Water desalination via novel positively charged hybrid nanofiltration membranes filled with hyperbranched polyethyleneimine modified MWCNT

Abstract

Novel positively charged hybrid nanofiltration membranes were fabricated via incorporation of hyperbranched polyethyleneimine modified multiwall carbon nanotubes into polyethersulfone matrix. The main aim of this research is induction of positive charge to negatively charged polymeric membrane by means of self-assembly of positively charged nanoparticles via phase inversion technology. The prepared membranes were evaluated in terms of morphology, surface properties, thermal and mechanical stabilities, nanofiltration performance and antifouling property. The best hybrid membrane with loading of 0.6% of nanoparticles, showed high thermal and mechanical stabilities with mean pore size, molecular weight cut off (MWCO) and isoelectric point of 0.81nm, 600Da and 10, respectively. Pure water flux (PWF) of the hybrid membrane compared to the neat polyethersulfone membrane was enhanced 109% and reached to 75.7L/m2h. Effects of pressure, temperature, feed concentration and feed pH on separation performance of the membranes were also investigated. The hybrid membrane represented superior performance for heavy metals removal in rejection order of Zn (99.06%)>Mg (97.36%)>Cd (96.72%)>Cu (95.84%)>Ca (95.25%)>Ni (94.63%)>Pb (93.39%), indicating domination of Donnan exclusion mechanism. In addition, the hybrid membrane with higher hydrophilicity and lower roughness showed improved antifouling property and life span.