Preparation Of Modified Sugar Beet Pulp Fiber And Its Application In Sugar Purity

This paper used sugar beet pulp as raw material and got the fiber by removing pectin from sugar beet pulp by acid extraction and alcohol precipitation.A new adsorbent was prepared for sugar decolorization and decalcification by chemical modification.In this paper,the modification parameters,structural characteristics,adsorption mechanism and the regeneration test of modified sugar beet pulp fiber was studied and the conclusions are as follows:(1)The adsorbent was prepared by the reaction between sugar beet pulp fiber and epichlorohydrin/ethylenediamine.The modification parameters were optimized as ethylenediamine content of 30%,temperature of 80?,reaction time of 7h,and sodium bicarbonate content of 1.5%,which yielded 1.25% increase of nitrogen content in modified sugar beet pulp fiber.The performance of the modified fiber was characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron micrographs(SEM).FTIR and XRD analysis showed epoxy groups and amino groups had been successfully grafted into modified sugar beet pulp fiber;SEM analysis indicated that the surface morphology was changed after modification.(2)The decolorization parameters were optimized as modified sugar beet pulp fiber content of 5.0 g,pH of 5.0,temperature of 80? and time of 30 min,which yielded 60.8% of decolorization rate.Furthermore,the regeneration studies showed the adsorbent had a good reuse performance over several regeneration cycles and the regeneration efficiency of adsorbent was decreased to 89% after being regenerated for 8 times.(3)Carboxyl is adopted to modify the properties of the sugar beet pulp fiber.The processes were optimized with the content of carboxyl functional groups in the adsorbent as index,and the optimum conditions of modified were ascertained: citric acid content of 9.0 g,temperature of 90?and time of 7h,which yielded 4.12 mM/g of carboxyl content in modified sugar beet pulp fiber.Characterization of the modified fiber was respectively done through the X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron micrographs(SEM)before and after the test,and results showed that carboxyl functional groups had been successfully introduced into the adsorbent and the structure and form of modified fiber had been changed.(4)The decalcification parameters were optimized as adsorbent content of 6.0 g,p H of 6.0,temperature of 45?and time of 60 min,which yielded 68.8% of decalcification rate.Study of adsorption kinetics indicated that the process followed the pseudo-second-order chemisorption model.The adsorption behavior was well described by the Langmuir isotherm model,showing a monomolecular layer capacity for calcium ions.Moreover,the regeneration studies showed the adsorbent had a good reuse performance over several regeneration cycles and the regeneration efficiency of adsorbent was maintained at more than 86% after being regenerated for 8 times.