Preparation Of Sodium Alginate-based Hydrogel Doped With Inorganic Materials And Its Adsorption Properties

Recently,with the development of industrialization and urbanization in China,the problem of water pollution is becoming more and more serious.A large amount of dye wastewater is produced in chemical industry and discharged into groundwater without treatment,which will pose a great threat to human health.Therefore,it is of great significance to find a suitable method to remove dye contamination.At present,the adsorption method has been widely used as a water pollution treatment method because it is simple,convenient and recyclable.Hydrogel is a kind of biocompatible three-dimensional hydrophilic material with high recycling rate.As an adsorbent,it has been studied in wastewater.In this paper,three inorganic materials doped sodium alginate hydrogels were prepared as adsorbents.The hydrogel samples were characterized by IR,XRD,TEM,FTIR,SEM and the adsorption performance of methyl blue（MB）was studied at the same time.Magnesium aluminum hydrotalcite（Mg-Al LDH）was prepared by hydrothermal method and dispersed in acrylamide（AM）and sodium alginate（SA）monomers to prepare composite hydrogel（PAM/SA/Mg-Al LDH）.The Al³⁺in Mg-Al LDH can chelate with the carboxylate in SA.At this time,Mg-Al LDH acts as a crosslinking agent in the hydrogel.The hydrogel prepared by this method can effectively remove methyl blue（MB）dye,and the removal rate of MB dye can still exceed 50%after fourth times of adsorption.Meanwhile,the PAM/SA/Mg-Al LDH hydrogel has good antibacterial properties against two different bacteria such as Escherichia coli and Staphylococcus aureus.The mass of tannic acid（TA）and talc was used in a ratio of 1:1 to prepare tannic acid coated talc（TA@talc）solid powder with lamellar structure.The TA@talc was mixed with acrylamide（AM）and sodium alginate（SA）monomer to prepare composite hydrogel（PAM/SA/TA@talc）.The hydrogel has certain adhesion and tensile properties.TA coated talc can uniformly disperse in the hydrogel monomer and provide more adsorption sites for the dye.The removal rate of methyl blue（MB）dye can reach more than 90%by the composite hydrogel.A one-pot method was used to prepare polyvinyl alcohol（PVA）and sodium alginate（SA）pregel solution.Then magnesium oxide（MgO）powder was dispersed and mixed with the pregel solution under certain conditions.Finally,the hydrogel balls（PVA/SA/MgO）were evenly injected into 3%calcium chloride and saturated boric acid solution.To explore the effect of different factors such as p H,temperature and time on the adsorption of methyl blue（MB）dye by PVA/SA/MgO hydrogel ball,the maximum adsorption capacity can reach 586.9 mg/g.The obtained adsorption data were applied to the kinetic and thermodynamic model fitting.The results showed that the PVA/SA/MgO hydrogel ball conformed to the quasi-second-order kinetic model and the Freundlich model.