Date of Award

1998

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Engineering Science (Interdepartmental Program)

First Advisor

Michael Saska

Abstract

Alkaline degradation of pure invert and invert in refining materials including washed sugar liquor, melt liquor and affination syrup has been investigated. The pseudo-first-order reaction kinetics of invert alkaline degradation was demonstrated for a pH range of 9.0-11.0 and a temperature range of 70-90$\sp\circ$C. In this range, rate constants of invert degradation increased 5 to 6 times with one unit increase in pH. The effects of pH and temperature on rate constants were quantified and could be expressed as: log k = 19.42 - 6712/T - 0.712pOH. Rate constants of invert alkaline degradation at different pH-temperature-base combinations calculated by this equation are very close to experimental data, but are significantly different from the rate constants calculated from Vukov's equation: log k = 16.9 - 5260/T - pOH. Activation energy of invert alkaline degradation was 30.95 kcal/mol and was found to be pH independent when Ca(OH)$\sb2$ suspension was used as a base. Activation energy changed with pH when NaOH and KOH solutions were used. Under constant pH and temperature, the rate constant increased 0.004 min$\sp{-1}$ or about 12% with 10% increase in sucrose concentration. The second-order polynomial correlation between the production of lactic acid and the concentration of invert degraded was obtained. The correlation between color formation and invert concentration was also second-order polynomial. Ca$\sp{2+}$ favored the formation of lactic acid and inhibited the formation of color under the experimental conditions. The effects of sucrose on the rate constant of invert degradation and the formation of lactic acid were explained by the effect of sucrose concentration on the behavior of pH electrode. The study of invert degradation of washed sugar liquor in a laboratory continuous carbonation system demonstrated that, if the operation conditions were proper and well controlled, the efficiency of the operation evaluated by decolorization, decalcification and filter ability of carbonation would not be influenced by invert destruction. The experiments of invert degradation in melt liquor and affination syrup demonstrated that the dose of lime had significant effect on the efficiency of carbonation. The destruction of invert in affination syrup very costly because a considerable amount of lime is needed and a large amount of cake is produced.

ISBN

9780591998160

Pages

139

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