{
  "name": "Chlor-alkali cell types compared: introduction, separation method, caustic leaving the cell and main issue",
  "description": "Side-by-side comparison of the mercury, diaphragm and membrane chlor-alkali cell processes, compiled from the 2000 European Commission BREF for the chlor-alkali industry. Every value is stated in that document; strengths are as produced at the cell, before any evaporation.",
  "page": "https://casrai.org/guides/chlor-alkali",
  "publisher": "CASRAI",
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "dateModified": "2026-11-12T21:10:51Z",
  "temporalCoverage": "2000",
  "spatialCoverage": null,
  "columns": [
    {
      "name": "Cell type",
      "unit": "",
      "description": ""
    },
    {
      "name": "Named design and year",
      "unit": "",
      "description": "As given in the BREF"
    },
    {
      "name": "How chlorine is kept apart from caustic",
      "unit": "",
      "description": ""
    },
    {
      "name": "NaOH strength leaving the cell stage",
      "unit": "% NaOH",
      "description": ""
    },
    {
      "name": "Main issue named in the BREF",
      "unit": "",
      "description": ""
    }
  ],
  "rows": [
    {
      "Cell type": "Mercury cell",
      "Named design and year": "Castner-Kellner cell, 1892",
      "How chlorine is kept apart from caustic": "Sodium forms an amalgam with the flowing mercury cathode and reacts with water in a separate decomposer",
      "NaOH strength leaving the cell stage": "50 (directly from the decomposers)",
      "Main issue named in the BREF": "Mercury: about 12,000 tonnes held in EU mercury cells in 2000; historical site contamination"
    },
    {
      "Cell type": "Diaphragm cell",
      "Named design and year": "Griesheim cell, 1885",
      "How chlorine is kept apart from caustic": "Porous diaphragm (usually asbestos) between anode and cathode compartments; brine percolates through it",
      "NaOH strength leaving the cell stage": "10-12 (with about 15% NaCl; evaporation recovers salt and 50% caustic)",
      "Main issue named in the BREF": "Asbestos: employee exposure and environmental releases"
    },
    {
      "Cell type": "Membrane cell",
      "Named design and year": "Developed 1970; first industrial plant in Japan 1975",
      "How chlorine is kept apart from caustic": "Water-impermeable ion-conducting membrane lets sodium ions through and blocks chloride",
      "NaOH strength leaving the cell stage": "32-35 (salt-free; evaporation only if 50% is wanted)",
      "Main issue named in the BREF": "Feed brine must be very pure; membrane economic life about 3 years (range 2-5)"
    }
  ],
  "sources": [
    {
      "title": "European Commission IPPC BREF: Best Available Techniques in the Chlor-Alkali Manufacturing Industry (October 2000)",
      "url": "https://en.prtr-es.miteco.gob.es/Data/images//BREF%20Cloro-sosa-288EB04F5F668E4F.pdf",
      "accessed": "2026-11-12"
    }
  ]
}