primary activated carbon


At present, the domestic activated carbon market is still in a relatively chaotic development period, and there is still a lack of supervision. There are many activated carbons in the market. Strictly speaking, activated carbon can be recycled. This technology is also used abroad. It is a mature technology, but since the water treated by the terminal water purification is directly supplied to the human body, its safety is in the first place. The source of the recycled activated carbon is complicated, and it may be water treatment. However, it may be used in industrial treatment, and may even be used in chemical treatment. The residual material after adsorption cannot be completely decomposed and desorbed during the regeneration process. Once the harmful substances are released into the water, The consequences of drinking the human body are unimaginable, so the recycled activated carbon can only be used for industrial processing, and it can never be used in the end water treatment. So how to distinguish whether it is recycled activated carbon? First of all, look at the appearance, the color of the regenerated activated carbon is relatively dark, the gloss is small, and some may have pale yellow rust (some regenerative carbon manufacturers will use the polishing process, but after careful observation can still be discerned) The second is the detection intensity. This is something that any regenerative carbon manufacturer can't cover. The regeneration process is actually the process of secondary activation. Its strength will be greatly damaged. Generally, the strength of recycled activated carbon is below 95. The last is to look at the price. It is best not to purchase activated carbon at a low price. The difference in the price of real raw activated carbon cannot be too great.