Study On The Construction Of Bivariate Nanoparticle Doped Mixed Matrix Membrane By Reversed-phase Microemulsion And Its Pervaporation Properties

Pervaporation,with its characteristics of high efficiency,energy saving and environmental protection,can be applied to the separation of organic mixtures,which has attracted great attention from academic and industrial community.In this paper,silver nanoparticles（AgNPs）were prepared by inverse phase microemulsion constructed by three block polyether surfactants（L31,L35 and L61）（Among them,the HLB values of L31 and L61 are close,but their molecular weights are quite different.The molecular weights of L35and L61 are close,but the HLB values are different）,and then the mixed matrix membrane of Ag nanoparticles（AgNPs）and Graphene oxide（GO）was prepared by in situ polymerization method for Separation of benzene and cyclohexane by pervaporation.Firstly,the composition and structure of the inverse microemulsion system were studied,especially in the inverse microemulsion system structure properties of surfactant（molecular weight,HLB value）and add quantity,concentration of AgNO₃solution(C_AgNO3),Solubilization water（ω,the ratio of the number of moles of water to surfactant）effect on the stability of the system,The suitable composition range of L31,L35 and L61 surfactants wasobtainedforAgNPs/（MMA+St）/L31,AgNPs/（MMA+St）/L35and AgNPs/（MMA+St）/L61reversed-phasemicroemulsion.Transmissionelectron microscope（TEM）and X-ray electron spectroscopy（XPS）analysis were used to characterize the morphology and structure of AgNPs formed in the reversed-phase microemulsion system.The experimental results showed that the particle sizes of AgNPs prepared by the reversed-phase microemulsion system constructed by L31,L35 and L61 were all within the range of 3 to 10 nm.An appropriate amount of GO and initiator was added to AgNPs/（MMA+St）/L31,AgNPs/（MMA+St）/L35 and AgNPs/（MMA+St）/L61 reversed-phase microemulsion system for microemulsion polymerization.The viscosity of the emulsion was obtained by controlling the reaction time.The experiment showed that the coating solution was suitable when the polymerization reaction time was about 2.5 hours and the emulsion viscosity was about 400 mpa·s.AgNPS/Poly（MMA-St）（L31）and AgNPS/GO/Poly（MMA-St）（L31）mixed matrix membranes were prepared by coating emulsion with appropriate viscosity respectively.Using Infrared Spectroscopy（FT-IR）,scanning electron microscope（SEM）,Zeta potential,water contact Angle,The rmogravimetric Analysis（TGA）of membrane structure,the diffusion and separation properties of the membrane were investigated by swelling and pervaporation experiments,the results show that:（1）for L31 to build the inverse microemulsion,within the appropriate range ofω、m _L31、C_AgNO3,composition AgNPs evenly dispersed in the membrane,and as C_AgNO3,ω,m _L31increases,the number of AgNPs in the membrane increased,But when C_AgNO3,ωand the addition of L31 was too large(C_AgNO3=0.3 mol·L^-1,ω=3,m _L31>8wt%;C_AgNO3=0.3 mol·L^-1,m _L31=8wt%,ω>3;m _L31=8wt%,ω=3,C_AgNO3>0.3 mol·L^-1),AgNPs particles in the membrane produced agglomeration.（2）The swelling adsorption experiment results show:the equilibrium swelling degree of AgNPs/Poly（MMA-St）（L31）membrane in the mixture of benzene and cyclohexane with mass ratio of 1:3 is about 8 to 9 times of that in cyclohexane,diffusion coefficient is about 2 times of cyclohexane,The results show that the introduction of AgNPs can improve the preferential adsorption and diffusion of membrane to benzene;whenm _GO=0.3wt%,the equilibrium swelling degree of AgNPs/GO/Poly（MMA-St）（L31）membrane in the mixture of benzene and cyclohexane with mass ratio of 1:3 is about 9.5 times of that in cyclohexane,and the diffusion coefficient is about 2.6 times of that in cyclohexane,The results showed that the introduction of GO could further improve the preferential adsorption and diffusion of the membrane to benzene.（3）When C_AgNO3=0.3 mol·L^-1,m _L31=8wt%,ω=3,the separation factor of AgNPs/Poly（MMA-St）（L31）membrane was 9.4 and the osmotic flux reached 940.36 g·m^-2·h^-1,which were 8.5 times of the Poly（MMA-St）membrane separation factor and 3.2 times of the Poly（MMA-St）membrane osmotic flux,respectively.This indicated that the introduction of AgNPs could effectively improve the performance of the pervaporous separation of the mixed matrix membrane to benzene and cyclohexane.After adding a further 0.3wt%GO,the separation factor of AgNPs/GO/Poly（MMA-St）（L31）membrane was 11.9and the osmotic flux reached 1265.49 g·m^-2·h^-1,which were 10.8 times of the Poly（MMA-St）membrane separation factor and 4.3 times of the Poly（MMA-St）membrane osmotic flux,respectively.It shows that the introduction of GO can further improve the pervaporation separation performance of the mixed matrix membrane for benzene and cyclohexane.On the basis of the above research,AgNPs/GO/Poly（MMA-St）（L35）and AgNPs/GO/Poly（MMA-St）（L61）mixed matrix membranes were prepared by inverse microemulsion and their polymerization combined with coating method respectively.Swelling and adsorption and pervaporation experiments were carried out to investigate the diffusion and separation properties of the membranes,the results showed that:（1）The molecular weights of L35 and L61 are similar,but the HLB value of L35 is large.Under the conditions ofω=5,m _L35=m _L35=8wt%,C_AgNO3=0.3 mol·L^-1and m _GO=0.3wt%,and under the above conditions,the separation factor of AgNPs/GO/Poly（MMA-St）（L35）membrane in the benzene and cyclohexane mixture with m_benzene:m_cyclohexane=1:3 reached 8.2,and the permeation flux reached 1294.89 g·m^-2·h^-1,while under the same conditions,the separation factor of AgNPs/GO/Poly（MMA-St）（L61）membrane reached 6.9,and the permeation flux reached 946.22 g·m^-2·h^-1,Therefore,AgNPs/GO/Poly（MMA-ST）（L35）membrane had better swelling and separation performance.The HLB of L31 was similar to L61,but the molecular weight of L31 was small,Under the conditions ofω=3,m _L31=m _L61=8wt%,C_AgNO3=0.3 mol·L^-1and m _GO=0.3wt%,the equilibrium swelling degree and diffusion coefficient of AgNPs/GO/Poly（MMA-St）（L61）in benzene and cyclohexane mixture system are lower than AgNPs/GO/Poly（MMA-St）（L31）membrane.Under the above conditions,the separation factor of AgNPs/GO/Poly（MMA-ST）（L61）membranes in the benzene and cyclohexane mixture with m_benzene:m_cyclohexane=1:3 had only reached 4.6,and the permeation flux reached 948.46 g·m^-2·h^-1,which was significantly smaller than that of AgNPs/GO/Poly（MMA-St）（L31）membrane.Therefore,AgNPs/GO/Poly（MMA-ST）（L31） membranes prepared from L31 with lower molecular weight had better swelling and separation performance.