PVDF membranes containing alkyl and perfluoroalkyl-functionalized graphene nanosheets for improved membrane distillation
PVDF membranes containing alkyl and perfluoroalkyl-functionalized graphene nanosheets for improved membrane distillation
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DOI：
10.1016/j.jece.2023.109898
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发表时间：
2023-04
影响因子：
7.7
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制备了含有疏水性石墨烯纳米填料的聚偏二氟乙烯 (PVDF) 膜，并针对膜蒸馏应用进行了测试。纳米填料通过两步过程获得：第一）将疏水性分子（辛胺（OA）或全氟辛胺（PFOA））化学接枝到氧化石墨烯（GO）纳米片上，第二）化学还原功能化GO（rGO）以去除未反应的含氧官能团。这产生了 OA 功能化还原 GO (OA-rGO) 和 PFOA 功能化 rGO (PFOA-rGO)。将这些纳米材料添加到通过相转化过程制备的PVDF膜中导致膜接触角增加，因此疏水性更高，以及膜孔隙率增加。当比较纳米填料 OA-rGO 和 PFOA-rGO 时，由于氟原子的存在，后者在实现更高接触角方面更有效，而 OA-rGO 与 PFOA-rGO 相比，膜孔隙率更大。含有 0.7 wt% 纳米填料的 OA-rGO 和 PFOA-rGO 的 MMM 分别达到了 9.1 和 8.8 L m−2h−1 的最高水通量，脱盐率超过 99.9%，对前者的运行至少 162 小时进行了监测。与纯 PVDF（通量为 5 L m−2h−1）相比，添加 OA-rGO 和 PFOA-rGO 纳米填料的通量分别增加了 82% 和 76%。
Polyvinylidene fluoride (PVDF) membranes containing hydrophobic graphene nanofillers were prepared and tested for membrane distillation applications. The nanofillers were obtained by a two-step process: 1st) chemical grafting of hydrophobic molecules, either octylamine (OA) or perfluoroctylamine (PFOA), to graphene oxide (GO) nanosheets, and 2nd) chemical reduction of functionalized GO (rGO) to remove unreacted oxygen-containing functional groups. This resulted in OA-functionalized reduced GO (OA-rGO) and PFOA-functionalized rGO (PFOA-rGO). The addition of these nanomaterials to PVDF membranes prepared by the phase inversion process led to an increase in the membrane contact angle, and therefore higher hydrophobicity, as well as an increase in the membrane porosity. When comparing both nanofillers, OA-rGO and PFOA-rGO, the latter was more efficient in achieving higher contact angles due to the presence of fluorine atoms, whereas OA-rGO led to a greater enhancement in membrane porosity as compared to PFOA-rGO. MMMs containing 0.7 wt% nanofiller loadings of OA-rGO and PFOA-rGO achieved the highest water fluxes of 9.1 and 8.8 L m−2h−1, respectively and salt rejection above 99.9%, which was monitored for at least 162 h of operation for the former. In comparison with pure PVDF (flux of 5 L m−2h−1), the addition of OA-rGO and PFOA-rGO nanofillers results in a flux increment of 82% and 76%, respectively.