BS ISO 9277:2010 pdf free.Determination of the specific surface area of solids by gas  adsorption- BET method.
BS ISO 9277 specifies the determination of the overall (see Note) specific external and internal surface area of disperse (e.g. nano-powders) or porous solids by measuring the amount of physically adsorbed gas according to the Brunauer, Emmett and Teller (BET) method (see Reference [1]). It takes account of the International Union for Pure and Applied Chemistry (IUPAC) recommendations of 1984 and 1994 (see References [7][81).
NOTE For solids exhibiting a chemically heterogeneous surface, e.g metal-carrying catalysts, the BET method gives the overall surface area, whereas the metallic portion of the surface area can be measured by cheniisorption methods.
The BET method is applicable only to adsorption isotherms of type II (disperse, nonporous or macroporous solids) and type IV (mesoporous solids, pore diameter between 2 nm and 50 nm). Inaccessible pores are not detected. The BET method cannot reliably be applied to solids which absorb the measuring gas.
A strategy for specific surface area determination of microporous materials (type I isotherms) is described in Annex C.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 8213, Chemical products for industrial use — Sampling techniques — Solid chemical products in the form of particles varying from powders to coarse lumps
ISO 14488, Particulate materials — Sampling and sample splitting for the determination of particulate properties
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply adsorption
enrichment of the adsorptive gas at the external and accessible internal surfaces of a solid material
(ISO 159012:2006(21, 3.4]
3.2 physisorptlon weak bonding of the adsorbate, reversible by small changes in pressure or temperature
4 Symbols and abbreviated terms
Table 1 presents the symbols used in this International Standard, together with their common units derived from the SI. For comparison purposes, the IUPAC symbols (see References [7][8]) are also given. These may differ from the symbols generally used in International Standards. All specific dimensions are related to sample mass in grams.
5 Principle
The BET method is applicable only to adsorption isotherms of type II (disperse, nonporous or macroporous solids) and type IV (mesoporous solids, pore diameter between 2 nm and 50 nm) (see Figure 1). Inaccessible pores are not detected. The BET method cannot reliably be applied to solids which absorb the measuring gas. A strategy for specific surface area determination of microporous materials (type I isotherms) is described in Annex C.
The method specified involves the determination of the amount of adsorbate or adsorptive gas required to cover the external and the accessible internal pore surfaces of a solid (see Figure 2) with a complete monolayer of adsorbate. This monolayer amount can be calculated from the adsorption isotherm using the BET equation [see Equation (1)]. Any gas may be used, provided it is physically adsorbed by weak bonds at the surface of the solid (van der Waals forces), and can be desorbed by a decrease in pressure at the same temperature.BS ISO 9277 pdf download.