ASTM D4607-14 Standard Test Method for Determination of Iodine Number of Activated Carbon

The standard "ASTM D4607-14 Standard Test Method for Determination of Iodine Number of Activated Carbon" developed by the American Society for Testing and Materials (ASTM) describes a test method for determining the relative activation level of unused or reactivated carbons by adsorption of iodine from aqueous solution. The amount of iodine (in milligrams) adsorbed by 1 g of carbon using the test conditions listed here is called the iodine number.

The test method described is based on the three-point adsorption isotherm (see also “ASTM D3860-98 Standard practice for Determining the adsorption capacity of activated carbon by the aqueous phase isotherm technique” on this subject.

According to ASTM D4607-14, an iodine solution is treated with three different weights of activated carbon under specified conditions. The carbon-treated solutions are filtered to separate the carbon from the treated iodine solution (filtrate). The iodine remaining in the filtrate is measured by titration. The amount of iodine removed per gram of carbon for each carbon dosage is determined and the resulting data are used to plot an adsorption isotherm. The amount of iodine adsorbed per gram of carbon at a residual iodine concentration of 0,02 N is reported as the iodine number (in milligrams).

The iodine concentration in the standard solution affects the iodine adsorption capacity of activated carbon. Therefore, the normality of the standard iodine solution should be kept at a constant value for all iodine number measurements.

The apparatus required consists of various laboratory glassware used to prepare solutions and to contact the carbon with standard iodine solution. Filtration and titration equipment is also required.

The iodine number is a relative indicator of porosity in activated carbon. It does not provide a measure of the ability of the carbon to absorb other species. The iodine number can be used as an estimate of surface area for some types of activated carbon. However, it should be understood that any relationship between surface area and iodine number cannot be generalized. It will vary with changes in the carbon feedstock, processing conditions, and pore volume distribution.

The presence of adsorbed volatiles, sulfur, and water extractables can affect the measured iodine number of activated carbon.

The main equipment used in these tests includes:

• Analytical balance (accuracy plus/minus 0.0001 g)
• Burette (10 mL capacity or 5 mL precision burette)
• Flasks (Erlenmeyer 250 mL capacity, with ground glass stopper)
• Flask (Erlenmeyer flask, wide mouth, 250 mL capacity)
• Beakers (various sizes)
• Bottles (amber, for storage of iodine and thiosulfate solutions)
• Funnels (100 mm top inner diameter)
• Filter paper (18,5 cm pre-folded paper)
• Pipettes (volumetric type, 5,0, 10,0, 25,0, 50,0 and 100,0 mL capacity)
• Volumetric flasks (1 L9
• Graduated cylinders (100 mL and 500 mL)

All volumetric measuring equipment must meet or exceed the requirements of National Institute of Standards and Technology (NIST) circular 602. Volumetric glassware meeting these specifications is often referred to as “Class A.”

Reagents used in the tests include:

• Purity of reagents: Reagent grade chemicals should be used in all tests. Unless otherwise specified, all reagents are intended to conform to the specifications of the American Chemical Society Committee on Analytical Reagents, where such specifications are available. Other grades may be used if it is initially determined that the reagent is of sufficiently high purity to permit its use without diminishing the accuracy of the determination.
• Purity of water: References to water should be understood as reagent water complying with ASTM D1193-06 standard for Type II reagent water.
• Hydrochloric acid: Concentrated.
• Sodium thiosulfate.
• Iodine: US Pharmacopeia, resublimed crystals.
• Potassium iodide.
• Potassium iodate.
• Starch: Soluble potato or arrowroot.
• Sodium carbonate.

Among the numerous testing, measurement, analysis and evaluation studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the standard “ASTM D4607-14 Standard test method for determining the iodine number of activated carbon” with its trained and expert staff and advanced technological equipment.