Poly(acrylonitrile) based ultrafiltration membranes: Optimization of preparation parameters

Supported ultrafiltration (UF) membranes based on poly(acrylonitrile) were prepared while varying crucial parameters responsible for controlling membrane porosity, viz.; polymer concentration, solvent and additives in the dope solution. Insight into membrane porosity and morphology was obtained by water flux, solute rejection, bubble point, pore size distribution, SEM and AFM analyses. It was found that merely increasing polymer concentration does not necessarily reduce pore size of membranes. Among four solvents used for the dope solution preparation, N-methyl pyrrolidone was found to offer membranes with optimal combination of flux and rejection of various solutes. Some of the PAN 17 (17% w/w PAN concentration in the dope solution) membranes prepared using organic acid as the additive (citric acid, tartaric acid or maleic acid) offered 1.2–1.7 times higher flux than the membrane prepared using inorganic salt, ZnCl 2 as an additive. The porosity of PAN 17 membrane prepared using CA as an additive was larger as compared to membrane prepared using ZnCl 2 as an additive. Atomic force microscopy (AFM) analysis of this membrane exhibited higher surface roughness as compared to the ZnCl 2 based membrane. Both these membranes exhibited bacteria (E. Coli) log reduction value (LRV) of at least 6; depicting applicability of these membrane for water disinfection. ► Effect of varied PAN amount, solvent and additives in dope solution is investigated. ► 17% PAN in dope offered optimum membrane for water disinfection. ► Citric acid as additive and NMP as solvent offered better membrane performance.