Preparation of hybridizing zeolitic imidazolate frameworks with carboxymethylcellulose for adsorption separation of n-hexane/3-methylpentane

A novel ZIF-8-CMC hybrid material was fabricated from the hybridization of ZIF-8 and carboxymethylcellulose (CMC) by impregnation method for n-hexane/3-methylpentane separation. The surface properties of ZIF-8 were tailored by introducing CMC into ZIF-8 nanoparticles. In this work, adsorption separation of n-hexane (nHEX) and 3-methylpentane (3MP) on ZIF-8-CMC were investigated by batch vapor-phase adsorption and liquid-phase breakthrough adsorption. The adsorption selectivity of nHEX/3MP reversed from preferable adsorption of nHEX to preferable adsorption of 3MP upon the increasing of CMC containing in the hybrid materials. As the temperature increases, the adsorption amounts of nHEX and 3MP decrease. With the increasing of CMC contents, the nHEX uptake decreased, the uptake capacity of 3MP increased gradually. For liquid-phase breakthrough adsorption, the dynamic adsorption capacity of nHEX also decreased with the increasing of temperature.     

Decorating MXene with tiny ZIF-8 nanoparticles: An effective approach to construct composites for water pollutant removal

MXenes have attracted increasing research enthusiasm owing to their unique physical and chemical properties. Although MXenes exhibit exciting potential in cations adsorption due to their unique surface groups, the adsorption capacity is limited by the low specific surface area and undeveloped porosity. Our work aims at enhancing the adsorption performance of a well-known MXene, Ti₃C₂T_x, for methylene blue (MB) by decorating tiny ZIF-8 nanoparticles in the interlayer. After the incorporation of ZIF-8, suitable interspace in the layers resulting from the distribution of tiny ZIF-8 appears. When employing in MB, the adsorption capacity of composites can reach up to 107 mg·g^-1 while both ZIF-8 (3 mg·g^-1) and Ti₃C₂T_x (9 mg·g^-1) show nearly no adsorption capacity. The adsorption mechanism was explored, and the good adsorption capacity is caused by the synergistic effect of ZIF-8 and Ti₃C₂T_x, for neither of them is of suitable interspace or surface groups for MB adsorption. Our work might pave the way for constructing functional materials based on the introduction of nanoparticles into layered materials for various adsorption applications.     

Preparation of ZIF-8—Pebax 1657 nanocomposite membranes for n-hexane/nitrogen separation as a representative of gasoline vapour recovery

Gasoline vapour emission is hazardous to both human health and the ecosystem and also results in capital loss, altogether revealing the necessity of its recovery. Some ZIF-8–Pebax flat nanocomposite membranes were fabricated by the method of solution casting and used for gasoline vapour recovery as represented by n-hexane vapour/nitrogen separation. Microporous ZIF-8 nanoparticles were synthesized and characterized by Fourier transform infrared (FTIR) and Brunauer–Emmett–Teller (BET) analysis. BET results revealed specific surface area, total volume, and average pore diameter of 940.8 m² · g⁻¹, 0.36 cm³ · g⁻¹, and 1.54 nm, respectively. Pure nitrogen and n-hexane vapour/nitrogen gas mixture permeabilities were measured through the membranes. There was a decline in both permeation rate and selectivity up to 5.0 wt.% of ZIF-8 loading and the next increment at their higher loadings to considerably more values that the pristine membrane. The maximum n-hexane vapour permeability and selectivity at 10.0 wt.% loading of ZIF-8 nanoparticles, the feed flow rate of 173 mL · min⁻¹, and permeate side pressure of −200 mbar were observed as 280.1 Barrer and 106.7, respectively, revealing 60.0% and 36.9% improvements compared with those of the pristine Pebax membrane. Observed 86%–92% n-hexane vapour recovery approves the successful application of the ZIF-8–Pebax nanocomposite membranes for n-hexane/nitrogen separation. The long-term separation performance of 5.0 wt.% ZIF-8 loaded nanocomposite membrane was improved by 76.5% compared with that of the pristine Pebax membrane.     

Triblock copolymer-assisted synthesis of hierarchical ZIF-67 in the presence of 1,3,5-trimenthylbenzene

A hierarchically porous ZIF-67 was successfully synthesized by using non-ionic block copolymers P123 as a supramolecular templating surfactant and 1,3,5-trimethylbenzene (TMB) as a swelling agent. It was noted that TMB was an effective swelling agent to expand the pore size. Pore size distribution analyses reveal that the as-synthesized hierarchical ZIF-67 has a typical trimodal pore size distribution showing simultaneous micro-, meso- and macropore channel systems. Due to the effect of TMB and P123, the diameter of ZIF-67 nanoparticles was about twice of that synthesized with P123 only and larger pores were formed among the enlarged nanoparticles. This strategy is expected to be a facile and efficient method for the preparation of hierarchical ZIF-67.     

Fabrication of single-walled carbon nanotube three-dimensional networks inside the pores of a porous silicon structure

Single-walled carbon nanotube (SWCNT) three-dimensional (3-D) networks were first fabricated in the pores of a porous silicon substrate using thermal decomposition of C₂H₂ at 800 °C. Catalyst nanoparticles were uniformly distributed on the inner wall surfaces of the pores using a dipping method combined with ultrasonication. SWCNTs were synthesized along the inner wall surface of the pores, and spanned it. The suspended SWCNTs inside the pores formed 3-D networks in the results of the chaotic overgrowth of SWCNTs in a confined space under thermal vibration, and van der Waals interactions between SWCNTs.     

Mussel‐Inspired Membrane Adsorber with Thiol Ligand for Patulin Removal: Adsorption and Regeneration Behaviors

Mussel‐inspired membrane adsorber with thiol ligand (SH‐membrane adsorber) is prepared by polydopamine‐assisted poly(ethylene imine) grafting and subsequent thiolation modification for efficient removal of patulin. The effects of temperature, contact time, pH, and initial patulin concentration on the adsorption capacity of the membrane adsorber are investigated. The results show that the SH‐membrane adsorber is effective to remove patulin. The adsorption capacity of the membrane can reach 1245.11 µg g^?1 for patulin. In static adsorption tests, the adsorption kinetic and equilibrium data are well fitted by the pseudo‐second‐order kinetic model and Freundlich isotherm model, respectively, meaning that the adsorption process is a multilayer chemical adsorption. The SH‐membrane adsorber can be recovered by l ‐cysteine, and the removal efficiency of patulin is maintained at about 89.23% after eight reuse cycles, compared to the 17.33% of control membrane. These results demonstrate that the SH‐membrane adsorber has a potential application for patulin removal.     

White-light fluorescent nanoparticles from self-assembly of rhodamine B-anchored amphiphilic poly(poly(ethylene glycol)methacrylate)-b-poly(glycidyl methacrylate) block copolymer

Rhodamine B (RhB)-anchored amphiphilic poly(poly(ethylene glycol)methacrylate)-b-poly(glycidyl methacrylate) block copolymer (PPEGMA-b-PGMA/RhB) has been prepared by a sequential atom transfer radical polymerization and post-functionalization of RhB. The chemical structure of PPEGMA-b-PGMA/RhB is characterized with gel-permeation chromatography, Fourier-transform infrared spectroscopy, and ¹H nuclear magnetic resonance spectroscopy. PPEGMA-b-PGMA/RhB has shown self-assembly behaviors in tetrahydrofuran and aqueous solutions. The RhB aggregation induced with the inter-molecular interaction of RhB results in the various core–shell structures of the assembled nanoparticles. The photoluminescent properties of the PPEGMA-b-PGMA/RhB nanoparticles are structure-dependent and exhibit yellow-light, blue-light, and white-light emissions. The fluorescent organic nanoparticles of PPEGMA-b-PGMA/RhB in aqueous solution show low cytotoxicity and have been used as a bio-dye for cell labelling. Internalization of PPEGMA-b-PGMA/RhB nanoparticles into HELA cells to exhibit fluorescent images has been demonstrated.     

Facilitated propylene transport in mixed matrix membranes containing ZIF-8@Agmim core-shell hybrid material

The ZIF-8@Agmim core-shell hybrid material was synthesized via a favorable post-modification method of ion exchange (PMIE). This infrequent ZIF-8@Agmim core-shell structure maintains a well-integrated pore size that is almost the same as ZIF-8. The similar equilibrium isotherms with ZIF-8 and better kinetic separation toward propylene/propane than ZIF-8 render ZIF-8@Agmim to be an interesting candidate for propylene/propane separation. The core-shell hybrid nanomaterial was further used as nanofillers in the polymer of intrinsic microporosity matrix (PIM-1) for propylene/propane separation. The resultant mixed-matrix membranes (MMMs) exhibited a simultaneous increase in C₃H₆ permeability and C₃H₆/C₃H₈ ideal selectivity compared to pure polymer membrane owing to a synergistic effect of molecular sieving from ZIF-8 and π-complexation of Ag⁺ with propylene. The separation performance of the prepared MMM surpasses the upper bound line of polymer membranes. Furthermore, the hybrid materials possess superb photochemical stability and the corresponding MMMs exhibit excellent anti-aging property and long-term stability.     

Uranium Adsorption Properties of Hydrous Titanium Oxide Granulated with Polyacrylonitrile

Abstract

The performance of hydrous titanium oxide (HTO) adsorber granulated with polyacrylonitrile (PAN) has been studied by a batch method using natural seawater. The adsorber was classified into four classes of 24/28, 28/32, 32/35, and 35/48 mesh, and the seawater temperature was varied from 15 to 30°C. The effects of particle size and seawater temperature on the liquid film mass transfer coefficient and the intraparticle diffusion coefficient of the uranium ion were estimated. It was found that the uranium adsorption rate was dependent on both liquid film mass transfer and intraparticle diffusion for the PAN-HTO adsorber. The equilibrium adsorption capacity was in the range of 175 to 127 μg-U/g-AD at 30°C. Particle size of PAN-HTO adsorber had no distinct influence on the adsorption capacity and rates. Both adsorption capacity and rates increased with increasing seawater temperature.     

Pd nanoparticles supported on ZIF-8 as an efficient heterogeneous catalyst for the selective hydrogenation of cinnamaldehyde

Palladium nanoparticles supported on ZIF-8 (Pd/ZIF-8) were prepared by a facile impregnation method and characterized by XRD, TEM, ICP and N₂ adsorption. The prepared Pd/ZIF-8 catalyst exhibited excellent catalytic performance for the selective hydrogenation of cinnamaldehyde. The reaction solvents had great influences on the catalytic performance of the prepared Pd/ZIF-8 catalyst. Pd nanoparticles supported on ZIF-8 gave much higher catalytic activity and hydrocinnamaldehyde selectivity than those supported on other MOFs or the conventional inorganic supports. The prepared Pd/ZIF-8 catalyst could be reused at least four times without significant loss in activity and selectivity.     

The adsorption behaviors of the multiple stimulus‐responsive poly(ethylene glycol)‐based hydrogels for removal of RhB dye

In this article, the multiple stimulus‐responsive organic/inorganic hybrid hydrogels by combining poly(2‐(2‐methoxyethoxy) ethyl methacrylate‐co‐oligo (ethylene glycol) methacrylate‐co‐acrylic acid) (PMOA) hydrogel with magnetic attapulgite/Fe₃O₄ (AT‐Fe₃O₄) nanoparticles were applied to the removal of Rhodamine B (RhB) dye from wastewater. The adsorption of RhB by the hydrogels was carried out under different external environmental, such as pH, temperature and magnetic‐field. The results showed that the hydrogels still possessed temperature, pH and magnetic‐field sensitivity during the adsorption process, which indicated that the adsorption could be controlled by the hydrogels responsive. The dye adsorption had a significant increment at 30°C and the removal of RhB could reach to over 95%. Besides, the low pH values were also favorable for the RhB adsorption, the removal was over 90% at pH = 4.56. Kinetic studies showed that the pseudo‐second order kinetic model well fitted the experimental data. The rate constant of adsorption was 0.0379 g/mg min. Langmuir and Freundlich isotherm models were applied to the equilibrium adsorption for describing the interaction between sorbent and adsorbate. The maximum K_L and K_F were 2.23 (L/g) and 0.87 (mg/g) at 30°C, respectively. Under the external magnetic‐field, the adsorption rate significantly increased within 250 min and the hydrogels could be separated easily from wastewater. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42244.     

Synthesis,gas adsorption and reliable pore size estimation of zeolitic imidazolate framework-7 using CO2 and water adsorption

Reliable estimation of the pore size distribution(PSD) in porous materials such as metal–organic frameworks(MOFs) and zeolitic imidazolate frameworks(ZIFs) is crucial for accurately assessing adsorption capacity and corresponding selectivity. In this study, the so-called zeolitic imidazolate framework-7(ZIF-7) is successfully synthesized via relatively fast and convenient microwave technique. The morphology and structure of the obtained MOF were characterized by XRD, SEM and N_2 and CO_2adsorption/desorption isotherms at 77 K and0 °C respectively. Then, to determine the PSD of the fabricated MOF, carbon dioxide isotherms are experimentally measured at various temperatures up to atmospheric pressure. Afterward, the experimental CO_2 isotherms data are utilized in two recently proposed in-house algorithms of SHN1 and SHN2 to extract the true PSD of manufactured ZIF-7. The obtained results revealed that median pore diameter of the fabricated ZIF-7 is estimated around 0.404 nm and 0.370 nm by using CO_2 isotherms at 273 K and 298 K respectively. These values are in good agreement with the real pore diameter of 0.42 nm. Moreover, experimental data of water adsorption isotherms over four different MOFs, borrowed from literature, are employed to illustrate further effectiveness of the above algorithms on successful determination of the corresponding pore size distributions. All predicted PSDs are proved to be in good agreement with those obtained from independent methods such as topology and morphology studies.     

A novel poly(vinylidene fluoride) composite membrane for catalysis and separation

Timely separation of products from the reactant is a great challenge for a catalytic reaction process. In this study, we fabricated a novel poly(vinylidene fluoride) composite membrane with noble metal (Au, Ag, and Pd) nanoparticles in membrane pores to solve the faced challenge. The composite membrane has a unique structure comprising membrane surfaces with only PVDF and membrane pores with poly(methacrylic acid) microspheres coated by noble metal nanoparticles. The composite membrane is used for the catalytic reduction of p‐nitrophenol and the results indicate that the catalytic reaction can rapidly proceed. What is more, the product formed in reaction process can be immediately isolated from the reactant. Other drawbacks such as the easy aggregation and the difficult separation generally encountered by the metal nanocatalysts are also avoided by using the composite membrane. In operation process, the composite membrane shows good thermal, mechanical and catalytic stability. These attracted merits make the prepared composite membrane have desirable prospects in catalytic application. POLYM. ENG. SCI., 58:150–159, 2018. © 2017 Society of Plastics Engineers     

新型温敏超滤膜处理印染废水的研究

印染废水中含有大量有机染料和重金属等物质,对生态环境及人类健康产生了严重的危害。以聚（N-异丙基丙烯酰胺）@聚苯乙烯（PNIPAM@PS）球形聚合物刷为主体,Cd（OH）₂纳米线作为牺牲层,聚碳酸酯（PC）膜为支撑层,经简单过滤制备得到对温度有响应性的高分子超滤膜。通过傅里叶变换红外光谱（FT-IR）、扫描电镜（SEM）、动态光散射仪（DLS）及水接触角测量仪对其进行表征,结果表明该超滤膜表面由PNIPAM@PS球形聚合物刷构成,其表面平整,结构规则,且具有良好的温度响应性。随后考察了PNIPAM@PS超滤膜对有机染料（甲基蓝和罗丹明B）和CdSe重金属颗粒的过滤效果,并通过紫外分光光度计（UV-vis）、原子荧光光谱仪（PL）等对其进行表征。结果显示,随着PNIPAM链增长、PS核粒径减小、实验操作压力增大,超滤膜的过滤效果显著改善。同时超滤膜的孔径可以通过温度实时调节,当环境温度高于PNIPAM链的LCST时,超滤膜的孔径较大;温度降低,超滤膜的孔径变小。PNIPAM@PS超滤膜的孔径可调节性使其在废水处理中有着广泛的应用前景。     

Metal-organic framework as a host for synthesis of nanoscale Co3O4 as an active catalyst for CO oxidation

Co₃O₄ nanoparticles were prepared from cobalt nitrate that was accommodated in the pores of a metal-organic framework (MOF) ZIF-8 (Zn(MeIM)₂, MeIM = 2-methylimidazole) by using a simple liquid-phase method. The ZIF-8 host was removed by pyrolysis under air and subsequently washing with an NH₄Cl–NH₃·H₂O aqueous solution. Transmission electron microscopy (TEM) analysis shows that the obtained Co₃O₄ is composed of separate nanoparticles with a mean size of 18 nm. The Co₃O₄ nanoparticles exhibit excellent catalytic activity, cycling stability, and long-term stability in the low temperature CO oxidation.     

Structure and Performance of Poly(vinylidene chloride‐co‐vinyl chloride) Porous Membranes with Different Additives

Poly(vinylidene chloride‐co‐vinyl chloride) (P(VDC‐co‐VC) membranes were prepared by non‐solvent‐induced phase separation and adjusted by adding water‐soluble polyethylene glycol (PEG) and water‐insoluble silicon dioxide (SiO₂) hydrophilic nanoparticles. The structure of pores and antifouling performance were investigated to illustrate the effect of these nanoparticles. The cross section of the P(VDC‐co‐VC) membrane exhibited more macropores and the typical finger‐like pores turned into more vertically interconnected ones with increasing PEG content, while the number and size of finger‐like pores became less with increasing SiO₂ content. Considering the filtration and antifouling experiments, the presence of hydrophilic PEG and SiO2 nanoparticles in the P(VDC‐co‐VC) polymer matrix improved the membrane performance in terms of high flux, high BSA rejection ratio, and fouling resistance.     

High gas permselectivity in ZIF-302/polyimide self-consistent mixed-matrix membrane

Zeolitic imidazolate framework-302 (ZIF-302) was incorporated within a polyimide (PI) matrix in order to develop a highly selective and permeable mixed-matrix membrane (MMM) for gas separation processes. On the basis of varying fabrication procedures, two different MMMs were formed: a dense MMM (ZIF-302/d-PI) and a spongy, self-consistent MMM (ZIF-302/s-PI). The spongy membrane was shown to have self-consistent and disconnected pores with a reduction in overall membrane density. For ZIF-302/d-PI, a 1.2–1.5-fold increase in the permeability of H₂, O₂, N₂, CO₂, and CH₄ was observed when compared with the pure d-PI membrane. For ZIF-302/s-PI, even better improvements (up to 19-fold higher) in permeance were achieved with negligible effects on selectivity. The gas transport mechanism was then analyzed and showed a considerable enhancement of diffusion coefficients for ZIF-302/s-PI, while ideal gas pair selectivities for CO₂/N₂, H₂/CH₄, and H₂/N₂ were found to be 24.8, 42.3, and 62.6, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48513.     

基于不同粒径ZIF-8多孔液体的二氧化碳捕集性能

通过粒径调控策略制备了基于不同粒径ZIF-8的多孔液体(PLs),并用于CO₂的捕集。考察了ZIF-8粒径对多孔液体捕集CO₂的吸附容量、吸附速率、CO₂/N₂选择性及循环稳定性的影响,并对不同粒径多孔液体的CO₂吸附动力学进行研究。结果表明,多孔液体中具有永久的孔隙结构,不同多孔液体均具有优异的流动性。3种不同粒径的多孔液体室温下放置60 d或4500 r/min下离心5 min后均未出现聚集、沉积现象,表明不同粒径多孔液体均具有较好的稳定性。由不同粒径ZIF-8合成的多孔液体对CO₂的吸附过程包括物理吸附和化学吸附。其中,ZIF-8粒径为43 nm的多孔液体ZIF-8-PLs(43)对CO₂的饱和吸附容量最大,为63.0 mg/g;ZIF-8-PLs(145)展现了较快的CO₂吸附速率,准二级动力学常数为1.91×10^–3 g/(mg·min);ZIF-8-PLs(1400)具有最高的C...     

ZIF-8 Filled Polydimethylsiloxane Membranes for Pervaporative Separation of n-Butanol from Aqueous Solution

ZIF-8-filled polydimethylsiloxane (PDMS) membranes, PDMS/ZIF-8, were prepared by a two-step polymerization process and were used to recover n-butanol from an aqueous solution by pervaporation (PV). Compared with pure PDMS membrane, PDMS/ZIF-8 membranes demonstrated an obviously higher n-butanol permselectivity. As an increase of ZIF-8 content, n-butanol/water selectivity increased initially and then decreased, while the n-butanol and water permeability decreased monotonously. PDMS/ZIF-8 membrane containing 2 wt% ZIF-8, that is, PDMS/ZIF-8-2 showed the highest selectivity. On the other hand, selectivity and permeability for n-butanol and water of PDMS/ZIF-8-2 membrane decreased with the increase of operating temperature. The selectivity and permeability for n-butanol reached 7.1 and 3.28 × 10⁵ barrer, respectively, at 30°C when the feed concentration of n-butanol was 0.96 wt%.     

TiO2协同增强ZIF-8光催化降解特性研究

工业有机废水污染危害人类健康,阻碍经济的发展,是当前急需解决的问题。金属有机骨架(MOFs)材料因其独特的孔道结构、较大的比表面积、优异的吸附性能,有望成为工业有机废水处理的潜在新材料。ZIF-8(沸石咪唑酯骨架-8)具有复杂的SOD拓扑结构和高稳定性,其工业废水吸附应用价值逐渐受到关注。本文首先通过溶胶-凝胶法和温度调控制备最佳相比例的锐钛矿/金红石混合相TiO₂纳米颗粒,采用溶剂法在TiO₂颗粒表面原位生长制备了包覆型ZIF-8复合材料。结果表明,引入10%(质量分数)TiO₂与ZIF-8构筑的复合材料对亚甲基蓝(MB)污染物的降解率和反应速率遵循一级动力学模型,分别是纯ZIF-8的1.27和2.3倍。可控制备且均匀分布在ZIF-8有机框架材料孔道中的Zn/ZnO_x纳米异质结作为活化位点,增加与MB分子的接触面积,提升对载流子的俘获数量,同时TiO₂与裸露的高活性异质结界面形成协同增强效应,构成立体催化降解复合体系,提高催化降解能力。