Preparation and properties of elliptic leaves SiO2/polyvinyl alcohol pervaporation composite membranes
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摘要: 如何制备含形貌可控且高度分散无机纳米颗粒的高性能复合分离膜,是当前膜分离领域的研究热点和难点。本文采用溶胶-凝胶和溶液刮涂法将聚乙烯醇(PVA)、马来酸(MA)和SiO2三者交联制备得到混合基质膜。通过SEM、FTIR、XRD对SiO2/交联PVA混合基质膜进行结构表征,在50℃下对97wt%乙醇水溶液进行渗透汽化性能测试。结果表明,含椭圆叶片状SiO2聚集体的SiO2/交联PVA混合基质膜,椭圆叶片状SiO2纳米颗粒聚集体可作为表面预筛选层,且在基体内高度分散,能够同时增加对醇水溶液的渗透通量和选择性。对97wt%乙醇水溶液的渗透通量和选择性分别高达 0.072 kg·m−2·h−1和12301。分离性能提高的原因可能是由于该混合基质膜具有表面预筛功能和更致密的网络结构。该结果将促进纳米SiO2/PVA复合材料的研究及该类材料在分离领域的应用。Abstract: How to prepare high-performance separation membranes with morphology controlled and well-dispersed nanoparticles, has been a hotspot and difficulty in the field of membrane separation. Mixed matrix membranes were prepared by crosslinking polyvinyl alcohol (PVA), maleic acid (MA) and SiO2 via an aqueous sol-gel route and solution casting method. The membrane was characterized by SEM, FTIR, XRD and tested for its perfor-mance in pervaporation separation of ethanol/water mixtures with feed ethanol concentration of 97wt% at 50℃. Membrane characterization results reveal that SiO2/crosslinked PVA membrane shows that elliptic leaves SiO2 nano-particles cover the surface and act as a water prescreening layer, are well disperse within the polymer matrix. It results in a significantly enhanced effect in both flux and selectivity. The membranes achieve high water flux of 0.072 kg·m−2·h−1 and separation factor of 12301 for separation of 97wt% ethanol aqueous solution. The enhanced membrane performance can be attributed to the surface prescreening ability and dense crosslinking membrane network. The research results would promote the study of SiO2/PVA composite materials, and their application in the field of membrane separation.
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Key words:
- pervaporation /
- mixed matrix membrane /
- SiO2 /
- polyvinyl alcohol /
- sol-gel route
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表 1 SiO2/交联聚乙烯醇(cPVA)混合基质膜的命名
Table 1. Naming of SiO2/crosslinked polyvinyl alcohol (cPVA) mixed matrix membranes
Sample Mass ratio of SiO2 to PVA/
%Maleic acid (MA)/g PVA/g 0.1 mol/L HCl/mL SiO2/cPVA-0 5 3.2 16.0 0 SiO2/cPVA-1 5 3.2 16.0 1 SiO2/cPVA-5 5 3.2 16.0 5 表 2 50℃水扩散系数DWater的计算
Table 2. Diffusion coefficients of water DWater at 50℃
Di×108 /(m2·s−1) SiO2/cPVA-5 SiO2/cPVA-1 SiO2/cPVA-0 DWater 14.4 9.8 10.6 Note: Di—Apparent diffusion coefficient. 表 3 SiO2/cPVA混合基质膜与其他渗透汽化膜的比较
Table 3. Comparison of SiO2/cPVA mixed matrix membranes with other pervaporation membranes
Nanofiller Polymer matrix Application Temperature/℃ Flux/(g·m−2·h−1) Separation Factor Ref. Titanate nanotubes PVA Water/isopropanol 50 ~30 5520 [26] GO Polyimide Water/isopropanol 60 161.5 >5000 [27] MXene CS Water/ethanol 50 1424 1421 [28] SiO2 PDMS Recover phenol 50 7.16 4.29 [29] GOF PVA Water/ethanol 70 ~300 330 [30] PMA PDMS Water/butanol 70 923 42 [31] Elliptic
silicaPVA Water/ethanol 50 72 12301 This work Notes: GO—Graphite oxide; CS—Chitosan; PDMS—Polydimethylsiloxane; GOF—Graphene oxide framework; PMA—Propylene glycol methyl ether acetate. -
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