Activated carbon is processed to have small, low-volume pores that increase the surface area available for adsorption. It has applications in the medical, environmental and energy realms, among others.
Since 1962, ASTM Committee D28 on Activated Carbon has developed standards that play a pre-eminent role in how activated carbon is used. A D28 subcommittee, D28.02 on Liquid Phase Evaluation, is currently working on two proposed standards.
WK47401, Xylenol Orange Dye
The xylenol orange dye test is a way to determine the relative adsorption rate of unused or reactivated carbons by adsorption of xylenol orange from aqueous solution. This is an important means for deciding which type of activated carbon to use for a specific water treatment application.
“Activated carbon performance can roughly be defined as a combination of the ability to adsorb a particular contaminant and the ability to adsorb that contaminant quickly,” says ASTM member Adam Redding, Ph.D., a scientist at Evoqua Water Technologies LLC. “The proposed method will provide relative quantification of the rate with which a particular carbon can adsorb a contaminant.”
The proposed standard, WK47401, Test Method for Xylenol Orange Dye Test, will cover activated carbons that are used for the treatment of drinking water as well as those used to produce consumer products or treat wastewater from production facilities. The proposed standard describes the relative adsorption rate of unused or reactivated carbons by adsorption of xylenol orange from aqueous solution.
“Both producers of activated carbon and users can apply this standard,” says Redding. “The proposed method has been designed with the goals of both simplicity and accuracy.”
According to Redding, D28.02 has already evaluated the proposed standard for applicability to both groundwater and surface water treatment and have found that the test method offers insight into both carbon performance and prediction of that performance.
WK47421, Particle Size Distribution
Mercury flue gas, home water filters and potable water treatment are the main applications in which powdered and fine mesh carbons are used. A proposed new test method will describe how a laser light scattering technique can determine the particle size distribution of fine mesh activated carbon.
ASTM member Neal Megonnell, vice president, sales and marketing, Haycarb USA, says the proposed test method will be welcomed since the test has been run for many years, but without a standard. This has led to disputes between manufacturers and end users, which this ASTM standard, once approved, can help resolve.
Primary users of WK47421, Test Method for Particle Size Distribution of Fine Mesh Activated Carbon Material by Laser Light Scattering, will be activated carbon suppliers, laboratories and end users.
D28.02 welcomes all interested parties to participate in the development of WK47401 and WK47421. The subcommittee is particularly interested in having potential end users conduct the proposed methods at their facilities and offer feedback on the results.