Synthesis Of Hydrogels Based On Cellulose And Their Adsorption Properties For Heavy Metal Ions And Drug Release

Cellulose is the most abundant renewable biomass resource in the world,with good biocompatibility,biodegradability and environmental friendliness.Based on these characteristics,hydrogels prepared on cellulose substrates are very suitable for biomedical,drug controlled release,heavy metal ion treatment and other fields.In this paper,a cellulose-based hydrogel with strong binding ability to heavy metals was synthesized,and its adsorption behavior for heavy metal ions was studied.A double-membrane structure hydrogel was prepared and the composite drug was controlled and released.Cellulose-based hydrogels were prepared by dissolving cellulose in a NaOH/urea system,using acrylamide?AM?as a monomer,and diethylenetriamine?DETA?as a functionalized reactant.The effect of monomer dosage on the swelling properties of hydrogel and the ability to adsorb Cu²⁺was investigated.The chemical structure and morphology of the hydrogel were characterized by infrared spectroscopy?FTIR?and scanning electron microscopy?SEM?.The results showed that the carboxyl group and the amine group were introduced into the cellulose segment of the porous hydrogel.The swelling rate of the hydrogel increased first and then decreased with the increase of the monomer amount.At pH=7,the swelling ratio was the largest up to 9100%.The adsorption amount of Cu²⁺increases first and then decreases with the increase of monomer amount and environmental pH value.When the mass ratio of monomer to cellulose is 5:1,pH=7,the removal rate of Cu²⁺is the highest,and the maximum adsorption capacity of hydrogel to Cu²⁺can reach 229 mg/g.The kinetics and isothermal adsorption of Cu²⁺by hydrogels were consistent with the Langmuir model and the quasi-secondary kinetic model.At the same time,Cu²⁺and Pb²⁺were adsorbed,and the competitive adsorption behavior of Cu²⁺and Pb²⁺was studied.Nano-cellulose was used as a filler and added as a reinforcing phase to the hydrogel.The effect of the amount of nano-cellulose added on the mechanical properties and recycling efficiency of the composite gel was investigated.The results showed that the presence of Pb²⁺inhibited the adsorption of Cu²⁺by hydrogel,the antagonistic effect of Pb²⁺and Cu²⁺.The two-component competitive adsorption of Cu²⁺and Pb²⁺in accordance with the LCA model,the hydrogel has a higher selectivity for Pb²⁺than Cu²⁺.The addition of nanocellulose can significantly improve the mechanical properties and cycle times of the hydrogel.When the addition amount is 3.5%,the compression strength of the composite gel is 0.073 Mpa.After 5 cycles of recycling,the removal rate of Cu²⁺is still Can reach 76%.A biocompatible hydrogel having a double membrane structure was prepared using cationic cellulose and anionic sodium alginate.The structure of the two-membrane hydrogel includes an outer membrane composed of pure alginate,an internal composite hydrogel that enhances structural stability by electrostatic interaction between cationic cellulose and anionic alginate.The thickness of the outer layer can be adjusted by continuously adsorbing the pure alginate.After 3 hours of adsorption,the thickness reaches a maximum of 700?m.Introducing two drugs?theophylline,bovine serum albumin?into different membranes of the hydrogel to achieve different release behaviors of the two drugs,namely rapid release of the drug in the external hydrogel,and the drug in the internal hydrogel continues Slow release.