Detail of GB/T 44149-2024

Introduction of GB/T 44149-2024

GB/T 44149-2024 Fine ceramics - Measurement of iso-electric point of ceramic powders - zeta potential method 1 Scope This document specifies the test method to determine the iso-electric point of fine ceramic powders, which is measured in the state of suspension. This document applies to the determination of iso-electric point of fine ceramic powders in dispersion. 2 Normative references The following documents contain requirements which, through reference in this text, constitute provisions 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 4316:1977 Surface active agents- Determination of pH of aqueous solutions- Potentiometric method Note: GB/T 6368-2008 Surface active agents - Determination of pH of aqueous solution - Potentiometric method (ISO 4316:1977, IDT) ISO 13099-1 Colloidal systems- Methods for zeta-potential determination- Part 1: Electroacoustic and electrokinetic phenomena Note: GB/T 32671.1-2016 Colloidal systems - Methods for zeta-potential determination - Part 1 : Electroacoustic and electrokinetic phenomena (ISO 13099- 1:2012, IDT) ISO 13099-2 Colloidal systems- Methods for zeta- potential determination- Part 2: Optical methods Note: GB/T 32671.2-2019 Colloidal systems - Methods for zeta-potential determination - Part 2 : Optical methods (ISO 13099-2:2012, IDT) ISO 13099-3 Colloidal systems - Methods for zeta- potential determination- Part 3: Acoustic methods 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 13099-1, ISO 13099-2 and ISO 13099-3 and the following apply. 3.1 zeta potential ζ-potential difference between the electric potential at the slipping plane and that of the bulk liquid, where the electric potential difference is proportional to the electrophoretic mobility of the charged particle to the electrode when the electric field is applied to the dispersed particles in the solution Note 1: See Figure 1. Note 2: Zeta potential is expressed in volts. Electrophoretic mobility (μ) is electrophoretic velocity divided by electric-field strength. Electrophoretic mobility is positive if the particles move towards a lower potential (negative electrode) and negative in the opposite case. Electrophoretic mobility is expressed in square metres per volt second (m 2 /V·s). 3.2 iso-electric point condition of a liquid medium, usually the value of pH, that corresponds to zero zeta potential of dispersed particles Note: See Figure 2. 4 Principle Zeta potential is the potential in the interfacial double layer at the location of the slipping plane versus a point in the bulk fluid away from the interface. According to general colloid chemistry principles, an electrostatically stabilized dispersion system typically loses stability when the magnitude of the zeta potential decreases. As a result, there will be some region surrounding the condition of zero potential (i.e. the iso-electric point) for which the system is not particularly stable. Within this unstable region, the particles may agglomerate, thereby increasing the particle size. Determining the pH conditions where the zeta potential becomes zero (the iso-electric point) is, therefore, important for zeta potential analysers. Zeta potential may be determined by the electrophoretic light-scattering (ELS) method, the streaming potential method and the electroacoustic method, according to ISO 13099-1, ISO 13099-2 and ISO 13099-3, respectively. 5 Apparatus and calibration 5.1 Zeta potential analyser and calibration The zeta potential analyser may vary according to the measurement principle, such as electroacoustic and electrokinetic phenomena, the optical method or the acoustic method, and shall conform to ISO 13099-1, ISO 13099-2 and ISO 13099-3, respectively. The calibration of the analyser shall be performed using the standard sample with a predefined zeta potential. Note: The standard sample provided by the zeta potential analyser supplier could be applied. 5.2 pH meter The pH meter should be within the measuring range of pH 2 to pH 10. The calibration of the pH meter shall conform to the standard procedure detailed in ISO 4316. 5.3 Sample dispersion vessel A vessel of polypropylene or glass in the dimension range of 100 cm 3 to 1000 cm 3. It is used for dispersing the powder sample in the electrolyte solution. Materials that do not elute in the range of pH 2 to pH 10 shall be used. Special care is needed for soda lime glass, which may elute in a strong base condition. 5.4 Sonicator The sample should be dispersed by a tip sonicator, preferably, or a bath-type sonicator. A homogenizer, mortar, or vacuum degassing machine can be applied when needed. 5.5 Balance A balance with a measuring capacity of 200 g or above with 10-mg precision. 5.6 Temperature-control device A thermometer with a measuring range of 0 °C to 50 °C with a precision of 0.5 °C. A built-in temperature sensor is also applicable. 5.7 Magnetic stirrer A stirrer or magnetic stirrer coated with polytetrafluoroethylene resin.

Contents of GB/T 44149-2024