Chemically activated carbon nanofibers for adsorptive removal of bisphenol-A:Batch adsorption and breakthrough curve study

Activated carbon nanofibers(ACNFs)with small diameter can significantly increase the accessibility of intra pores and accelerate adsorption of molecules from water.In this study,ACNFs were made by blending K_(2)CO_(3)or ZnCl_(2)as the activating agent into the polyacrylonitrile(PAN)in dimethylformamide solution for electrospinning prior to pyrolysis.Bisphenol-A(BPA),an endocrine disruption pollutant,is widely applied in the production of polycarbonate plastics and epoxy resins.Accordingly,BPA is often used as a model contaminant commonly removed via adsorption.Batch adsorption studies were used to evaluate the kinetics and adsorption capacity of the ACNFs.Redlich-Peterson(R-P)and Langmuir models were found to fit the isotherm of BPA adsorption better than Freundlich model,showing the homogeneous nature of the PAN originated ACNFs.The adsorption kinetics was better described by the pseudo second-order model than that by the pseudo first-order model.The fitting by intraparticle diffusion model indicates the adsorption of BPA onto ACNFs is mainly controlled by pore diffusion.High pH value and ionic strength reduced BPA adsorption from aqueous solution.The breakthrough curves studied in two different fixed bed systems(cross flow bed system and packed flow bed system)confirmed the scalability of BPA removal by ACNFs in dynamic adsorption processes.The modified dose-response model predicted well the fixed-bed outlet concentration profiles.

Preparation and Characterization of Singlehanded Helical Carbonaceous Nanofibers using 1,4-Phenylene Bridged Polybissilsesquioxanes

Single-handed helical carbonaceous materials attracted much attention for varieties of potential applications. Herein, single-handed helical 1, 4-phenylene bridged polybissilsesquioxane nanofibers were prepared through a supramolecular templating approach using a pair of enantiomers. After carbonization at 700 ℃ for 2.0 h and removal of silica using HF aqueous solution, single-handed helical carbonaceous nanofibers were obtained. The obtained samples were characterized using the field-emission scanning electron microscopy, transmission electron microscopy, N_2 sorptions, X-ray diffraction, Raman spectroscopy and diffuse reflectance circular dichroism（DRCD）. The Raman spectrum indicated that the carbon was amorphous. The DRCD spectra indicated that the carbonaceous nanofibers exhibited optical activity. The surface area of the left-handed helical carbonaceous nanofibers was 907 m^2/g. Such material has potential applications as chirality sensor and supercapacitor electrode.

Preparation of metal oxide doped ACNFs and their adsorption performance for low concentration SO_2

Metal oxide （TiO2 or Co304） doped activated carbon nanofibers （ACNFs） were prepared by electrospinning. These nanofibers were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and Brunner- Emmett-Teller method （BET）. The results show that the average diameters of ACNFs were within the range of 200-500 nm, and the lengths were several tens of micrometers. The specific surface areas were 1146.7 m2/g for TiO2-doped ACNFs and 1238.5 m2/g for Co304-doped ACNFs, respectively. The electrospun nanofibers were used for adsorption of low concentration sulfur dioxide （SO2）. The results showed that the adsorption rates of these ACNFs increased with an increase in SO2concentration. When the SO2 concentration was 1.0 μg/mL, the adsorption rates of TiO2-doped ACNFs and Co3Oa-doped ACNFs were 66.2% and 67.1%, respectively. The adsorption rate also increased as the adsorption time increased. When the adsorption time was 40 min, the adsorption rates were 67.6% and 69.0% for TiO2-doped ACNFs and Co304-doped ACNFs, respectively. The adsorption rate decreased as the adsorption temperature increased below 60℃, while it increased as the adsorption temperature increased to more than 60℃.

Characteristic Assessment of Stabilized Polyacrylonitrile Nanowebs for the Production of Activated Carbon Nano-Sorbents

Polyacrylonitrile （PAN） nanofibers with average diameter of 300 nm were produced by electro-spinning. The nanofibers were stabilized at different temperatures in the range of 180-270 ℃in several duration times and heating rates. Fourier transforms infrared （FTIR） spectroscopy, differential scanning calorimetry （DSC） and X-ray diffraction （XRD） analyzing techniques were employed to measure the extent of stabilization reaction. By all procedures, the ranges of temperature and duration time recommended were about 250-270 ℃ and 1-2 h, respectively. Increasing the activation temperature from 800 ℃ to 1200 ℃ caused porosity and pore volume development up to 60% and 0.532 cm3/g, respectively. Pore width of all samples was calculated to be about 0.7 nm confirming micro-pore structure of the produced PAN based activated carbon nanofibers. Comparing dye adsorption for different adsorbents including chitin and granular activated carbon （GAC） showed the highest efficiency for the produced activated carbon nanofibers （ACNFs）.

Electrospun porous carbon nanofibers derived from bio-based phenolic resins as free-standing electrodes for high-performance supercapacitors

Phenolic resins were employed to prepare electrospun porous carbon nanofibers with a high specific surface area as free-standing electrodes for high-performance supercapacitors.However,the sustainable development of conventional phenolic resin has been challenged by petroleum-based phenol and formaldehyde.Lignin with abundant phenolic hydroxyl groups is the main non-petroleum resource that can provide renewable aromatic compounds.Hence,lignin,phenol,and furfural were used to synthesize bio-based phenolic resins,and the activated carbon nanofibers were obtained by electrospinning and one-step carbonization activation.Fourier transform infrared and differential scanning calorimetry were used to characterize the structural and thermal properties.The results reveal that the apparent activation energy of the curing reaction is 89.21 kJ·mol–1 and the reaction order is 0.78.The activated carbon nanofibers show a uniform diameter,specific surface area up to 1100 m^(2)·g^(-1),and total pore volume of 0.62 cm^(3)·g^(-1).The electrode demonstrates a specific capacitance of 238 F·g^(-1)(0.1 A·g^(-1))and good rate capability.The symmetric supercapacitor yields a high energy density of 26.39 W·h·kg^(-1)at 100 W·kg^(-1)and an excellent capacitance retention of 98%after 10000 cycles.These results confirm that the activated carbon nanofiber from bio-based phenolic resins can be applied as electrode material for high-performance supercapacitors.