QUALITY OF CARBON

Following are certain measurable parameters of activated carbon

01

Porosity

Porosity is an important characteristic to denote the adsoprtion capability of activated carbon. The three broad categories are: macroporous ('large' - greater than 50 Å, or larger than 5 nm); mesoporous ('medium' 20 Å - 50 Å, or 2 - 5 nm); and microporous ('small' - less than 20 Å, or up to 2 nm).

02

Iodine Number

As Activated Carbon adsorbs iodine well, the iodine capacity (mg/g) is normally used as an indication of the total surface area. Iodine number is a measure of activity level and a fundamental parameter to denote activated carbon performance - higher the Iodine number higher the degree of activation). The Iodine number is a basic measurement used to characterize activated carbon performance. The Iodine number represents the micropore content of the activated carbon relative to the amount of iodine adsorbed from solution. Iodine Number coincides with Surface Area measurements of activated carbon between 900 m²/g and 1200 m²/g.

03

Molasses

Some activated carbons are more inclined to adsorb large molecules. A molasses number indicates the macropore content of the activated carbon (larger than 20 Å or 2 nm) by adsorption of molasses from solution. A high molasses number indicates a high adsorption of big molecules (range 95-600). Since color molecules are typicallylarge, the Molasses Number is a measure of the degree of decolorization. Due to the size of color bodies, the molasses number represents the potential pore volume available for larger adsorbing activated carbons.

04

Tannin

Tannins have a mix of medium and large size molecules. Activated carbons that have macropores and mesopores adsorb tannins efficiently. The ability to adsorb tannins is reported in parts per million concentration (range 200 ppm-362 ppm).

05

Methylene blue

Activated carbons with a mesopore (20 Å - 50 Å, or 2 - 5 nm) structure adsorb medium size molecules like the dye Methylene Blue. Methylene Blue adsorption is reported in g/100g (range 11-28 g/100g).

06

Dechlorination

Dechlorination is the ability to remove chlorine. The dechlorination half-value is the key parameter here. The dechlorination half-value length is the depth of carbon required to reduce the chlorine level of a flowing stream from 5 ppm to 3.5 ppm. A lower half-value length indicates superior performance.

07

Apparent density

The solid density of activated carbons will typically range between 2.0 and 2.1 g/cm3 (125–130 lbs./cubic foot). However, a large part of an activated carbon sample will consist of air space between particles, and the actual or apparent density will therefore be lower, typically 0.4 to 0.5 g/cm3 (25–31 lbs./cubic foot). Better-quality activated carbon will have higher density that provides greater volume activity.

08

Hardness/abrasion number

Abrasion Number is a measure of activated carbon’s resistance to attrition. It is an important indicator of activated carbon to maintain its physical integrity and withstand frictional forces.

09

Ash content

Ash content reduces an activated carbon's activity potential.

10

Carbon tetrachloride activity (CTC)

The Carbon Tetrachloride number (45 - 70% by weight) measures the porosity of an activated carbon for air/vapor applications according to the amount of carbon tetrachloride vapor it will adsorb.

11

Particle size distribution

Particle size determines the surface area and the finer particle size of an activated carbon provides more surface area resulting in faster rate of adsorption.

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