Fig. 1. Synthetic route for NWF-bif

Fig. 2. FTIR spectra of NWF samples before and after modification

Fig. 3. TG and DTG curves of NWF samples before and after modification (color online)

Fig. 4. Water contact angles of NWF samples before and after modification

Fig. 5. SEM images of (a) PE/PP NWF, (b) NWF-g-P(AN-co-AA), (c) NWF-bif, and (d) Au@NWF-bif

Fig. 6. Effect of pH on the Au(Ⅲ) adsorption (initial concentration, 25 mg/L; sorbent dosage, 0.1 g/L; time, 240 h )(color online)

Fig. 7. (a) Effect of adsorption time on Au(Ⅲ) adsorption capacity; fitting results of (b) pseudo-first-order and (c) pseudo-second-order models (initial concentration, 25 mg/L; sorbent dosage, 0.1 g/L; pH, 2)

Fig. 8. (a) Adsorption isotherm curve of NWF-bif to Au(III); Fitting results of (b) Langmuir and (c) Freundlich isotherm models (sorbent dosage, 0.1 g/L; time, 240 h; pH, 2)

Fig. 9. Selectivity of NWF-bif in mixed metal ion solution (initial concentration of each ion, 10 mg/L; sorbent dosage, 1 g/L; time, 120 h; pH, 2)

Fig. 10. Optical photos of Au@NWF-bif before and after high-temperature treatment

Fig. 11. Elements distribution of NWF-bif before and after Au(III) adsorption

Fig. 12. (a) XPS spectra of NWF-bif before and after adsorption; (b) Au 4f fine spectra of Au@NWF-bif; (c) XRD spectra of pristine PE/PP NWF, NWF-bif, and Au@NWF-bif; (d) O 1s, (e) N 1s, and (f) S 2p XPS fine spectra of NWF-bif before and after adsorption