Journal of Chemical Engineering of Japan, Vol.35, No.11, 1050-1054, 2002
Crystal growth rate of a fixed K-alum crystal in suspended solution of MSMPR crystallizer
The surface structure of the grown crystals and crystal growth rate in suspended supersaturation solution were investigated by using a differential interference microscope with a VTR system and an AFM system. It was found that the surface of the growing crystal had many fine crystals and new growth steps generated from the place of adhered fine crystals. Most of the fine crystals were in the range of 10 mum to 40 mum in size, and their orientations were random. Also the heights of the new growth steps were in the range of a few nm to about 70 nm. The crystal growth rate Gs in suspended solution was faster than the rate Gn in non-suspended solution at the same supersaturation. These rates can be given by Gs = 1.1 x 10(-1)DeltaC(0.47) (suspended) Gn = 4.8 x 10(-2) DeltaC(0.60) (non-suspended) where DeltaC (=Cs - C) is supersaturation, Cs and C were the saturated and fixed concentration, respectively. The growth rate Gs increased with decrease of the average crystal size Lav of the suspended crystal in an MSMPR crystallizer. An adequate linear correlation between Gs and Lav was obtained.