Adsorptive removal of nitrate from aqueous solution by polyacrylonitrile–alumina nanoparticle mixed matrix hollow-fiber membrane

Hollow fiber mixed matrix membrane (MMM) of polyacrylonitrile and alumina nanoparticle was prepared. Incorporation of alumina in membrane matrix was confirmed by elemental analysis. The membrane was characterized by scanning electron microscopy, contact angle, permeability, neutral polymer rejection, pore size, mechanical strength and zeta potential. Hydrophilicity, mechanical strength and zeta potential of MMM increased with alumina concentration. Langmuir isotherm fitted the best for adsorption of nitrate by the membrane and it was confirmed by FTIR. The breakthrough performance of MMM was studied conducting continuous cross-flow experiments. Effects of operating conditions, like feed concentration, cross flow rate and transmembrane pressure on filtration performance, were investigated. The membrane was regenerated by passing 0.1 M sodium hydroxide solution for 15 min. Increasing cross-flow rate had an adverse effect and transmembrane pressure had a marginal effect on the removal of nitrate. The presence of other co-ions like chloride, sulfate and carbonate has a negative effect on nitrate removal.