Synthesis of β-Cyclodextrin Immobilized Starch and Its Application for the Removal of Dyestuff from Waste-Water

摘要

A natural polymeric adsorbent, -cyclodextrin immobilized starch (CS-CD) was prepared by introducing host functional molecule -cyclodextrin (-CD) onto starch in presence of citric acid. The immobilization conditions were optimized to: m CA:m CS=1:2, reaction time of 2h and reaction temperature at 120 degrees C, by varying the input levels of the reactant, CS-CD with a series of immobilization ratio (IR) and carboxyl content (CC) could be obtained. The FT-IR and C-13-NMR analysis indicated the -CD molecules have been immobilized onto starch via the formation of ester linkages. The XRD and SEM analysis showed CS-CD had more looser structure and more irregular surface compared with native starch. The GPC analysis showed CS-CD had a reduced molecular weight but a more complicated molecular configuration. The adsorbing capacities of CS-CD to three cationic dyes (methylene blue, methyl purple and basic fuchsin) were significantly improved compared with native starch, diatomite and zeolite. The adsorption behaviors of CS-CD to the three dyes had high fitting degrees to both Langmuir and Freundlich models (R-20.98). The decolourization ratio of CS-CD to the mixed dyestuff waste-water had reached 88.75%, which was much higher than other absorbents. The results indicated the CS-CD would become a high-efficiency dyestuff adsorbent, and would have a promising application in the industrial dyestuff waste-water treatment.