Study On Preparation And Adsorption Properties Of Sodium Alginate-based Double Network Composite Hydrogels

With the acceleration of urbanization and industrialization,the problem of water pollution caused by various organic dyes is becoming increasingly serious.Due to the toxic,high chromaticity and poor biodegradability of dye wastewater,its random discharge is a serious threat to the ecological environment and human health.Hydrogel adsorption materials have attracted wide attention in the field of dye wastewater treatment because of their excellent adsorption properties.In this paper,two kinds of interpenetrating double network composite hydrogels are prepared using natural polymer sodium alginate(SA)as matrix material,and their adsorption properties for methylene blue dye is studied.Using sodium alginate and polyvinyl alcohol(PVA)as basic raw materials,SA/PVA/GO interpenetrating double network composite hydrogel spheres are prepared by two-step cross-linking reaction of ionic gel and polycondensation polymerization with nano-reinforced graphene oxide(GO).The gel spheres have uniform size,regular shape and porous structure.When the addition of GO is 4 wt%,the adsorption properties of the gel spheres for methylene blue dye is greatest.The adsorption process accords with the quasi-second-order kinetic model and Langmuir isotherm model,which indicates that the adsorption of methylene blue dye by gel spheres is controlled by chemical adsorption process and belongs to monolayer adsorption,and the maximum theoretical adsorption capacity of SA/PVA/GO(1,2,4,6)gel spheres for methylene blue dye is 119.9,174.52,209.2 and 128.04 mg/g respectively.After four adsorption-desorption-adsorption cycle experiments,the equilibrium adsorption capacity can still maintain 87.17%,91.27%,90.44% and 95.32% of that of the first adsorption,and has good reusability.The gel spheres can be used as an efficient and reusable dye adsorbent.Using sodium alginate,polyacrylamide(PAM)and cellulose nanofiber(CNFs)as raw materials,SA/PAM/CNFs interpenetrating double network composite hydrogels are prepared by free radical polymerization and ionic gel two-step cross-linking reaction.The composite hydrogels have good mechanical properties,excellent swelling properties and p H sensitivity.The maximum adsorption capacity of methylene blue dye is 107.8 mg/g.The adsorption process accords with the quasi-second-order kinetic model and Freundlich isotherm model,which shows that the adsorption of methylene blue on the composite hydrogels are controlled by the chemical adsorption process and belongs to microporous and multilayer adsorption.After four adsorption-desorption-adsorption cycle experiments,it still has good adsorption properties,and the equilibrium adsorption capacity can maintain 64.74% of that of the first adsorption,and the composite hydrogels can be used as an effective and reusable dye adsorbent.Figure [39] Table [8] References [93]...