Preparation Of Chitosan/β-cyclodextrin Porous Aerogel Beads And Their Adsorption Properties

In this thesis,a chitosan-based natural polymeric porous material was prepared for the removal of dyes and heavy metals from printing and dyeing wastewater by a two-step cross-linking method using a small amount of glutaraldehyde at low concentrations to address the problems of complicated product preparation procedures and structural instability due to the use of large amounts of organic solvents in the cross-linking method.The adsorption capacity of the adsorbent was 945.7 mg/g for the reactive dye RB 5 and 1432.2 mg/g for the metal Hg²⁺.The adsorbent was prepared with high adsorption capacity while simplifying the preparation process and reducing the amount of organic solvents,and the high adsorption efficiency was maintained after five adsorption-desorption cycle tests.The specific work is as follows:（1）A high-capacity adsorbent material was synthesized by a two-step process of chemical cross-linking of chitosan withβ-cyclodextrin using a 1%glutaraldehyde solution by mixed-solvent thermal method and ionic cross-linking and curing using a 1%sodium polyphosphate solution with stirring in water.The effects of cross-linker concentration and cross-linking reaction temperature on its adsorption performance were investigated.The experimental results showed that 200 m L 1%glutaraldehyde was the optimum concentration and 50℃was the optimum cross-linking reaction temperature.（2）Using ionic dyes as the target adsorbent,the adsorption effect experiments showed that the optimum adsorbent dosage was 20 mg;the optimum p H value for adsorption was 4.0.The maximum adsorption of chitosan/β-cyclodextrin porous aerogel beads was 945.7 mg/g for RB 5,149.3 mg/g for MO,392.4 mg/g for AB 25 and 878.9 mg/g for BG.The adsorption kinetics showed that the adsorption dynamic equilibrium was reached within 60 min for RB 5and BG,and within 120 min for AB 25 and MO.The cycling experiments showed that the chitosan/β-cyclodextrin porous aerogel beads could maintain 83.3%of adsorption capacity after five cycles.The adsorption mechanism was mainly electrostatic and host-guest interactions.（3）Using Hg²⁺and Cu²⁺as the target adsorbents,the adsorption effect experiments showed that the optimal p H for Hg²⁺adsorption was 7.0 and for Cu²⁺adsorption was 5.0.The maximum adsorption of chitosan/β-cyclodextrin porous aerogel beads was 1432.2 mg/g for Hg²⁺and 1264.6 mg/g for Cu²⁺.adsorption kinetics The dynamic equilibrium of adsorption was reached within 300 min.The adsorption mechanism is mainly intermolecular chelation.Theoretical calculations showed that the overall adsorption capacity of the reactive groups on chitosan was greater than that on cyclodextrin,and the amino group in chitosan had the strongest binding capacity...