Qian Shao

Esterification synthesis of ethyl oleate catalyzed by Brønsted acid–surfactant-combined ionic liquid

ABSTRACT 3-(N,N-dimethyldodecylammonium) propanesulfonic acid hydrogen sulfate ([SB3-12][HSO4]), a Brønsted acidic-surfactant-combined ionic liquid, was successfully prepared from cheap materials and applied to catalyze the esterification synthesis of ethyl oleate using oleic acid and ethanol as precursors. The produced condition of oleic acid ethyl ester was optimized including the amount of catalyst, reaction time, molar ratio and content of water. Under optimal condition (ethanol to oleic acid molar ratio, 3:1; amount of the catalyst, 5u2005wt% (based on the mass of oleic acid); reaction time, 3u2005h; reaction temperature, 78°C; and content of water, 0.4u2005wt%), the conversion of oleic acid was over 97%. Due to the reverse micelles formed by [SB3-12][HSO4], the micro-reactor not only promoted the esterification toward the desired side of the ester, but also avoided the hydrolysis of ester. Moreover, the [SB3-12][HSO4] could be reused by a simple decantation separating process and noticeable loss of catalytic activity was not observed even after being recycled for five cycles. The green system offers several advantages, such as excellent yield, efficient catalytic activity, free-solvent and simple operational procedure. GRAPHICAL ABSTRACT

Reinforced carbon fiber laminates with oriented carbon nanotube epoxy nanocomposites: Magnetic field assisted alignment and cryogenic temperature mechanical properties

The epoxy nanocomposites with ordered multi-walled carbon nanotubes (MWCNTs) were used to influence the micro-cracks resistance of carbon fiber reinforced epoxy (CF/EP) laminate at 77u202fK, Oxidized MWCNTs functionalized with Fe3O4 (Fe3O4/O-MWCNTs) with good magnetic properties were prepared by co-precipitation method and used to modify epoxy (EP) for cryogenic applications. Fe3O4/O-MWCNTs reinforced carbon fiber epoxy composites were also prepared through vacuum-assisted resin transfer molding (VARTM). The ordered Fe3O4/O-MWCNTs were observed to have effectively improved the mechanical properties of epoxy (EP) matrix at 77u202fK and reduce the coefficient of thermal expansion (CTE) of EP matrix. The ordered Fe3O4/O-MWCNTs also obviously improved the micro-cracks resistance of CF/EP composites at 77u202fK. Compared to neat EP, the CTE of ordered Fe3O4/O-MWCNTs modified CF/EP composites was decreased 37.6%. Compared to CF/EP composites, the micro-cracks density of ordered Fe3O4/O-MWCNTs modified CF/EP composites at 77u202fK was decreased 37.2%.

The facile preparation of novel magnetic zirconia composites with the aid of carboxymethyl chitosan and their efficient removal of dye

Novel composites based on magnetic zirconia was synthesized with the aid of carboxymethyl chitosan (Fe3O4/ZrO2–CMCS) by a facile method. The as-synthesized products were characterized by wide-angle powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR). The magnetic zirconia carboxymethyl chitosan (Fe3O4/ZrO2–CMCS) composites consisted of particles which show a better regularity and uniform with 200–300 nm in diameter. The as-obtained Fe3O4/ZrO2–CMCS nanocomposites exhibited high adsorption activity and the adsorption capacity for sunset yellow was up to 143.2 mg g−1 without adjusting pH of the solution. Interestingly, after the carboxymethyl chitosan being eliminated by calcining in air, the as-obtained Fe3O4/ZrO2 showed enhanced photocatalytic activity under sunlight irradiation. The degradation rate of rhodamine B as well as sunset yellow was 89% and 84% in 240 min, respectively, due to the addition of the Fe3O4/ZrO2 photocatalyst under sunlight irradiation. Both Fe3O4/ZrO2–CMCS and Fe3O4/ZrO2 can be recycled and reused easily, due to magnetism of iron oxide in the composites. Considering the high adsorption performance of Fe3O4/ZrO2–CMCS and the enhanced photocatalytic activity of Fe3O4/ZrO2 for dye stuff, these two nanocomposites can be applied in treating the waste water contaminated by organic dye stuff.

Excellent corrosion protection performance of epoxy composite coatings filled with silane functionalized silicon nitride

Silicon nitride was firstly used as anticorrosive pigment in organic coatings. An effective strategy by combining inorganic fillers and organosilanes was used to enhance the dispersibility of silicon nitride in epoxy resin. The formed nanocomposites were applied to protect Q235 carbon steel from corrosion. The anticorrosive performance of modified silicon nitride with silane (KH-570) was investigated by electrochemical impedance spectroscopy (EIS), water absorption and pull-off adhesion methods. With the increase of immersion time, the corrosion resistance as well as adhesion strength of epoxy resin coating and unmodified silicon nitride coating decreased significantly. However, for the modified silicon nitride coating, the corrosion resistance and adhesion strength still maintained 5.7×1010 Ω cm2 and 7.6xa0MPa after 2400-h and 1200-h immersion, respectively. The excellent corrosion resistance performance could be attributed to the chemical interactions between KH-570 functional groups and silicon nitride powders, which mainly came from the easy formation of Si-O-Si bonds. Furthermore, the modified silicon nitride coating formed a strong barrier to corrosive electrolyte due to the hydrophobic of modified silicon nitride powder and increased bonds.

Carbon Nanomaterials in Direct Liquid Fuel Cells

Fuel cells have attracted more attentions due to many advantages they can provide, including high energy efficiency and low environmental burden. To form a stable, low cost and efficient catalyst, we presented here the state of the art of electrocatalyst fabrication approaches, involving carbon nanotubes and their multifunctional nanocomposites incorporated with noble metals, such as Pt, Pd, Au, their binary and ternary systems. Both fuel oxidation reactions and oxygen reduction reactions were emphasized with comprehensive examples and future prospects.

Controllable Synthesis of Monolayer Poly(acrylic acid) on the Channel Surface of Mesoporous Alumina for Pb(II) Adsorption

Polymer/inorganic nanocomposites exhibit special properties due to highly intimate interactions between organic and inorganic phases and thus have been deployed for various applications. Among them, nanocomposites with monolayer polymer coverage on the inorganic surface demonstrate the highest efficiency for applications. However, the controllable synthesis of the polymer monolayer in mesopores of inorganic substrates remains a challenge. In this study, poly(acrylic acid)/γ-alumina nanocomposites (PAA/alumina) were synthesized via the in situ polymerization of acrylic acid impregnated in mesopores of alumina. By applying the preneutralization of monomers, the polymerization was found to be highly controllable in generating monolayer PAA coverage. The formation of monolayers was verified by thermogravimetry, semiquantitative Fourier transform infrared spectroscopy, N2 adsorption-desorption, and Pb(II) adsorption. Alternatively, the organic loadings of PAA/alumina composite samples could be controlled in the range of 0.2 to 1.0 equiv of monolayer, together with the linearly correlated metal ion adsorption capacity. As calculated by the complexation model, one Pb(II) is combined with two carboxylate groups of PAA. The formation of the monolayer polymer inside mesoporous oxide channels represents a method for the development of highly promising functional nanocomposites.

Hexavalent chromium removal over magnetic carbon nanoadsorbents: synergistic effect of fluorine and nitrogen co-doping

Fluorine and nitrogen co-doped magnetic carbons (FN-MCs) were obtained through a facile pyrolysis–carbonization processes. The physical and chemical properties of FN-MCs were comprehensively studied by various characterization techniques. FN-MCs were applied as adsorbents for the removal of chromium(VI) ions from aqueous solutions. The adsorption performance and kinetic characteristics were evaluated in batch mode. The results showed that the FN-MCs displayed an enhanced removal efficiency in neutral solution, higher than solo N or F doped adsorbents. The highest removal capacity in both neutral and acidic solutions was 188.7 and 740.7 mg g−1, respectively, competitive with the state-of-the-art carbon adsorbents. The unexpectedly high adsorption performance in the neutral solution can be attributed to the incorporation of the fluorine and nitrogen atoms simultaneously, which increased the negative charge density on the surface of the adsorbent. The removal efficiency increased along with the content of the heteroatoms and the defect value. The density functional theory (DFT) calculations demonstrated that the F and N co-doping reduced the adsorption energy between the Cr(VI) ions and adsorbent, thus boosting the adsorption efficiency in the neutral solution. Furthermore, the FN-MCs showed high stability in recycling tests for Cr(VI) removal.

Yeast-template synthesized Fe-doped cerium oxide hollow microspheres for visible photodegradation of acid orange 7.

Fe-doped cerium oxide (CeO2) hollow microspheres were successfully synthesized by a simple co-precipitation route using yeast asa bio-template and nitrate as the oxide precursor. The products were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption-desorption isotherms and UV-Vis diffuse reflectance spectroscopy. It was found that the products had a well-defined ellipsoidal morphology and the size of the hollow microspheres was about 1.5-2.5μm. The formation mechanism of Fe-doped CeO2 hollow microspheres was proposed and discussed as well. The photocatalytic test results showed that the Fe-doped CeO2 hollow microspheres exhibited a higher photocatalytic activity in the degradation of acid orange 7 (AO7) aqueous solutions containing H2O2 under visible irradiation compared with CeO2 hollow microspheres and Fe-doped CeO2 nanoparticles, which was attributed to their more oxygen vacancies, higher specific surface area and lower band gap. The degradation rate of the Fe-doped CeO2 hollow microspheres was found to be 93% after 80min and the degradation reaction followed pseudo-first-order kinetics.

Long-term antibacterial stable reduced graphene oxide nanocomposites loaded with cuprous oxide nanoparticles

Stable reduced graphene oxide-cuprous oxide (rGO-Cu2O) nanocomposites with long-term antibacterial activities were prepared by reducing copper sulfate supported on GO using ascorbic acid as reducing agent in the presence of polyethylene glycol (PEG) and sodium hydroxide at room temperature. The rGO provided a protective barrier for Cu2O, preventing Cu2O from reacting with external solution to leach copper ions too quickly. Meanwhile, the rGO also promoted the separation of photoexcited charge carriers of Cu2O nanoparticles to enhance the oxidative stress reactive and protected Cu2O from falling apart in the phosphate buffered solution (PBS) solution to prolong the generation time of reactive oxygen species (ROS). More importantly, the large specific surface area of rGO improved the dispersibility of Cu2O by electrostatic interaction. The synergistic effect of sustained release of copper ions, elevated ROS production ability and uniform dispersion of rGO-Cu2O nanocomposites resulted in the excellent antibacterial activities of rGO-Cu2O nanocomposites against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) which were maintained around 70% and 65% and were increased by 40% and 35% compared with free Cu2O after immersing 30u202fdays in PBS solutions.

Electrodeposition Synthesis of Polyaniline-Modified TiO2 Nanotube Arrays with Enhanced Photoelectrochemical Property

Polyaniline-modified TiO2 nanotube arrays (PANI/TNTs) were fabricated by a constant voltage electropolymerization method. The self-organized TiO2 nanotube arrays with an inner diameter of approximately 100u2005nm and a length of 4 μm were prepared by a two-step anodization at 20 V for 3u2005h, and then the polyaniline was deposited on the surface of the TiO2 nanotube arrays. The phase composition, morphology and property of PANI/TNTs were characterized by X-ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy and UV-vis diffuse reflectance spectroscopy. The prepared PANI/TNTs showed enhanced visible light absorption and corresponding visible light photocatalytic activity. Furthermore, the PANI/TNTs also exhibited higher electrochemical behaviour than that of TiO2 nanotube arrays.