A novel ultrafiltration grade nickel iron oxide doped hollow fiber mixed matrix membrane: Spinning, characterization and application in heavy metal removal

Nickel iron oxide nanoparticle incorporated hollow fiber mixed matrix membrane was prepared to achieve high throughput as well as high selectivity for heavy metals. The fibers were characterized in terms of their morphology, permeability, molecular weight cut off, zeta potential, surface roughness and adsorption capacity of various toxic heavy metal species. Scanning electron micrograph images showed that the tear drop-like pores in cross section of the fibers were changed into finger-like macropores on addition of nanoparticles. Porosity and pore size in the fibers increased with nanoparticle concentration. Membrane permeability increased almost twice by addition of 3 wt% nanoparticles compared to pure polysulfone membrane. Similar concentration of nanoparticles made the membrane more hydrophilic reducing its contact angle from 77° to 64° and at the same time, molecular weight cut off of the hollow fibers increased from 17 kDa to 34 kDa. Surface zeta potential of the fibers decreased with pH and the membrane with 3 wt% nanoparticles showed a surface potential about −16 mV at pH 9. The maximum adsorption capacity of membrane with 3 wt% nanoparticles was the highest for lead (52 mg/g) followed by copper (42 mg/g), zinc (35 mg/g) and cadmium (24 mg/g). Nickel (17.5 mg/g) and chromium (18 mg/g) had comparable adsorption capacity. Thus, the mixed matrix membrane developed in this study has significant potential in removal of heavy metals from aqueous solution.