Study On Crosslinked Starch And Its Adsorption Properties By Reversed-suspension Polymerization

In this dissertation,cross-linked starch and starch microspheres were prepared and their adsorption properties were measured and applied.The contents of the study were studied.Potato starch was used as raw material to cross-link the raw starch to obtain cross-linked starch,and the obtained starch was prepared.Starch microspheres were prepared by cross-linking the cross-linked starch.The physicochemical properties and structural characteristics of the samples were studied.The adsorption properties of the products were determined,including the following five aspects:1.The cross-linked starch was prepared by emulsion cross-linking method.The effect of the reaction conditions on the product water absorption/oil absorption rate during the cross-linking reaction was systematically investigated,and the optimum conditions for the preparation of the cross-linked starch were determined;the water absorption rate up to 236%under the optimal reaction conditions was measured,and the Fourier transform was obtained.The scanning results of infrared spectroscopy confirmed the existence of its characteristic functional groups.Electron microscopy showed that there were a lot of pores on the surface of cross-linked starch.The X-ray powder diffraction was used to characterize the change in the crystallinity of the cross-linked starch.The cross-linked starch was examined by BET.Size and specific surface area,measured specific surface area of 10.40m²/g.2.The starch microspheres were prepared by cross-linking the crosslinked starch prepared as described above by reverse emulsification polymerization.The sedimentation product value of the prepared starch microspheres was measured to be 1.92 mL;the specific surface area of the starch microspheres was 0.41m²/g.The adsorption/desorption isotherms of starch microspheres did not coincide and a hysteresis loop appeared.The hysteresis loop was the result of capillary condensation of N₂ in the crosslinked starch microspheres,indicating that the starch microspheres had a three-dimensional network-like porous structure.3.The adsorptive properties of cross-linked starch and starch microspheres on simulated dye wastewater were studied.The adsorption mechanism of dyestuff was preliminary investigated,and the adsorption kinetics of the dyestuff was explored.The results showed that cross-linked starch and starch microspheres were adsorbed in dye wastewater.Adsorption equilibrium was reached at h.Linear fitting results showed that the adsorption of basic fuchsine was in accordance with the Freundlich model,the adsorption of methylene blue was consistent with the Langmuir isotherm adsorption equation for monolayer adsorption,and the pseudo-second-order kinetic model was comparable to quasi-first-order kinetics.The reaction mechanism of the dye solution adsorbed by the adsorbent can be more truly reflected that the speed control step of adsorption is not solute diffusion but chemical adsorption,and the influence of temperature on dye adsorption is not significant..4.The adsorption of chromium?VI?wastewater was simulated using cross-linked starch and starch microspheres as adsorbents,and the effect of the best adsorption conditions on the concentration of residual ions in the solution was determined.The results showed that the best adsorption time was 150min,the best pH value was 3,the best adsorbent dosage was 250mg,and the best reaction temperature was 25°C.5.The cross-linked starch was used as the wall material and the cumin essential oil was used as the core material to prepare the cumin oil microcapsules.The optimized preparation process was obtained by single factor test and response surface analysis.The results showed that:The best embedding process conditions are:the ratio of core material to wall material is3.2:1,the embedding temperature is 52°C,the embedding time is 62min,the embedding rate of the essential oil is 97.21%,and the embedding yield is 85.88%.By measuring the sustained release properties of the cumin essential oil microcapsules,it was confirmed that the microencapsulated product has a good sustained release property.