engleski

Crystallization of different salts during spray drying

Spray drying is used in many industries since it results in complemented powders of good quality, low moisture content and narrow particle size distribution. Characteristics of the solution and the hot drying air have major influence on the physical, structural and granulometric properties of the resulting powder. It is very important to properly select the process conditions which will results with the formation of crystalline (not amorphous) powder and the particular polymorph. The influence of the process conditions on the properties of the powders produced by spray drying has been investigated on a laboratory scale. The experiments have been performed at different drying air temperature, flow rate of the solution, flow rate of the spraying air and concentration of the solution. The aqueous solutions of two organic (glycine and pentaerythritol) and three inorganic (sodium chloride, potassium chloride and potassium sulfate) salts have been chosen for that purpose. The obtained powders were characterized by means of an X-ray powder diffractometry (XRD), differential scanning calorimetry (DSC), Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Particle and pore size distribution as well as the specific surface area and the average particle and pore size were also determined. The final moisture content and the solubility in water were determined gravimetrically. The obtained powders are mostly crystalline, with a very small portion of amorphous. Final moisture content and the solubility of powders were influenced by the investigated process conditions. The glycine polymorphism is affected by the drying air temperature, concentration and the flow rate of the solution.

crystallization; powder characterization; spray drying

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