Size control of precipitated particles of amino acids using a bubble column evaporator

Abstract

The precipitation of five amino acids: DL-alanine, L-arginine, L-leucine, DL-methionine and L-tyrosine was studied at their solubility limits and isoelectric point by using a bubble column evaporator (BCE). The precipitation of amino acids via a bubble column evaporator and a standard stirring method were compared via turbidity measurements. Particle size, zeta potential and polydispersity index (PDI) were also measured using a Malvern Zeta-sizer and the particle morphology was examined using Scanning Electron Microscopy (SEM). The novel BCE process emerges as a much more effective method than precipitation by standard stirring methods. Better control of fine particle size and growth rates is achieved. The amino acids in zwitterionic form exhibit the same unexplained bubble coalescence inhibition phenomenon as do common salts. This suggests obvious applications in flotation technologies.

Keywords

• Precipitation
• Amino acids
• Size control
• Bubble column evaporator
• Stirring and particle growth rates