| Superabsorbent resin is widely used in industry and agriculture because of its superior water absorption and water retention. For the development of starch-based superabsorbent materials selection and the expansion of its scope of application, waxy corn starch is selected as raw materials of this research, the superabsorbent resin is synthesized with acrylic acid garafted on waxy corn starch by solution polymerization, A better preparation conditions of corn starch-based superabsorbent is identified, and the influence on adsorption properties of starch composition and ratio from the starch composition and molecular structure are analyzed, and resin application on food waste is discussed. The main conclusions are as follows:Combined with enzymatic extraction and alkali,the best process condition of waxy corn starch obtained are temperature 48℃, Substrate ratio is 5:1, pH 11.5, extracting time is 8 h. The starch content and protein content is 63.55% and 0.36%, respectively.Waxy corn starch granules are polygons with an average diameter of 14.27μm and crystal structures of the A-type. The amylose content of the waxy corn starch is 4.80% and its pasting temperature is 71℃. The freeze-thaw stability of the waxy corn starch paste is poor and its retrogradation properties is not good as the corn starch and the tapioca starch; but, its solubility, swelling power and transmission rate are higher than the corn starch. The viscosity-average molecular weight and number-average molecular weight of waxy corn starch are 1.07×10~6 and 1.84×10~7 g / mol respectively. The branching degree of the amylopectin of the waxy corn starch is bigger than the corn starch. With the increase of amylose content, starch number-average molecular weight and weight-average molecular are increasing in the mixture of the waxy corn starch and the corn starch, but their values are decreasing in the mixture of the waxy corn starch and the high amylose corn starch.Optimum preparation solution of resin based on waxy corn starch is that the temperature is 75℃, the ratio of monomer and starch is 15:1, monomer neutralization degree is 4.8, the amount of initiator is 0.15%, and the amount of cross-linking agent is 0.11‰, the water absorption of the super absorbent resin based on waxy maize starch is 1641.78 g/g.FTIR and SEM indicated that acrylic acid was grafted on waxy corn starch. Through studying the relationship between the adsorption of the three resins and the molecular weight and the amylose content of the starch, it is concluded that the absorbency of superabsorbent and water retention are increasing as amylose starch content increases. The absorption rate of the resin is related with the valence of cations, and the absorption rate of resin decreases with the valence increases. The resin has a higher water absorbent rate and a better water retention properties in the low valence than the high valence under the same concentration of solution.The water retention properties of the resin declines with the increase of the number-average molecular weight and the weight-average molecular. Appropriate molecular weight can stabilize the resin structure and improve the adsorption properties of the resin. High amylose corn starch resin has a better water retention capacity than the waxy corn starch resin under the high temperature.Waxy corn starch super absorbent resin had better effect of flocculant than other inorganic flocculant used in the experiment. The optimum conditions of the flocculation treatment on wastewater is: Flocculant dosage is 6.0 mg/L, stirring time of 5 min, pH is between 4 and 5. |
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