Effects of Temperature and Cationic Surfactant on the Clarification of Sugar Syrup by Air Dissolved Flotation

Impurities responsible for color and turbidity of dissolved crude crystal sugar in water can be separated by dissolved air flotation (DAF) process according to a specified refined sugar. Clarifying agents help to adsorb and precipitate these impurities forming precipitates, which adhere to micro bubbles generated by injected pressurized air, forming agglomerates that float and are removed from the surface. Experiments of DAF were conducted using cationic surfactant (150, 225 and 300 ppm), to clarify sugar syrup at 66°Brix, at temperatures of 26, 40 and 55°C, 895 kPa pressure, 300 s agitation, followed by 2 hours of phase separation. The clarification of sugar syrup was judged by physicochemical analyzes of conductivity, color, turbidity and filterability. The best result was obtained with 225 ppm clarifying agent and 40°C resulting 36% color and 98% turbidity removal, a 50% increase in the rate of filterability, although with 32% increase in ash content. The study has demonstrated that color and turbidity can be removed and filterability rate can be increased for the clarified sugar syrup by DAF process using only a cationic surfactant without adding any other chemical agent, and conducting the process at a relatively low temperature.