National Primary Standard Get 210-2014 for the Units of Specific Absorption of Gases, Specific Surface, Specific Volume, and Pore Size of Solid Substances and Materials

Abstract

The most important characteristics of the structure of porous and dispersed substances and materials are the specifi c surface, specifi c volume, and size of the pores. The absorptive capacity of adsorbent, the effi ciency of solid catalysts, and the characteristics of fi lter materials depend on the sorption properties of substances. The specifi c surface of active carbon ranges from 500–1500 m 2 /g, that of silicagels ranges up to 800 m 2 /g, that of macropore ion exchange resins is no more than 70 m 2 /g, that of diatomite carriers for gas-liquid chromatography is less than 10 m 2 /g, and that of nonporous metal and ceramic powders is less than 1 m 2 /g [1–4]. The specifi c surface characterizes the dispersion of powdered materials: mineral binding materials, fi llers, pigments, pulverized fuels, etc. [1]. The range of values of the specifi c surface extends from tenths to several thousands of square meters per gram. In accordance with the IUPAC classifi cation, materials are divided into three groups with respect to pore size: microporous (less than 2 nm), mesoporous (2–50 nm), and macroporous (more than 50 nm). Microporous zeolites are used in isomerization of benzene fractions and oil cracking and are employed in the pre- and hydropurifi cation of oil and oil products. Mesoporous metal oxides are used to remove various contaminants from gaseous and liquid media, as in automobile catalyzers for cleaning of exhaust gases, in the nanosystems and nanomaterials industry for creating and processing composite materials, polymers, and elastomers, and in the rubber, chemical, and other branches of industry. Macroporous and nonporous metallic micro- and nanopowders are used to produce coatings and new composite materials employed in welding, as well as in machine building, aviation, chemistry, etc. Copper powder is used in the production of antiwear compounds and automobile casings. The most active metal powders are used in powder metallurgy. The development of new materials, whose properties must be monitored, has led to the appearance of a large number of instruments for these measurements. According to data from the Federal Information Foundation for Support of the Uniformity of Measurements (FIF), 25 types of instrumentation are included in the register of certifi ed means of measurement [5]. The relative error of the means of measuring sorption properties is ±(2–30)%. Thus, there is a need for centralized metrological support of these instruments, of which there are estimated to be more than 300 in Russia. This has led to the creation and certifi cation of a National Primary Standard (GET 210-2014) for the units of specifi c absorption of gases, specifi c surface, specifi c volume, and pore size of solid substances and materials [6].