One-Step Preparation of PVDF/GO Electrospun Nanofibrous Membrane for High-Efficient Adsorption of Cr(VI)

Abstract

Mass loading of functional particles on the surface of nanofibers is the key to efficient heavy metal treatment. However, it is still difficult to prepare nanofibers with a large number of functional particle loads on the surface simply and efficiently, which hinders the further improvement of performance and increases the cost. Here, a new one-step strategy was developed to maximize the adhesion of graphene oxide (GO) particle to the surface of polyvinylidene fluoride (PVDF) nanofibers, which was combined with coaxial surface modification technology and blended electrospinning. The oxygen content on the as-prepared fiber surface increased from 0.44% to 9.32%, showing the maximized GO load. The increased adsorption sites and improved hydrophilicity greatly promoted the adsorption effect of Cr(VI). The adsorption capacity for Cr(VI) was 271 mg/g, and 99% removal rate could be achieved within 2 h for 20 mL Cr(VI) (100 mg/L), which was highly efficient. After five adsorption-desorption tests, the adsorption removal efficiency of the Cr(VI) maintained more than 80%, exhibiting excellent recycling performance. This simple method achieved maximum loading of functional particles on the fiber surface, realizing the efficient adsorption of heavy metal ions, which may promote the development of heavy-metal-polluted water treatment.

Keywords: Cr(VI) adsorption; coaxial electrospinning; graphene oxide; heavy metal wastewater treatment.

Figure 1

Schematic diagram of preparation by different electrospinning strategy: (a) preparation of original PVDF ENFM, (b) blended electrospinning, (c) coaxial electrospinning, and (d) coaxial electrospinning combined with blended electrospinning.

Figure 2

FTIR spectra of GO powder, PVDF, PVDF–1GO, PVDF–2GO, PVDF–1GO@GO, and PVDF–2GO@GO nanofibers.

Figure 3

SEM of (a) PVDF (×10k), (b) PVDF–1GO (×20k), (c) PVDF@GO (×20k), (d) PVDF–2GO (×20k), (e) PVDF–1GO@GO (×20k), and (f) PVDF–2GO@GO (×20k).

Figure 4

(a) Oxygen element content and (b) water contact angle of different nanofibers.

Figure 5

(a) Comparison of adsorption effect of different nanofibers and (b) effect of pH on the adsorption capacity by the PVDF–2GO@GO nanofibers.

Figure 6

Adsorption capacity of PVDF–2GO@GO ENFM for Cr(VI) under different time.

Figure 7

(a) Pseudo-first-order kinetic model and (b) pseudo-second-order kinetic model.

Figure 8

Effect of initial concentration of Cr(VI) aqueous solution on the adsorption capacity of PVDF–2GO@GO nanofibrous membranes.

Figure 9

(a) Langmuir isotherm model and (b) Freundlich isotherm model for adsorption of Cr(VI).

Figure 10

(a) Reusability of Cr(VI) from PVDF–2GO@GO nanofibrous membranes in cyclic adsorption–desorption test and (b) nanofibrous membranes after adsorption and desorption.