查找使用阿拉丁产品的科研文献

EM waves absorption properties of nitrogenous porous carbon derived from PANI fiber clusters carbonization

Xiang Luo,Haifeng Li,Jihui Sun,Xutao Yan,Yijian Liu,Li Sun,Meijie Zhang

The carbon source, graphitization degree and microstructure of pure carbon materials have strong effects on their electrical conductivity , impedance matching and electromagnetic (EM) waves absorption properties. A novel microstructure nitrogenous porous carbon (NPC) material with excellent EM waves absorption properties was synthesized by carbonizing polyaniline (PANI) fiber clusters. When the filler loading is only 30  wt %, the widest effective absorption bandwidth ( EAB ) reached 5.5 GHz from 12.41 GHz to 17.91 GHz (almost the entire Ku band) with a thickness of only 1.5 mm and the EAB /thickness was up to 3.67 GHz/mm, which is not inferior or even better than many composites with complex structure. The nitrogen atoms in NPC lattice reduced its graphitization degree. The synergistic effect of optimized impedance matching and enhanced dielectric loss improved EM waves absorption of NPC. The EM waves dissipation mechanisms of NPC material mainly include dipole polarization, interface polarization and conductance loss. The synthesized NPC is a potential EM waves absorption material.

Kinetics of CO2 absorption into ethanolamine + water + ethanol system—mechanism, role of water, and kinetic model

Qinlan Luo,Qiang Sun,Qi Liu,Sen Liu,Min Xiao,Mengjie Chen,Yuanyuan Li,Hongxia Gao,Zhiwu Liang

The kinetics of CO 2 absorption in ethanolamine (MEA) + H 2 O + ethanol systems was investigated using stopped-flow apparatus. The first-order reaction rate constant ( k 0 ) values were tested with varying H 2 O and MEA concentrations. Transiting from the aqueous to non-aqueous solvents, the k 0 decreases and the reaction order for MEA shifts from 1.05 to 1.88. The zwitterion mechanism with the rate-limiting step of deprotonation was used to explore the role of water and its effect. Results showed that water could impact reactions through direct involvement and changing solvation environment. An improved kinetic model based on the zwitterion mechanism was obtained to indicate the quantitative influence of H 2 O concentration on the reaction kinetics of MEA + H 2 O + ethanol systems. The predicted values from the model well agreed to the experimental data with the average absolute relative difference of 6.73%. This study highlights the important effects of water on the reaction kinetics of CO 2 absorption into water-lean amine solutions.

Mesoporous hollow nanospheres with amino groups for reverse osmosis membranes with enhanced permeability

Xu Dong,Xiaojuan Wang,Huacheng Xu,Yijun Huang,Congjie Gao,Xueli Gao

Aiming at enhancing the permeability of reverse osmosis (RO) membranes, polyaniline-co-polypyrrole hollow mesoporous nanospheres (PPHMNs) were synthesized with aniline and pyrrole monomers via a simple and rapid one-step method, and then added to the aqueous phase of interfacial polymerization to fabricate thin-film nanocomposite (TFN) membranes. Hollow cores of the PPHMNs embedded in polyamide layers could reduce the interior transfer resistance of the membrane and shorten the transmission pathway of water molecules. Mesoporous shell of PPHMNs provided more channels for rapid transmission of water molecules. Moreover, amino groups in PPHMNs originated from the monomer of aniline could not only be bonded to polyamide (PA) layer by reacting with acyl chloride groups to prevent the leakage but also improve hydrophilicity of the membrane. Water flux of TFN membrane doped with PPHMNs (TFN-Ps) of 0.005 wt% addition concentration was 34.1 L·m − 2 ·h − 1 which is 76.7% higher than that of thin-film composite (TFC) membrane, and the NaCl rejection all kept over 99.0%. The TFN-Ps also showed excellent long-term stability, chlorine resistance and anti-fouling performance. This work opens an avenue for application of mesoporous hollow nanospheres with amino groups synthesized by simple and time-saving methods in developing TFN membranes with improved water flux.

A carbon dot based metal-free photoelectrochemical cell using O2/H2O redox couple in real seawater

Zhaomin Chen,Zhenyu Wu,Jia Xu,Rui Zhao,Xiaoxia Han,Jiwei Jiang,Mingwang Shao,Bin Dong,Zhenhui Kang

Photochemical devices show great potential in applications ranging from electrical energy storage to future smart grids. Here, we report a metal-free composite film cell based on carbon dots (CDots) and polyaniline (PANI), which could achieve 24/7 discharge and photo-charging in seawater. CDots/PANI film cell has an open-circuit-voltage (OCV) of 0.95 V, a maximum power density of 380 mW m 2 , and the ability to discharge continuously for 40 h under solar irradiation of AM 1.5 G. It couples the reduction reaction of PANI, and the CDot-catalyzed oxygen reduction reactions (ORR) during discharge. While the light-induced CDot-catalyzed oxygen evolution reaction (OER) and the reduction reaction of PANI during charging. In particular, in-situ TPV tests were used to verify the effect of the light-induced OER and the kinetic properties of the catalyst on the charge transfer at the interface. We believe this research may provide new ideas for sustainable energy conversion and storage.

Monomer-mediated fabrication of microporous organic network@silica microsphere for reversed-phase/hydrophilic interaction mixed-mode chromatography

Hao-Fei Sun,Yuan-Yuan Cui,Chang-Qing Zhen,Cheng-Xiong Yang

Microporous organic networks (MONs) are promising in high performance liquid chromatography (HPLC) with large specific surface area, good hydrophobicity and stability. However, their superhydrophobic structures restrict MONs-based HPLC only in reversed-phase mode. To decrease the hydrophobicity of pristine MONs and to expand their broad application in HPLC, here we described the monomer-mediated fabrication of core-shell MON-2COOH@SiO 2 microspheres for reversed-phase liquid chromatography (RPLC)/hydrophilic interaction liquid chromatography (HILIC) mixed-mode chromatography for the first time. The –COOH groups were introduced into MONs’ skeleton to improve their hydrophilicity and to provide hydrophilic interaction sites. The MON-2COOH was grafted onto silica via a monomer mediated method to produce monodispersed core-shell microspheres. By adjusting the concentration of reactants, the thickness of MON-2COOH shell was easily manipulated. The packed MON-2COOH@SiO 2 column showed high resolution and selectivity for separating both hydrophobic (alkylbenzenes, polycyclic aromatic hydrocarbons , anilines and phenols) and hydrophilic (nucleoside and nucleic bases) probes, highlighting the promise of MONs in mixed-mode HPLC. The MON-2COOH@SiO 2 column also achieved good separation to sulfonamides, nonsteroidal anti-inflammatory drugs, flavonoids and phenylurea herbicides , and offered better resolution than commercial C18 and pristine SiO 2 column. Multiple retention mechanisms were also found on MON-2COOH@SiO 2 packed column, underlining the great potential of MONs in mixed-mode HPLC.

Preparation and Performance Study of Carboxy-Functionalized Graphene Oxide Composite Polyaniline Modified Water-Based Epoxy Zinc-Rich Coatings

Zhonghua Chen,Yuande Cai,Yunyun Lu,Qi Cao,Peibin Lv,Yiru Zhang,Wenjie Liu

Graphene oxide is obtained by oxidation of graphite followed by ultrasonic exfoliation. It is a two-dimensional layered material with a large number of oxygen-containing functional groups on its surface. Polyaniline is a conductive polymer and has a unique corrosion protection mechanism. In this study, carboxy-functionalized graphene oxide/polyaniline (CGO/PANI) composites with a lamellar structure were prepared by in situ polymerization. The lamellar layer was used to form a labyrinthine structure in the coating to effectively retard the penetration of corrosive media. The electrical conductivity of polyaniline can promote the formation of conductive pathways between zinc particles and improve the utilization of zinc powder. Polyaniline is also able to passivate the substrate, further improving the coating’s ability to protect steel substrates against corrosion. In this paper, the in situ polymerization of aniline on carboxy-functionalized graphene oxide flakes was confirmed by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), and the improvement of the corrosion resistance of the prepared composites on the epoxy zinc-rich coatings was evaluated by SEM, electrochemical impedance spectroscopy (EIS), and salt spray resistance tests. The results showed that aniline was successfully polymerized in situ on carboxy-functionalized graphene oxide, and the modified coating had significantly improved anticorrosive properties, where the best anticorrosive improvement was achieved when CGO: PANI = 0.03.Keywords:graphene oxide;polyaniline;composites;coating;epoxy zinc-rich;anticorrosive

Novel co-polymerization of polypyrrole/polyaniline on ferrate modified biochar composites for the efficient adsorption of hexavalent chromium in water

Wei Mao,Ying Zhang,Jinen Luo,Lingtiao Chen,Yuntao Guan

It is still a huge challenge to prepare cheap and effective composite materials for removing hexavalent chromium (Cr(VI)) in sewage treatment . In this study, a noval co-polymerization of polypyrrole/polyaniline on ferrate modified biochar (Ppy/PANI/FBC) was fabricated via ferrate-promoted pyrolysis and in-situ oxidative polymerization of pyrrole and aniline molecules to effectively remove Cr(VI) from polluted water. The Ppy/PANI/FBC quickly decreased Cr(VI) concentration from 38.92 to 3.92 mg/L within 400 min, with an efficient removal efficiency (89.92%), which was significantly higher than that of FBC (4.75%), Ppy/FBC (72.30%), and PANI/FBC (42.43%). These results are mainly caused by its conjugated connection and well-dispersion of Ppy and PANI on the surface of a carbon-based material. Meanwhile, the experimental results were in line with the pseudo-second-order kinetic and Freundlich models. The Ppy/PANI/FBC is featured by a high capacity of Cr(VI) adsorption (up to 203.71 mg/g). In addition, it could be adopted for efficiently removing Cr(VI) over a wide pH range (4–9) because of the positively charged nitrogen (–NH .+ – and = N + –). The sorption mechanisms of Cr(VI) were identified, including electrostatic interaction with surface protonated nitrogen (N + ), ion exchange between the doped Cl − ions and Cr(VI), chemical decrease of the Cr(VI) to Cr(III) by the iron valence cycle and efficient electron transfer of Ppy/PANI/FBC, as well as surface complexation by amine and oxygen-containing groups. More importantly, 97.98% Cr(VI) was efficiently removed in 20 min by coupling a photocatalytic reaction, also providing a novel idea for the practical use of adsorbents in wastewater treatment .

Facile fabrication of flexible alginate/polyaniline/graphene hydrogel fibers for strain sensor

Yu Wu,Sihao Zhou,Jie Yi,Dongsheng Wang,Wen Wu

Continuous production of conductive hydrogel fibers has received extensive interests due to their wide application in strain sensors. In this paper, we report on the fabrication of continuous alginate/polyaniline/graphene hydrogel fibers by the in situ polymerization and wet spinning methods. The obtained hydrogel fiber with good flexibility, high water absorbability (11.37 g/g), proper resistivity (220 Ω·m ) and stable resistance changes at both low strain (10%) and high strain (20% and 50%) could be used as a working strain sensor for a wearable human movements monitor. The conductive alginate/polyaniline/graphene hydrogel fiber shows highly sensitive, flexible, and recoverable (90% retention after five cycles) properties when monitoring palm, elbow, and knee movements. This kind of hydrogel with high elasticity and high sensitivity provides a possibility for the preparation of electromechanical sensors.

Effect of bicarbonate on nitrate-induced photosensitive degradation of sulfamethoxazole under UV irradiation

Yiqing Liu,Shixiang Wang,Dongbin Fu,Yongsheng Fu

Stretchable, self-healable and anti-freezing conductive hydrogel based on double network for strain sensors and arrays

Sun Xiao,Zhong Wenzhao,Zhang Zhanzhan,Liao Haiyang,Zhang Changfan

The application of hydrogels for flexible sensor is gravely hampered due to their poor freezing resistance and fatigue fracture associated with durable deformation, hence hydrogels that can operate correctly at sub-zero temperatures and sustain long-term deformation are urged for wearable electronics and implantable sensors. In this paper, we develop conductive hydrogel (HB-Hydrogel) based on multi-hydrogen-bonded double network of polyvinyl alcohol (PVA) and polyaniline (PANI) via in-situ polymerization and solvent conversion. Tannin in the ethylene/water (EG/H 2 O) binary solvent induces multiple dynamic hydrogen bonding network that closely connect PVA and PANI together, enduring HB-Hydrogel with outstanding self-healing capability and remarkable mechanical properties. On the other hand, HB-Hydrogel retains good flexibility even at − 20 °C by exchanging the aqueous solvent with EG/H 2 O binary solvent. In-situ polymerization of conductive PANI conquers the dispersion issue in PVA hydrogel to generate a homogeneous conductive network, resulting in very high sensitivity (GF =  ~ 3.52) at low strain and outstanding linear dependence of sensitivity on strain. The assembled strain sensor equipped with the HB-Hydrogel can efficiently collect data of human monitoring, including the joint movements, pulses and voice-prints. Furthermore, a prototype 2D sensor array is built to detect strains or pressures in two dimensions, which is promising for electronic skin, touchpads, biosensors, human–machine interfaces, biomedical implants, wearable electronic devices and other applications.

Melem based mesoporous metal-free catalyst for cycloaddition of CO2 to cyclic carbonate

Yuanping Zhang,Hongguang Liang,Xiaoyun Li,Qifeng Li,Junwei Wang

A highly efficient melem based mesoporous metal-free catalyst with amino and hydroxyl groups was successfully developed by template method with melamine as precursor and nano-SiO 2 as template. In the absence of any co-catalyst and solvent, the catalyst mp-CN-450 exhibits high catalytic activity for catalytic cycloaddition reaction between CO 2 and polyfunctional epoxides , and the epoxides conversion and corresponding cyclic carbonates selectivity are 99.7 % and 99.5 %, respectively. And the catalyst has hardly loss of catalytic activity after being reused for four cycles. The characterization results disclose that the high catalytic activity of the catalyst is closely related to its large specific surface area, abundant mesoporous structure and synergistic effect of N species and hydroxyl groups of melem hydrates. Additionally, through the study of different N-containing compounds, it was found that the primary amine may underwent a ring-opening reaction with epoxide. But with the addition of CO 2 , amine groups prior to reacted with CO 2 to form carbamate salt , avoided the formation of by-products, thereby improved the selectivity of cyclic carbonate. Finally, based on the above research, a possible reaction mechanism for the coupling of CO 2 to epoxides was proposed.

A label-free electrochemical sensor constructed with layer-by-layer assembly of GCE-AuNPs-Q[7]·HAuCl4 for detection of diphenylamine

Wang Cheng-Yan,Ge Qingmei,Jiang Nan,Cong Hang,Tao Zhu,Liu Mao,Fan Ying

Metal–organic frameworks (MOFs) including cucurbit[7]uril block (Q[7]·HAuCl 4 ) were employed to develop a diphenylamine (DPA) sensor in electrochemical method, the presence of HAuCl 4 improved the conductivity of the macrocyclic compound. To further enhance of the sensitivity, Au nanoparticles were inserted between the surface of glassy carbon electrode and Q[7]·HAuCl 4 MOFs (GCE-AuNPs-Q[7]·HAuCl 4 ). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) were applied for evaluation on the electrochemical behavior. For the electrochemical inertness of DPA, a label-free electrochemical sensor in 5 mM K 3 [Fe(CN) 6 ] solution was achieved, to produce a limit of detection as low as 4.6 µM in a linear range of 5–1000 µM with good reproducibility, high stability and acceptable anti-interference ability. Application of the proposed electrode for the quantitative determination of DPA in tap water and apple juice confirms its real value. Graphical abstract