A covalently integrated ZIF-8/polyamide acid mixed matrix membrane with superior gas separation performance

Zeolitic imidazolate framework-8(ZIF-8)is a typical filler used to fabricate mixed matrix membranes(MMMs)on account of its attractive advantage of high selective permeability for gas separation.However,the performance is usually affected by filler aggregation due to strong interactions among fillers and weak interactions between the polymer and fillers,However,the performance is usually affected by filler aggregation due to strong interactions among fillers and weak interactions between the polymer and fillers,which will lead to a decrease of selectivity and the performance of gas separation will be strongly influenced.Herein,we modified ZIF-8 with 3-amino-1,2,4-triazole to obtain ZIF-8-NH_(2),Kapton polyamide acid was selected as the polymer matrix.Results showed that the ZIF-8-NH_(2)/Kapton MMMs has a good compatibility interface between ZIF-8 and Kapton because of the covalent bridging,even the filler loading up to 45%(mass).The 45%(mass)of ZIF-8-NH_(2)/Kapton membrane showed 297 barrer(1 barrer=10^(-10)10 cm^(3)·cm·cm^(-2)·s^(-1)·cmHg^(-1),1 cmHg=1333.22 Pa,standard temperature and pressure)of the permeability of H_(2)and 43.9 and 62.2 of selectivities for H_(2)/N_(2)and for H_(2)/CH_(4),respectively,which are beyond the upper limit of Robeson 2008.

High-performance ZIF-8 membranes:preparation and their uranium adsorption performance

In this study,the ZIF-8 membrane(ZIF-8/PP-g-MAH)is prepared by in situ synthesis of ZIF-8 on irradiation-pretreated polymer substrates to improve the uranium adsorption performance and address the recycling problems of ZIF-8 powder.The effects of pH,contact time,and uranium concentration on the adsorption of ZIF-8/PP-g-MAH were investigated.Adsorption isotherm and kinetics analysis show that ZIF-8/PP-g-MAH has a high adsorption capacity of 478.5 mg/g,which is 1.26 times higher than that of ZIF-8,and a rapid adsorption equilibrium of 120 min,which is shortened to one-third of that required for ZIF-8(360 min).The adsorption process of ZIF-8/PP-g-MAH is consistent with that of the Langmuir isotherm and pseudo-second-order dynamic model.ZIF-8/PP-g-MAH also exhibits good selectivity for uranium in simulated seawater.The high adsorption performance of ZIF-8/PP-g-MAH is attributed to its membrane structure,which improves the utilization of coordination sites,including Zn-OH,C-N,and C=N.This study provides an efficient adsorption material for rapid uranium extraction,thus promoting the development of uranium extraction technologies.

ZIF-67@Cellulose nanofiber hybrid membrane with controlled porosity for use as Li-ion battery separator

Zeolitic imidazolate framework-67(ZIF-67) was synthesized on the surface of cellulose nanofibers(CNFs)in methonal to address the problems of unhomogeneous pore size and pore distribution of pure CNF membrane.A combination of Energy Dispersive X-Ray Spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS) and X-ray powder diffraction(XRD) patterns were used to determine the successful synthesis of ZIF-67@CNFs.The size of the ZIF-67 particles and pore size of the ZIF-67@CNF membrane were50-200 nm and 150-350 nm, respectively.The prepared ZIF-67@CNF membrane exhibited excellent thermal stability,lower thermal shrinkage and high surface wettability.The discharge capacity retention of the Li-ion batteries(LIBs) made with ZIF-67@CNF,glass fiber(GF),CNF and commercial polymer membranes after 100 th cycle at 0.5 C rate were 88.41%,86.22%,83.27%,and 81.03%,respectively.LIBs with ZIF-67@CNF membrane exhibited a better rate capability than these with other membranes.No damage of porous structure or peel-off of ZIF-67 was observed in the SEM images of ZIF-67@CNF membrane after100 th cycle.The improved cycling performance,rate capability,and good electrochemical stability implied that ZIF-67@CNFs membrane can be considered as a good alternative LIB separator.

基于ZIF-7纳米容器的主动腐蚀预警与控制涂层的制备及性能

将负载罗丹明B酰肼(RBH)的ZIF-7纳米容器(ZID-7@RBH)添加到环氧涂层中,制备了主动腐蚀预警和控制双功能一体化的智能防腐蚀涂层。采用扫描电镜(SEM)、X射线衍射仪(XRD)和傅里叶红外光谱仪(FT-IR)分析了ZIF-7@RBH的微观形貌、结构和化学组成。通过盐雾试验和电化学测试考察了ZIF-7@RBH添加量对涂层耐蚀性的影响。结果表明:制备的纳米容器形貌规整、尺寸均一,并且成功负载了RBH;在涂层中添加0.5%的ZIF-7@RBH能够有效抑制界面腐蚀扩展,该涂层在海水中浸泡20 d后,其低频阻抗模量|Z|_(0.01 Hz)比纯环氧涂层高近一个数量级,显著提升了涂层的防腐蚀性能;破损涂层在海水浸泡20 min后,其缺陷处即可显现荧光,展现出优异的腐蚀自预警效果。

Fabrication of ZIF-8 membranes on dual-layer ZnO-PES/PES organic hollow fibers by in-situ crystallization

Compared to inorganic supports, polymeric supports can offer additional benefits, e.g., easier processing and cheaper. However, the organic surface has weak adhesion to the zeolitic imidazolate frameworks(ZIFs) membrane layer, which usually requires complex surface modification or seeding. Herein, we demonstrate that a dual-layer asymmetric polymer support prepared by a simple spinning process is a good candidate for the preparation of ZIF-8 membrane. The inner layer of the support is an organic hollow fiber(PES) with finger-like pores, and the outer layer is a ZnO-PES composite layer with finger-like pores also. The ZnO-PES composite layer is expected to contain uniform ZnO crystals in the polymer matrix, i.e., the ZnO particles in the skin layer of the support are not easy to fall off. Under the induction of ZnO particles in the outer layers, continuous ZIF-8 membranes can be prepared by single in-situ crystallization, showing good adhesion to the supports. The obtained ZIF-8 membranes show a H_(2) permeance of 8.7 × 10^(-8)mol·m^(-2)·s^(-1)·Pa^(-1) with a H_(2)/N_(2) ideal separation selectivity of 18.0. The design and preparation of this dual-layer polymer support is expected to promote the large-scale application of MOF membranes on polymer supports.

Preparation of ZIF-8@PEBAX/PVDF nanocomposite membrane by the combination of self-assembly and in-situ growth for removing thiophene from the model gasoline

Metal-organic frameworks(MOFs)have gained attention in the development of MOFs/polymer hybrid membranes for pervaporation.However,the agglomeration of MOFs particles and interfacial defects limit its further application.In this study,we present a novel approach to fabricate a ZIF-8@PEBAX/PVDF nanocomposite membrane for removing thiophene from the model gasoline by combination of selfassembly and in-situ growth.Firstly,a PVDF supporting membrane was modified to have a negative charge.Next,positively charged zinc ions were attracted onto the negatively charged PVDF supporting membrane through electrostatic interaction.Afterwards,the Zinc ions deposited PVDF membrane was immersed into dimethylimidazole solution to form a uniform ZIF-8 layer.Finally,the ZIF-8 layer was coated with poly(ether-block-amide)(PEBAX)using the pouring method.Experimental results showed that the separating efficiency of the ZIF-8@PEBAX/PVDF nanocomposite membrane was improved significantly compared to that of pristine PEBAX membrane.The optimal permeation flux and enrichment factor of membrane were 27.80 kg(m^(2)h)^(-1)and 6.9,respectively.

The effect of ZIF-90 particle in Pebax/Psf composite membrane on the transport properties of CO2,CH4 and N2 gases by Molecular Dynamics Simulation method

Nowadays,mixed matrix membranes(MMMs)have considered by many researchers to overcome the problems of polymeric membranes.In addition,molecular dynamics(MD)and Monte Carlo(MC)simulation Methods are suitable tools for studying transport properties and morphology in MMMs.For this purpose,in this study using material studio 2017(MS)software,the transport properties of CO2,CH4 and N2 in Pebax,Psf neat Pebax/Psf composite and Pebax/Psf composite filled with ZIF-90 particles have been investigated.By adding Psf to Pebax matrix,the selectivity of CO2/CH4 and CO2/N2 gases has significantly increased.In addition,adding ZIF-90 particles to the Pebax/Psf composite increased the permeability of CO2,CH4 and N2 compared to neat and composite membranes.The morphological properties of the membranes,such as the fractional free volume(FFV),radial distribution function(RDF),glass transition temperature(TG),X-ray diffraction(XRD)and equilibrium density have calculated and acceptable results have obtained.

ZIF-7基多孔碳材料制备与氙吸附性能研究

乏燃料后处理废气中的放射性氙(Xe)和氪(Kr)的捕集和分离是核燃料循环的重要一环。固体吸附分离法在室温条件下实现氙与氪的分离更有效率,具有诸多优点,而高性能的吸附材料是该方法的关键。本文通过直接碳化ZIF-7前驱体的方法制备了MOF衍生的微孔碳材料Z7CB-1000。298 K及100 k Pa条件下Z7CB-1000对Xe的静态吸附容量为3.72 mmol·g-1,亨利系数为69.6 mmol·g-1·bar,Xe/Kr亨利选择性为19.1;穿透实验结果表明,298 K及100 k Pa条件下Z7CB-1000对Xe的动态吸附容量为17.6 mmol·kg-1,表明Z7CB-1000是一种有潜力的Xe吸附分离孔材料,可望用于核燃料循环中废气中Xe的捕集与分离。

ZIF-78膜的制备及其在油气回收中的应用研究

采用反应晶种合成方法，在ZnO撑体（锌源）上制备ZIF-78膜，用XRD，TGA，SEM对合成的粉末和膜进行表征。将制备完整的ZIF-78／ZnO膜用于油气分离实验，考察了操作压力，进料浓度，操作温度及切割比对ZIF-78膜分离n-C6H1gN2体系性能的影响，实验表明，膜的分离因子随进料浓度的增加而增大，且分别在0．06MPa、20℃和切割比θ=0．2时达到最大值；膜的渗透系数均随操作压力、进料浓度、操作温度和切割比的增加而增大。实验研究了烷烃（C5～C7）／N2模拟油气体系在不同压力下对膜分离性能的影响，结果表明在操作温度20℃，操作压力0．06MPa，进料浓度30％（V）的条件下，n-C5H1JN2、n-C6H1VN2和n-C7H16／N2的分离因子分别为2．45、2．27和2．13，渗透性分别为9．20×10^-8、6．22×10^-8。3．96×10^-8mol．（m^2．S．Pa）^-1。

基于钴金属有机骨架材料（ZIF-67）催化性能的牛奶中大肠杆菌O157:H7快速定量检测

建立一种基于金属有机骨架催化性能的快速定量检测牛奶中大肠杆菌O157:H7的方法。以2-甲基咪唑和CoCl2 6H2O为原料,Bola型两亲性表面活性剂为溶剂合成一种钴金属有机骨架材料(ZIF-67)。对ZIF-67的催化性能进行研究,发现ZIF-67具有和辣根过氧化物酶类似的催化活性,并能在无过氧化氢存在的情况下催化3,3’,5,5’-四甲基联苯胺显色。基于此建立一种通过磁性微球进行特异性富集,通过检测与靶标结合的ZIF-67的量间接检测牛奶中大肠杆菌O157:H7的方法,该方法的检测范围为17~1.7×108 CFU/mL,检测限为17 CFU/mL,检测过程在1 h以内。该方法能快速、简单、高灵敏度、高选择性定量地检测出牛奶中的大肠杆菌O157:H7,在食源性致病菌的快速筛查中具有重要的应用价值。

磁性硅藻土杂化ZIF-7材料对水中Cr(Ⅵ)的吸附研究

采用原位生长法在磁性壳聚糖硅藻土(M-CS-DE)表面生长ZIF-7制备新型复合材料,用于吸附水中重金属Cr(Ⅵ)。首先,采用磁性壳聚糖对硅藻土进行磁改性,然后将ZIF-7原位生长到改性后的硅藻土上,成功制备新型复合材料(M-CS-DE/ZIF-7),并采用SEM、FT-IR、XRD等手段对其进行表征分析。通过研究Cr(Ⅵ)溶液的初始浓度、吸附剂用量、吸附时间、吸附温度和溶液酸碱度等因素对新型复合材料吸附容量的影响,优化了该材料对Cr(Ⅵ)的吸附条件。吸附实验还表明ZIF-7、M-CS-DE/ZIF-7均符合准二级动力学模型,表明吸附类型主要为化学吸附。通过Langmuir拟合获得ZIF-7和M-CS-DE/ZIF-7对水中Cr(Ⅵ)的最大吸附量分别为6.49和27.38mg·g^(-1)。因此,M-CS-DE修饰的ZIF-7比ZIF-7具有更好的吸附性能,是一种颇具潜力的新型吸附剂,可用于吸附去除水中的Cr(Ⅵ)。

ZIF-7负载CoB催化剂的制备及其在制氢中的应用

先后采用化学浸渍和还原的方法制备了不同比例的沸石咪唑酯骨架材料ZIF-7负载CoB的催化剂,对其结构进行了表征,并系统探究了该催化剂在催化硼氢化钠水解制氢中的催化活性。结果表明,相比于纳米CoB粉末催化剂,负载型CoB/ZIF-7催化剂在硼氢化钠水解制氢中具有更高的催化活性,25℃时NaBH_4水解产氢速率大约为252.19 m L/(min·g)。化学反应动力学表明:负载型CoB/ZIF-7催化剂催化NaBH_4水解制氢反应属于一级反应,其表观活化能约为51.48 k J/mol,远远低于纳米CoB粉末催化剂的活化能72.01 k J/mol。

MG@ZIF7-MIP的制备及对水环境中双酚A的电化学传感检测

为了解决常规双酚A检测分析方法无选择性、需要标准样品、预处理过程复杂等缺陷,以磁性石墨烯(MG)为基底、ZnO作为Zn源在MG表面原位生长ZIF-7,合成了高效导电复合膜MG@ZIF-7;选择MG@ZIF-7为载体、内分泌干扰物双酚A(BPA)为模板分子、丙烯酰为功能单体、二乙烯基苯为交联剂,采用表面分子印迹技术成功制备了分子印迹杂化膜(MG@ZIF7-MIP),并通过TEM、XRD、XPS、FT-IR等测试手段对其进行了分析表征;构建了以MG@ZIF7-MIP修饰电极为工作电极的分子印迹电化学传感器,对水环境中内分泌干扰物BPA进行选择性检测。结果表明:MG@ZIF7-MIP修饰电极对BPA的线性响应范围为0.001~0.100μmol/L(R=0.9763),响应平衡时间为4 min,检测限为9.84 ng/L(S/N=3),建立了一种快速响应、实用性强、高灵敏检测双酚A的分析方法。

功能化无机粒子修饰大孔载体反扩散法制备ZIF-7膜

采用功能化无机粒子“二合一”修饰的方法，通过将3-氨丙基三乙氧基硅烷（APTEs）功能化的α-Al2O3粒子负载在大孔的管状载体上制备了类沸石咪唑框架（ZIF-7）膜，考察了APTES的用量对ZIF．7膜制各的影响。结果表明，嫁接有APTES的α-Al2O3粒子负载在载体上，有效降低了载体表面孔尺寸并增加了载体表面异相成核的位点，促进了膜的生长，在APTES与α-Al2O3粒子的摩尔比为1：3时，能够制得致密连续较薄的ZIF-7膜，膜厚度大约为2～3um，H2的渗透通量为4．70×10-7mol／（m2·s·Pa），H2／C02、H2／N2的理想分离因数分别为5．87、4．59，均大于努森扩散系数。

ZIF-7@carbon composites as multifunctional interlayer for rapid and durable Li-S performance

The notorious"shuttle effect"of polysulfide during charge-discharge process induces grievous capacity fading,while the sluggish polysulfide conversion kinetics significantly hinders the development of practically viable lithium-sulfur(Li-S)batteries.In this study,a novel ZIF-7@carbon composite with ZIF-7 sheets vertically rooted on carbon cloth was developed as multifunctional interlayer to address these issues.The composite shows directional layered structure with outstanding compactness,and thus can provide massive active sites for accelerated redox reactions.The pore channels are perpendicular to the square surface,resulting in extremely high utilization of one-dimensional channels.Therefore,this structure can not only maintain the structural stability during the charge-discharge process by providing enough space for volume expansion,but also contribute to efficient exposure and utilization of active sites for the physical/chemical adsorption and catalytic conversion of polysulfide.As a result,Li-S batteries with the as-developed interlayer deliver a considerable areal capacity of 4.75 mAh cm^(-2) at an elevated sulfur loading of 5.5 mg cm^(-2),and an impressive cyclability with an extremely low capacity-fading rate of merely 0.04%per cycle over 500 cycles at 1 C.

Characterization of Function of Three Domains in Dishevelled-1: DEP Domain is Responsible for Membrane Translocation of Dishevelled-1

Wnt signaling plays an important role in embryogenesis and tumorgenesis. Although the mechanism about how Wnts transduce their signaling from receptor frizzled (Fz) to cytosol has not been understood, dishevelled (Dvl) protein was considered as the intersection of Wnt signal traffic. In this study, we characterized the function of three domains (DIX,PDZ and DEP) of Dvl-1 in canonical Wnt signal transduction and Dvl-1 membrane translocation. It was found both DIX and DEP domain were sufficient to block Wnt-3a-induced LEF-1 transcriptional activity and free cytosol β-catenin accumulation; whereas PDZ domain and a functional mutant form of DEP domain (DEP-KM) had no effect on canonical Wnt signaling. In addition, when cotransfected with Fz-7, DEP domain, but not DIX, PDZ or DEP-KM, translocated and co-localized with Fz-7 to the plasma membrane, which was similar to Dvl-1. Furthermore, it was DEP domain that could block Fz-7-induced membrane translocation of Dvl- 1 via a possible competitive mechanism. These results strongly suggest that DEP domain is responsible for the membrane translocation of Dvl-1 protein upon Wnt signal stimulation.

ZIF-67吸附AO7的动力学特性研究

采用简单快速的合成法制备多级孔Zeolitic Imidazole Frameworks-67(ZIF-67)并将其应用到染料废水AO7的吸附处理中。通过SEM、BET、XRD、TG等手段对吸附前后的ZIF-67进行了表征,并对吸附动力学、吸附速率控制步骤及ZIF-67再生特性进行了详细研究。结果表明:合成的ZIF-67尺寸均匀,具有微孔材料的吸附特征;其在400℃仍具有热稳定性且在吸附反应前后晶型和结构基本没有发生变化,表明其具有较强的热稳性和水稳性。ZIF-67对AO7表现出良好的吸附性能,其对初始质量浓度为20 mg/L、50 mg/L、100 mg/L和150 mg/L的AO7的吸附量分别为38.96 mg/g、96.87 mg/g、182.39 mg/g和255.25 mg/g。不同初始质量浓度的AO7在ZIF-67上的吸附均符合伪二级动力学方程(R2> 0.999),伪二级动力学方程拟合的理论吸附量qe,cal与实测平衡吸附量qe,exp的相对误差仅为5.44%~8.66%;吸附反应受颗粒内扩散和吸附反应过程2个步骤控制。溶液p H值是影响ZIF-67吸附AO7效率和材料重复利用性能的重要因素;初始pH=8(接近AO7的p Ka)时,ZIF-67显示出对AO7最强的吸附能力(qe=39.10 mg/g,ρ0=20 mg/L,V0=100 m L,ZIF-67投加量500 mg/L,T=25℃)和较为理想的可再生性(3次循环后吸附量仅降低12.69%)。

水相中GOx@ZIF-7/PDA的制备及酶学性能研究

原位包埋策略因制备条件温和、操作简单,被普遍应用在酶-金属有机骨架(metal-organic frameworks,MOFs)生物复合材料的制备中。但只有少部分MOFs能在水相中通过原位包埋法合成酶-MOFs生物复合材料。该研究首次在水相中采用原位包埋法将葡萄糖氧化酶(glucose oxidase,GOx)封装在ZIF-7(zeolitic imidazolate frameworks-7)载体中,并在所得的GOx@ZIF-7生物复合材料上合成了亲水性的聚多巴胺(polydopamine,PDA)修饰层,得到GOx@ZIF-7/PDA。采用单因素试验优化了GOx@ZIF-7/PDA的制备条件。结果表明,固定化pH值为7.0,酶质量浓度为5 g/L,苯并咪唑(benzimidazole,Bim)浓度为50 mmol/L,Zn^(2+)与苯并咪唑的摩尔比为1∶9,固定化温度为35℃,固定化时间为40 min,多巴胺的最佳质量浓度为2 g/L的条件下,GOx@ZIF-7/PDA具有最高酶活力回收率为(43.34±2.00)%。与游离酶相比,GOx@ZIF-7/PDA具有高的热稳定性、pH稳定性、贮存稳定性和良好的重复使用性,重复10次后,GOx@ZIF-7/PDA催化活性仍能保持(96.53±2.26)%。以上结果表明,水相原位包埋法制备固定化酶GOx@ZIF-7/PDA策略是高效可行的,有望实现低成本长期稳定的酶催化应用。

巯基化对复合填料(ZIF-7@FG)改性环氧涂层的力学及摩擦磨损性能的影响

通过水浴搅拌法分别在氟化石墨烯(FG)表面负载沸石咪唑酯骨架材料(ZIF-7)及其巯基化材料(SH-ZIF-7)以制备复合填料ZIF-7@FG和SH-ZIF-7@FG,并应用于环氧涂层。采用红外光谱仪(FT-IR)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)对复合填料进行表征,并通过拉伸测试和摩擦磨损试验对改性环氧涂层性能进行了研究。结果表明:利用水浴搅拌法可成功制备ZIF-7@FG和SH-ZIF-7@FG复合填料,改性环氧涂层的力学及摩擦磨损性能明显提升,其中,SH-ZIF-7@FG改性环氧涂层的性能最佳,拉伸强度为26.43 MPa,磨损率为1.8×10^(-4)mm^(3)(/m·N)。

低成本Nb掺杂Li_(7)La_(3)Zr_(2)O_(12)固态电解质的性能与应用研究

固态电池因其在能量密度、循环寿命和安全性等方面的优异性能受到关注。其核心组件为固态电解质材料。具有石榴石结构的Li_(7)La_(3)Zr_(2)O_(12)(LLZO)氧化物固态电解质由于具备宽电化学窗口、良好的离子传导性、稳定的化学性能及简单的制备工艺等特点而得到广泛研究。本研究采用Nb元素对LLZO进行掺杂,成功制备得到Li_(6.75)La_(3)Zr_(1.75)Nb_(0.25)O_(12)(LLZNO)氧化物固态电解质,其离子电导率达到了7.79×10^(-4)S/cm,且制备成本与未掺杂的LLZO相比无明显增加。将其涂覆在聚乙烯(PP)隔膜表面形成PP-LLZNO隔膜,表现出良好的热稳定性和离子电导率。与Al_(2)O_(3)涂覆隔膜或固态电解质Li_(6.75)La_(3)Zr_(1.75)Ta_(0.25)O_(12)(LLZTO)涂覆隔膜组装的电池相比,组装了PP-LLZNO涂覆隔膜的扣式电池和软包电池的容量保持率分别达到了84.99%(50圈)和57.40%(100圈),展现出更优异的性能。因此,高离子电导率和低成本LLZNO的制备对固态电解质的大规模生产及在固态电池中的广泛应用具有一定的参考意义。