Functionalized Polyacrylonitrile Fiber Research Articles

A novel tetra(4-pyridyl)porphyrin-palladium(0) functionalized polyacrylonitrile fiber as highly efficient and recyclable heterogeneous catalyst for the Heck reaction

A novel tetra(4-pyridyl)porphyrin-chelated palladium(0) nanoparticles functionalized polyacrylonitrile fiber (PANTPPF-Pd(0)) was prepared for the first time. Some necessary methods including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), etc. were used to verify the micro structure and properties of PANTPPF-Pd(0). Furthermore, with the Heck reaction chosen as a model reaction to determine the catalytic activity of PANTPPF-Pd(0), the experiment results shows that PANTPPF-Pd(0) can efficiently catalyze the Heck reaction with high yields (47–99%) in extensive substrate scope (46 examples) under non-solvent condition. Noteworthily, the average size of Pd(0) nanoparticles observed by transmission electron microscopy (TEM) slightly increased from 2.32 nm to 2.59 nm after recycled 8 times achieving an 99% isolated yield of Heck reaction catalyzed by PANTPPF-Pd(0), which proves that the PANTPPF-Pd(0) can maintain satisfactory recyclability. Finally, based on the π-π stacking interactions and dipolar-dipolar interaction between tetra(4-pyridyl)porphyrin moieties in PANTPPF-Pd(0) and substrates, a novel heterogeneous “capture-catalyze” mechanisms was proposed.

Multi-dimensional application of dithizone functionalized polyacrylonitrile fiber: Colorimetric recognition of Ag+ and In Situ catalyzed dye reduction

A functionalized polyacrylonitrile fiber PANODF modified by ethanolamine and dithizone is successfully prepared to selectively identify Ag+ by colorimetric method and then reduce various dyes in situ cooperating with NaBH4. The color of functionalized fiber changes from orange to bright red when it is soaked in solution with Ag+ ions. It's even more satisfying that no relevant color change of the fiber has been observed in the solution of other 12 kinds of metal ions. Obvious color change can occur within 3 min and the detection limit can reach 1 ppm for Ag+. In addition, the process of recognizing Ag+ will not be interfered by other ions in the real water sample. Moreover, the functionalized fiber can be reused up to 10 times for Ag+ recognition. Additionally, the Ag+ ions absorbed on the fiber can be reduced to Ag0, creating a new fiber (PANOD-Ag0F) that can be used as a catalyst to reduce various dyes in situ with NaBH4. The experimental results show that the six kinds of dyes can be quickly reduced to the colorless and less-toxic substance under the condition of NaBH4 as the reducing agent and PANOD-Ag0F as the catalyst. The catalytic reduction capacity of PANOD-Ag0F can still reach more than 99 % when it is recycled for 10 times, which proves the practical application potential of the functionalized fiber.

Recyclable bispyridine functionalized polyacrylonitrile fibers as ligand of Cu(II) for A3 coupling reaction

Developing an effective and economical technology to achieve the recovery of catalysts in the process of organometallic synthesis has attracted significant attention. Herein, a novel functional fiber catalyst with bispyridine structure was successfully constructed by modifying the commercial polyacrylonitrile fiber. Modified bidentate ligand fiber-based can be used to efficiently complexe Cu(II). The functional fibers were fully characterized by FTIR, ICP, XPS, XRD, SEM, and TGA. To verify the catalytic activity of PANbis(Py)-Cu(II)F, A3 coupling reaction was applied in this work. The results showed that only 0.1 mol% catalyst dosage was needed and the maximum isolated yield was up to 99%. Recycle experiments showed that PANbis(Py)-Cu(II)F has fine recycling performance, and there is no decrease in catalytic efficiency during the first six cycles. Consequently, as a recyclable functional fiber catalyst based on commercial polyacrylonitrile fiber, it provided a new insight for green synthesis and industrial production.

Immobilization of Pd(0) nanoparticles on polyaza-ligand-functionalized polyacrylonitrile fiber as highly active catalyst for the Heck reaction

An novel aza-ligand functionalized polyacrylonitrile fiber (PANPALF) with amino groups and quaternary ammonium salt moieties was synthesized, and then a highly active catalyst for the Heck reaction was obtained by immobilizing Pd(0) nanoparticles on PANPALF through chelation and in situ reduction. The functionalized fibers were characterized by appropriate instruments, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), etc., in order to further confirm that the modification process has been successfully carried out. The catalytic properties of the prepared fiber were evaluated in Heck reaction. The experimental results show that PANPALF-Pd(0) can catalyze Heck reactions and achieving 42 kinds of products with yields ranging from 43% to 99% under solvent-free condition, and verifies that the reactive activation of iodized aromatics is better than that of brominated aromatics. Noteworthily, the TON value of the reaction catalyzed by PANPALF-Pd(0) can reach up to 89000, showing that the fiber catalyst has excellent catalytic activity. Moreover, after PANPALF-Pd(0) reused 11 times, the isolated yield was still as high as 93%, and the average single Pd(0) leaching is only 0.075%, indicating that PANPALF-Pd(0) has satisfactory recyclability. Finally, a rational reaction mechanism was proposed to explain the role of fiber catalyst in the reaction.

The adsorption of U(VI) by persimmon tannin modified aminated polyacrylonitrile fiber

In this study, a green and efficient persimmon tannin functionalized polyacrylonitrile fiber (PAN-TETA-PT) was prepared and used to treat U(VI). The influence of pH value, adsorption temperature and time, and fiber material dosage on the adsorption U(VI) of PAN-TETA-PT fibers were investigated, and the kinetics, isotherm, and thermodynamics of fibers were analyzed. When the pH is 6, the temperature is 30°C, and the fiber dosage is 0.2 g·L−1, the adsorption rate of PAN-TETA-PT fibers to U(VI) was 96.5%, and the U(VI) adsorption capacity was 159.75 mg/g. The kinetic and isothermal studies show that the adsorption of PAN-TETA-PT fibers to U(VI) is chemisorbed and multilayer adsorption. The thermodynamic analysis reflects that the PAN-TETA-PT is spontaneously endothermic for the adsorbed U(VI).

Anchoring Cu-N active sites on functionalized polyacrylonitrile fibers for highly selective H2S/CO2 separation

As an essential part of clean energy, natural gas is often mixed with varying degrees of H2S and CO2, which poses a serious environmental hazard and reduces the fuel's calorific value. However, technology for selective H2S removal from CO2-containing gas streams is still not fully established. Herein, we synthesized functional polyacrylonitrile fibers with Cu-N coordination structure (PANFEDA-Cu) by an amination-ligand reaction. The results showed that PANFEDA-Cu exhibited a remarkable adsorption capacity (143 mg/g) for H2S at ambient temperature, even in the presence of water vapor, and showed a good separation of H2S/CO2. X-ray absorption spectroscopy results confirmed the Cu-N active sites in as-prepared PANFEDA-Cu and the formed S-Cu-N coordination structures after H2S adsorption. The active Cu-N sites on the fiber surface and the strong interaction between highly reactive Cu atoms and S are the main reasons for the selective removal of H2S. Additionally, a possible mechanism for the selective adsorption/removal of H2S is proposed based on experimental and characterization results. This work will pave the way for the design of highly efficient and low-cost materials for gas separation.

Phenylboronic acid functionalized polyacrylonitrile fiber for efficient and green synthesis of bis(indolyl)methane derivatives

The use of fiber as a catalyst carrier to construct heterogeneous catalysts with good catalytic activity and recycling performance has received wide attention. In this study, three phenylboronic acid functionalized polyacrylonitrile fiber (PANF) catalysts were synthesized by amination and quaternization. Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to verify the successful grafting of phenylboronic acid and the structural integrity of the fiber catalyst after recycling. The activity of the catalysts was explored with the Friedel–Crafts alkylation between indole and aromatic aldehydes. The results indicate that the synthesized catalyst (PAN p -BA F) in which the phenylboronic acid functional group was linked at the para position, exhibited the highest catalytic activity for the Friedel–Crafts alkylation. The substrate scope experiments confirmed that the catalyst has outstanding catalytic activity for most aromatic aldehydes, especially for those containing moderate electron donating groups. Moreover, the catalyst can be reused eight times in water without significant decrease in its catalytic activity. Further, the scale-up experiment confirmed that the fiber catalyst has a certain potential for industrial application.

Tertiary amine-bisquaternary ammonium functionalized polyacrylonitrile fiber for catalytic synthesis of pyran-annulated heterocycles

Polyacrylonitrile fiber supported bisquaternary ammonium salts with varying interchain quaternary ammonium (QA) to tertiary amine (TA) ratio, counter ions and linker groups were prepared and characterized by TGA, FTIR, XPS, XRD, SEM, EA and water contact angle. The functionalized fibers were used to catalyze three-component reaction (3CR) and tandem deacetalization-3CR for the synthesis of pyrano[4,3-b]pyrans, pyrano[3,2-c]chromenes and pyrano[3,2-c]quinolines in ethanol-water mixture. Under varying reaction conditions such as time, temperature, catalyst amount and solvents, the catalytic ability of the prepared fiber catalyst was investigated. Under the optimum conditions, the bisquaternary ammonium fiber with acetate counter ion and an interchain QA to TA ratio of 1:1 (PANBQAcF) showed the best catalytic activity among the prepared fiber catalysts, and it can be used for 10 runs consecutively with only a slight depreciation in catalytic activity. Interestingly, PANBQAcF can efficiently catalyze tandem deacetalization-Knoevenagel reaction and the relevant novel tandem deacetalization-3CRs for the synthesis of pyran-annulated heterocycles. In the tandem deacetalization reactions, the acetate ion plays an important role of facilitating proton transfer, which makes PANBQAcF a cooperative and reusable heterogeneous catalyst.

Immobilization of Ag(0) nanoparticles on quaternary ammonium functionalized polyacrylonitrile fiber as a highly active catalyst for 4-nitrophenol reduction.

Ag(0) nanoparticles were immobilized on various pyridine salt, imidazole salt and quaternary ammonium functionalized polyacrylonitrile fibers (PANFs) to prepare Ag(0)-immobilized fiber catalysts. The catalytic activities of these immobilized catalysts for 4-nitrophenol (4-NP) reduction were detected. Among them, the quaternary ammonium fiber with butyl group immobilized Ag(0) nanoparticle catalyst PANQA-C4F-Ag(0) showed the best catalytic activity, and can effectively catalyze 4-nitrophenol (4-NP) reduction with a high conversation rate of 99.6%. Furthermore, PANQA-C4F-Ag(0) can be easily recovered, and it was reused 20 times with little decrease in catalytic activity and moderate Ag retention (53.5%). Notably, the cationic groups in the functionalized fibers can stabilize Ag(0) nanoparticles through electrostatic interactions and steric effects, and play an important role in phase transfer catalysis. Accordingly, possible mechanisms for the 4-NP reduction catalyzed by PANQA-C4F-Ag(0) were proposed.

Efficient capture of phosphate from wastewater by a recyclable ionic liquid functionalized polyacrylonitrile fiber: a typical “release and catch” mechanism

A novel recyclable ionic liquid functionalized polyacrylonitrile fiber for phosphate removal was prepared, and the fiber shows a low adsorption limit and can be used to purify phosphate in a continuous flow process with high removal efficiency.

Carbohydrazide modified polyacrylonitrile fiber as efficient and recyclable furfural adsorbent

A novel carbohydrazide functionalized polyacrylonitrile fiber (PANJF) was designed and prepared for removal of furfural from water. Compared with other amino-containing functionalized fibers, the PANJF fiber exhibits the highest adsorption capacity due to the highest reactivity of carbohydrazide. Batch experiments were performed to explore the influence of pH, initial concentration of furfural, dosage of adsorbent, adsorption time, and temperature on the process of adsorption. Under the optimized condition, the maximum adsorption capacity of PANJF for furfural reaches 140.4 mg g−1. Kinetic and isothermal curves show that the adsorption process is in accordance with the pseudo-second-order model and the Langmuir isothermal adsorption model. Furthermore, the thermodynamic result indicates that the furfural adsorption on PANJF is an endothermic and spontaneous process. More satisfactorily, the PANJF still maintains 90% removal efficiency even after five cycles, which certifies it is an excellent scavenger and can be utilized to remove furfural in practice.

Immobilization of Pd(0) nanoparticles on gemini quaternary ammonium functionalized polyacrylonitrile fibers as highly active catalysts for heck reactions and 4-nitrophenol reduction

Palladium salts and Pd(0) nanoparticles were immobilized on a series of amine and quaternary ammonium functionalized polyacrylonitrile fibers (PANFs) to prepare functionalized fiber catalysts. The catalytic activities of these materials for Heck reaction were investigated. Among which, the Gemini quaternary ammonium fiber immobilized Pd(0) nanoparticles catalyst PANGQAF-Pd(0) exhibited the best catalytic activity, which was able to effectively catalyze Heck reaction and 4-nitrophenol (4-NP) reduction with high yields of 76–99%. And the catalyst can tolerate an extensive scope of substrates under mild reaction conditions. In addition, PANGQAF-Pd(0) was easily recovered, and it can be reused 10 times with little decrease in catalytic activity and low Pd leaching (only 3.69%). The experimental results confirmed that Pd(II) was converted into Pd(0) during the coupling reactions, which helped to promote the reaction. This explains why the catalytic activity of PANF-immobilized Pd(0) is better than that of PANF-immobilized Pd(II). Accordingly, possible mechanisms for the catalytic Heck reaction and reduction reaction of PANGQAF-Pd(0) were proposed.

Phenanthroline functionalized polyacrylonitrile fiber with Pd(0) nanoparticles as a highly active catalyst for the Heck reaction

A series of polyacrylonitrile fibers (PANF) functionalized with nitrogen-containing ligands were prepared and then used to synthesize fiber-supported Pd(0) nanoparticle catalysts. The phenanthroline-functionalized PANF with immobilized Pd(0) nanoparticles (PANPhenF-Pd(0)) had the best catalytic activity for the Heck reaction under solvent-free conditions. The PANPhenF-Pd(0) efficiently stabilized the nanoparticles and they were well-dispersed with Pd(0) particle sizes of about 3 nm. The PANPhenF-Pd(0) structure was further characterized by a variety of instrumental methods. A probable mechanism based on the fiber's microenvironment is proposed for the Heck reaction catalyzed by PANPhenF-Pd(0). The PANPhenF-Pd(0) catalyst is easily recovered from the reaction system and can be used up to six times with only a slight decrease in catalytic activity and with low Pd leaching. The PANPhenF-Pd(0) catalyst also has excellent catalytic activity for gram-scale use.

Amine functionalized polyacrylonitrile fibers for the selective preconcentration of trace metals prior to their on-line determination by ICP-MS.

Amine functionalized polyacrylonitrile fibers (PANFs) were prepared and applied for the simultaneous separation and preconcentration of V(v), As(iii), Sn(iv), Sb(iii) and Bi(ii) from environmental water samples in this paper. The functional PANFs were first prepared by nucleophilic substitution reaction between hydroxylamine hydrochloride and polyacrylonitrile fibers, and then the reactant obtained in the first step was subjected to a ring opening reaction with epichlorohydrin, followed by modification with triethylenetetramine (TETA). The structure of the final polymer fibers was analyzed by Fourier transform infrared spectroscopy (FT-IR), and the morphology was characterized by scanning electron microscopy (SEM). A home-made solid phase extraction (SPE) pretreatment column was filled with PANFs, and then online connected with inductively coupled plasma mass spectrometry (ICP-MS) for quantitative determination of metal ions. Under the optimized experimental conditions, the target metal ions were eluted rapidly and quantitatively using 0.3 mol L-1 HNO3 solution. Only with 30 mL sample solution, high enrichment factors of 120 were obtained for V(v), As(iii), Sn(iv) and Sb(iii), and 115 for Bi(ii), respectively. The detection limits achieved were low: 1.2, 0.9, 1.7, 1.5 and 2.3 ng L-1 for V(v), As(iii), Sn(iv), Sb(iii) and Bi(ii), respectively, and the relative standard deviations (RSDs) were below 3.0%. The advanced fiber materials prepared in this work have the advantages of low cost, environmental friendliness and high adsorption efficiency, and the on-line preconcentration method has greatly improved the analysis efficiency. Finally, the feasibility and accuracy of the method were validated by successfully analyzing Certified Reference Materials (CRMs) as well as lake, river and sea water samples.

Enhanced phosphate removal from wastewater by recyclable fiber supported quaternary ammonium salts: Highlighting the role of surface polarity

Abstract The application of fiber adsorbents in water treatment has recently received major attention due to its cost-effectiveness, good recyclability, and easy separation. Herein, we developed a novel strategy to prepare quaternary ammonium salt functionalized polyacrylonitrile fibers with a polarity tunable surface micro-environment to enhance the removal of wastewater phosphate. For this purpose, quaternized fibers with hydrophilic hydroxyl (PANT-C2-OHF) and hydrophobic alkyl with different chain lengths (PANT-C2F, PANT-C4F, PANT-C6F, and PANT-C8F) were constructed and characterized. Results of the adsorption experiment revealed that PANT-C2-OHF containing hydrophilic hydroxyl groups had the best adsorption capacity for phosphate (24.44 mg P g−1) within the adsorption equilibrium of 5 min. Furthermore, PANT-C2-OHF could effectively remove wastewater phosphate in a wide pH range (3–9), even in the presence of Cl-, CO32–, NO3–, etc. The adsorption kinetics and isotherms of PANT-C2-OHF for phosphate were better described by the pseudo-second kinetics and Langmuir isotherm models, indicating a monolayer chemical adsorption process. Besides, PANT-C2-OHF possessed excellent recyclability of at least 10 times and an extremely low adsorption limit for phosphate (0.02 mg P L-1) in actual wastewater. In brief, this study provides proof for PANT-C2-OHF as a new environmental adsorbent with high efficiency, selectivity, and reusability for removal and recovery of phosphate.

Influence of Surface Polarity on Catalytic Properties of Aminopyridine Functionalized Polyacrylonitrile Fiber Catalyst

This work has been developed to study the effect of fiber catalyst surface polarity on catalyst performance. Taking 4-dimethyl amine pyridine (DMAP) derivative functionalized polyacrylonitrile fiber catalyst (PANDMAPF) as the template catalyst, its surface property was adjusted through the introduction of phenyl and hydroxyl groups on PANDMAPF. Elemental analysis (EA), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and mechanical strength test are used to characterize and demonstrate the successful synthesis of different fiber catalysts. The catalytic performance of different fiber catalysts was tested by the reaction of one-pot three-component synthesis 2-amino-2-chromenes. The results showed that reducing the surface polarity of the catalyst could not only improve the activity of the catalyst, but also make the three-component reaction which could only be carried out in high polar solvents (water and methanol), but also proceed effectively in lower polar solvents (such as ethanol and n-butanol). Therefore, the activity and selectivity of the catalyst can be effectively regulated by introducing different polar auxiliary functional groups on the surface of the fiber catalyst, which provides a theoretical basis for the design and synthesis of high activity and selectivity fiber catalyst.

Persimmon tannin functionalized polyacrylonitrile fiber for highly efficient and selective recovery of Au(III) from aqueous solution

An efficient fibrous adsorbent (PANF-TETA-PT) was prepared via grafting triethylenetetramine (TETA) on polyacrylonitrile fiber (PANF), followed by persimmon tannin (PT) immobilizing. Detailed characterization certified that plenty amounts of amino and phenolic hydroxyl groups existed on the surface of PANF-TETA-PT, which would provide excellent active sites for Au(III) adsorption. The batch characteristic results found that the adsorption equilibrium data could be fitted well with Langmuir equation, while the obtained kinetic data were consistent with the Pseudo-second-order equation. The maximum equilibrium adsorption capacity of PANF-TETA-PT towards Au(III) (801.2 mg/g) was apparently superior than that of the reported adsorbents, and the competitive adsorption showed that PANF-TETA-PT had a good preference to adsorption Au(III) in spite of some coexisting pollutants. The characterization analysis of Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer spectrum (XRD) revealed that the electrostatic attraction and chelation dominated the uptake of Au(III) on PANF-TETA-PT, in which a part of loaded Au(III) was reduced to Au particles with the help of reductive functional groups. Thus, this adsorbent could be as a promising candidate to separation and preconcentration of Au(III) from wastewater.

Quaternary ammonium functionalized polyacrylonitrile fiber supported phosphotungstic acid as efficient heterogeneous catalyst: Hydrophobic tuning of the catalytic microenvironment

Thirteen novel amine or quaternary ammonium functionalized polyacrylonitrile fiber (PANF) supported phosphotungstic acid (PTA) catalysts were designed and prepared, and their catalytic activities were screened by choosing condensation/annulation tandem synthesis of 2,3-dihydroquinazolin-4(1H)-one compound via C–N bond formation between 2-aminobenzamide and p-chlorobenzaldehyde as a model reaction. By adjusting the functionality and hydrophobic/hydrophilic property of the amine/ammonium structure as well as the density of PTA sites, the fiber catalyst CAT-12 prepared from quaternary ammonium functionalized PANF containing benzyl group with high PTA loading achieved the best catalytic activity for most reactions in water. The CAT-12 can be easily separated from the reaction system and recycled for 7 times without significant loss of catalytic activity. Moreover, the reaction proceeded smoothly in gram scale and gave nearly quantitative yield using this efficient, eco-friendly and easily recyclable catalyst with great industrial potential which was also demonstrated in Friedel-Crafts alkylation of indoles with β-nitrostyrene. Vivid PTA immobilization processes and the corresponding “catch-catalyze” catalytic modes were further schematically described to address the effect of microenvironment-tuning on immobilization and catalysis, and accordingly the possible catalytic mechanisms of the two reactions were proposed.

Functionalized polyacrylonitrile fibers with durable antibacterial activity and superior Cu(II)-removal performance

To develop functionalized polyacrylonitrile (PAN) fibers with superior adsorption performance and durable antibacterial activity, adhesive polydopamine (PDA) layers were introduced for effective immobilization of silver nanoparticles (AgNPs). The results showed that the pre-treatment (acidization and oxidation) may lead to the slight degradation of PAN and the formation of unsaturated CC double bonds, which can significantly promote the loading of PDA and AgNPs. Further scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses indicated that the average sizes of the AgNPs on sulfonated PAN fibers and p-toluenesulfonated PAN fibers were 166.7 nm and 158.6 nm respectively, and their corresponding atomic percentages were 0.65% and 0.31% respectively. As expected, two functionalized PAN fibers showed excellent antibacterial activities against both gram-negative and gram-positive bacteria. Particularly, the antimicrobial ratio of the two functionalized PAN fibers could retain more than 90% after 5 laundering cycles. On the other hand, the spontaneous Cu(II) ion adsorption process followed the pseudo-second order kinetics, Langmuir and Freundlich models, and the adsorption mechanism of the two functionalized PAN fibers is the combination of surface adsorption and intraparticle diffusion. Last but not least, the two functionalized PAN fibers can be used for multiple metal ions removal simultaneously.

Copper and nickel removal from aqueous solutions using functionalized polyacrylonitrile fibers: equilibrium, kinetic, and thermodynamic studies

Copper and nickel removal from aqueous solutions using functionalized polyacrylonitrile fibers: equilibrium, kinetic, and thermodynamic studies