Activated carbon is a highly efficient adsorbent and activated carbon can be used in almost every aspect of life. The quality of activated carbon is mainly obtained by testing its various indicators, and different qualities of activated carbon can be classified according to their indicators.
The main performance indicators of activated carbon are iodine value, methylene blue, molasses value, phenol value, CTC, strength, specific surface area, moisture, ash, flotation rate, abrasion factor, uniformity factor, effective particle size, water soluble matter acid soluble matter, etc. This article mainly introduces the meaning of these indicators in detail, which will make you understand the basics knowledge of activated carbon, so that you can better choose the activated carbon which meet your demand .
The iodine (adsorption) value is the ability of an activated carbon column to adsorb iodine from iodine solutions in mg/g. It is the relative indicative value of the pore structure of activated carbon, as the diameter of iodine molecule is only 0.335 nm , therefore the iodine value reflects the degree of development of the micro-pores of activated carbon and indicates the adsorption capacity of activated carbon for small molecules.
In liquid phase adsorption applications, the iodine value is one of the important performance indicators. The higher iodine value, the higher production cost and the higher price. Generally, activated carbon for water treatment requires an iodine value of 800mg/g or more.
For special applications, such as activated carbon for gold refining, the iodine value should be more than 1000mg/g for a good adsorption results.
Methylene blue adsorption value refers to the number of milligrams of methylene blue absorbed when 1.0g of charcoal reaches equilibrium with a 1.0mg/L concentration of methylene blue solution.
The methylene blue molecular size is slightly larger than the odour-causing substances 2-MIB (2-methylisothiophenol and hyoscyamine) in water. The adsorption value of methylene blue thus reflects the deodorising capacity of the activated carbon, and a high adsorption value of methylene blue gives a good deodorising effect.
PS: Common units are mg/g and ml/0.1g.
The unit conversion formula: 1ml/0.1g = 15mg/g, e.g. methylene blue value 8ml/0.1g = 120mg/g.
Coal activated carbon is usually tested for methylene blue in mg/g and wood-based activated carbon in ml/0.1g.
In terms of activated carbon for decolorization (sugar decolorization, oil decolorization, monosodium glutamate decolorization, etc.), methylene blue is a very important indicator, but the effect of decolorization is not only related to methylene blue, but also to the pore size of activated carbon.
With the same methylene blue value, the decolorization effect may also be different. At this time, it may be caused by the different pore size of activated carbon.
The molecular diameter of molasses is larger than that of methyl blue, and the molasses value is a measure of the relative decolorization ability of activated carbon in a boiling molasses solution. At present, there is no testing standard for molasses value in China. Generally, the standard of Calgon in the United States is used for testing. In China, only agglomerated activated carbon with high molasses value will be tested, and other carbon types will not be tested for molasses value.
Activated carbon with high molasses value also has a very good effect in decolorization. We currently have customers for palm oil by-product glycerin refining and amine liquid impurity removal to achieve the effect of recycling.
CTC adsorption value refers to the adsorption ratio of activated carbon to carbon tetrachloride. Under specific temperature conditions, carbon tetrachloride vapor is mixed through activated carbon. After a period of time, weigh and repeat this step continuously until the weight remains unchanged, that is, when the activated carbon adsorption is saturated, the total amount of carbon tetrachloride adsorbed by the activated carbon is the carbon tetrachloride adsorption value of the activated carbon.
CTC is mainly used to evaluate the gas-phase adsorption capacity of activated carbon, which is a very important indicator for measuring gas-phase carbon.
Regarding the activated carbon used in automobile carbon canisters, the butane adsorption capacity of the activated carbon needs to reach (≥10.5%), so the CTC value of the activated carbon is required to reach at least 110%, and at the same time, it is necessary to add chemicals. Our company can provide qualified products. Consult for details (lydia@huameicarbon.com)
The concentration of pollutants in drinking water sources is much lower than that in non-drinking water, generally several ppm or even several ppb. This requires the activated carbon for drinking water purification, in the range of low concentration, has a strong adsorption capacity. Phenol value is an index to measure the ability of activated carbon to adsorb low-concentration substances.
The phenol value is defined as: the dosage of powdered activated carbon (gm/L) when the phenol content in water is reduced from 100 ppm to 10 ppb. Contact our expert Mia (mia@huameicarbon.com) for more information.
When activated carbon is put into the aqueous solution, the ratio of carbon floating on the water surface to the total input amount, the unit is percentage.
The floating rate of agglomerated activated carbon is almost zero. The floating rate of raw coal crushed activated carbon is above 5%. The lower the flotation rate, the better the quality of activated carbon.
Granular activated carbon will be affected by various external forces in the process of transportation, filling and backwashing, which will cause friction between particles and generate carbon powder, so it needs better wear resistance.
The agglomerated activated carbon has better wear resistance because of its round particles, and the raw coal crushed activated carbon has less wear resistance because of its more edges and corners and more flakes.
Content of activated carbon soluble in aqueous solution/content of activated carbon soluble in acid solution.
Granular activated carbon (mesh): 4X8, 6X12, 8X30, 12X40, 20X40, 30X60
Granular carbon is generally used for liquid phase adsorption, water treatment generally uses 830mesh, 816mesh 1240mesh, filter CTO generally uses 30-60mesh, and larger particles are generally used for gas phase adsorption, such as 4-8mesh, 4-12mesh.
Pellet Activated Carbon (mm): 0.9mm, 1.5mm, 2mm, 3mm, 4mm, 6mm(Diameter)
Pellet Activated Carbon is generally used for gas phase adsorption, 0.9mm is generally used for gas masks, and 3mm and 4mm are the most commonly used sizes.
Powder activated carbon (mesh): 200-325
Powdered carbon is generally used for decolorization and has a high adsorption value of methylene blue, such as glycerol decolorization, sugar decolorization, etc.
Also known as drying loss, it is the data measured after drying the activated carbon at a constant temperature of about 150 degrees Celsius for 3 hours.
There are two kinds of ash in activated carbon, one is surface ash and the other is internal ash. Usually, the ash we measure is internal ash.
Some applications have very strict requirements on the ash content of activated carbon, and we can provide high-quality activated carbon with an ash content of less than 2%.
In simple terms, it is the bulk specific gravity of activated carbon per unit.
The ratio of the sieve size (d60) through which 60% of the product passes to the sieve size (d10) through which 10% of the same product passes. is an indicator of the uniformity of reactive carbon particles.
The sieve size (d10) that allows 10% of the product to pass through, for example: if the particle size distribution of 10% of the product is less than 0.5mm, the effective particle size of this product is 0.5mm, which is an indicator of the effectiveness of the reactive carbon particle size.
Note: Both effective particle size and uniformity factor are not applicable to columnar activated carbon.
Specific surface area, in m2/g, the larger the specific surface area, the more developed the micropores, which also reflects the better quality of activated carbon.
