Porous SiO2 coated AlxFeyZr1-x-yO2 solid superacid nanoparticles with negative charge for polyvinylidene fluoride (PVDF) membrane: Cleaning and partial desalinating seawater
2020
Zhang, Yuqing | Hu, Yanhua | Zhang, Longfei | Wang, Ying | Liu, Wei | Ma, Chengbo | Lau, R. S. M. (Ronald S. M.)
In this work, porous SiO₂ coated AlₓFeyZr₁₋ₓ₋yO₂ solid superacid nanoparticles with negative charge (CS-SAFZr) were synthesized via hydrolysis, sulfation and sulfonation, and characterized by SEM, TEM, XRD, BET and so on. The results show that the size of CS-SAFZr nanoparticles prepared under the optimum preparation conditions is around 80 nm, thickness of the porous SiO₂ shell is about 20 nm, Hammett acidity is -16.197 and ion exchange capacity (IEC) is 0.98 mmol·g⁻¹. Correspondingly, ferrum (Fe) and aluminum (Al) elements are successfully doped into the ZrO₂ lattice and the doped nanoparticles present a specific surface area of 396.2 m² g⁻¹ with abundant hydroxyl and sulfonic acid groups on the surface. To investigate the properties of the nanoparticles as the filler, polyvinylidene fluoride (PVDF) was used as a candidate to prepare CS-SAFZr/PVDF ultrafiltration (UF) composite membranes and the performance were characterized via cleaning and desalinating seawater. Results indicate that the CS-SAFZr nanoparticles strengthen their compatibility with the membrane via hydrogen bonds and improve performances of PVDF membrane. The suspended solid and conductivity decline ratio of permeate seawater was 1.8 mg L⁻¹ and 13.20% respectively, indicating that CS-SAFZr/PVDF membrane performs seawater cleaning and partial desalination. Therefore, CS-SAFZr nanoparticles can be a promising candidate to modify PVDF membrane for cleaning and desalinating seawater.
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