Construction And Properties Of Layered Chitosan/Graphene Oxide Composite Hydrogels

Chitosan has a wide range of sources,low cost,high biocompatibility,abundant functional groups,good degradability and other advantages.It has good performance in drug release,tissue engineering,wastewater treatment and so on.Chitosan/graphene oxide composite hydrogel has the advantages of both chitosan and graphene oxide.It has a large number of functional groups on the surface,and has strong metal coordination ability.To some extent,it overcomes the shortcomings of mechanical properties of chitosan hydrogel.Based on the reaction-diffusion theory,the layered chitosan hydrogel was constructed by discontinuous alkali treatment.The surface morphology of the hydrogel was analyzed by SEM.The reaction-diffusion principle in the preparation of the hydrogel from chitosan solution was explained through the study of its layered structure.The layered chitosan hydrogel was obtained by analyzing the classical Liesegang ring law.The relationship between layered chitosan hydrogel and Liesegang ring was discussed.The layered graphene oxide/chitosan hydrogel was constructed by introducing graphene oxide into the reaction-diffusion system of chitosan.The morphology was characterized by SEM,and the effect of graphene oxide on the layer structure was obtained.The results show that with the increase of graphene oxide concentration,the number of hydrogel layers increases and the thickness decreases.When the concentration of graphene oxide is 0.3 g/L,the number of layers is 38 and the average layer thickness is 88.80?m.It is due to that graphene oxide reduces the diffusion coefficient of OH~-.The mechanical properties of chitosan/graphene oxide hydrogels were characterized.The results show that graphene oxide as a nano-reinforced material can significantly improve the mechanical properties of hydrogels.When the concentration of graphene oxide was 1.0 g/L,the compressive strength and tensile strength increased by 223.78%and 103.89%,respectively.This is because the introduction of graphene oxide increases the density of hydrogels.The hydrogen bonding and electrostatic interaction between chitosan and graphene oxide also play a positive role in improving the mechanical strength of hydrogels.The adsorption mechanism of Ni(II)on chitosan/graphene oxide composite hydrogel was studied.The results show that the adsorption of Ni(II)by composite hydrogels is a mixed adsorption process dominated by chemical adsorption,the adsorption rate is controlled by internal diffusion model,and the adsorbates are mainly arranged in a single layer on the surface of the hydrogels.The maximum adsorption capacity of the hydrogels for Ni(II)is 121.58 mg/g.