Preparation of MOFs/chitosan positively charged nanofiltration membrane by electrospray method
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摘要: 将壳聚糖的直接成膜性与电喷雾技术结合,并引入金属有机骨架(MOFs),制备了胺基修饰的UIO-66(Zr) NH2-UIO-66(Zr)/壳聚糖荷正电纳滤膜,实现对Ni2+的高效分离和富集。通过电喷雾技术可有效解决传统壳聚糖纳滤膜成膜周期长、膜层较厚、通量较低等问题。实验表明,与传统涂覆工艺相比,电喷雾法制备的壳聚糖复合膜在保持较高截留率的情况下,渗透性提高了634%。然而,单一壳聚糖基质膜受trade-off效应影响,分离性能难以进一步提升。引入NH2-UIO-66(Zr)作为填料可有效缓解trade-off效应,所制备的复合膜在不牺牲截留率的情况下,通量进一步提升38%(水通量为4.7×10−5 L·m−2·h−1·Pa−1,对NiCl2截留率为92%)。Abstract: Electrospray technology can solve the problems of long membrane formation period, thicker membrane layer and low flux of traditional chitosan nanofiltration membranes. In this study, the NH2-UIO-66(Zr)/chitosan positively charged nanofiltration membrane based on NH2-UIO-66(Zr)/chitosan was successfully prepared by combining the direct membrane-forming properties of chitosan with electrospray technology and introducing metal-organic frameworks (MOFs). This membrane has achieved efficient separation and enrichment of Ni2+. The morphology, structure and properties of membrane were investigated by SEM, EDS, Zeta potential, water contact angle measurements, etc. The results showed that compared with the traditional coating process, the permeability of the chitosan composite membrane prepared by the electrospray method was increased by 634% and the membrane can still maintain a good rejection. However, pure chitosan matrix membranes are usually affected by trade-off effect, and it is difficult to further improve the separation performance. The introduction of NH2-UIO-66 (Zr) as a filler can effectively alleviate the trade-off effect. Hybridization improved the hydrophilicity of the separation layer and formed a special membrane surface structure, thereby increasing permeability of the composite membrane. Experiments showed that the limit of NH2-UiO-66(Zr) loading was 5 wt% (the ratio of MOFs to chitosan). The optimized NH2-UIO-66(Zr)/chitosan membrane had a higher flux than pristine chitosan membrane (increased by 38%). The prepared membrane exhibited a high NiCl2 rejection of 92% and a water permeability of 4.7×10−5 L·m−2·h−1·Pa−1 (test pressure: 4×105 Pa; feed concentration: 0.5 g/L). In addition, the hybrid membrane exhibited excellent mechanical strength and had the potential to separate a single solution of MgCl2, ZnCl2 and Pb(NO3)2.
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Key words:
- chitosan /
- metal-organic framework /
- nanofiltration membrane /
- electrospray
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表 1 样品的Zeta电位测试
Table 1. Zeta potential test of samples
Item Zeta potential
(pH=4)/mVZeta potential
(pH=6)/mVZeta potential
(pH=8)/mVPSF −15.1±0.4 −30.88±0.82 −39.06±0.42 MCS-0 8.85±0.32 7.33±0.35 4.05±0.02 MCS-5 7.34±0.37 6.14±0.01 3.86±0.02 -
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