Study On Preparation Of Polyaniline Nanofiber Composite UF Membrane

In recent years, to prepare nanocomposite membrane with high performance through the incorporation of nanomaterials has been a new research direction of membrane technology. This paper initially investigated the preparation and characterization of polyaniline (PANI) nanofibers/polysulfone (PS) nanocomposite UF membrane.PANI/PS nanocomposite membrane was prepared through the filtration of PANI aqueous dispersion with PS membrane. PANI/PS membrane had a hydrophilic and porous layer of PANI nanofibers. Pure water flux of PANI/PS membrane was 1.6 times that of PS membrane. For PS membrane, rejections of BSA and PEG-20000 were 98.8% and 27.2%, respectively. For PANI/PS membrane, rejections of BSA and PEG-20000 were 99.2% and 27%, respectively. When feed pH was less than 7, the amines and imines of PANI were protonated and PANI/PS membrane surface had positive charge. The BSA adsorption quantity of PS membrane was 6 times than that of PANI/PS membrane. During the filtration of BSA solution, PANI/PS membrane showed higher permeate flux and lower flux decline rate than PS membrane.PANI/PS blend membrane was prepared with the immersion phase inversion method. Compared with PS membrane, PANI/PS blend membrane had better hydrophilic property and higher porosity. The connectivity of blend membrane pores was improved by the migration of PANI nanofibers. Pure water flux of the blend membrane was higher than that of PS membrane. Pure water flux of the blend membrane with PANI– PS mass ratio of 1 wt. % was 1.6 times that of PS membrane, and pure water flux of the blend membrane with PANI– PS mass ratio of 15 wt. % was 2.4 times that of PS membrane. For PS membrane, rejections of BSA and AE were 96% and 93%, respectively. For the blend membrane, rejections of BSA and AE were in the range of 96%~99% and 93%~98%, respectively. During the filtration of BSA solution, all the blend membranes showed higher permeate fluxes than PS membrane and their fluxes increased with the rise of PANI nanofibers content. Stable permeate fluxes of the blend membranes with PANI– PS mass ratio of 1 wt. % and 15 wt. % were 2.0 and 2.5 times that of pure PS membrane, respectively. In addition, PANI/PS blend membrane showed lower flux decline rate and higher flux recovery ratio. With the rise of PANI nanofibers content, the breaking strength of the blend membrane increased and the elongation at break decreased. Mechanical property of the blend membrane with PANI– PS mass ratio of 1 wt. % had no obvious change. The blend membranes presented similar thermal behavior to PS membrane.The in-situ growth of PANI nanofibers on PS membrane surface was explored. PANI nanofibers could grow homogeneously on PS membrane under lower temperature, shorter stir time, and suitable doping acid and SDBS concentration to form PANI/PS composite membrane. With the extension of polymerization time, the composite membrane had better hydrophilic property, lower pure water flux, higher PEG-35K rejection, and higher conductivity. After 24 h polymerization, the conductivity of the composite membrane was 0.04 S/cm.