Abstract
In this work, vacuum filtered and polymer mixed e-spinning membranes (ESPMs) made from or doped with Fe-based nanomaterials were successfully fabricated to remove Cd2+ ions from a neutral aqueous solution. The used Fe-based nanomaterials including FeOOH precursor Nanowires (NWs), α-Fe2O3 NWs and Fe3O4 nanoparticles (NPs) were synthesized by elevating the hydrothermal reaction temperature from 250 °C to 500 °C or doing post-heating treatment. The adsorption results showed that vacuum filtered membranes (VFMs) overall performed a better Cd2+ ions removal behavior than e-spinning ones. Among them, VFM made from Fe3O4 NPs has the highest adsorption capacity (qt) with the adsorption amount of Cd2+ ions reaching about 29.3 mg/g within only 2 min due to the high specific surface area of NPs. Models of pseudo-first-order, pseudo-second-order and intraparticle diffusion were used to study the kinetics of Cd2+ ions removal process, and a high correlation coefficient (R2) of 0.99 was obtained when pseudo-second-order model was used. It was calculated that the equilibrium rate constant of VFM made from Fe3O4 NPs has reached about 0.28 g mg−1 min−1, much smaller than those of other membranes, which indicated a high Cd2+ ions removal efficiency.