8 Parameters to Specify When Writing an Activated Carbon Specification

The most common mistake in activated carbon procurement is writing only “iodine number ≥900” into the specification. Yet two carbons with the same iodine number can perform completely differently in the field. An incomplete spec leads to insufficient capacity, early breakthrough, high pressure drop and post-delivery disputes. The following 8 parameters let you compare offers fairly and receive the right product.

The 8 Core Parameters to Request

• Iodine number (mg/g) — indicator of micropores and general adsorption (ASTM D4607).
• BET surface area (m²/g) — total internal surface; complements the iodine number.
• Molasses number or methylene blue — removal power for large molecules (color, TOC).
• Particle size / mesh distribution — governs pressure drop and adsorption kinetics.
• Hardness / abrasion resistance (ball-pan hardness, %) — service life, especially in backwashed and agitated systems.
• Moisture (%) — the water content at shipment; affects net carbon weight.
• Ash content (total and water-soluble, %) — impurities and leachables.
• Apparent (bulk) density (g/cm³) — determines how many kg the column holds and the dosage.

Bonus Items to Add to the Spec

Alongside the 8 core parameters, add these depending on the application: pH (especially for drinking water and food), wettability, raw material type (shell/coal/wood), the relevant conformity statement if food or drinking-water contact is required, and a batch-based certificate of analysis (CoA) for every shipment. A CoA requirement guarantees delivery on measured values, not claimed ones.

Finally: write acceptance criteria and the right to sample/trial into the spec. A small-scale test with your own water or gas stream before purchase is far more reliable than values on paper.