Preparation Of Amino-terminated Hyperbranched Polymer Modified Loofah And Study On Its Adsorption Properties For Dyes

Dyes not only bring more colors to our lives,but also cause serious harm to our health and living environment.In recent years,a large number of azo-structured dyes have been banned in the European Union.Therefore,the effective degradation of dyes in wastewater has become one of the urgent problems to be solved.Natural polymer cellulose can be chemically modified by a specific method under certain conditions to prepare the substances we need.Loofah contains a large amount of cellulose.In this paper,chemical modification was used to modify loofah,and a new adsorbent for adsorbing anion dyes from wastewater was successfully prepared.First,GMA(glycidyl methacrylate)monomer was used for graft copolymerization with loofah,epoxy groups were introduced on the surface of loofah,and then the amino-terminated hyperbranched polymer(HPEI)was used to chemically modify the graft copolymer of loofah.So,a large number of amino and imino were introduced into the surface of loofah.An amino-terminated hyperbranched polymer modified loofah adsorbent was prepared successfully.In this paper,the controlled variable method was used to optimize the reaction conditions of GMA grafting reaction and hyperbranched polymer modification reaction.The experiments showed that 1.5 g of loofah and 4 g of GMA monomers were reacted in distilled water for 80 min under the initiation of 4 g of potassium persulfate and 2 g of sodium bisulfite at 35 °C to obtain the best-performing loofah graft copolymer.At 85 °C,1 g of the copolymerized graft and 6 g of the amino-terminated hyperbranched polymer were reacted in a mixed solution of water and dioxane(volume ratio of 1: 4)for 25 hours to obtain the adsorbent with the best performance.FTIR,SEM,EDS,XRD,and TGA were used to characterize the structure of the prepared adsorbent.The results showed that GMA was successfully grafted with loofah,and after modification with amino-terminated hyperbranched polymers,a large amount of amino and imino was successfully introduced on the surface of loofah.Adsorption experiments were carried out on the three dyes,reactive brilliant red,reactive brilliant blue,and reactive black,using the prepared adsorbents,respectively from six aspects,including pH,reaction time,amount of adsorbent,initial dye concentration,temperature,and interference ionic strength.At the same time,the dynamic,thermodynamic and isothermal adsorption laws were explored.The results show that three dyes are favorable for adsorption under acidic conditions.Active brilliant red dyes and reactive black dyes have the best adsorption effect at pH2,while reactive brilliant blue dyes have the best adsorption effect at pH1.The adsorption capacity decreases with the increase of the amount of the adsorbent and the intensity of the interfering ions.The adsorption capacity increases as the initial concentration of the dye increases.The adsorption process could be best described by the pseudo-second order equation and the Langmuir isotherm adsorption model.And the adsorption process is an endothermic reaction and spontaneous process,The research shows that the active brilliant red dye reaches adsorption equilibrium after 120 min,the maximum adsorption reaches 1552 mg/ g when the initial concentration is 500 mg/L,the reactive brilliant blue dye reaches adsorption equilibrium after 300 min,the maximum adsorption reaches 1076 mg/g when the initial concentration is 800 mg/L.And the reactive black dye reached its adsorption equilibrium at 120 min,the maximum adsorption reached 785 mg/g when an initial concentration is 600 mg/L.And the results of adsorption and desorption experiments show that the adsorbent has good regeneration performance.