Study On New Processes For Clarifying And Decoloring Sugar Liquor

Clarification technique is one of the key aspects of the sugar manufacturing process.Four new methods for clarifying sugar liquor were studied. Moreover, based on the optimalclarification process conditions, the flocculated structure was measured by Zeta electricpotential and scanning electron microscope and the mechanism of flocculation was discussed.The main contents of studies were as follow:1. Two-step clarification process was studied. Chitosan and magnesium hydroxide astwo kinds of flocculants has been used to clarify the sugar. By single-factor and multi-factororthogonal experiment methods, the optimum conditions were obtained as the following:chitosan dosage was0.3g/L. Magnesium sulfate heptahydrate dosage was5g/L. Chitosanreaction pH was4.8. Magnesium sulfate heptahydrate reaction pH was11.2. The synergisticeffect exists between chitosan and magnesium hydroxide during clarifying decoloring.2. The brown granulated sugar syrup was clarified via chitosan and γ-polyglutamic acidcooperative flocculation. The conditions were optimized by single-factor and multi-factororthogonal experiment methods. The optimal process conditions for chitosan andγ-polyglutamic acid clarification were chitosan dosage0.5g/L, γ-polyglutamic acid dosage0.06g/L, reaction pH5.0, reaction temperature20oC. Under the optimal condition, aclarification rate of66.5%was achieved.3. The ZTC natural clarifying agent was employed to clarify brown sugar juice. Tooptimize the reaction condition, the experiment was arranged by orthogonal design in thebase of analyzing of single factor. The optimum condition of reaction was obtained asfollows: the adding sequence of ZTC natural clarifying agent was clarifier B before clarifierA. The adding proportion of B and A was3:1. The total dosage of A and B was6mL. Thereaction temperature was40oC. Under the condition, the clarification rate and the removalrate of turbidity may achieve63.5%and94.7%, respectively. The mechanism of flocculationwas discussed via the theory of Zeta electric potential.4. Ammonium carbonate instead of CO2with milk of lime to clarify sugar wasresearched. To optimize the reaction condition, the experiment was arranged by orthogonaldesign in the base of analyzing of single factor. The optimum condition of reaction wasobtained as follows: The dosage of calcium hydroxide, ammonium carbonate, and PAM was1.1g,0.9g, and6ppm, respectively. The reaction time was15min. Under the condition, theclarification rate may achieve52.9%.