Regeneration-promoting Of Alcohol-soluble Pigments And Mixed Bed On Decalcification Resin In Sugar Industry

Coupled Regeneration of sugar resins on the basis of non-sugar resource uilization is the basic idea to reduce ion exchange wastewater in sugar industry. The complexation of sugar pigments and Ca²⁺ can generally promote the regeneration of decolorization resins and decalcification resins in sugar industry. Alcohol-soluble pigment is one of the sugar pigments which the main ingredient is phenols. This paper mainly researched the promoting effect of alcohol-soluble pigment and mixed bed resins on the regeneration of decolorization resins and decalcification resins in sugar industry.In this paper, in order to increase the regeneration rate and extend resin life, response surface experimental design was used to optimize process conditions for the regeneration of decalcification resins. At the same time, the desorption kinetics and isothermal model on the regeneration of decalcification resin were discussed. Moreover, the decolorization, the decalcification and regeneration of mixed bed resins were also researched. Furthermore, this paper discussed the effect of ultrasound on the regeneration of decalcification resin and mixed bed resins. The present study aims to investigate the possible mechanism by which the alcohol-soluble pigment promotes the regeneration of decalcification resin. Such goal was achieved by analyzing the physical and chemical properties of the solution which before and after regeneration. Conculsions were submitted as follow:The presence of alcohol-soluble pigment contributed to the revival of decalcification resin. The response-surface method was used to optimize the process conditions for the regeneration of decalcification resins using regenerating solution with alcohol-soluble pigment, which based on the single factor experiment. Meanwhile, the optimized conditions were as follows: regenerating solution was composed of 5 g/L alcohol-soluble pigment and 12%（w/v） sodium chloride solution, temperature 89℃, flow velocity 1.7 BV/h, height-to-diameter ratio 8.5:1, respectively. Under these specifications, the regeneration rate of decalcification resin reached up to 95.37 ± 0.19%. Moreover, after decalcification-regeneration experiments for 6 cycles, decalcification resin regeneration rate is still above 90%, which much better than traditional methods.In this paper, the desorption kinetics of decalcification resin and isothermal model on the regeneration of the resin were discussed. An integrating equation of moving boundary model was used to describe the kinetics of desorption of decalcification resin, the results showed that the process was mainly controlled by particle diffusion. The reaction order was 1.14, apparent activation energy was 36.90 k J/mol and apparent frequency factor k0 was 1679 min-1. Further research results of kinetics showed that the desorption kinetics of decalcification resin complied with pseudo-second-order kinetic model（R2>0.99）. Moreover, the desorption behavior of calcification on the resin fitted well with the Freundlich isotherm model, showing the desorption process is not in monomolecular layer type. The kinetic equation was also derived as .In this paper, the decolorization, decalcification and regeneration of mixed bed resins were researched. Under static conditions, the optimized syrup decolorizing and decalcifying technology conditions were as follows: mixing ratio of anion resin and cation resin 1:1, temperature 65⁷0℃, resin usage 24 g, processing time 120 min, respectively. An orthogonal experiment was used to analysis variance based on the single factor experiment, and the results showed that resin usage was a significant factor for decolorization of mixed bed resins, resin usage,processing time and temperature were three extremely significant factors for decalcification of mixed resins. The optimized regeneration technology conditions were as follows: temperature 70℃, flow velocity 2 BV/h, height-to-diameter ratio 8:1, respectively. Sugar pigments and Ca²⁺ desorbed by the anion resin and cation resin contributed to the revival of mixed bed resins.We analyzed the influence of ultrasound on the regeneration of decalcification resin and mixed bed resins. As a result, ultrasound promoted the regeneration and desorption rates of decalcification resin and mixed bed resins. Reaction equilibrium time was also reduce by ultrasound.Meanwhile, with a lower level of temperature and ultrasound, regeneration rate was same as when the regeneration of decalcification resin and mixed bed resins in higher temperature but no ultrasound experimental conditions, which reduce energy consumption.The physical and chemical properties of the solution which before and after regeneration were analyzed by using Infrared Spectroscopy and X-ray diffraction spectra. The result of IR showed that hydroxy association was occur during the regeneration and the hygroscopicity of the solution after regeneration was enhanced. Additionally, the characteristic absorption peak of phenolic hydroxyl was strong and sharp, which can inferred the complexation of alcohol-soluble pigment and Ca²⁺ can promoted the regeneration of decalcification resin. Meanwhile, the result of X-ray diffraction showed that Ca²⁺ and Na+ were exchange during the regeneration, and the degree of crystallinity of regeneration byproducts was decline, it probably caused by the complexation of amino acid and Ca²⁺. This paper also assessed the antioxidant activities of the samples using three methods. The clearance rate of DPPH free radical of the solution which before and after regeneration were 72.67% and 86.26%, respectively. The clearance rate of ABTS free radical of the solution which before and after regeneration were 76.26% and 88.49%, respectively. The inhibition of pyrogallol autoxidation of these two solutions was not significant. Moreover, the antioxidant activities of these two solutions were weaker than vitamin C.