Preparation And Transfer Properties Of Cu(?) Molecularly Imprinted Supported Liquid Membrane

As wastewater contained heavy metal ions to produce a variety of detriments to our daily life has become more and more widespread in the world,and this serious situation has gradually caused great attention from the people.Numerous scientific research workers have concentrated their efforts on the development of innovative approaches in an attempt to replace those conventional water treatment methods,whereby this issue can be resolved thoroughly.Among various new methods,molecularly imprinted supported liquid membrane has been attracting considerable attention with its outstanding advantages such as high structural stability,high mass transfer flux,low energy consumption and no secondary pollution.It is widely believed that molecularly imprinted structure possesses infinite potential in the field of water treatment.This study prepares Cu(?)molecularly imprinted membrane by using PVDF as the supported membrane,and discusses the transfer process of Cu(?)in supported liquid membrane system,the results are shown as follows:(1)The transfer process of Cu(?)is studied by using 2-Ethylhexylphosphoric acid mono-2-ethylhexyl ester as carrier,kerosene as membrane solvent and Polyvinylidene fluoride membrane as matrix and the permeability coefficient formula is established in this section.This article also analyzes the effects of Cu(?)concentration,migration time,carrier concentration and feed solution pH.The results indicate that the optimical conditions are as following:Cu(?)concentration at 4×10-4mol/L,migration time at 120min,carrier concentration at 7%and feed solution pH at 5.0,the migration rate of Cu(?)attains to 85.5%under these conditions.(2)Response surface methodology(RSM)is used to investigate the effects of Cu(?)concentration,migration time,carrier concentration and feed solution pH on migration rate of Cu(?)and the interaction among these variables in migration process of supported liquid membrane based on single factor experiment.Then,quadratic polynomial mathematic model is established.The results show that the R2 of quadratic polynomial mathematic model is 0.995,which indicates a good significance.The migration rate of Cu(?)is calculated to 84.85%,which exists a error of 0.65%compared with experimental result through this model,the results of analysis prove that the supported liquid membrane system possesses a excellent separation ability.(3)Cu(?)molecularly imprinted supported membrane based on PVDF is prepared by the method of surface graft polymerization.The Cu(?)molecularly imprinted supported membrane are characterized by SEM,XPS and contact angle.Permeability and selectivity of Cu(?)molecularly imprinted supported membrane are also evaluated via transfer experiments.The SEM images indicates that the microvoids of Cu(?)molecularly imprinted supported membrane are uniformly distributed on the surface and changed obviously,and a smaller pore size of 1-3?m can be observed.The XPS spectrum confirms that the molecularly imprinted polymer layer is combined with PVDF membrane through C-O bond,whereby improving the membrane structure stability.The contact angle measurement shows that The hydrophobicity of modified membrane is decreased,and the surface energy is increased.The transfer experiment results indicates that the permeability coefficient of Cu(?)molecularly imprinted supported membrane is higher than that of PVDF membrane,the transfer rate of Cu(?)can reach 92%through Cu(?)molecularly imprinted supported membrane,whereas the transfer rate of Mn(?),Co(?)and Ni(?)is less than 10%.Thus,Cu(?)molecularly imprinted supported membrane is of excellent selectivity and permeability.