Functionalized Polyacrylonitrile Fiber Research Articles

Highly selective removal of cationic dyes from water by acid-base regulated anionic functionalized polyacrylonitrile fiber: Fast adsorption, low detection limit, reusability

A series of anionic functionalized polyacrylonitrile fibers were prepared and used to remove cationic dyes from water. The phenolate immobilized fiber (PANP(−)F) exhibited excellent adsorption capacities for cationic dyes, among which the best results was obtained for Brilliant cresyl blue (BCB) with color changing of the solution from sapphire to light yellow. Additionally, PANP(−)F can selectively remove cationic dyes from dye mixtures containing both anionic and cationic dyes. After acid-base regulating, the highest adsorption capacity of PANP(−)F was obtained at pH 10. Moreover, adsorption kinetic illustrated that PANP(−)F can achieve half adsorption capacity within 10 mins and follow pseudo-second-order model. The maximum adsorption capacity calculated from isotherms experiments reached 2.306 mmol/g (890.1 mg/g) at 25 °C. The activation energy of the adsorption process was 30.74 kJ/mol indicating that the BCB adsorption process occurs via chemical adsorption. Furthermore, the PANP(−)F can be readily separated from solution and reused 10 cycles. Under a continuous flow condition, the BCB concentration can be reduced to 20 ppb at first and remained below 1.69 ppm during the 825 mins adsorption process. At the same time, the removal ratio kept above 98.31%. In general, this novel PANP(−)F adsorbent is eco-friendly, highly efficient, selective, reusable, and has great potential for the removal of dyes from industrial wastewaters.

Carbon-dot modified polyacrylonitrile fibers: Recyclable materials capable of selectively and reversibly adsorbing small-sized anionic dyes

Amine-rich carbon dot (CD) functionalized polyacrylonitrile fibers (PANF-g-CDs) were prepared by a facile hydrothermal method. These fibers are fluorescent and contain nano-sized pores. Dye adsorption experiments demonstrated that PANF-g-CDs preferred to adsorb small-sized anionic dyes with high aspect ratio, such as methyl orange (MO). The maximum adsorption capacity for MO reached 422 mg/g. The adsorption kinetics satisfied the pseudo second-order adsorption model, and the adsorption behavior was monolayer uniform adsorption. After adsorption, PANF-g-CDs could be separated conveniently just by taking it out from the solution. Moreover, the used PANF-g-CDs could be regenerated in an alkaline aqueous solution very rapidly within 30 min. Its adsorption performance was so stable that it did not show obvious performance loss even after ten adsorption-desorption cycles. In addition, the fluorescence of the fiber exhibited periodical change during the adsorption-desorption processes. Thus, this CD modified fibers with the combined advantages of simple synthesis, high dye-adsorption efficiency and selectivity, moderate dye-adsorption rate, fast dye-desorption, easy recyclability, stable adsorption performance and photoluminescent nature could be promising adsorbents for practical dyestuff wastewater treatment.

Quaternary Ammonium-Based Functionalized Polyacrylonitrile Fibers with Polarity Tunable Inner Surface Microenvironment for C–C Bond Forming Reactions under Continuous Flow Conditions

A series of quaternary ammonium-based (QAB) functionalized polyacrylonitrile fibers as superbase catalysts for C—C bond forming reactions in water were prepared. Alkyl with different chain lengths ...

Proton sponge functionalized polyacrylonitrile fibers as an efficient and recyclable superbasic catalyst for Knoevenagel condensation in Water

Fiber catalysts with high catalytic activity and good recyclability have attracted much attention. In this work, proton sponge 1,8-bis(dimethylamino)naphthalene functionalized polyacrylonitrile fiber is prepared to construct a superbasic microenvironment, which is applied to catalyze the Knoevenagel condensation in water for the synthesis of α,β-unsaturated compounds. Different characterization techniques of XPS, 13C solid-state NMR, FTIR, SEM etc. Are used to verify the successful grafting of the proton sponge during modification as well as evaluate the stability of the fiber catalyst in specific application. The fiber catalyst exhibits distinctly higher catalytic activity and efficiency in water than in other solvents, with a low catalytic dosage of 5 mol% under room temperature within 3 h. Besides, a synergistic microenvironment can be formed between the hydrophilic polar surface of the fiber and the superbasic catalytic sites, promoting the efficient catalysis of Knoevenagel condensation reaction. In addition, the fiber possesses high reusability that it can be easily recovered and reused for at least 10 times without obvious loss of its catalytic activity. More interestingly, the fiber can be fixed in a reactor to catalyze the Knoevenagel condensation, in which process pure α,β-unsaturated compounds are continuously obtained by simple filtration, avoiding the use of toxic solvents and time-consuming column chromatography, which presents great potential in cleaner and more efficient production. In brief, with such advantages as high catalytic activity, simple separation operation and good economic efficiency, the proton sponge modified fiber is fairly attractive in fixed-bed reactors in cleaner industrial production.

Prolinamide functionalized polyacrylonitrile fiber with tunable linker length and surface microenvironment as efficient catalyst for Knoevenagel condensation and related multicomponent tandem reactions

A series of new prolinamide polyacrylonitrile fiber catalysts with tunable length of alkyl linker and different linker group were prepared by covalent bonding for the first time and well characterized by mechanical strength, FT-IR, XRD, EA, TGA, SEM and water contact angel. The catalytic activities of these fiber catalysts were evaluated in Knoevenagel condensation and one-pot Knoevenagel-Michael multicomponent tandem reactions to synthesize α, β-unsaturated nitrile and 2-amino-4H-chromene derivatives in water. The result show that the suitable linker length attaching amines to fiber matrix as well as the constructed hydrophobic microenvironment by linker group within the surface layers of fiber materials effectively promotes the reactions. In addition, the good swollen capacity of fiber in solvent ensure that the reaction proceed well. Fiber catalyst PANPA−2F modified by prolinamide with a C2 alkyl chain exhibited the best catalytic performance and can be easily recovered and reused for at least ten consecutive cycles without significant loss of catalytic activity and active sites leaching.

Construction of a phosphate-rich polyacrylonitrile fiber surface microenvironment for efficient purification of crystal violet wastewater.

Wastewater purification using fibrous adsorbents has received much attention due to their high efficiency, low cost, and recyclability. In this work, phosphate modified polyacrylonitrile fiber (B-PANEAPF) was prepared and used to remove cationic dyes. The B-PANEAPF showed the best adsorption capacity for crystal violet (CV) when compared with rhodamine B, methyl green, Victoria blue B, methylene blue, and neutral red. The adsorption tests revealed that the fiber possessed high adsorption efficiency and achieved semi-saturated adsorption within 15 min. The maximum adsorption capacity of 354.46 mg g−1 as calculated by the Langmuir adsorption model was higher than many other adsorbents. Furthermore, the B-PANEAPF was used to remove 210 mL of CV in a continuous-flow process with a high removal efficiency over 90%. Besides, the phosphate functionalized fiber could easily decrease the concentration of CV to below 0.5 mg L−1 which is below the maximum effluent discharge standard of 15 mg L−1 prescribed in China. It could also be fully recovered and easily separated from the solution to achieve re-use 10 cycles. Moreover, the adsorption mechanism indicated that the adsorption process of the fiber for CV was mainly attributed to electrostatic interaction and hydrogen bonding. In conclusion, the results suggested that the B-PANEAPF characterized by its simplicity, efficiency, eco-friendliness, and reusability, could be a promising candidate for CV removal.

Green chemical method for the synthesis of chromogenic fiber and its application for the detection and extraction of Hg2+ and Cu2+ in environmental medium.

To advocate environment friendly detection idea, we adopted the green chemical method to synthesis the 1-(2 amino ethyl) piperidine functionalized polyacrylonitrile fiber (APF) and the chromogenic fiber 4-(2-pyridylazo) resorcinol (APF-PAR). The APF has high adsorption selectivity of Hg2+ and Cu2+, and the change of structure, surface morphology and thermo-stability before and after adsorption have been characterized by the infrared spectra, scanning electron microscope and thermogravimetric analysis. The APF achieved the adsorption equilibrium of Hg2+ just in 25 min and the adsorption capacity is 435.1 mg/g, while the adsorption equilibrium of Cu2+ costs 30 min and the adsorption capacity is 141.7 mg/g. The chromogenic fiber APF-PAR can recognize the Hg2+ and Cu2+ in 2 s, which benefits from the rapid mass transfer and small fluid resistance of the chelating PAN fiber. The color changed from orange to purplish red due to the variation of HOMO-LOMO energy gaps during the reaction which confirmed by the UV-vis absorption spectrum. It also has high selectivity and excellent adsorption performance, which provides more convenient, accurate, reliable and faster testing methods of Hg2+ and Cu2+ in environmental medium.

Copper(II)‐Schiff Base Complex‐Functionalized Polyacrylonitrile Fiber as a Green Efficient Heterogeneous Catalyst for One‐Pot Multicomponent Syntheses of 1,2,3‐Triazoles and Propargylamines

AbstractA series of copper(II)‐Schiff bases‐functionalized polyacrylonitrile fiber catalysts were successfully prepared using copper acetate as copper source and characterized by elemental analysis, fourier‐transfer infrared spectroscopy, ultraviolet‐visible spectroscopy, X‐ray photoelectron spectroscopy and inductively coupled plasma analysis. Excellent physical strength and thermal stability of the fiber catalysts were demonstrated by scanning electron microscopy, X‐ray diffraction, thermogravimetric/differential scanning calorimetry analysis and mechanical strength measurements. Furthermore, these catalysts were successfully applied to one‐pot multicomponent copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) reaction and aldehyde, alkyne, amine (A3) coupling reaction in which the influences of different substituent groups on the catalytic activities of fiber catalysts were investigated in detail. Among them, the bis[N‐ethyl‐3,5‐di‐tert‐butyl‐salicylideneiminato]copper(II)‐functionalized polyacrylonitrile fiber (PANS2F−Cu) as a green, efficient catalyst exhibited the best catalytic activity for its high hydrophobic micro‐environment can aggregate the reactants to the catalytic sites and accelerate the reaction. In addition, the PANS2F−Cu has performed well in scaled‐up experiment and shown excellent recyclability (at least ten times), and these enable it to have great potential for further applications.magnified image

L-Lysine Functionalized Polyacrylonitrile Fiber: A Green and Efficient Catalyst for Knoevenagel Condensation in Water

The l-lysine functionalized polyacrylonitrile fiber (PANLF) was prepared by grafting the l-lysine into a commercially available polyacrylonitrile fiber and showed highly catalytic activity for Knoevenagel condensation reaction. With low temperature (45 °C) and short reaction time (1 h), the fiber catalyst was well applicable to Knoevenagel condensation of a wide range of aldehydes and the yields could reach up to 99%. Interestingly, only in water could the reaction take place smoothly (with a yield of 88%) and a polar micro-environment promoted reaction process had been proposed to explain this phenomenon. Besides, the fiber catalyst has advantages of easy preparation, high functional degree, strong mechanical strength and thermal stability, etc. And it can be reused at least 5 times without further treatment and performed well in scaled-up experiment (amplified 50 times) and flow chemistry experiment (no loss of catalytic activity after 48 h), which indicates its potential application in industry application.

Efficient removal of uranium(vi) from simulated seawater with hyperbranched polyethylenimine (HPEI)-functionalized polyacrylonitrile fibers

Readily synthesized PAN–HPEI fibers for efficient removal of U(vi) from simulated seawater.

Highly selective and efficient adsorption of Hg2+ by a recyclable aminophosphonic acid functionalized polyacrylonitrile fiber

Mercury ions, even an ultra-trace amount in water, present a serious environmental concern. Hence, searching for cost-effective and high-performance Hg2+ adsorbents has acquired increasingly attention but still remained challenging. In this work, aminophosphonic acid was immobilized onto polyacrylonitrile fiber by chemical grafting approaches. The functionalized fiber (PANAPF) possessed high adsorption selectivity and efficiency for Hg2+ when compared with other coexisting ions viz. Pb2+, Cd2+, Ag+, Zn2+, Cu2+, Ni2+, Co2+, Ca2+ and Mg2+. The adsorption results revealed that PANAPF exhibited high removal capacities for Hg2+ over a wide pH range from 3 to 11. The adsorption process was better described by the pseudo second-order kinetic model, indicating the chemical interaction between Hg2+ and active groups on the PANAPF. Moreover, the maximum adsorption capacity as calculated from the Langmuir adsorption model of 358mgg−1 was higher than that of many other adsorbents. The PANAPF could be reused more than 10 times and it is able to decrease Hg2+ below 50μgL−1 which is the maximum discharge standard for mercury containing wastewater in China. A continuous-flow process was also implemented to remove Hg2+. The results suggested the environmentally friendly PANAPF could be a promising candidate for Hg2+ removal in wastewater treatment.

Tuning the Catalytic Activity of Tertiary‐Amine Functionalized Polyacrylonitrile Fibers by Adjusting the Surface Microenvironment

AbstractPolyacrylonitrile fibers were functionalized with different amines to construct special tridimensional catalytic microenvironments at the surface. The polarity of the microenvironments at the surface of the fiber catalyst was tuned by changing the ratio of hydrophobic and hydrophilic amines. The catalytic performances of these microenvironments were examined for a cyanation reaction in water. Among these fiber catalysts with different microenvironments, the one modified with more hydrophobic benzylamine groups (PANBTF) shows much higher catalytic activity than that modified by hydrophilic ethanolamine groups. PANBTF can efficiently and rapidly catalyze the cyanation reaction of benzaldehyde and ethyl cyanoformate in water with a yield of 94 % at room temperature within 40 min. Moreover, a mechanism promoted by the hydrophobic microenvironment has been proposed to explain the high and specific catalytic activity of PANBTF. In addition, this fiber catalyst exhibited excellent recyclability and reusability (8 times) without further treatment, and it also performed well in flow‐chemistry tests and scaled‐up experiments, which indicated potential for the application of PANBTF in industrial production.

A recyclable phosphinic acid functionalized polyacrylonitrile fiber for selective and efficient removal of Hg2+

A novel phosphinic acid functionalized polyacrylonitrile fiber (PANAPCF) was prepared and its adsorption properties were investigated. The PANAPCF shows excellent selectivity and efficiency for Hg2+ in the presence of other common metal ions, viz. Pb2+, Cd2+, Ag+, Zn2+, Cu2+, Ni2+, Co2+, Ca2+, Mg2+. Adsorption kinetics studies show that PANAPCF quickly captures Hg2+ and achieves equilibrium within 3h. In addition, PANAPCF is effective over a wide range of pH values (from 3 to 11). The maximum adsorption capacity for Hg2+ as calculated by a Langmuir isotherm model was 434mgg−1. PANAPCF could also efficiently remove Hg2+ from practical wastewater and the concentration of Hg2+ could be decreased as low as 27ppb, which is below the maximum contamination level of 50ppb for mercury containing wastewater in China. Furthermore, the PANAPCF can be used to remove Hg2+ from a flow process with a 99% removal efficiency even after ten cycles. Finally, XPS analysis proved that the PO/POH and –NH– functional groups play a major role in the adsorption mechanism.

Preparation of silver nanoparticles/polydopamine functionalized polyacrylonitrile fiber paper and its catalytic activity for the reduction 4-nitrophenol

The study reports on the preparation of polyacrylonitrile fiber paper (PANFP) functionalized with polydopamine (PD) and silver nanoparticles (Ag NPs), named as Ag NPs/PD/PANFP. The composite material was obtained via a simple two-step chemical process. First, a thin polydopamine layer was coated onto the PANFP surface through immersion into an alkaline dopamine (pH 8.5) aqueous solution at room temperature. The reductive properties of polydopamine were further exploited for the deposition of Ag NPs. The morphology and chemical composition of the composite material were characterized using scanning electron microscopy (SEM), X-ray diffraction pattern (XRD) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of the nanocomposite was evaluated for the reduction of 4-nitrophenol using sodium borohydride (NaBH4) at room temperature. The Ag NPs/PD/PANFP displayed good catalytic performance with a full reduction of 4-nitrophenol into the corresponding 4-aminophenol within 30min. Moreover, the composite material exhibited a good stability up to 4 cycles without a significant loss of its catalytic activity.

Phosphorous acid functionalized polyacrylonitrile fibers with a polarity tunable surface micro-environment for one-pot C–C and C–N bond formation reactions

Novel hydrophilic/hydrophobic surface micro-environment modified phosphoric acid-functionalized PANFs are prepared for one-pot C–C and C–N bond formation reactions with high efficiencies and preeminent reusability.

ChemInform Abstract: Pyrrolidine Modified PANF Catalyst for Asymmetric Michael Addition of Ketones to Nitrostyrenes in Aqueous Phase.

AbstractThree chiral pyrrolidine functionalized polyacrylonitrile fiber catalysts are designed, prepared, and evaluated for their catalytic performance in asymmetric Michael addition of ketones to nitrostyrenes in water.

Highly Efficient Polyacrylonitrile Fiber Catalysts Functionalized by Aminopyridines for the Synthesis of 3-Substituted 2-Aminothiophenes in Water

Four aminopyridine (AP) functionalized polyacrylonitrile fibers (PANAPFs) were developed. UV–vis, FTIR, EA, and SEM were used to demonstrate the successful preparation of the fiber catalysts. Among the prepared catalysts, the PANp-AP-3F (with a C3 chain linker) and PANp-AP-6F (with a C6 chain linker) exhibited the best catalytic activity to efficiently catalyze the Gewald reaction of ethyl cyanoacetate and 2,5-dihydroxy-1,4-dithiane in water with yields up to 92% under a low catalyst dosage of 1 mol %. The influences of the position and length of the linker, i.e., the carbon chain between the fiber backbone and the aminopyridine moiety, on the catalytic activities were investigated in detail. In addition, the selected catalyst PANp-AP-3F was applied to the Gewald reaction of a series of active nitriles and 2,5-dihydroxy-1,4-dithiane and reused without further treatments. A possible mechanism and a microenvironment promoting process were conceived to explain the excellent catalytic properties of this catalytic system. Furthermore, the PANp-AP-3F performed well in a scaled-up experiment indicating its potential application in industry.

Thiourea modified polyacrylnitrile fibers as efficient Pd(ii) scavengers

N-(2-Aminoethyl)thiourea functionalized polyacrylonitrile fiber was prepared and used for scavenging Pd in the synthesis of active pharmaceutical ingredients (APIs).

Pyrrolidine modified PANF catalyst for asymmetric Michael addition of ketones to nitrostyrenes in aqueous phase

Three chiral pyrrolidine functionalized polyacrylonitrile fiber catalysts have been designed, prepared, and evaluated for their catalytic performance in asymmetric Michael addition of ketones to nitrostyrenes in water.

Application of the polyacrylonitrile fiber as a support for the green heterogeneous base catalyst and supported phase-transfer catalyst

Highly efficient and recyclable polyethylene polyamine functionalized polyacrylonitrile fiber as the heterogeneous base catalyst and supported phase-transfer catalyst.