ISO 23604:2022 PDF

Overview

ISO 23604:2022 - Method of determining specific surface area of coal - specifies a gas-adsorption volumetric method to determine the specific surface area of coal and other powder or porous materials (including nano-powders). The method covers a broad determination range (0.001 m2/g to 1 000 m2/g) and defines procedures from sample preparation and degassing through adsorption isotherm measurement and surface-area calculation.

Key topics and technical requirements

• Principle: Specific surface area is derived from equilibrium gas adsorption at controlled temperature using theoretical models (e.g., BET).
• Reagents & equipment: High‑purity gases (nitrogen ≥99.99 %, helium ≥99.99 %, CO2 ≥99.9 %), liquid nitrogen (77 K), and a specific surface area analyser with degasser, manifold, valves, vacuum pump and temperature probes.
• Sample preparation:
  • Fresh coal preferred; remove oxide layer or salts if present.
  • Particle size and mass guidelines: typically 0.28–0.45 mm particle fraction; sample masses vary by lithology (e.g., 1–5 g).
  • Air‑dry below 40 °C; seal and store in a desiccator.
• Degassing and temperature control:
  • Vacuum degassing to