Study On The Adsorption Performance Of Pullulan/polyacrylamide Composite Hydrogel Material On Methylene Blu

With the continuous improvement of social productivity and the rapid development of social economy,all kinds of toxic organism will cause serious pollution to water resources,thus potentially affecting people’s health,among which the water pollution caused by organic dyes had been a hot issue to deal with.Because of the complex aromatic structure of organic dyes,they are not biodegradable,so wastewater containing excessive dyes must be treated before being discharged into natural water.At present,the known technologies to remove dyes from wastewater include physical(membrane separation technology,adsorption),chemical(chemical oxidation,electrochemical)and biological(fungal treatment,bacterial treatment).Among all kinds of methods to treat water pollution,adsorption method was a more effective method to treat water pollution.Looking for cheap and harmless adsorbents had became an important trend in current research.Pullulan(PUL)has excellent water retention properties,viscosity and renewable properties.It is crosslinked with Polyacrylamide(PAM)to make hydrogels.Using PUL’s own space to wrap Graphene oxide(GO)and Activated Carbon(AC),PUL/PAM/GO composite and PUL/PAM/AC composite were prepared,and the optimal ratio of PUL:GO4:1 and PUL:AC 6:1 were determined according to the adsorption results.PUL/PAM/GO and PUL/PAM/AC showed excellent performance under different conditions.When the adsorption dose increased gradually,the removal rate of MB increased slowly,and both reached the optimal adsorption dose at 10 mg.The removal efficiency of the two hydrogels was the highest at 140 min and 180 min.Under alkaline conditions,the adsorption effect of the two hydrogels is better.With the increase of temperature,the adsorption capacity will decrease,and the reaction with MB is spontaneous exothermic.The adsorption isotherms of PUL/PAM/GO and PUL/PAM/AC on MB conform to the Langmuir model,and the maximum adsorption capacities are 438.7 mg/g and 591.4 mg/g,respectively,showing high adsorption capacity.Swelling experiments at different p H values showed that the swelling capacity of PUL/PAM/GO hydrogels was lower than that of PUL/PAM hydrogels,and the hydrogels had a certain recycling capacity.PUL/PAM/AC hydrogels have higher swelling capacity,slightly higher than PUL/PAM hydrogels,and have better hydrophilic capacity and swelling performance.Both of them show greater swelling capacity at high p H.The mechanical properties of PUL/PAM/GO and PUL/PAM/AC have certain tensile capacity.The tensile strength of PUL/PAM/GO hydrogels is high,but the corresponding strain is small,so the material texture is hard.PUL/PAM/AC hydrogel,on the other hand,is relatively soft,with large strain and low tensile strength,which not only perfectly develops the advantages of PUL and improves the adsorption efficiency of Methylene Blue(MB),but also solves the problem of difficulty in recovering GO and AC after adsorption.