A Comparison of Compacting and Caking Behavior of Carbonate-Based Washing Powders

Abstract

Two types of sodium carbonate powder produced by spray drying (SD) and dry neutralization (DN) were studied for their compaction properties using a uniaxial compression tester. A comparison was also made with Persil washing powder. Dry neutralized sodium carbonate showed greater resistance to compression and also produced a weaker compact when compressed to 100 kPa. Spray-dried sodium carbonate had an absence of fine particles but compacted easily. Differential scanning calorimetry (DSC) showed that both types of powder were predominantly amorphous in nature. Moisture sorption measurements showed that both powders behaved in a similar way below 50% relative humidity (RH). However, dry neutralized sodium carbonate had a high moisture affinity above this RH. Particle structures were also examined using scanning electron microscopy, showing the heterogeneous interior of the spray-dried particles.

Keywords:

• Caking
• Compaction characteristics
• Spray drying

ACKNOWLEDGMENTS

The test materials were supplied by Unilever Research, Port Sunlight, Quarry Road East, Bebington, Wirral, CH63 3JW, UK. This study was funded by the UK Engineering and Physical Sciences Council (EPSRC).