Study On Morphological Changes Of CaCO₃ And Adsorption Of Non-sugar In Sugar Juice

Sugar juice purifying process in the sugar factory of carbonated method includes four main processes, which are preliming, main liming, the first carbonation and the second carbonation. The lime from preliming and main liming processes and the CO₂ from the carbonation process are reacted to form calcium carbonate. Calcium carbonate is an important product of the sugar juice purifying process, and the generated calcium carbonate particles have a strong adsorption capacity that they can adsorb protein, colloid, organic acids, and pigment, etc. The adsorption capacity can greatly remove the non-sugar part in sugar juice, which provides favorable conditions for subsequent sugar making process. This paper mainly studies the influence of sugar juice purifying process on the morphology of the generated calcium carbonates, and the absorption efficiency of the generated calcium carbonates on the non-sugars part of pectin and protein, obtaining the optimal process condition, increasing the removal rate of pectin and protein in the sugar juice, consequently providing reference for the improvement of sugar juice purifying process.Domestic and foreign research shows that the morphology of calcium carbonate particle is influenced by a number of factors in the process of synthesis; the formation of calcium carbonate in carbonated juice is no exception. In this paper, liming amount, stirring speed, flow rate of CO₂ and carbonated temperature were selected to study the changes of morphology of the calcium carbonate particles in aqueous solution and simulation of carbonated juice to determine the optimum technological conditions of every factor for the minimum size of calcium carbonate. The optimum technical condition in the aqueous solution was: liming amount 1 g, stirring speed 1400 r/min, CO₂ flow rate 1 L/min, carbonated temperature 30 oC, the size of the generated calcium carbonate under this condition was measured to be 289 nm. The optimum technical condition in the simulation of carbonated juice was: liming amount 3 g, stirring speed 1800 r/min, CO₂ flow rate 1 L/min, carbonated temperature 30 oC, and the size of the generated calcium carbonate under this condition was measured to be 605 nm. The study also found that the morphology of the generated calcium carbonate particles was cube in aqueous solution, but were mixtures of regular cube and sphere in the simulation of carbonated juice.The paper selects two kinds of non-sugar part which were pectin and protein to study the adsorption efficiency of the generated calcium carbonate on non-sugar part in different process conditions. When there was only one kind of non-sugar of pectin or protein in the simulation of carbonated juice, the optimum technical condition for pectin adsorption was: liming amount 10 g, stirring speed 1000 r/min, CO₂ flow rate 1 L/min, and carbonated temperature 60 oC, the adsorption efficiency under this condition was measured to be 803.67 mg. The optimum technical condition for protein adsorption was: liming amount 10 g, stirring speed 1000 r/min, CO₂ flow 1 L/min, carbonated temperature 60 oC, and the adsorption efficiency under this condition was measured to be 851.33 mg. While there were protein and pectin in the simulation of carbonated juice. The optimum technical condition for the adsorption of pectin and protein was: liming amount 9 g, stirring speed 1000 r/min, CO₂ flow 1 L/min, carbonated temperature 70 oC, the adsorption efficiencies were measured to be pectin 709.67 mg, and protein 682.33 mg.