Incorporating the magnetic alignment of GO composites into Pebax matrix for gas separation

The mixed matrix membranes(MMMs) were developed by incorporating graphite oxide(GO) flakes functionalized with iron oxide(Fe_3O_4) into Pebax matrix. The Pebax/Fe_3O_4–GO MMMs were used to separate CO_2/CH_4 and CO_2/N_2 gas mixture. The results showed that the MMMs with magnetic alignment presented the better gas separation performance than that of random arrangement of Pebax/Fe_3O_4–GO mixed matrix membranes. The reason was that the Fe_3O_4–GO flakes arranged magnetically in the membrane played a multiple role in improving the performance of MMMs. Firstly, under the action of the magnetic field,the magnetic alignment of Fe_3O_4–GO flakes in Pebax matrix constructed the shorter transfer path for gas molecule, increasing the CO_2 permeability. Secondly, the hydroxyl groups in GO flakes and the presence of Fe_3O_4 have stronger binding force for water, improving the CO_2 solubility selectivity. Thirdly, the better interaction between the magnetic alignment of GO composites and polymer matrix, reduced the interface defects. Especially, the optimum gas separation performance was obtained at the Fe_3O_4–GO flakes content of 3 wt% in Pebax matrix at vertical arrangement with selectivity of 47 and 75 for CO_2/CH_4 and CO_2/N_2, respectively, and CO_2 permeability of 538 Barrer at 0.2 MPa and room temperature.

Design and synthesis of Al-MOF/PPSU mixed matrix membrane with pollution resistance

To enhance the performance of the polyphenylene sulfone(PPSU) membrane,a novel mixed matrix membrane with hydrophilicity and antifouling properties was prepared.Using PPSU as the ba sic membrane material,polyvinyl pyrrolidone(PVP) as the porogen,N-Methyl pyrrolidone(NMP) as the solvent,and MOF-CAU-1(Al_(4)(OH)_(2)(OCH_(3))_4(H_2 N-BDC)_(3)·xH_(2) O) as the filler,PPSU/CAU-1 mixed matrix membrane(MMM) was prepared by an immersion precipitation and phase transformation technique.By changing the amount of MOF-CAU-1,the properties and performance of the MMM membrane were investigated in terms of hydrophilicity,pore morphology,surface roughness,and dye removal.The results show that the highest pure water flux of the mixed reached 47.9 L·m^(-2)·h^(-1), when the CAU-1 addition amount was 1.0 wt%, which was 23% higher than that of the pure PPSU membrane.Both the rejection rate and the antifouling performance of the MMM membrane also noticeably improved.

Mixing matrix estimation of underdetermined blind source separation based on the linear aggregation characteristic of observation signals

Under the underdetermined blind sources separation(UBSS) circumstance,it is difficult to estimate the mixing matrix with high-precision because of unknown sparsity of signals.The mixing matrix estimation is proposed based on linear aggregation degree of signal scatter plot without knowing sparsity,and the linear aggregation degree evaluation of observed signals is presented which obeys generalized Gaussian distribution(GGD).Both the GGD shape parameter and the signals' correlation features affect the observation signals sparsity and further affected the directionality of time-frequency scatter plot.So a new mixing matrix estimation method is proposed for different sparsity degrees,which especially focuses on unclear directionality of scatter plot and weak linear aggregation degree.Firstly,the direction of coefficient scatter plot by time-frequency transform is improved and then the single source coefficients in the case of weak linear clustering is processed finally the improved K-means clustering is applied to achieve the estimation of mixing matrix.The proposed algorithm reduces the requirements of signals sparsity and independence,and the mixing matrix can be estimated with high accuracy.The simulation results show the feasibility and effectiveness of the algorithm.

Enhanced permeation performance of polyether-polyamide block copolymer membranes through incorporating ZIF-8 nanocrystals

Membrane-based CO_2 separation is a promising alternative in terms of energy and environmental issues to other conventional techniques. Polyether-polyamide block copolymer(Pebax) membranes are promising for CO_2 separation because of their excellent selectivity, but limited by their moderate gas permeability. In this study,fresh-prepared zeolitic imidazolate framework-8(ZIF-8) nanocrystals were integrated into the Pebax?1657matrices to form mixed matrix membranes. The resulting membrane exhibits significantly improved CO_2permeability(as high as 300% increase), without the sacrifice of the selectivity, to the pristine polymer membrane. Several physical characterization techniques were employed to confirm the good interfacial interaction between ZIF-8 fillers and Pebax matrices. The effect of added ZIF-8 fillers on the transport mechanism through MMMs is also explored. Mixed-gas permeation for both CO_2/N_2 and CO_2/CH_4 was also evaluated. The separation performance for CO_2/CH_4 mixtures on the ZIF-8/Pebax MMMs is very close to the Roberson upper bound, and thus is technologically attractive for purification of natural gas.

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.

MAXIMUM LIKELIHOOD SOURCE SEPARATION FOR FINITE IMPULSE RESPONSE MULTIPLE INPUT-MULTIPLE OUTPUT CHANNELS IN THE PRESENCE OF ADDITIVE NOISE

Blind identification-blind equalization for Finite Impulse Response (FIR) Multiple Input-Multiple Output (MIMO) channels can be reformulated as the problem of blind sources separation. It has been shown that blind identification via decorrelating sub-channels method could recover the input sources. The Blind Identification via Decorrelating Sub-channels(BIDS)algorithm first constructs a set of decorrelators, which decorrelate the output signals of subchannels, and then estimates the channel matrix using the transfer functions of the decorrelators and finally recovers the input signal using the estimated channel matrix. In this paper, a new approximation of the input source for FIR-MIMO channels based on the maximum likelihood source separation method is proposed. The proposed method outperforms BIDS in the presence of additive white Gaussian noise.

Partial pore blockage and polymer chain rigidification phenomena in PEO/ZIF-8 mixed matrix membranes synthesized by in situ polymerization

Nanostructured zeolitic imidazolate frameworks(ZIF-8) was incorporated into the mixture of poly(ethylene glycol) methyl ether acrylate(PEGMEA) and pentaerythritol triacrylate(PETA) to synthesize mixed matrix membranes(MMMs) by in situ polymerization for CO_2/CH_4 separation. The solvent-free polymerization between PEGMEA and PETA was induced by UV light with 1-hydroxylcyclohexyl phenyl ketone as initiator. The chemical structural characterization was performed by Fourier transform infrared spectroscopy. The morphology was characterized by scanning electron microscope. The average chain-to-chain distance of the polymer chains in MMMs was investigated by X-ray diffraction. The thermal property was evaluated by differential scanning calorimetry. The CH_4 and CO_2 gas transport properties of MMMs are reported. The relationship between gas permeation–separation performances or physical properties and ZIF-8 loading is also discussed. However, the permeation–separation performance was not improved in Robeson upper bound plot compared with original polymer membrane as predicted. The significant partial pore blockage and polymer rigidification effect around the ZIFs confirmed by the increase in glass temperature and the decrease in the d-spacing, were mainly responsible for the failure in performance improvement, which offset the high diffusion induced by porous ZIF-8.

Separation of Comprehensive Geometrical Errors of a 3-DOF Parallel Manipulator Based on Jacobian Matrix and Its Sensitivity Analysis with Monte-Carlo Method

Parallel kinematic machines （PKMs） have the advantages of a compact structure,high stiffness,a low moving inertia,and a high load/weight ratio.PKMs have been intensively studied since the 1980s,and are still attracting much attention.Compared with extensive researches focus on their type/dimensional synthesis,kinematic/dynamic analyses,the error modeling and separation issues in PKMs are not studied adequately,which is one of the most important obstacles in its commercial applications widely.Taking a 3-PRS parallel manipulator as an example,this paper presents a separation method of source errors for 3-DOF parallel manipulator into the compensable and non-compensable errors effectively.The kinematic analysis of 3-PRS parallel manipulator leads to its six-dimension Jacobian matrix,which can be mapped into the Jacobian matrix of actuations and constraints,and then the compensable and non-compensable errors can be separated accordingly.The compensable errors can be compensated by the kinematic calibration,while the non-compensable errors may be adjusted by the manufacturing and assembling process.Followed by the influence of the latter,i.e.,the non-compensable errors,on the pose error of the moving platform through the sensitivity analysis with the aid of the Monte-Carlo method,meanwhile,the configurations of the manipulator are sought as the pose errors of the moving platform approaching their maximum.The compensable and non-compensable errors in limited-DOF parallel manipulators can be separated effectively by means of the Jacobian matrix of actuations and constraints,providing designers with an informative guideline to taking proper measures for enhancing the pose accuracy via component tolerancing and/or kinematic calibration,which can lay the foundation for the error distinguishment and compensation.

Optical Characteristics of Porous Glasses Matrix and Its Light-conducted Mechanism

The optical properties of matrix of porous glasses and phase-separated glasses were investigated by visible spectroscopy and infrared spectroscopy. The experimental results show that, both the porous glasses and phase-separated glasses have very good light transmission in visible light region that wavelenth is longer than 560nm. The micropores of porous glasses and the boron-rich phase of phase-separated glasses have strong Rayleigh scatter effects on the visible light, the largest scatter occurrs at 360-370nm; the thicker the glasses, the larger the light scattering. Thus, the pore size distribution and the size of heterogeneous micro zone in boron-rich phase of phase-separated glasses can be measured. After coupled into porours glasses, the most intense absorption of hydrated ions of 〔Co(H 2O) 6〕 2+ shifts from 508nm to 515nm. The production of the most intense absorption and the red shift were owed to Jahn-Teller effect of octahedral field formed by six H 2O molecular and perturbation effect resulted by microporous of porous glasses for its physics-chemical circumstance. As a result, the porous glasses are perfect optical function materials in visible region, which can be assembled by chemical method.

Enhanced gas separation performance of mixed matrix hollow fiber membranes containing post-functionalized S-MIL-53

Mixed matrix hollow fiber membranes（MMHFMs）filled with metal-organic frameworks（MOFs）have great potential for energy-efficient gas separation processes,but the major hurdle is polymer/MOFs interfacial defects and membrane plasticization.Herein,lab-synthesized MIL-53 was post-functionalized by aminosilane grafting and subsequently incorporated into Ultem-1000 polymer matrix to fabricate high performance MMHFMs.SEM,DLS,XRD and TGA were performed to characterize silane-modified MIL-53（S-MIL-53）and prepared MMHFMs.Moreover,the effect of MOFs loading was systematically investigated first;then gas separation performance of MMHFMs for pure and mixed gas was evaluated under different pressures.MMHFMs containing post-functionalized S-MIL-53 achieved remarkable gas permeation properties which was better than model predictions.Compared to pure HFMs,CO2permeance of MMHFM loaded with 15%S-MIL-53 increased by 157%accompanying with 40%increase for CO2/N2selectivity,which outperformed the MMHFM filled with naked MIL-53.The pure and mixed gas permeation measurements with elevated feed pressure indicated that incorporation of S-MIL-53 also increased the resistance against CO2plasticization.This work reveals that post-modified MOFs embedded in MMHFMs facilitate the improvement of gas separation performance and suppression of membrane plasticization.

Simultaneous determination of seven impurities in high-purity cobalt oxide by ICP-AES after matrix separation using 1-nitroso-2-naphthol as a precipitant

A method was developed for the simultaneous determination of seven trace impurities (Cd, Mn, Pb, Zn, Cu, Fe and Ni) in high purity cobalt oxide by ICP AES. The matrix effect was eliminated by preci pitation with 1 nitroso 2 naphthol. The matrix effect of cobalt on the absorptions of trace impurities, the effects of reaction time, pH value, dosage of precipitant on the formation of cobalt 1 nitroso 2 naphthol complex, the effects of hydrochloric acid on the stability of this complex and masking of elements were studied. Recoveries of the impurities in spiked sample are from 90% to 110% with a precision of 1.1% 5.0% RSD. The detection limits of the seven elements are in the range of 0.01 0.24μg/g. The method can be applied to the analysis of high purity cobalt metal, cobalt oxide and other cobalt compounds.

Distinguished discriminatory separation of CO2 from its methane-containing gas mixture via PEBAX mixed matrix membrane

Highly selective separation of CO_2 from its methane-containing binary gas mixture can be achieved by using Poly(ether-block-amide)(PEBAX)mixed matrix membranes(MMMs).According to FESEM and AFM analyses,silica-based nanoparticles were homogenously integrated within the polymer matrix,facilitating penetration of CO_2 through the membrane while acting as barrier for methane gas.The membrane containing 4.6 wt% fumed silica(FS)(PEBAX/4.6 wt%FS)exhibits astonishing selectivity results where binary gas mixture of CO_2/CH_4 was used as feed gas.As detected by gas chromatography,in the permeate side,data showed a significant increase of CO_2 permeance,while CH_4 transport through the mixed matrix membrane was not detectable.Moreover,PEBAX/4.6 wt%FS greatly exceeds the Robeson limit.According to data reported on CO_2/CH_4 gas pair separation in the literature,the results achieved in this work are beyond those data reported in the literature,particularly when PEBAX/4.6 wt%FS membrane was utilized.

Recent progress in ternary mixed matrix membranes for CO_(2) separation

Mixed matrix membranes(MMMs)could combine the advantages of both polymeric membranes and porousfillers,making them an effective alternative to conventional polymer membranes.However,interfacial incompatibility issues,such as the presence of interfacial voids,hardening of polymer chains,and blockage of micropores by polymers between common MMMsfillers and the polymer matrix,currently limit the gas sep-aration performance of MMMs.Ternary phase MMMs(consisting of afiller,an additive,and a matrix)made by adding a third compound,usually functionalized additives,can overcome the structural problems of binary phase MMMs and positively impact membrane separation performance.This review introduces the structure and fabrication processes for ternary MMMs,categorizes various nanofillers and the third component,and summarizes and analyzes in detail the CO_(2) separation performance of newly developed ternary MMMs based on both rubbery and glassy polymers.Based on this separation data,the challenges of ternary MMMs are also discussed.Finally,future directions for ternary MMMs are proposed.

Formulation of Mixed-Matrix Membrane (PSF/Zeolite) for CO<SUB>2</SUB>/N<SUB>2</SUB>Separation: Screening of Polymer Concentration

This research investigates the permeability of CO2 and N2 as well as selectivity of CO2 over N2 of polysulfone (PSF) mixed matrix membranes filled with zeolite 4&Aring particles. The membranes were prepared by solution-casting method and utilized to determine the permeation rates of N2 and CO2. It was characterized by FTIR and the gas separation performance was analysed by Design of Expert (DOE) method. FTIR result revealed the intensity of peak for sulfone S=O vibration at 1322 cm-1;it was related to O=S=O bound of polysulfone in the sample. The single concentration variable has low outcome, however the mixture concentration interaction was effectively to lead better selectivity of CO2 over N2. In terms of interaction between mixture concentrations, interaction between PSF and N-Methyl-2-pyrrolidone (NMP) has considerable effect on the permeability of CO2 with the highest F value of 0.46 membrane. NMP exhibited a high degree of polarity and hydrogen bonding which led to effect of selective skin and permeation rate. The model regression equations were developed as the potential use for screening the permeability of CO2 and N2 based on the deviation effect of polymer concentration.

A nonwoven supported mixed matrix membrane for CH4/N2 separation

Efficiently enriching low-concentration CH4 is pivotal for enhancing the utilization of unconventional energy sources and mitigating greenhouse gas emissions.This study focuses on modifying the overall performance of CH_(4)/N_(2)separation membranes.A novel mixed matrix membrane(MMM)with a reinforced substrate structure was developed through a straightforward dip-coating technique.This MMM incorporates a polytetrafluoroethylene(PTFE)porous membrane as the supporting framework,while a composite of block polymer(styrene-butadiene-styrene)and metal-organic framework(Ni-MOF-74)forms the selective separation layer.Comprehensive characterization of Ni-MOF-74 and the fabricatedmembranes was conducted using X-rays diffraction,scanning electron microscope,Brunauer-Emmett-Teller analysis,and gas permeance tests.The findings indicate a robust integration of the PTFE porous support with the membrane layer,enhancing the mechanical stability of theMMM.Under optimal conditions,the mechanical strength of the PM20 membrane(containing 20%Ni-MOF-74)was observed to be 37.7 MPa,representing remarkable increase compared to the non-reinforcedMMM.Additionally,thePM20membrane exhibited an impressive CH4 permeation rate of 92 barrer(1 barrer﹦3.35×10^(-16)mol·m·m^(-2)·s^(-1)·Pa^(-1))alongside a CH_(4)/N_(2)selectivity of 4.18.These results underscore the MMM's substantial performance and its promising potential in methane enrichment applications.

构建界面兼容的Por-POF/PIM-1混合基质膜用于CO_(2)/N_(2)高效分离

混合基质膜(MMMs)在实现优异的CO_(2)分离方面潜力很大,但其性能往往受到填料与基质之间界面兼容性差的限制.本研究将卟啉基多孔有机框架(Por-POF)分散在可溶性的固有微孔聚合物(PIM-1)中,制备了一系列高渗透选择性MMMs.Por-POF的纯有机属性增强其与纯有机聚合物基质的相互作用,从而制备界面相容性良好的膜材料.多孔的Por-POF可以增加膜的自由体积分数,提高了薄膜的渗透通量.此外,Por-POF孔壁上富集了大量氮,对CO_(2)具有较强的吸附作用,从而提高CO_(2)/N_(2)选择性.气体渗透实验表明,与纯PIM-1膜相比,Por-POF/PIM-1膜的CO_(2)渗透通量和CO_(2)/N_(2)选择性分别提高了157%和64%.本研究为合理设计和构建高性能的分离膜提供了一种独特的思路.

分离胶促凝管联合MALDI-TOF MS直接检测血培养阳性细菌

目的建立用分离胶促凝管联合基质辅助激光解析电离飞行时间质谱（MALDI-TOF MS）直接检测血培养阳性待测菌的方法并评估其鉴定符合率。方法共收集阳性血培养491例,利用分离胶促凝管直接从血培养瓶中富集并提纯菌体,采用MALDI-TOF MS对待测菌进行菌种鉴定,同时对报阳性血培养瓶进行转种培养,纯菌落用Vitek 2 Compact全自动微生物分析系统（简称Vitek 2 Compact）进行鉴定。若两者鉴定结果不一致,则以基因测序结果予以确证。结果 491例阳性血培养瓶鉴定出的待测菌包括30个属和64个种。在462例单菌株感染血培养瓶中,菌株的种、属鉴定符合率分别为73.6%和3.7%。其中175例革兰阴性菌的种、属鉴定率分别为84.0%（147例）和2.9%（5例）;251例革兰阳性菌的种、属鉴定率分别为75.3%（189例）和4.4%（11例）;36例念珠菌的种、属鉴定率分别为19.4%（7例）和2.8%（1例）。在29例复数菌感染血瓶中,鉴定出其中一种细菌的种、属鉴定率分别为79.3%（23例）和10.3%（3例）。血流感染中常见病原菌的菌种鉴定符合率达83.3%～96.9%。结论本研究建立了分离胶促凝管联合MALDI-TOF MS直接检测血培养阳性待测菌的方法,与传统的培养鉴定方法相比,对血流感染中主要病原菌的鉴定符合率较高,且方法快速、简便,成本低廉,适合在临床微生物实验室中推广应用。

基于MOFs的混合基质膜在气体分离方面的研究进展

综述了基于MOFs的混合基质膜在CO_(2)/N2、CO_(2)/CH_(4)气体分离方面的研究进展,以及气体在混合基质膜中的传质机理。最后指出现在研究存在的问题并对未来发展方向进行了展望。

MALDI-TOF MS直接鉴定阳性厌氧血培养瓶中细菌的研究

目的探讨基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)直接鉴定阳性厌氧血培养瓶中细菌的可行性和准确性,评价不同前处理方法用于质谱快速鉴定的临床应用价值。方法收集2017年8月至2018年8月临床非重复阳性厌氧血培养瓶,经革兰染色镜检确认均有菌生长。利用分离胶促凝管法和0.5%十二烷基硫酸钠(SDS)法处理阳性厌氧血培养瓶并用MALDI-TOF MS直接鉴定,与转种后菌落鉴定结果相比较,分析鉴定准确率和一致性。结果共收集阳性厌氧血培养瓶240瓶,包括单菌阳性234瓶,混合菌6瓶,平均报阳时间为(16.87±13.12)h;218瓶(90.83%)可用MALDI-TOF MS直接鉴定,4瓶(1.67%)混合菌生长仅鉴定其中一种菌或无可靠鉴定结果。SDS法和分离胶法对革兰阴性菌的鉴定准确率(94.81%、94.16%)显著高于革兰阳性菌(87.50%、81.25%),差异有统计学意义(χ2=3.96、9.53,P<0.05);SDS法和分离胶法直接鉴定与菌落鉴定结果的一致率分别为92.31%、89.74%。SDS法前处理鉴定的准确率和鉴定分值≥2.0的比例(94.17%、69.23%)均高于分离胶法(90.83%、65.81%);SDS法厌氧菌的鉴定分值≥2.0的比例(83.33%)明显高于分离胶法(58.33%)。结论MALDI-TOF MS可应用于临床常见厌氧血培养阳性菌的鉴定,SDS法前处理对厌氧菌的快速鉴定有较高的准确率。

机械化学法合成多配体MOF填料用于高效CO_(2)分离

以ZIF-8为母体材料通过机械化学手段引入苯并咪唑(Bim)和咪唑-2-甲醛(Ica)两种配体,得到多配体的MOF材料ZIF-8-Bim-Ica.与聚醚共聚酰胺(Pebax-1657)混合制得混合基质膜(MMMs).利用XRD、FT-IR、核磁共振氢谱等方法确定了ZIF-8-Bim-Ica的化学结构,利用SEM对混合基质膜的断面进行表征.结果表明,引入Bim和Ica配体后,ZIF-8的结构没有被破坏,ZIF-8-Bim-Ica颗粒均匀分散于Pebax聚合物中.加入ZIF-8-Bim-Ica提高了混合基质膜的CO_(2)渗透通量和对CO_(2)/CH_(4)的选择性.与纯膜相比,掺杂质量分数为10%时,混合基质膜的CO_(2)渗透通量可达269.3Barrer,提高了29.3%,CO_(2)/CH_(4)的选择性由18.5提高到43.8,并且膜性能至少可保持40h的稳定性.由本方法制备的ZIF-8-Bim-Ica/Pebax混合基质膜对CO_(2)的选择性较高,在CO_(2)气体分离领域展现出良好的应用前景.