A High Flux Electrochemical Filtration System Based on Electrospun Carbon Nanofiber Membrane for Efficient Tetracycline Degradation

In this work, an electrochemical filter using an electrospun carbon nanofiber membrane (ECNFM) anode fabricated by electrospinning, stabilization and carbonization was developed for the removal of antibiotic tetracycline (TC). ECNFM with 2.5 wt% terephthalic acid (PTA) carbonized at 1000 °C (ECNFM-2.5%-1000) exhibited higher tensile stress (0.75 MPa) and porosity (92.8%), more graphitic structures and lower electron transfer resistance (23.52 Ω). Under the optimal condition of applied voltage 2.0 V, pH 6.1, 0.1 mol L−1 Na2SO4, initial TC concentration 10 ppm and membrane flux 425 LMH, the TC removal efficiency of the electrochemical filter of ECNFM-2.5%-1000 reached 99.8%, and no obvious performance loss was observed after 8 h of continuous operation. The pseudo-first-order reaction rate constant in flow-through mode was 2.28 min−1, which was 10.53 times higher than that in batch mode. Meanwhile, the energy demand for 90% TC removal was only 0.017 kWh m−3. TC could be converted to intermediates with lower developmental toxicity and mutagenicity via the loss of functional groups (-CONH2, -CH3, -OH, -N(CH3)2) and ring opening reaction, which was mainly achieved by direct anodic oxidation. This study highlights the potential of ECNFM-based electrochemical filtration for efficient and economical drinking water purification.

Grafting macromolecular chains on the surface of graphene oxide through crosslinker for antistatic and thermally stable polyethylene terephthalate nanocomposites

The graphene oxide (GO) and polyethylene terephthalate (PET) molecular chains are connected together by the two amino groups of the crosslinking agent p-phenylenediamine (PPD).

An overview of polymeric nano-biocomposites as targeted and controlled-release devices

In recent years, controlled drug delivery has become an important area of research. Nano-biocomposites can fulfil the necessary requirements of a targeted drug delivery device. This review describes use of polymeric nano-biocomposites in controlled drug delivery devices. Selection of suitable biopolymer and methods of preparation are discussed.

Synthesis of Graphene Oxide-Polystyrene Graft Polymer Based on Reversible Addition Fragmentation Chain Transfer and Its Effect on Properties, Crystallization, and Rheological Behavior of Poly (Lactic Acid)

Graphene oxide-polystyrene graft polymer (SGO-PS) was prepared by reversible addition-fragmentation chain transfer radical polymerization method. Orthogonal experiments indicated that the optimum synthesis reaction conditions for SGO-PS were as follows: the millimole ratio of chain transfer agent to initiator was 0.15 : 0.3, and the amount of styrene was 8 mL at 80°C for 12 hours. The products were characterized by Fourier transform infrared spectroscopy and thermal weightlessness analysis, and the highest grafting rate of SGO-PS was 62.46%. Then, PLA/SGO-PS nanocomposites were prepared using SGO-PS as fillers by melt intercalation method, and its crystallinity, mechanical properties, and thermal stability were significantly improved. Compared with pure PLA, the crystallinity of PLA/SGO-PS (0.3 wt%) nanocomposites was increased by 5 times. Multiple melting behavior tests showed that the introduction of SGO-PS caused the PLA molecular chain to be discharged into the unit cell in time, and the melting temperature shifted to a higher temperature, which ultimately made the grain structure of PLA composites more complete and stable than pure PLA. The rheological performance test showed that the uniform dispersion of SGO-PS in the PLA matrix inhibited the free movement of the PLA molecular chain and caused higher flow resistance, resulting in an increase in the complex viscosity, storage modulus, and loss modulus of PLA/SGO-PS.

Superior decontamination of toxic organic pollutants under solar light by reduced graphene oxide incorporated tetrapods-like Ag3PO4/MnFe2O4 hierarchical composites

To fabricate an efficient, eco-friendly and stable photocatalyst, the current work describes a demonstration of simple synthesis approach of Ag₃PO₄/MnFe₂O₄(x wt%)/reduced graphene oxide composites. Ag₃PO₄/MnFe₂O₄ (5 wt%) revealed superior activity for decontamination of dye pollutant. Further, rGO was incorporated with Ag₃PO₄/MnFe₂O₄ (5 wt%) to investigate its effect on their overall properties. The resultant composites were characterized by various analytical techniques to confirm their structural and physical-chemical features. FESEM analysis showed that morphology of Ag₃PO₄ varied significantly from orthorhombic dodecahedrons to tripods and tetrapods with the combinations MnFe₂O₄ (5 wt%), and MnFe₂O₄ (5 wt%)+rGO respectively. The photocatalytic decontamination of toxic organic dyes tested against Rhodamine B(RhB) and 4-Nitrophenol. The outstanding performance for decontamination of RhB was observed for Ag₃PO₄/MnFe₂O₄(5 wt%)/rGO (~99% in 5 min) with the rate of k = 7.28 × 10^-1 min^-1. The enhanced activity of Ag₃PO₄/MnFe₂O₄(5 wt%)/rGO composites credited to co-catalytic effects of MnFe₂O₄ and physiochemical properties of rGO which leads to making intimate contact with Ag₃PO₄ to form heterojunction and rGO served as a medium for charge transfer to prevent their recombination. The incorporation of rGO in Ag₃PO₄/MnFe₂O₄ (5 wt%) composite leads to a considerable increase in the photocatalytic activity by offering improved surface area and properties, high electron stability and mobility. Based on experiment results, the photocatalytic enhancement mechanism for organic pollutants degradation was discussed. The recyclability of Ag₃PO₄/MnFe₂O₄(5 wt%)/rGO hierarchical composite was evaluated by replicated photocatalytic reaction trials. Overall, the morphological transformation of Ag₃PO₄/MnFe₂O₄(5 wt%)/rGO composites played a dynamic role in determining their photocatalytic activity towards the organic industrial dye pollutants.

Hydrated FePO4 nanoparticles supported on P-doped RGO show enhanced ORR activity compared to their dehydrated form in an alkaline medium

One-step hydrothermal growth of FePO4 nanoparticles (15-25 nm) uniformly decorated on the P-doped reduced graphene oxide (PRGO) was studied for oxygen reduction reaction (ORR) activity. The role of lattice water in the enhancement of catalytic activity in the hydrated FePO4·2H2O with respect to its dehydrated form in the alkaline medium was contested. The hydrodynamic LSV at 1600 rpm in alkaline medium (0.1 M KOH electrolyte) indicates an increase in the cathodic current density of the PRGO supported FePO4·2H2O catalyst, which reaches as high as 5.8 mA cm-2, close to the best known commercially available Pt/C catalyst. The stability in terms of retention of activity after 22 000 s with the hydrated form was found to be 90.7% which is 26.7% higher than that of the dehydrated form.

A Facile Method for Batch Preparation of Electrochemically Reduced Graphene Oxide

The electrochemical reduction of graphene oxide (GO) is an environmentally friendly and energy-saving method for improving the characteristics of GO. However, GO films must be coated on the cathode electrode in advance when usingthis technique. Thus, the formed electrochemically reduced GO (ERGO) films can be used only as sensing or conductive materials in devices because mass production of the flakes is not possible. Therefore, this study proposes a facile electrochemical reduction technique. In this technique, GO flakes can be directly used as reduced materials, and no GO films are required in advance. A 0.1 M phosphate buffered saline solution was used as the electrolyte, which is a highly safe chemical agent. Experimental results revealed that the as-prepared GO flakes were electrochemically reduced to form ERGO flakes by using a -10 V bias for 8 h. The ratio of the D-band and G-band feature peaks was increased from 0.86 to 1.12, as revealed by Raman spectroscopy, the π-π stacking interaction operating between the ERGO and GO has been revealed by UV-Vis absorption spectroscopy, and the C⁻O ratio was increased from 2.02 to 2.56, as indicated by X-ray photoelectron spectroscopy. The electrical conductivity of the ERGO film (3.83 × 10^-1 S·cm^-1) was considerably better than that of the GO film (7.92 × 10^-4 S·cm^-1). These results demonstrate that the proposed electrochemical reduction technique can provide high-quality ERGO flakes and that it has potential for large-scale production.

High-Performance Biobased Unsaturated Polyester Nanocomposites with Very Low Loadings of Graphene

Graphene-reinforced tung oil (TO)-based unsaturated polyester nanocomposites were prepared via in situ melt polycondensation intergrated with Diels–Alder addition. Functionalized graphene sheets derived from graphene oxide (GO) were then extracted from the obtained nanocomposites and carefully characterized. Furthermore, dispersion state of the graphene nanosheets in the cured polymer composites and ultimate properties of the resultant biobased nanocomposites were investigated. Mechanical and thermal properties of the TO-based unsaturated polyester resin (UPR) were greatly improved by the incorporation of GO. For example, at the optimal GO content (only 0.10 wt %), the obtained biobased nanocomposite showed tensile strength and modulus of 43.2 MPa and 2.62 GPa, and T_g of 105.2 °C, which were 159%, 191%, and 49.4% higher than those of the unreinforced UPR/TO resin, respectively. Compared to neat UPR, the biobased UPR nanocomposite with 0.1 wt % of GO even demonstrated superior comprehensive properties (comparable stiffness and T_g, while better toughness and thermal stability). Therefore, the developed biobased UPR nanocomposites are very promising to be applied in structural plastics.

Fabrication of Thermal Conductivity Enhanced Polymer Composites by Constructing an Oriented Three-Dimensional Staggered Interconnected Network of Boron Nitride Platelets and Carbon Nanotubes

The orientation of ultrahigh aspect ratio thermally conductive fillers can construct a heat transfer path to enhance the thermal conductivity of composite materials effectively with low filler loading. Nevertheless, single orientation (vertical or horizontal) limited the application of these materials when there was the need for isotropic heat transferring. Here we report a novel strategy to prepare thermally conductive flexible cycloaliphatic epoxy resin nanocomposites with an oriented three-dimensional staggered interconnected network of vertically aligned h-BN (hexagonal boron nitride) platelets and randomly dispersed CNT-NH₂ (aminated carbon nanotubes). In this structure, h-BN platelets coated with magnetic particles could respond to the external magnetic field; however, the CNT-NH₂ couldn't. The obtained composites exhibited both through-plane (0.98 ± 0.037 W/m·K) and in-plane (0.99 ± 0.001 W/m·K) thermal conductivity enhancement at low h-BN loading of 30 wt %, and also presented excellent electrical insulating properties (<1.2 × 10^-12 S/cm). In addition, the equal value of thermal conductivity of two directions (in-plane and through-plane) was shown when the content of h-BN was about 26.43 wt % and of CNT-NH₂ was 2 wt %, displaying no difference between the thermal conductivity of two directions (in-plane and through-plane). The infrared imaging tests showed the outstanding heat dissipation capability of the composites by capturing the surface temperature variations of a heater with the composites as the heat dissipating material.

Effects of Modified Graphene Oxide on Thermal and Crystallization Properties of PET

In this article, graphene oxide nanosheets grafted with low molecular weight poly(ethylene terephthalate) were in situ synthesized via carboxylation, acyl chlorination and grafting modification in order to improve the compatibility between GO and PET phases and enhance the thermal stability and crystallization properties of PET. Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Atomic Force Microscopy (AFM) characterization results demonstrated that LMPET chains have been successfully grafted onto the surface of GO. To further investigate the influence of modified GO on properties of PET, modified PET was prepared by incorporating the GL-g-LMPET nanofillers into the PET matrix using the melt-blending method. Due to the similar polarity and strong interaction between LMPET and PET molecules, GL-g-LMPET nanofillers were homogeneously dispersed in PET matrix. Thermal properties and crystallization properties of obtained nanocomposites were systematically characterized using Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), and Thermo Gravimetric Analysis (TGA). Results show that GL-g-LMPET nanofillers could improve the thermal stability of PET, e.g., increase up to 16.6 °C in temperature at the maximum rate of weight loss. In addition, the GL-g-LMPET also acts as an efficient nucleating agent for PET, exhibiting (1) higher crystallization temperatures; (2) higher degrees of crystallinity; and (3) faster rates of crystallization.

In situ polymerization and characterization of graphite nanoplatelet/poly(ethylene terephthalate) nanocomposites for construction of melt-spun fibers

This work described a set of graphite nanoplatelet/poly(ethylene terephthalate) (GnP/PET) nanocomposites synthesized via an in situ polymerization for construction of melt-spun fibers with enhanced antistatic property.

Facile and green preparation of biobased graphene oxide/furan resin nanocomposites with enhanced thermal and mechanical properties

A facile and green approach was developed to prepare biobased graphene oxide (GO)/furan resin nanocomposites by directly transferring GO from water dispersion into furan resin.

Fabrication of a graphene coated nonwoven textile for industrial applications

A hybrid electrically conductive polyester–graphene textile was fabricated as a high-performance smart textile for geotextile and/or heating element applications.

Reduction degree and property study of graphene nanosheets prepared with different reducing agents and their applicability as a carrier of the Ru(phen)3Cl2 luminescent sensor for DNA detection

Recently, graphene nanosheets (GNS) have been widely investigated and used in capacitors, catalysts, biological/chemical sensors, etc.

Biomimic modification of graphene oxide

Synthetic polymer modified graphene oxide was prepared via combination of mussel inspired chemistry and Michael addition reaction in aqueous solution.

A critical review on in situ reduction of graphene oxide during preparation of conducting polymeric nanocomposites

In situ reduction of graphene oxide during preparation of conducting polymeric nanocomposites.

Recent advances in the synthesis and applications of graphene–polymer nanocomposites

We summarize the recent advances in the modification of graphene with polymers and the synthesis and applications of high quality graphene–polymer nanocomposites.

Electromagnetic interference shielding of segregated polymer composite with an ultralow loading of in situ thermally reduced graphene oxide

An in situ thermally reduced graphene/polyethylene conductive composite with a segregated structure was fabricated, which achieved a high electromagnetic interference shielding effectiveness of up to 28.3-32.4 dB at an ultralow graphene loading of 0.660 vol.%. Our work suggests a new way of effectively using graphene.