Oxidized regenerated cellulose nanofiber membranes for capturing heavy metals in aqueous solutions

One of the major public health concerns is heavy metal contaminated drinking water. Various water treatment processes with new effective materials play an important role in improving water quality. This research describes the modification of electrospun cellulose acetate nanofiber membrane for capturing heavy metal ions from aqueous solutions. Electrospun nanofiber membranes of cellulose acetate were prepared by the electrospinning technique and oxidized via the use of TEMPO/NaBr/NaOCl with different conditions so as to introduce carboxylate functional groups on fiber surfaces. These membranes were characterized, measured for their permeability and tested for their ion exchange properties for copper and lead ions in aqueous solutions. Oxidized cellulose membrane samples showed remarkably high permeability at 60,000 L/m²/h/bar and low permeability reduction at 10% after the oxidizing process. ORC membrane samples with higher oxidizing levels exhibited higher ion exchange capacities of up to 20 mg of copper/g of membrane and 200 mg lead/g of membrane possibly because of the high amount of carboxylate groups. Additionally, it was found that all samples were more selective toward Pb(II) over that of Cu(II) owing to differences in hydration stabilities of each metal and stability effects of metal and carboxylate functional group complexes.