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Preparation and characterization of novel carbon molecular sieve membrane/PSSF composite by pyrolysis

Ying Yan, Peng Huang, Huiping Zhang

《化学科学与工程前沿（英文）》 2019年 第13卷 第4期   页码 772-783 doi: 10.1007/s11705-019-1827-y

摘要： Carbon molecular sieve membrane (CMSM)/paper-like stainless steel fibers (PSSF) has been manufactured by pyrolyzing poly (furfuryl alcohol) (PFA) coated on the metal fibers. PFA was synthesized using oxalic acid dihydrate as a catalyst and coated on microfibers by dip coating method. For the purpose of investigating the effects of final carbonization temperature, the composites were carbonized between 400°C and 800°C under flowing nitrogen. The morphology and microstructure were examined by X-ray diffraction, Fourier transforms infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, N adsorption and desorption, Raman spectra and X-ray photoelectron spectra. The consequences of characterization showed that the CMSM containing mesopores of 3.9 nm were manufactured. The specific surface area of the CMSM/PSSF fabricated in different pyrolysis temperature varies from 26.5 to 169.1 m ∙g and pore volume varies from 0.06 to 0.23 cm ∙g . When pyrolysis temperature exceeds 600°C, the specific surface, pore diameter and pore volume decreased as carbonization temperature increased. Besides, the degree of graphitization in carbon matrix increased with rising pyrolysis temperature. Toluene adsorption experiments on different structured fixed bed that was padded by CMSM/PSSF and granular activated carbon (GAC) were conducted. For the sake of comparison, adsorption test was also performed on fixed bed packed with GAC. The experimental results indicated that the rate constant ′ was dramatically increased as the proportion of CMCM/PSSF composites increased on the basis of Yoon-Nelson model, which suggested that structured fixed bed padded with CMSM/PSSF composite offered higher adsorption rate and mass transfer efficiency.

关键词： carbon molecular sieve membrane     stainless steel fibers     pyrolysis     structured fixed bed     toluene    

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Thermal decomposition of poly(ethylene terephthalate)/mesoporous molecular sieve composites

RUN Mingtao, ZHANG Dayu, WU Sizhu, WU Gang

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 50-54 doi: 10.1007/s11705-007-0010-z

摘要： The nonisothermal and isothermal degradation processes of poly (ethylene terephthalate)/mesoporous molecular sieve (PET/MMS) composites synthesized by in-situ polymerization were studied by using thermogravimetric analysis in nitrogen. The nonisothermal degradation of the composite is found to be the first-order reaction. An iso-conversional procedure developed by Ozawa is used to calculate the apparent activation energy (), which is an average value of about 260 kJ/mol with the weight conversion from 0% to 30%, and is higher than that of neat PET. Isothermal degradation results are confirmed with the nonisothermal process, in which PET/MMS showed higher thermal stability than neat PET. The polymer in mesoporous channels has more stability due to the protection of the inorganic pore-wall. These results indicate that mesoporous MMS in PET/MMS composites improve the stability of the polymer.

关键词： polymerization     isothermal degradation     conversion     nonisothermal degradation     activation    

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Catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over the

Zhidan Fu, Lisha Liu, Yong Song, Qing Ye, Shuiyuan Cheng, Tianfang Kang, Hongxing Dai

《化学科学与工程前沿（英文）》 2017年 第11卷 第2期   页码 185-196 doi: 10.1007/s11705-017-1631-5

摘要： The Pd catalyst supported on cryptomelane-type manganese oxide octahedral molecular sieve (OMS-2) were prepared. The effect of Pd loading on the catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over Pd/OMS-2 has been investigated. The results show that the Pd loading plays an important role on the physicochemical properties of the Pd/OMS-2 catalysts which outperform the Pd-free counterpart with the 0.5Pd/OMS-2 catalyst being the best. The temperature for 50% conversion was 25, 240 and 160 °C, and the temperature for 90% conversion was 55, 285 and 200 °C for oxidation of CO, toluene, and ethyl acetate, respectively. The low-temperature reducibility and high oxygen mobility of Pd/OMS-2 are the factors contributable to the excellent catalytic performance of 0.5Pd/OMS-2.

关键词： cryptomelane-type manganese oxide octahedral molecular sieve     oxygen mobility     reducibility     carbon monoxide oxidation     volatile organic compound combustion    

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Mechanism of ethanol/water reverse separation through a functional graphene membrane: a molecular simulation

《化学科学与工程前沿（英文）》 2023年 第17卷 第3期   页码 347-357 doi: 10.1007/s11705-022-2246-z

摘要： Reverse-selective membranes have attracted considerable interest for bioethanol production. However, to date, the reverse-separation performance of ethanol/water is poor and the separation mechanism is unclear. Graphene-based membranes with tunable apertures and functional groups have shown substantial potential for use in molecular separation. Using molecular dynamics simulations, for the first time, we reveal two-way selectivity in ethanol/water separation through functional graphene membranes. Pristine graphene (PG) exhibits reverse-selective behavior with higher ethanol fluxes than water, resulting from the preferential adsorption for ethanol. Color flow mappings show that this ethanol-permselective process is initiated by the presence of ethanol-enriched and water-barren pores; this has not been reported in previous studies. In contrast, water molecules are preferred for hydroxylated graphene membranes because of the synergistic effects of molecular sieving and functional-group attraction. A simulation of the operando condition shows that the PG membrane with an aperture size of 3.8 Å achieves good separation performance, with an ethanol/water separation factor of 34 and a flux value of 69.3 kg∙m‒2∙h‒1∙bar‒1. This study provides new insights into the reverse-selective mechanism of porous graphene membranes and a new avenue for efficient biofuel production.

关键词： reverse separation     graphene membrane     ethanol/water separation     molecular simulation    

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Tetra-detector size exclusion chromatography characterization of molecular and solution properties ofsoluble microbial polysaccharides from an anaerobic membrane bioreactor

Qingbin Guo,Sheng Chang

《环境科学与工程前沿（英文）》 2017年 第11卷 第2期 doi: 10.1007/s11783-017-0922-x

摘要： Tetra-detector HPSEC was evaluated for the SMP characterization Molecular weight and intrinsic viscosity of the SMP were characterized Specific viscosity and osmotic pressure of the SMP solution were studied Approach to analyze the concentration polarization of the SMP was discussed Characterization of the molecular properties of soluble microbial products (SMP) is critical for understanding the membrane filtration and fouling mechanisms in anaerobic and aerobic membrane bioreactors (AnMBR & MBR). In this study, the distributions of the absolute molecular weight and intrinsic viscosity of SMP polysaccharides from an AnMBR were effectively determined by a high performance size exclusion chromatography (HPSEC) that was coupled with the refractive index (RI), diode array UV (DAUV), right and low angle light scattering (LS), and viscometer (Vis) detectors. Based on the tetra-detector HPSEC determined absolute molecular weights and intrinsic viscosity, a universal calibration relationship for the SMP polysaccharides was developed and the molecular conformations, average molecular weights, and hydrodynamic sizes of the SMP polysaccharides were also explored. Two factors which can be derived from the tetra-detector HPSEC analysis were proposed for the characterization of the viscous and osmotic pressure properties of the SMP polysaccharides. In addition, it was also extrapolated how to analyze the resistance characteristics of the concentration polarization layers formed in membrane filtration based on the molecular properties determined by the tetra-detector HPSEC analysis.

关键词： Soluble microbial product     Extracellular polymeric substance     Membrane bioreactor     Membrane fouling     Molecular weight     Intrinsic viscosity    

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Ti incorporation in MCM-41 mesoporous molecular sieves using hydrothermal synthesis

Shengping WANG, Changqing MA, Yun SHI, Xinbin MA

《化学科学与工程前沿（英文）》 2014年 第8卷 第1期   页码 95-103 doi: 10.1007/s11705-014-1405-2

摘要： Titanium-containing mesoporous materials (Ti-MCM-41) were obtained by hydrothermal synthesis. Such materials are active catalysts for the transesterification of dimethyl oxalate and phenol to produce diphenyl oxalate. To understand the role of the Ti in the catalytic process, Ti-MCM-41 samples with different Si/Ti ratios (from 5 to 100) were prepared and the samples were analyzed by Fourier transform infrared spectroscopy, UV-visible spectroscopy, and ammonia temperature programmed desorption. It was concluded that the Ti is incorporated into the framework of the MCM-41 and formed weak Lewis acid sites. In addition, the number of Ti(IV) sites increased as the amount of titanium increased. X-ray powder diffraction, N adsorption-desorption and transmission electron microscopy results showed that the Ti-MCM-41 samples have a hexagonal arrangement of mono-dimensional pores. A large number of Ti(IV) sites coupled with the mesoporous structure and large pore diameters are favorable for the transesterification catalytic properties of Ti-MCM-41.

关键词： Ti-MCM-41     mesoporous molecular sieve     acid sites     transesterification     hydrothermal synthesis    

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Enhanced separation of tetrafluoropropanol from water via carbon nanotubes membranes: insights from molecular

《环境科学与工程前沿（英文）》 2023年 第17卷 第11期 doi: 10.1007/s11783-023-1740-y

摘要：

● MD simulations unveil the transport mechanism for TFP-water mixture through CNTs.

关键词： Fluorinated alcohol     Carbon nanotube     Molecular simulation     Fluorine modified    

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Integration of molecular dynamic simulation and free volume theory for modeling membrane VOC/gas separation

Bo Chen, Yan Dai, Xuehua Ruan, Yuan Xi, Gaohong He

《化学科学与工程前沿（英文）》 2018年 第12卷 第2期   页码 296-305 doi: 10.1007/s11705-018-1701-3

摘要： Gas membrane separation process is highly unpredictable due to interacting non-ideal factors, such as composition/pressure-dependent permeabilities and real gas behavior. Although molecular dynamic (MD) simulation can mimic those complex effects, it cannot precisely predict bulk properties due to scale limitations of calculation algorithm. This work proposes a method for modeling a membrane separation process for volatile organic compounds by combining the MD simulation with the free volume theory. This method can avoid the scale-up problems of the MD method and accurately simulate the performance of membranes. Small scale MD simulation and pure gas permeation data are employed to correlate pressure-irrelevant parameters for the free volume theory; by this approach, the microscopic effects can be directly linked to bulk properties (non-ideal permeability), instead of being fitted by a statistical approach. A lab-scale hollow fiber membrane module was prepared for the model validation and evaluation. The comparison of model predictions with experimental results shows that the deviations of product purity are reduced from 10% to less than 1%, and the deviations of the permeate and residue flow rates are significantly reduced from 40% to 4%, indicating the reliability of the model. The proposed method provides an efficient tool for process engineering to simulate the membrane recovery process.

关键词： membrane vapor separation     membrane process modeling     process engineering     free volume theory     volatile organic compound    

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The use of carbon nanomaterials in membrane distillation membranes: a review

Sebastian Leaper, Ahmed Abdel-Karim, Patricia Gorgojo

《化学科学与工程前沿（英文）》 2021年 第15卷 第4期   页码 755-774 doi: 10.1007/s11705-020-1993-y

摘要： Membrane distillation (MD) is a thermal-based separation technique with the potential to treat a wide range of water types for various applications and industries. Certain challenges remain however, which prevent it from becoming commercially widespread including moderate permeate flux, decline in separation performance over time due to pore wetting and high thermal energy requirements. Nevertheless, its attractive characteristics such as high rejection (ca. 100%) of non-volatile species, its ability to treat highly saline solutions under low operating pressures (typically atmospheric) as well as its ability to operate at low temperatures, enabling waste-heat integration, continue to drive research interests globally. Of particular interest is the class of carbon-based nanomaterials which includes graphene and carbon nanotubes, whose wide range of properties have been exploited in an attempt to overcome the technical challenges that MD faces. These low dimensional materials exhibit properties such as high specific surface area, high strength, tuneable hydrophobicity, enhanced vapour transport, high thermal and electrical conductivity and others. Their use in MD has resulted in improved membrane performance characteristics like increased permeability and reduced fouling propensity. They have also enabled novel membrane capabilities such as fouling detection and localised heat generation. In this review we provide a brief introduction to MD and describe key membrane characteristics and fabrication methods. We then give an account of the various uses of carbon nanomaterials for MD applications, focussing on polymeric membrane systems. Future research directions based on the findings are also suggested.

关键词： carbon nanomaterials     graphene     membrane distillation     desalination     carbon nanotubes    

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Nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment

《环境科学与工程前沿（英文）》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1630-3

摘要：

● A novel nonpolar super-aligned carbon nanotube (SACNT) membrane was prepared.

关键词： Membrane fouling     Wastewater     Membrane separation     Antifouling     Aligned carbon nanotube    

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Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content onmorphology, antifouling, and permeation properties of polysulfone ultrafiltration membrane: thermodynamic

《化学科学与工程前沿（英文）》 2023年 第17卷 第10期   页码 1484-1502 doi: 10.1007/s11705-023-2331-y

摘要： Various hydrophilic poly(ethylene-co-vinyl alcohol) (EVOH) were used herein to precisely control the structure and hydrodynamic properties of polysulfone (PSF) membranes. Particularly, to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol (VOH: 73%, 68%, 56%), the non-solvent-induced phase separation (NIPS) technique was used. Polyethylene glycol was used as a compatibilizer and as a porogen in N,N-dimethylacetamide. Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism. The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism. Accordingly, the addition of EVOH led to an increase in the rheology of the dopes. The resulting membranes exhibited a microporous structure, while the finger-like structures became more evident with increasing VOH content. The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics. Interestingly, the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m–2·h–1·bar–1, which was higher than that of pure PSF membranes (171 L·m–2·h–1·bar–1). In addition, PSF/EVOH32 rejected bovine serum albumin at a high rate (> 90%) and achieved a significant restoration of permeability. Finally, from the thermodynamic and hydrodynamic results, valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.

关键词： polysulfone     blend modification     ultrafiltration membrane     formation hydrodynamics     poly(ethylene-co-vinyl alcohol) copolymer    

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Molecular level understanding of CO2 capture in ionic liquid/polyimide composite membrane

Linlin You, Yandong Guo, Yanjing He, Feng Huo, Shaojuan Zeng, Chunshan Li, Xiangping Zhang, Xiaochun Zhang

《化学科学与工程前沿（英文）》 2022年 第16卷 第2期   页码 141-151 doi: 10.1007/s11705-020-2009-7

摘要： Ionic liquid (IL)/polyimide (PI) composite membranes demonstrate promise for use in CO separation applications. However, few studies have focused on the microscopic mechanism of CO in these composite systems, which is important information for designing new membranes. In this work, a series of systems of CO in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide composited with 4,4-(hexafluoroisopropylidene) diphthalic anhydride (6FDA)-based PI, 6FDA-2,3,5,6-tetramethyl-1,4-phenylene-diamine, at different IL concentrations were investigated by all-atom molecular dynamics simulation. The formation of IL regions in PI was found, and the IL regions gradually became continuous channels with increasing IL concentrations. The analysis of the radial distribution functions and hydrogen bond numbers demonstrated that PI had a stronger interaction with cations than anions. However, the hydrogen bonds among PI chains were destroyed by the addition of IL, which was favorable for transporting CO . Furthermore, the self-diffusion coefficient and free energy barrier suggested that the diffusion coefficient of CO decreased with increasing IL concentrations up to 35 wt-% due to the decrease of the fractional free volume of the composite membrane. However, the CO self-diffusion coefficients increased when the IL contents were higher than 35 wt-%, which was attributed to the formation of continuous IL domain that benefitted the transportation of CO .

关键词： carbon dioxide     ionic liquid     6FDA-TeMPD     composite membrane     molecular dynamics simulation    

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Effects of a dynamic membrane formed with polyethylene glycol on the ultrafiltration of natural organic

Boksoon KWON, Noeon PARK, Jaeweon CHO,

《环境科学与工程前沿（英文）》 2010年 第4卷 第2期   页码 172-182 doi: 10.1007/s11783-010-0002-y

摘要： The formation of a dynamic membrane (DM) was investigated using polyethylene glycol (PEG) (molecular weight of 35000 g/mol, concentration of 1 g/L). Two natural organic matters (NOM), Dongbok Lake NOM (DLNOM) and Suwannee River NOM (SRNOM) were used in the ultrafiltration experiments along with PEG. To evaluate the effects of the DM with PEG on ultrafiltration, various transport experiments were conducted, and the analyses of the NOM in the membrane feed and permeate were performed using high performance size exclusion chromatography, and the pore size distribution ( PSD) and molecular weight cut off ( MWCO) were determined. The advantages of DM formed with PEG can be summarized as follows: (1) PEG interferes with NOM transmission through the ultrafiltration membrane pores by increasing the retention coefficient of NOM in UF membranes, and (2) low removal of NOM by the DM is affected by external factors, such as pressure increases during UF membrane filtration, which decreases the PSD and MWCO of UF membranes. However, a disadvantage of the DM with PEG was severe flux decline; thus, one must be mindful of both the positive and negative influences of the DM when optimizing the UF performance of the membrane.

关键词： dynamic membrane     natural organic matters     ultrafiltration membrane performance     effective PSD     effective molecular weight cutoff    

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Preparation of adsorptive nanoporous membrane using powder activated carbon: Isotherm and thermodynamic

Majid Peyravi

《化学科学与工程前沿（英文）》 2020年 第14卷 第4期   页码 673-687 doi: 10.1007/s11705-019-1800-9

摘要： Adsorptive polyethesulfone (PES) membranes were prepared by intercalation of powder activated carbon (PAC) with and without functionalization. Accordingly, PAC was aminated with 1,5-diamino-2-methylpentane, and the physicochemical properties of the functionalized PAC were analyzed. Intercalation of PAC within the PES scaffold changed the porosity and mean pore size of the aminated membrane (AC-NH ) from 52.6% to 92.5% and from 22.6 nm to 3.5 nm, respectively. The effect of temperature on the performance of the modified membranes was monitored by the flux and chemical oxygen demand (COD) removal of leachate. At ambient temperature, the COD removal of the neat, AC-containing, and AC-NH membranes was 47%, 52%, and 58.5%, respectively. A similar increment was obtained for the membrane flux, which was due to the synergistic effect of the high porosity and large number of hydrophilic functional groups. The experimental leachate adsorption data were analyzed by Langmuir, Freundlich, and Dubinin- Radushkevich isotherm models. For all membranes, the significant thermodynamic parameters ( , , and ) were calculated and compared. The isosteric heat of adsorption was lower than 80 kJ∙mol , indicating that the interaction between the membranes and the leachate is mainly physical, involving weak van der Waals forces.

关键词： amine functionality     nanoporous membrane     adsorption isotherm     thermodynamic parameters     landfill leachate    

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Preparation of lithium ion-sieve and utilizing in recovery of lithium from seawater

Lu WANG, Changgong MENG, Wei MA

《化学科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 65-67 doi: 10.1007/s11705-009-0105-9

摘要： Lithium is one of the most important light metals, which is widely used as raw materials for large-capacity rechargeable batteries, light aircraft alloys and nuclear fusion fuel. Seawater, which contains 250 billion tons of lithium in total, has thus recently been noticed as a possible resource of lithium. While, since the average concentration of lithium in seawater is quite low (0.17 mg·L ), enriching it to an adequate high density becomes the primary step for industrial applications. The adsorption method is the most prospective technology for increasing the concentration of lithium in liquid. Among the adsorbents for lithium, the ion-sieve is a kind of special absorbent which has high selectivity for Li , especially the spinel manganese oxides (SMO), which among the series of ion-sieves, has become the most promising adsorption material for lithium. In this study, the SMO ion-sieve was prepared by a coprecipitation method. The preparation conditions were discussed and the sample characters were analyzed. Recovery of Li from seawater were studied in batch experiments using prepared ion-sieve, and the effect of solution pH and the uptake rates were also investigated in different Li solutions.

关键词： lithium     ion-sieve     seawater     spinel manganese oxide    

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标题 作者 时间 类型 操作

Preparation and characterization of novel carbon molecular sieve membrane/PSSF composite by pyrolysis

Ying Yan, Peng Huang, Huiping Zhang

期刊论文

Thermal decomposition of poly(ethylene terephthalate)/mesoporous molecular sieve composites

RUN Mingtao, ZHANG Dayu, WU Sizhu, WU Gang

期刊论文

Catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over the

Zhidan Fu, Lisha Liu, Yong Song, Qing Ye, Shuiyuan Cheng, Tianfang Kang, Hongxing Dai

期刊论文

Mechanism of ethanol/water reverse separation through a functional graphene membrane: a molecular simulation

期刊论文

Tetra-detector size exclusion chromatography characterization of molecular and solution properties ofsoluble microbial polysaccharides from an anaerobic membrane bioreactor

Qingbin Guo,Sheng Chang

期刊论文

Ti incorporation in MCM-41 mesoporous molecular sieves using hydrothermal synthesis

Shengping WANG, Changqing MA, Yun SHI, Xinbin MA

期刊论文

Enhanced separation of tetrafluoropropanol from water via carbon nanotubes membranes: insights from molecular

期刊论文

Integration of molecular dynamic simulation and free volume theory for modeling membrane VOC/gas separation

Bo Chen, Yan Dai, Xuehua Ruan, Yuan Xi, Gaohong He

期刊论文

The use of carbon nanomaterials in membrane distillation membranes: a review

Sebastian Leaper, Ahmed Abdel-Karim, Patricia Gorgojo

期刊论文

Nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment

期刊论文

Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content onmorphology, antifouling, and permeation properties of polysulfone ultrafiltration membrane: thermodynamic

期刊论文

Molecular level understanding of CO2 capture in ionic liquid/polyimide composite membrane

Linlin You, Yandong Guo, Yanjing He, Feng Huo, Shaojuan Zeng, Chunshan Li, Xiangping Zhang, Xiaochun Zhang

期刊论文

Effects of a dynamic membrane formed with polyethylene glycol on the ultrafiltration of natural organic

Boksoon KWON, Noeon PARK, Jaeweon CHO,

期刊论文

Preparation of adsorptive nanoporous membrane using powder activated carbon: Isotherm and thermodynamic

Majid Peyravi

期刊论文

Preparation of lithium ion-sieve and utilizing in recovery of lithium from seawater

Lu WANG, Changgong MENG, Wei MA

期刊论文