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    ASTM D1993 - 18

    Standard Test Method for Precipitated Silica-Surface Area by Multipoint BET Nitrogen Adsorption

    Active Standard ASTM D1993 | Developed by Subcommittee: D11.20

    Book of Standards Volume: 09.01

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    Significance and Use

    3.1 This test method is used to measure the surface area of precipitated, hydrated silicas that is available to the nitrogen molecule using the multipoint (B. E. T.) method.

    3.2 Solids adsorb nitrogen and, under specific conditions, the adsorbed molecules approach a monomolecular layer. The quantity in this hypothetical monomolecular layer is calculated using the BET equation. Combining this with the area occupied by the nitrogen molecule yields the total surface area of the solid.

    3.3 This test method measures the estimated quantity of nitrogen in the monomolecular layer by adsorption at liquid nitrogen temperature and at several (at least five) partial pressures of nitrogen.

    3.4 Before a surface area determination can be made it is necessary that the silica be stripped of any material which may already be adsorbed on the surface. The stripping of adsorbed foreign material eliminates two potential errors. The first error is associated with the weight of the foreign material. The second error is associated with the surface area that the foreign material occupies.

    1. Scope

    1.1 This test method covers a procedure which is used to measure the surface area of precipitated hydrated silicas by the conventional Brunauer, Emmett, and Teller (BET)2 theory of multilayer gas adsorption behavior using multipoint determinations, similar to that used for carbon black in Test Method D6556. This test method specifies the sample preparation and treatment, instrument calibrations, required accuracy and precision of experimental data, and calculations of the surface area results from the obtained data.

    1.2 This test method is used to determine the nitrogen surface area of precipitated silicas with specific surface areas in the range of 1 to 50 hm2/kg (10 to 500 m2/g).

    1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

    1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. The minimum safety equipment should include protective gloves, sturdy eye and face protection, and means to deal safely with accidental mercury spills.

    1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D1799 Practice for Carbon Black--Sampling Packaged Shipments

    D1900 Practice for Carbon BlackSampling Bulk Shipments

    D4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries

    D5900 Specification for Physical and Chemical Properties of Industry Reference Materials (IRM)

    D6556 Test Method for Carbon BlackTotal and External Surface Area by Nitrogen Adsorption

    ICS Code

    ICS Number Code 71.060.20 (Oxides)

    UNSPSC Code

    UNSPSC Code 12352309(Silica)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D1993-18

    Citation Format

    ASTM D1993-18, Standard Test Method for Precipitated Silica-Surface Area by Multipoint BET Nitrogen Adsorption, ASTM International, West Conshohocken, PA, 2018, www.astm.org

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