Morphological control of poly(vinylidene fluoride)@layered double hydroxide composite fibers using metal salt anions and their enhanced performance for dye removal
Morphological control of poly(vinylidene fluoride)@layered double hydroxide composite fibers using metal salt anions and their enhanced performance for dye removal
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金属盐阴离子对聚偏二氟乙烯@层状双氢氧化物复合纤维的形貌控制及其增强的脱染性能
DOI：
10.1039/c7ra08282g
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发表时间：
2017
期刊：
影响因子：
3.9
通讯作者：
Zheng Qiang
中科院分区：
文献类型：
--
作者：
Mei Qingqing;Lv Weiyang;Du Miao;Zheng Qiang
以含有不同阴离子的金属盐(NO3-−、Cl-−、SO42-−)为原料，采用静电纺丝和水热处理相结合的方法，制备了聚偏氟乙烯/层状双氢氧化物复合纤维的自立膜。阴离子对固定在PVDF纳米纤维表面的LDHs的形态和负载量有显著的影响。在单价阴离子(如硝酸盐)体系中，形成了较小的晶核。只有一小部分尺寸较大的LDH纳米晶长大为规则的大厚度六方LDH层状纳米晶。然而，在二价阴离子硫酸盐体系中，由于严重的空间位阻，首先会产生大的晶核，并且大多数晶核可以长大成细小的卷曲的LDH层状纳米晶。在硫酸盐体系中，PVDF@Coal-LDH复合纤维具有良好的层次化结构和均匀的芯/鞘形态，是处理染料溶液的优良吸附剂。所制得的聚偏氟乙烯/煤-乳酸脱氢纤维对甲基橙(MO)的最大吸附容量为621.17 mg g−1。此外，复合纤维膜性能优良，形态稳定，可直接用于膜过滤，具有较高的去除效率和循环稳定性。经过3次再生后，膜对MO的去除效率仍保持在93%以上，最大膜通量可达140M2h)−1，表明该膜可用于染料污染的有效处理。
Self-standing membranes of poly(vinylidene fluoride)@layered double hydroxide (PVDF@LDH) composite fibers were fabricated by using metal salts with different anions (NO3−, Cl−, SO42−) as the reactants through a combination of electrospinning and hydrothermal treatment. The anions have a significant effect on the morphology and loading amount of LDHs anchored onto the surface of PVDF nanofibers. In a monovalent anion (such as nitrate) system, small crystal nuclei were formed. Only a small proportion with a large size grew up to well-defined hexagonal LDH layered nanocrystals with large thicknesses. However in a divalent anion sulfate system, large crystal nuclei were generated first and most of them could grow up to thin and curly LDH layered nanocrystals owing to the serious steric hindrance. Well-defined PVDF@CoAl-LDH composite fibers with a hierarchical structure and uniform core/sheath morphology could only be obtained in the sulfate system, which could act as an excellent adsorbent for treating dye solutions. The obtained PVDF@CoAl-LDH core/sheath fibers present a maximum adsorption capacity of 621.17 mg g−1 for methyl orange (MO). Moreover, benefiting from the perfect properties and stable form, the composite fiber membrane could be used directly in membrane filtration with high removal efficiency and cycling stability. The MO removal rate of the membrane remained above 93% with a maximum flux of 140 L (m2 h)−1 despite three times of regeneration, indicating its practical application for the efficient treatment of dye pollution.