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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

This substance is stable under the methods of test devised to demonstrate dissociation and hydrolysis.

Additional information

This substance is an inorganic layered silicate structure with a unit cell of the following composition Na0.7[Li0.3Mg5.5Si8O20(OH)4]. The material is non-biodegradable, retaining its clay structure in the environment. At normal water course pH’s this material is stable and insoluble. It does not dissolve in water but disperses to form a clear sol so the usual methods to determine water solubility do not work because it appears by observation that total dissolution has taken place whereas in reality the structure has remained unchanged but simply dispersed to be invisible to the naked eye. To demonstrate whether any solubility to the component ions takes place, a dialysis method was devised to determine solubilised ions present. Based on the structure above, lithium, sodium and magnesium were determined to be key identifiers of whether the structure under defined conditions dissociates in water. The natural pH of this substance in water at a concentration of 2% by weight is 9.8. At that pH, no free lithium or magnesium ions are found in solution and only low level concentration of sodium ions which are present from dissociation of free sodium sulphate left over from the manufacturing process as a low level impurity.

To demonstrate hydrolysis at lower pH, the dialysis test was carried out by adjusting the dispersion to pH1, pH4 and pH7 and measuring Li, Mg and Na ions that pass through the membrane into demineralised water on the other side of the membrane. At pH4, and pH7 no Li and Mg ions were measured thus concluding that hydrolysis does not take place at the range of pH covered in the prescribed OECD method (4-9)