Parameters Expediting the Thermal Conversion of Ba-Exchanged Zeolite A to Monoclinic Celsian

Abstract EN

Four samples of Ba-exchanged zeolite A, bearing small residual amounts of Na (0.27, 0.43, 0.58, and 0.74 meq/g), were thermally treated in the temperature range 200–1500∘C for times up to 28 hours.

The same samples were pressed at 30 and 60 MPa to form cylindrical pellets which were thermally treated at 1300∘C for 5 hours.

All materials were characterized by room temperature XRD.

The sequence of thermal transformations that Ba-exchanged zeolite A undergoes (zeolite → amorphous phase → hexacelsian → monoclinic celsian) and the strong mineralizing action developed by Na are confirmed.

Pressing the Ba-exchanged zeolite A powder-like samples to obtain cylindrical pellets is found to expedite the sluggish final phase transition hexacelsian → monoclinic celsian.

The optimum residual Na content of Ba-exchanged zeolite A for transformation into monoclinic celsian is assessed to be between 0.27 and 0.43 meq/g.