Mitigating the relative humidity effects on the simultaneous removal of VOCs and PM2.5 of a metal–organic framework coated electret filter
Mitigating the relative humidity effects on the simultaneous removal of VOCs and PM2.5 of a metal–organic framework coated electret filter
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DOI：
10.1016/j.seppur.2021.120309
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发表时间：
2022-03
影响因子：
8.6
通讯作者：
Yu Zhang;Zan Zhu;Wei-Ning Wang;S. Chen
中科院分区：
文献类型：
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作者：
Yu Zhang;Zan Zhu;Wei-Ning Wang;S. Chen
一种包覆了高孔金属有机骨架(MOF，即本文中的MIL-125-NH_2)颗粒的驻极体过滤介质被称为E-MOFilter，用于同时去除细颗粒物(PM2.5，直径小于2.5微米的颗粒物)和挥发性有机化合物(如甲苯)。但随着相对湿度(RH)的升高，其对甲苯的吸附效率和吸附容量变差。这是由于MIL-125-NH_2的亲水性导致甲苯和水分子之间的竞争吸附。为了解决这一问题，人们采用了五种方法将MIL-125-NH_2从固有的亲水性转变为疏水性，包括内部(烷基化法)、外部(聚二甲基硅氧烷包覆)、组合(烷基化+PDMS包覆)、聚乙烯吡咯烷酮(PVP)表面活性剂和N-配位修饰。基于这些改性的MIL-125-NH_2制备了新型E-MOF，并系统地比较了它们在不同RH水平(从10%、30%、40%、50%到60%)下对甲苯的吸附效率和容量。除甲苯外，还考察了改进型E-MOFilter对PM的去除效果和对PM2.5的截留能力。甲苯吸附结果表明，PDMS包覆的E-MOFilter的吸附性能优于所有其他改性。所有改性的E-MOFilter都保持了去除PM的能力，表明驻极体介质的电荷和结构没有改变。本研究首次将MOF与驻极体滤料相结合，在不同的RHS条件下实现了低压降和同时去除PM和甲苯的效果。综合评价和讨论了不同改型的E-MOFilter在提高RH条件下对甲苯的吸附效果和性能。
An electret filter media coated with highly porous metal–organic framework (MOF, i.e., MIL-125-NH2in this work) particles, called E-MOFilter, has been developed to remove fine particulate matters (PM2.5, particulate matter less than 2.5 µm in diameter) and volatile organic compounds (VOCs, e.g., toluene) simultaneously. However, its adsorption efficiency and capacity of toluene was deteriorated at an elevated relative humidity (RH). This was due to the hydrophilic nature of MIL-125-NH2leading to competitive adsorption between toluene and water molecules. To address this issue, five modification methods were conducted to alter MIL-125-NH2from inherent hydrophilic into hydrophobic, which included the internal (alkylation method), external (coating with polydimethylsiloxane, PDMS), combined (alkylation plus PDMS coating), polyvinylpyrrolidone (PVP) surfactant, and N-coordination modifications. The new E-MOFilters were fabricated based on these modified MIL-125-NH2and then systematically compared for their toluene adsorption efficiency and capacity under various RH levels (from 10, 30, 40, 50 to 60%). In addition to toluene, the PM removal efficiency and PM2.5holding capacity by the modified E-MOFilters were also evaluated. The toluene adsorption results revealed the PDMS-coated E-MOFilter outperformed all other modifications. The PM removal ability were retained for all modified E-MOFilters indicating the charge and structure of the electret media were not altered. This study is the first to combine the MOFs with electret filter media for a low pressure drop and simultaneous removal of PM and toluene under different RHs. The effectiveness and performance towards toluene adsorption under elevated RH conditions for E-MOFilters with various modifications were comprehensively evaluated and discussed.