ISO 21822:2019 pdf download

ISO 21822:2019 pdf download.Fine ceramics (advanced ceramics, advanced technical ceramics) — Measurement of iso-electric point of ceramic powder
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.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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, Surface active agents — Determination of pH of aqueous solutions — Potentiometric method
ISO 13099-1, Colloidal systems — Methods for zeta-potential determination — Part 1: Electroacoustic and electrokinetic phenomena
ISO 13099-2, Colloidal systems — Methods for zeta-potential determination — Part 2: Optical methods
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.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
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.
6.2 pH-adjusting acid or base and electrolyte solution
The pH-adjusting acids or bases and the type of electrolyte solution shall be selected as follows.
a) The pH-adjusting acid and base shall be hydrochloric acid (HCl) or nitric acid (HNO 3 ) and sodium hydroxide (NaOH) or ammonium hydroxide (NH 4 OH), respectively. The electrolyte solution shall be a salt, sodium chloride (NaCl) or ammonium nitrate (NH 4 NO 3 ) solution with a concentration of 0,1 mol/l for acid and base and 1 mmol/l to 10 mmol/l for the electrolyte solution.
b) Any combination of inorganic acid and base with an oxidation number 1, except those in a), may be selected, and their electrolyte (1 mmol/l to 10 mmol/l) may be selected.