JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2021
·
IF 4.464
Qing Wang,Zihan Zhang,Shaojie Shi,Fan Wu,Zhiguo Zhang,Guoneng Li,Yange Suo
In this work, highly active cobalt- and nitrogen-doped carbon (Co-N-C) materials were prepared for oxygen reduction reaction (ORR). The Co-N-C materials were synthesized through co-pyrolysis of ZIF-67 and melamine (ZIF-67@melamine). Detailed powder X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy and thermo-gravimentry (TG) analyses suggest melamine could accelerate the decomposition of the ZIF-67 framework. Compared with CoNC derived from pure ZIF-67, the CoNC- x C 3 H 6 N 6 materials derived from ZIF-67@melamine exhibit more carbon defects, larger BET specific surface area, higher content of pyridinic-N and graphitic-N, resulting in the enhanced activity of the CoNC- x C 3 H 6 N 6 samples. The onset potential of CoNC-0.5C 3 H 6 N 6 -700 catalyst towards ORR is 0.96 V (vs. RHE) and the half-wave potential is 0.87 V (vs. RHE), which are close to the state-of-the-art commercial Pt/C. Besides, the electrochemical stability of the CoNC-0.5C 3 H 6 N 6 -700 catalyst is much higher than that of commercial Pt/C.
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RSC Advances
·
2021
·Vol. 11
·期 33
·20391-20402
·
IF 3.361
Chen Cheng,Yanling Lu,Weining Ma,Shaojie Li,Jun Yan,Shiguo Du
Polydopamine/melamine composite microencapsulated red phosphorus (RP@PDA/MA) was prepared and applied as the flame retardant for epoxy resin (EP) in this work. For comparison, polydopamine (PDA) coated red phosphorus (RP@PDA) was also prepared. The microstructure, chemical composition and thermal decomposition of the as prepared samples were systematically characterized. The results showed that PDA and PDA/MA shell structures were fabricated successfully via convenient water-based processes at room temperature. The flame retardance of red phosphorus (RP), RP@PDA, and RP@PDA/MA on EP was evaluated. The results showed that EP blending with 7 wt% RP@PDA/MA passed V-0 degree in the vertical burning test (UL-94), reached a limited oxygen index (LOI) of 30.9% and decreased the peak heat release rate of EP by 65.1% in the cone calorimeter test. The satisfactory flame retardance can be attributed to the intumescent flame retardant system consisting of RP@PDA/MA. The PDA and PDA/MA shell structures also improved the compatibility between RP and EP, thus RP@PDA and RP@PDA/MA had less significant impact on the tensile–strain properties of EP.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2021
·
IF 4.464
Yun-Yun Cheng,Tao Zhan,Xiao-Zhen Feng,Guo-Cheng Han
Novel synergistic effect between gold nanoparticles (AuNPs) and melamine (MEL) signal amplification were used to develop a sensor in this study to detect C-reactive protein (CRP). A ferrocene derivative (Fc-ECG) was used as electrochemical probe, as well as sensitive element, to prepare the sensor. The Fc-ECG/MEL/AuNPs/SPE disposable electrochemical sensor was fabricated by depositing AuNPs onto the SPE. Combination with MEL for their synergistic effect allowed for dual signal amplification, which was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the developed sensor presented a linear concentration range from 0.001 to 1000 μg mL −1 , and relationship between peak current response and logarithm of CRP concentration was represented by the following regression equation: I (μA) = 7.6468–0.78446 lgC (μg mL −1 ) with 0.99506 correlation coefficient (R 2 ). The detection limit for the sensor was 0.30 ng mL −1 and sensitivity was 11.10 μA μg −1 mL cm −2 . When compared to CS/Fc(COOH)/SPE sensor, the detection limit was lowered 1000 times, and sensitivity was improved 56 times by the prepared sensor. The sensor was also used in human serum samples, with 98.69–102.43% recovery and lower than 6.59% total R.S.D, indicating that it is also usable for rapid detection of CRP in actual samples.
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NANOTECHNOLOGY
·
2020
·Vol. 31
·期 47
·475406
·
IF 3.551
Fengzhi Wang,Weisheng Lei,Xinhua Pan,Zhizhen Ye
Graphitic carbon nitride (g-C3N4) has been regarded as an intriguing photocatalyst applying to hydrogen generation but suffering rapid recombination of photoinduced electron-hole pairs and insufficient absorption under visible light. We developed a novel one-pot thermal copolymerization method of melamine as a precursor and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a comonomer to synthesize modified g-C3N4 (abbreviated as X% TCNQ) for the first time, aiming to directly incorporate TCNQ molecular into carbon nitride skeleton for the substitution of low-electronegative carbon for high-electronegative nitride atom. Results revealed that the as-prepared photocatalysts by copolymerization of melamine with TCNQ retained the original framework of g-C3N4, and dramatically altered the electronic and optical properties of carbon nitride. Various measurements confirmed that as-synthesized samples exhibited larger specific surface areas, faster photogenerated charge transfer and broader optical absorption by decreasing the π-deficiency and extending the π-conjugated system, thus facilitating the photocatalytic activity. Specifically, the 0.3% TCNQ exhibited as high as seven times than the pristine g-C3N4 on photocatalytic H2 generation and kept its photoactivity for five circles. This work highlights a feasible approach of chemical protocols for the molecular design to synthesize functional carbon nitride photocatalysts by copolymerizing appropriate g-C3N4 precursor and comonomers.
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CARBOHYDRATE POLYMERS
·
2020
·
IF 7.182
Ce Gao,Xue-Lian Wang,Qing-Da An,Zuo-Yi Xiao,Shang-Ru Zhai
Superior mechanical properties, high adsorption capacity, and excellent regeneration property are crucial design criterions to develop a new-type aerogel for adsorptive applications towards heavy metal removal from water. Herein, chitosan and melamine not only introduced abundant functional groups to increase adsorbing sites for lead ions, but also reinforced the three-dimensional network skeleton structure of absorbents to improve the service life in adsorption applications. As-fabricated alginate/melamine/chitosan aerogel can extract Pb (II) from aqueous solution efficiently, i.e. , the optimum adsorption quantity of 1331.6 mg/g at pH 5.5, which exhibited excellent and selective adsorption capacity for Pb (II) against the competition of coexisting divalent metal ions. More importantly, alginate/melamine/chitosan aerogel could be regenerated using dilute acidic solution and recovered well after eight adsorption-desorption cycles. This work might offer a new idea for design and preparation of biomass-based aerogel sorbents with promising prospect in the remediation of Pb (II)-contaminated wastewater.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2020
·Vol. 138
·期 11
·50038
·
IF 2.52
Linjiong Zhang,Lianfang Feng,Xueping Gu,Cailiang Zhang
Oil spills and organic chemical leakage have caused serious environmental problems, calling for highly effective adsorbents at low cost. Superelastic and hydrophobic-oleophilic modified melamine foams with ultralow amounts of well-dispersed graphene were prepared via dip-coating. The composite foams showed high selectivity for adsorbing various organic chemicals from water and could be regenerated easily. Moreover, excellent adsorption capacity ranging from 80 to 170 times its own weight was found depending on the density of organic chemicals. These coated foams show great potential for continuous oil/water separation and oil fume removal.
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JOURNAL OF MATERIALS SCIENCE
·
2020
·Vol. 55
·期 27
·12836-12847
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IF 3.553
Zhu Zongmin,Lin Panlong,Wang Hao,Wang Luoxin,Yu Bin,Yang Feihua
Abstract In order to improve the flame retardancy and smoke suppression of epoxy resin (EP) simultaneously, we synthesized a melamine phenylhypophosphonate named as MABP via a simple one-step method and used it to modify EP materials. As expected, the addition of MABP not only largely improved the flame retardancy but also restrained the smoke release of EP. For details, when the content of MABP was 10 wt%, the EP composite possessed a limiting oxygen index value of 33% and achieved to a UL-94 V-0 rating as well as its PHRR, THR and TSP values decreased by 55.1%, 27.1% and 60% compared with that of neat EP, respectively. In addition, the flame-retardant mechanism was investigated by multiple instruments, and the corresponding results exhibited that the MABP could improve the compactness of char layer in condense phase and exerted fire-inhibition effect in gaseous phase. Graphic abstract
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Hualun Li,Ye Li,Yuzhi Zhou,Bolin Li,Dongbin Liu,Hanyang Liao
In this study, we prepared a hydrothermal carbon-based supramolecular organic framework (HTC-MA-TMA) by grafting melamine and trimesic acid on hydrothermal carbon (HTC) for efficient removal of U (VI) from aqueous solutions. The nano-sized supramolecular organic framework (SOF) particles consisted of N-donor-containing melamine and O-donor-containing trimesic acid self-assembled through hydrogen bonds . Their large number of specific active sites acted as the immobilization center for capturing U (VI). Chemical modification facilitated the dispersion of the SOF particles on HTC, which was synthesized using a novel covalent/non-covalent bond strategy. The HTC-MA-TMA adsorbent exhibited exceptional U (VI) adsorption capacity (271.83 mg/g) because of the coordination interaction between UO 2 2+ and its ligands (amino, carboxyl and amide groups). The adsorption equilibrium was achieved within 30 min and followed a pseudo-second-order equation, suggesting the occurrence of a chemical adsorption process . Furthermore, the U (VI) ions adsorbed onto the HTC-MA-TMA adsorbent could be easily desorbed using 0.1 M HNO 3 solution. This regeneration caused no significant decrease in the sorption capacity of the adsorbent. These results suggest that advanced HTC-MA-TMA adsorbent can be applied in the nuclear-fuel industry for extracting U (VI) from radioactive wastewater .
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2019
·Vol. 125
·期 11
·1-7
·
IF 1.784
Ge Bo,Li Fengyan,Zhao Xingchuan,Li Wenzhi,Ren Guina,Wang Min,Zhang Zhaozhu
Sewage not only contains water-soluble contaminants but water-insoluble contaminants as well. Superhydrophobic CdS–melamine foam prepared in this research satisfies the requirements of water purification. The photocatalyst CdS effectively adsorbs light energy to generate active species (⋅O 2 − ) for degrading water-soluble pollutants. At the same time, superhydrophobic/superoleophilic characteristic of the melamine sponge can be utilized to remove water-insoluble pollutants. Finally, the degradation mechanism of materials was obtained by studying the parameters such as band gap and valence band structure, as well as by analyzing the experimental data of active species.
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Applied Sciences-Basel
·
2018
·Vol. 8
·期 4
·560
·
IF 1.689
Guangyang Liu,Yongxin She,Sihui Hong,Jing Wang,Donghui Xu
Featured ApplicationThe developed method would be useful for monitoring melamine in milk and formula powdered milk.AbstractWe present a directly competitive fluorescence assay for highly sensitive detection of melamine in milk using magnetic dummy molecularly imprinted polymers (MDMIPs). The detection principle is based on competitive binding between the fluorescent label and melamine on the MDMIPs. The fluorescent label was obtained by combining fluorescein isothiocyanate (FITC) with melamine in ethanol and water. MDMIPs were prepared on the surface of Fe3O4@SiO2nanoparticles using 2,4-diamino-6-methyl-1,3,5-triazine as dummy template. The MDMIPs were characterized and their adsorption capacity was evaluated based on their static adsorption and Scatchard analysis. Results suggest that MDMIPs were successfully coated on the Fe3O4@SiO2surface and had a core–shell structure. Adsorption experiments suggested that the MDMIPs had higher specific recognition capacities for melamine and FITC–melamine (FITC-Mel) than did magnetic dummy molecularly non-imprinted polymers. Competitive binding between FITC-Mel and melamine was performed under the optimum conditions to determine melamine quantitatively. The linear range of this fluorescence assay was 0.1–20 mg/L for melamine detection. The detection limit was 0.05 mg/L in negative milk samples. The assay was also successfully employed to detect melamine in spiked milk samples, with satisfactory recoveries, i.e., between 70.2% and 92.7%.Keywords:ELISA-like fluorescence assay;magnetic dummy molecularly imprinted polymers;2,4-diamino-6-methyl-1,3,5-triazine;fluorescein isothiocyanate;melamine
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JOURNAL OF FOOD PROCESS ENGINEERING
·
2018
·Vol. 42
·期 2
·e12976
·
IF 1.955
Ning Yang,Liang-Liang Xie,Chen Pan,Min-Feng Yuan,Zhi-Han Tao,Han-Ping Mao
Ubiquitous food security control is desirable. However, the analysis methods, such as those for milk, are highly based on manual analysis, leading to low efficiency. Thus, we report a multilayer paper-based microfluidic chip transforming chromatic readout to electric signals. First, colloidal gold immunochromatographic assays (GICA) are used to achieve the colorimetric occurrence. Secondly, the test (T) lines and control (C) lines are patterned to encode different EAN-8 barcode. Furthermore, accurate scanning is accomplished by the automatic threshold segmentation. These technologies make the digital determination of melamine (MEL) and chloramphenicol (CAP) by phone readily accessible. Results indicate that the accurate machine-scanning can be assured when MEL and CAP is above 30 ng/mL and 6 ng/mL in milk respectively. The detection time is under 8 min, and the stable storage life is over 90 days. Therefore, this simple chip allows rapid, machine-readable, electric-recordable diagnostic directly from chromatic assays with satisfying stability, specificity and accuracy. Practical applications This article illustrates a method used to determine the concentration of melamine and chloramphenicol in milk. When melamine and chloramphenicol is above 30 and 6 ng/ml in milk, the produced EAN-8 barcode can be recognized with high accurate level, compared with international standards, the results are acceptable and sensitive. This method is highly intellectual and environmentally friendly, with the disposable materials and instant smartphone-readable EAN-8 results patterns. This article demonstrates a multilayer paper chip based on EAN-8 encoding rules, colloidal gold nanoparticles, and immunochromatographic assays. The EAN-8 format assay is achieved by color-development occurrence of colloidal GICA in different encoding areas of EAN-8 code, and the analysis device, namely smartphone, is accessible by almost every individual. Therefore, this chip can pave a potential way for massive health control and digital automated analysis for daily life and industrial manufacture.
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Advanced Science
·
2018
·Vol. 6
·期 2
·1801432
·
IF 12.441
Youshen Wu,Hui Zhang,Aizhao Pan,Qi Wang,Yanfeng Zhang,Guijiang Zhou,Ling He
Graphene quantum dot (GQD) encapsulated melamine-formaldehyde (MF) polymer microspheres with uniform particle size and tunable high-quality white-light emissions are prepared via a polymer-mediated GQD assembly and encapsulation strategy. In solution, GQDs are first aggregated with MF prepolymer through electrostatic interaction and further encapsulated inside the microspheres formed by polymerization of MF prepolymer under acid catalysis and heating. During this process, the aggregated GQDs are fixed in the MF polymer matrix with their emission extended from blue to full visible range, presenting bright white luminescence under ultraviolet excitation. The prepared white-light-emitting GQD-MF microspheres exhibit uniform morphology with an average particle size of 2.0 ± 0.08 µm and their luminescence properties are effectively regulated by the doping concentration of GQDs in the MF polymer matrix. A series of white-light-emitting GQD-MF microspheres with quantum yields from 0.83 to 0.43, Commission Internationale de L'Eclairage coordinates from (0.28, 0.28) to (0.33, 0.32), and color rendering index from 0.75 to 0.88 are obtained with excellent photostability and thermal stability. By dispersing the GQD-MF microspheres in cross-linked polydimethylsiloxane matrix, flexible film with dual functions of high-quality white-light-emitting and light diffusion is obtained and successfully applied for white light-emitting diode fabrication.
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