JOURNAL OF SEPARATION SCIENCE
·
2015
·Vol. 38
·期 20
·3655-3660
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IF 2.737
Ziru Lian,Zhenlin Liang,Jiangtao Wang
This research highlights the application of highly efficient molecularly imprinted solid-phase extraction for the preconcentration and analysis of melamine in aquaculture feed samples. Melamine-imprinted polymers were synthesized employing methacrylic acid and ethylene glycol dimethacrylate as functional monomer and cross-linker, respectively. The characteristics of obtained polymers were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy and binding experiments. The imprinted polymers showed an excellent adsorption ability for melamine and were applied as special solid-phase extraction sorbents for the selective cleanup of melamine. An off-line molecularly imprinted solid-phase extraction procedure was developed for the separation and enrichment of melamine from aquaculture feed samples prior to high-performance liquid chromatography analysis. Optimum molecularly imprinted solid-phase extraction conditions led to recoveries of the target in spiked feed samples in the range 84.6–96.6% and the relative standard deviation less than 3.38% ( n = 3). The aquaculture feed sample was determined, and there was no melamine found. The results showed that the molecularly imprinted solid-phase extraction protocols permitted the sensitive, uncomplicated and inexpensive separation and pre-treatment of melamine in aquaculture feed samples.
研究领域:
分析化学
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食品科学
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环境科学
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产品关联
DOI
PubMed
高影响因子
TALANTA
·
2018
·
IF 4.244
Xin-Yue Chen,Wei Ha,Yan-Ping Shi
In this study, the asymmetrically modified gold nanoparticles (AuNPs) with relatively large size are proposed for highly sensitive detection of melamine in raw milk. At first, we found that the sensitivity of colorimetric detection of melamine based on the conventional citrate-stabilized AuNPs could be significantly increased (limit of detection by visual observation: from 1 μmol L −1 to 1 nmol L −1 ) via enlarging the size of AuNPs (from 13 to 42 nm). However, the large-sized AuNPs are unstable in the solution, and the accuracy of relevant aggregation-based colorimetric detection method is dramatically decreased due to the rapid evanishment of the color of solution caused by the precipitation of large-scaled AuNPs aggregates after introducing melamine. In view of this limitation, the stabilizing agent polyethylene glycol (PEG) is introduced onto the selected area at the surface of AuNPs to stabilize the large-sized AuNPs sensor and further adjust the aggregation behavior in an oriented and controllable manner. As a result, the addition of melamine into asymmetrically PEGylated AuNPs with large size could still induce a color change from purple to blue, but the color change could be maintained in aqueous solution for a long time. This improvement is mainly caused by forming stable and oriented oligomers of AuNPs taking advantage of the asymmetrical modification of AuNPs with PEG chain in this system. Such a way of aggregation leads to remarkably enhanced long-term stability and an at least 2 orders of magnitude wider dynamic detection range (1.05 nmol L −1 to 1 mmol L −1 ) compared with conventional AuNPs sensors. Finally, such a novel asymmetrically modified AuNPs sensor is successfully applied to detect melamine in the raw milk with the satisfactory spiked recovery from 99.6% to 103.7% and RSD of about 3.0%. This work provides a sensitive and reliable method to detect melamine in pretreated milk, indicating a new avenue to make innovation on colorimetric sensors for real sample detection.
研究领域:
分析化学
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食品科学
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纳米技术
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产品关联
DOI
PubMed
高影响因子
Analytical Methods
·
2017
·Vol. 10
·期 4
·417-421
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IF 1.9
Jing-yan Kang,Yu-jie Zhang,Xing Li,Chen Dong,Hong-yu Liu,Li-jing Miao,Paul J. Low,Zhi-xian Gao,Narayan S. Hosmane,Ai-guo Wu
A colorimetric sensor for the pesticide pymetrozine (PYM) based on analyte-induced aggregation of melamine-modified gold nanoparticles (M-Au NPs) has been developed with high selectivity and sensitivity with a detection limit of 80 nM by the naked eye and 10 nM by UV-Vis spectroscopy. This colorimetric sensing design exhibits lower detection limits, compared with limits of 46–148 nM for existing instrumental methods. The new aggregation-induced nanoparticle sensor is applicable for rapid colorimetric detection of PYM in real water environments (tap water and lake water) and food samples (green tea and apple juice). The technical approach for the colorimetric sensor is easier and simpler than detection of PYM by, for example, HPLC whilst giving equivalent results within the error of the measurements.
研究领域:
环境科学
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分析化学
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食品科学
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Energy
·
2022
·
IF 9.257
Xiaochun Hu,Yuqing Luo,Xianyue Wu,Jiabin Niu,Mingwu Tan,Zhiqiang Sun,Wen Liu
Heteroatom-doped microporous carbon nanosheets (HMCNs) are used in a wide range of applications, including gas adsorption, energy storage, and catalysis. Here, we demonstrate a solvent-free, template-free, one-pot polycondensation approach for the synthesis of HMCNs using melamine (MEL) and pentaerythritol (PER) as precursors. By varying the ratio of MEL to PER and the pyrolysis temperature, the doping amount, surface area and porosity of the HMCNs can be controlled. When used for CO 2 capture, the HMCN synthesized by the pyrolysis of a 3:2 mixture of MEL and PER at 900 °C (3/2-HMCNs-900) affords a CO 2 uptake of 5.35 mmol g −1 at 273 K and 1 bar CO 2 partial pressure. Density functional theory calculations suggest that the high CO 2 uptake performance of the HMCNs is associated with the chemical modification of the surface, as a result of N- and O- co-doping. When assembled in a supercapacitor , 3/2-HMCNs-900 exhibits a high specific capacitance (475 F g −1 at 1.3 A) and a fast charge-discharge rate of 13.3 F s −1 g −1 . This study presents a novel, resource-efficient and environmentally friendly method for preparing HMCNs for energy and environmental applications.
研究领域:
材料科学
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能源与环境科学
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产品关联
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
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2022
·
IF 5.477
Chenchen Zhang,Yaozong Gao,Jian Yin,Yufeng Zhang,Jianqiang Meng
Background Porous organic polymers (POPs) are excellent candidates for supporting and stabilizing metal nanocatalysts. The preparation of POPs monolithic membranes as carrier materials for continuous flow catalytic reactors is of significant industrial value. Methods In this work, monolithic poly-melamine-formaldehyde (ah-PMF) gel-filled membranes were prepared by filling high internal phase emulsions containing melamine and paraformaldehyde into nickel membranes with specific shapes. After in situ loading of palladium nanoparticles (Pd NPs) in ah-PMF, the composite membranes were used for the catalytic reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) under both static and continuous flow conditions. Significant findings The ah-PMF with high specific surface area and advanced hierarchical porous structure can be obtained by regulating the F127 feed, which is beneficial to improving the catalytic efficiency. The results showed that the Pd@ah-PMF composite membrane had better catalytic activity when the F127 content was 35%, especially in the continuous flow catalytic process, with 99% conversion of 10 mg/L 4-NP in 21 min. In addition, the Pd@ah-PMF showed good recyclability. This work provides a strategy for the design of carrier materials for continuous flow reactors.
研究领域:
材料科学
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环境化学
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催化反应工程
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DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
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IF 5.518
Shiyu Luo,Yanping He,Linhua Zhu,Tian Si,Yanlin Sun
Core oils’ properties are significant for the microencapsulation process. 12 representative single componential core oils with different chemical structures , logP , solubility, interfacial tension (IFT) and viscosity were specially selected to fabricate melamine-formaldehyde (MF) microcapsules. Afterward, the effect of core oils’ properties on the performance of microcapsules was investigated. It was found that the morphology, the average particle sizes (7.83 µm∼27.06 µm), the encapsulation efficiencies (47.35 ± 3%∼92.86 ± 4%), zeta potentials (−52.37 ± 2.97 mV∼−65.03 ± 0.79 mV) and the rupture forces (0.28 ± 0.20mN∼0.82 ± 0.3mN) of microcapsules were influenced by core oils’ properties. Further comprehensive analysis indicated that logP≥ 1.66 and the solubility≥ 0.055 mL 3 /g were the premises for the successful encapsulation processes. Moreover, by increasing logP, IFT and viscosity, the size of microcapsules increased; as microcapsules size increased, the release rate decreased; the high IFT and the solubility increased the encapsulation efficiency of microcapsules; the mechanical property was influenced by logP. This work provided to use logP as the criterion to predict the encapsulation work, which hasn’t been studied before; and the correlations between microcapsules’ various performances and core oils’ properties were initially established. This work was meaningful since logP was used as a clear criterion to select core oils for encapsulation work and core oils’ properties were used to predict the application performances of microcapsules.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2023
·Vol. 30
·期 35
·84609-84619
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IF 5.8
Wu Zhaojiang,Lin Zheng,Wang Shengye,Yang Bo,Xiao Ke
The recovery of platinum from industrial waste is of critical importance. Usually, the recovery method is to dissolve the solid waste with acid to form a solution where platinum mainly exists in the form of Pt(IV). Therefore, it is urgent to efficiently and selectively adsorb Pt(IV) ions from acid leachates. In this study, a highly efficient adsorbent was developed by grafting of carboxyl and amine groups onto melamine sponge with alginate-Ca and polyethylenimine-glutaraldehyde (ML/ACPG). Combination of SEM, FTIR and XPS showed that the ML/ACPG sponge had a tree structure and the amino, carboxyl and hydroxyl groups were successfully introduced. Maximum adsorption capacity of ML/ACPG sponge reached up to 101.1 mg/L at pH of 1 (optimum initial pH value). The Pt(IV) ions were readily desorbed (within 60–80 min) using 0.1 M HCl + 0.025 M thiourea solution. Desorption efficiency remained higher than 83.3% while adsorption capacity decreased by less than 6.0% after 5 cycles operation. The ML/ACPG sponge was stable in 3 M of HNO 3 , NaCl after shaking for 72 h at 300 rpm with mass loss less than 2.5%. The mechanism of Pt(IV) adsorption onto ML/ACPG sponge mainly involved coordination by electrostatic attraction and carboxyl groups by protonated amine groups. The above results confirmed that the ML/ACPG sponge has a good practical application potential for Pt(IV) recovery from acid leachates.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Yonggan Ju,Jingxian Hua,Yawei Gu,Hongling Chen
Foams can be seen everywhere in human production and life. An uncontrolled foam event usually leads to product losses, equipment damage, and clean-up costs. Defoamer is one of the most effective strategies to eliminate or inhibit foam activities, which has been proved by long-term practices. In this work, we report new molecular defoamers with high-branched structure, which adopts melamine molecule as the parent structure, by incorporating alkyl-isocyanates with different chain lengths into the high-branched melamine derivatives (Hb-MDs) formula to replace the R − NH 2 (primary ammonia) on melamine structure. The substitution reaction processes can be readily tuned by varying the molar ratio or alkyl chain length of alkyl-isocyanate, enabling a facile control over the branched degree. The foam tests reveal that the high-branched melamine molecule defoamers exhibited excellent defoaming and anti-foaming properties for four typical foam systems, including an anionic SDBS , cationic DTAB , non-ionic AEO-9, and white cat (BM) detergent, with efficiency close to that of silicone-type LN1414 defoamer and far superior to that of high-carbon alcohol XS-02 defoamer, at the same addition level. Notably, the defoaming or anti-foaming performances of the high-branched melamine molecule defoamers were not always monotonically increased with the branched degree or hydrophobic chain length, but a suitable range needed to be maintained to support a good balance of defoamer structure with foam liquid films . Therefore, it is anticipated that this high-branched design principle could open a new avenue for the construction of molecular defoamers for complex industrial problems.
研究领域:
化学工程
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材料科学
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表面化学
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产品关联
DOI
PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Xiaozhen Hu,Mutian Yang,Dejian Yang,Defu Xu,Jiangang Lu,Lin Zhou
Interfacial solar desalination has shown great potential to address the global freshwater scarcity attributing to the advantages of high energy conversion efficiency, environmental friendly, cost effective and so on. However, accompanied by rapid vapor generation in the interfacial region, salt simultaneously crystallizes on the surface of photothermal materials, especially in highly concentrated brine, which would seriously affect the efficiency and long-term stability due to the blocking of vapor escaping channels as well as decreasing of solar absorption. In addition, organic substances in seawater may also pollute the absorbers during evaporation. Here, we demonstrate an omniphobic-hydrophilic melamine sponge based janus photothermal absorber by taking advantage of the 1H,1H,2H,2H-perfluorooctyltrichlorosilane modification, providing the upper layer both hydrophobic and oleophobic features, resulting in salt resistance and anti-fouling performance, respectively. Even with saturated NaCl solution as input, no salt accumulation was observed on the light absorbing surface during 8 h continuous evaporation. Moreover, the absorber exhibits excellent anti-fouling properties in oily water. Our strategy provides an avenue for the development of multifunctional solar absorbers aiming to sustainable treatment of highly concentrated brine and oil-bearing water.
研究领域:
材料科学
·
环境科学
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产品关联
DOI
高影响因子
ACS Applied Nano Materials
·
2023
·
IF 5.9
Meiqin Wu,Yunhui Chen,Hou-Yong Yu,Xiaosong Liu,Yanjuan Dong,Peng-Cheng Qian,Xiaohua Wang
Traditional halogenated flame retardants (FRs) have been severely hindered because they are toxic and hazardous carcinogenic byproducts during their application. In this study, we present a biobased FR composite consisting of cellulose nanocrystals (CNCs) modified with melamine (MEL) and phytic acid (PA) through successive grafting and electrostatic adsorption processes. It was found that the CNC/MEL/PA nanocomposite had a noticeable highly improved thermal blocking performance of the cellulose nanofibril aerogel, excellent carbon layer formation, and high thermal insulation ability because of a synergistic FR effect between the components in both the condensed and gas phases. These findings highlight the potential of nanoscale engineering in producing structural foams with excellent fire-retardant properties using cellulose and other nanosized fibrous biomaterials.
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产品关联
DOI
高影响因子
ChemCatChem
·
2023
·Vol. 15
·期 19
·e202300703
·
IF 4.5
Xinzheng Ma,Luyao Guo,Ziang Zhao,Yu Meng,Xiaoling Mou,Ronghe Lin,Yihui Li,Li Yan,Hejun Zhu,Yunjie Ding
Graphical Heptanol oxidation : Melamine modification of commercial activated carbon can greatly tune the performance of Pt−Bi catalysts in n -heptanol oxidation. C 3 N 4 -modified AC favors the formation of PtBi alloy in comparison to N-doped AC, and consequently boosts the activity and selectivity to heptanoic acid. Different bimetallic platinum and bismuth catalysts supported on melamine-modified activated carbon (AC) are designed by a co-impregnation method. Through controlling the activation temperatures of the melamine−AC mixture, a series of N-doped and C 3 N 4 -modified AC (N−AC and C 3 N 4 −AC) are prepared. Combined powder X-ray diffractions, X-ray photoelectron spectroscopic, and high-angle annual dark-field scanning transmission electron microscopic studies demonstrate that the introduction of C 3 N 4 favors the formation of PtBi alloy and leads to increased particle sizes in comparison to the pristine and N-doped AC-supported bimetallics. The catalytic performance of the developed catalysts is evaluated in the oxidation of n -heptanol oxidation in a batch mode using O 2 as the oxidant. PtBi/C 3 N 4 −AC exhibits significantly boosted activity as well as selectivity to heptanoic acid as compared with the other catalysts. A high yield of heptanoic acid of 69 % can be achieved under the optimized reaction conditions. Furthermore, our work points to the PtBi alloy as the most active sites for the alcohol oxidation. Catalyst deactivation occurs in the cycling tests, mainly due to the collapse of the alloy phase and likely the decrease in particle sizes.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yi Liu,Shuangjiang Li,Ying Chen,Mengrui Li,Zewen Chen,Tianding Hu,Lan Shi,Manoj Pudukudy,Shaoyun Shan,Yunfei Zhi
The development of highly efficient and metal- and halogen-free heterogeneous catalysts for the chemical conversion of CO 2 to cyclic carbonates plays a critical role in the reduction of greenhouse gas emissions. Herein, two melamine-based organic polymers namely UM-OP and AM-OP with abundant N sites and –NH- groups were synthesized by a facile method and their activity for cycloaddition of CO 2 with epoxides was investigated. The structural analysis shows that the UM-OP and AM-OP catalysts were composed of specially designed urea and amide group linkages, respectively. UM-OP and AM-OP are metal-free, halogen-free, and can efficiently catalyze CO 2 cycloaddition under solvent-free and cocatalyst-free conditions. Moreover, the UM-OP catalyst exhibited higher catalytic activity than AM-OP, good structural stability, recyclability, separability from the products, and shown high activity to a series of epoxides. The density functional theory (DFT) calculations revealed the activation of epoxides by –NH- groups and CO 2 by N sites in the samples, respectively, and N sites can also act as nucleophiles to realize ring opening of epoxides. Combining the results of experiments and calculations, it was further found that the double –NH- (urea group) is more efficient than single –NH- (amide group) to activate the epoxides. This paper reveals the mechanism of N sites and –NH- groups synergistically catalyzing the CO 2 cycloaddition, and further supports the theory that N atoms acts as nucleophile for ring opening, providing a reference for the design of metal- and halogen-free heterogeneous catalysts.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）