synthetic zeolites do not belong to the group of nanomaterials - scientific assessment

The graphic representation shows the result of a laser diffraction measurement made with a commercial LTA zeolite. The blue and the green curve show the crystal number size distribution before treating with a dispersing system, the red and the yellow curve are produced after the treatment of the zeolite with an ultrasonic system. The blue and the green curve are nearly identical, indicating that the measurement is very well reproducible. The ultrasound treatment leads to minor shifts of the curves only, indicating that the zeolite crystals are not agglomerated. The presence of nano-particles was not evidenced even following ultrasonic treatment. The particle size distributions evidenced were almost identical to those measured upon analysis of the SEM images. Similar results were obtained for the FAU zeolite structure type.

In conclusion, commercially produced synthetic zeolites are not nanomaterials. They do not fulfill the definition given in “Recommendation 2011/696” of the EU Commission. The zeolite crystals are larger than 100 nm and do not disintegrate upon application of dispersing systems (ultrasonic waves or shear forces).

Using modified synthesis procedures, it is possible to manufacture zeolite crystals smaller than 100 nm. These zeolite crystals are stable in diluted suspensionsonly These zeolites are a niche product and are neither covered by this statement nor by the existing REACH registrations of the Synthetic Zeolite Consortium and its member companies.