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Iodine number, BET surface area, and CTC: how to read an activated carbon datasheet

A plain-language guide to the numbers on every TDS — what each parameter actually measures and what it tells you about performance.

5 min read · Intermediate

The parameters you’ll see on every TDS

Every activated carbon Technical Data Sheet includes a set of standard test parameters. Here’s what each one actually measures — and what it tells you about real-world performance.

Iodine Number (IV)

Measured by the ASTM D4607 method. Reports how many milligrams of iodine are adsorbed per gram of carbon from a standard iodine solution. Range: typically 500–1200 mg/g. Higher = more adsorption capacity. Good general indicator of surface area for liquid-phase applications, but not reliable for gas-phase or gold recovery.

BET Surface Area

Measured using nitrogen gas adsorption at liquid nitrogen temperature. Reports total surface area in m²/g, using the Brunauer-Emmett-Teller method. Range: 500–1500 m²/g. The most direct measure of total surface area. More reliable than iodine number for comparing different carbon types.

CTC (Carbon Tetrachloride Activity)

Measures the mass of CCl₄ vapour adsorbed under standard conditions, expressed as a percentage. Range: 20–80%. Best indicator of micropore volume. Important for gas-phase VOC control and gold recovery applications.

Hardness Number

Measured by ball-pan hardness test (ASTM D3802). Percentage of original carbon remaining on a defined screen after a mechanical abrasion procedure. Range: 70–99%. Critical for applications with mechanical stress — column beds, CIL/CIP circuits.

A TDS tells you what the carbon can do under controlled conditions. Actual performance depends on your specific application conditions — temperature, contaminant concentration, flow rate, and contact time. When in doubt, request a sample.

Ash Content

The mineral residue remaining after complete combustion. Lower ash = higher purity = preferred for pharma, food, and high-specification water treatment. Typical range: 2–20%.

Moisture

As-packed moisture content. Lower moisture = higher active carbon per kilogram. Standard grades typically 5–15%. Critical for applications where moisture carry-over is problematic.

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