The preparation of calcium oxalate dihydrate crystals

✍ Scribed by Dr. W. O. S. Doherty; O. L. Crees; Prof. E. Senogles

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 513 KB
• Volume: 29
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.2170290412

✦ Synopsis

Abstract

Two simple related methods for exclusively preparing well‐developed tetragonal bipyramidal crystals of calcium oxalate dihydrate at moderate supersaturations and at ambient temperature are reported. These crystals have an average length of 5.7–7.2 μm and are easy to wash and filter. One of the methods is suitable for studies of the kinetics of spontaneous precipitation and crystal morphology of the oxalate in the presence and absence of additives. A tentative mechanism is given to account for the sole formation of this particular hydrate.

At 70 °C a mixture of the monohydrate and dihydrate phase were formed with various crystal shapes and sizes. These phases were also identified in the presence of sucrose at this temperature, although some of the crystals contained tetragonal habit as obtained at ambient temperature.