Activable carboxylic acid functionalized crystalline nanocellulose/PVA-co-PE composite nanofibrous membrane with enhanced adsorption for heavy metal ions

The heavy metal ions are harmful for both environment and human healthy, therefore it is highly demanded to remove them from environment. In this study, the crystalline nanocellulose (CNC)/ poly(vinyl alcohol-co-ethylene (PVA-co-PE) nanofibrous membrane functionalized with 1, 2, 3, 4 -butanetetracarboxylic acid (BTCA) was prepared to adsorb the heavy metal ions. To enhance the absorptivity, BTCA modified membrane was activated by NaHCO3. The structures of modified nanofibrous membranes were characterized by FESEM and FTIR. The modified membrane was then used to adsorb the Pb (II), and the mixture of Pb (II), Cr (VI), Mn (II) and Cu (II). The effect of pH value and initial concentration on the absorptivity of nanofibrous membrane to Pb (II) was studied and the adsorption kinetics was analysed. After NaHCO3 activation, the modified nanofibrous membrane demonstrated excellent adsorption capacity to the single metal ions and metal ions mixture. The equilibrium adsorption could reach 471.55 mg·g−1 at 15 °C, higher than other nanofibrous membranes reported. Moreover, the modified nanofibrous membrane was found to be stable and could maintain 50% of the initial data after three times reuse. All of the results indicated the NaHCO3 activated membrane was a good candidate for the heavy metal ions removal.