Calcium sulfite hemihydrate: Crystal growth rate and crystal habit

✍ Scribed by Tseng, Philip C. ;Rochelle, Gary T.

• Publisher: American Institute of Chemical Engineers
• Year: 1986
• Tongue: English
• Weight: 848 KB
• Volume: 5
• Category: Article
• ISSN: 0278-4491
• DOI: 10.1002/ep.670050107

✦ Synopsis

The crystal growth rate of CaS03 * V2H20 was measured by a pH-stat method in aqueous solution with pH 3.5 to 6.5, 1 to 25 mM dissolved sulfite, 0.01 to 0.3 M Ca", and 0 to 25 mM sulfate. The growth rate was a strong function of relative supersaturation and was strongly inhibited by dissolved sulfate. The growth rate per unit BET surface area, R' (moldcm2-min), is given by: 9.7 X low4 exp (-1025WRT) x (RScaso,-1)2 X RSCaSo4-l, where RSCaSO3 and RSCaSO4 are the relative saturations with respect to calcium sulfite and gypsum, respectively. Scanning electron microscopy and IR spectroscopy demonstrated that solids generated in the presence of dissolved sulfate contained solid solution sulfate and crystallized as agglomerates of very thin platelets. In the absence of solid or dissolved sulfate the solids were agglomerates of well-informed columnar, hexagonal crystals.