Journal of Water Process Engineering
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2024
·
IF 6.3
Elia Gadallah,Jinchao Chen,Mohamed N. Khalil,Sami Karam,Fang Li
The trade-off between permeability and selectivity, as well as membrane fouling remains a major challenge in membrane application, impacting the performance and lifespan. Herein, a novel approach has been proposed, involving the incorporation of melamine-modified Metal-Organic Frameworks (MOFs) into Polyethersulfone (PES) ultrafiltration membranes. The modified MOFs exhibit stable anchoring to the membrane surface through hydrogen bonding , forming a hydration layer that enhances resistance to foulants. Moreover, the MOF framework channels facilitate water transport via providing additional pathways. The optimized melamine-MOF modified membranes achieve a permeability of 50 L/m 2 .h and a 97.8 % bovine serum albumin (BSA) rejection. The antifouling experiment demonstrates an 87 % fouling recovery ratio (FRR) for the modified membrane. A computational study has been conducted to investigate the interaction between UiO-66 and melamine using molecular dynamics (MD) simulations. The simulations validated the formation of hydrogen bonds and confirmed previous findings. Overall, the melamine-modified MOF exhibits high permeability and antifouling ability due to its excellent hydrophilic properties , which offer promising application prospects in wastewater reclamation .
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Arabian Journal of Chemistry
·
2024
·
IF 5.3
Lu-Shuang Li,Su Li,Zong-Mei Huang,Yan-Ting Song,Wei Gong,Jing Li
The abuse of oxytetracycline (OTC) leaves serious environmental residues and triggers accumulation in organisms, constituting a threat to human health. Constructing an effective platform based on dual-functional materials for monitoring and removing OTC residues is a preferable solution. Herein, we proposed a novel composite material by doping carbon dots (CDs) into melamine–formaldehyde microsphere (MFM) through a one-pot method and named CDs@MFM, which inherited the fluorescence property of CDs and porous structure of MFM simultaneously. CDs@MFM demonstrated dual functions for the detection and removal of OTC concurrently within a few minutes, with its performance compared in detail with bare CDs and MFM as controls. By virtue of the pre-enrichment effect attributed to its porous structure, CDs@MFM exhibited a lower detection limit for OTC than bare CDs (0.027 mg/L vs 0.067 mg/L) and a higher adsorption capacity than MFM (73.01 mg/g vs 68.76 mg/g) resulting from more affiliated functional groups available for OTC provided by the CDs. Overall, CDs@MFM has proven to be an efficient and convenient candidate capable of monitoring and removing OTC synchronously, and this work offers an avenue for the design of dual-functional materials in the field of environmental science.
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ANALYTICAL CHEMISTRY
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2015
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IF 5.636
Tianwei Lv,Hongyuan Yan,Jiankun Cao,Shiru Liang
Hydrophilic molecularly imprinted resorcinol–formaldehyde–melamine resin (MIRFM) is synthesized in water and shows excellent molecular recognition in aqueous matrices. The double functional monomers resorcinol and melamine, and the cross-linker formaldehyde, are all hydrophilic, and then the hydrophilic groups (such as hydroxyls, imino groups, and ether linkages) can be introduced into MIRFM, which make the material compatible with aqueous samples. The general principle is demonstrated by the synthesis of MIRFM using sulfanilamide as a dummy template for the selective recognition to sulfonamides (SAs) in milk samples. Resorcinol and melamine can interact with the template mainly by hydrogen bonding and π–π interaction, which makes MIRFM and the analytes have strong affinity. Besides, melamine can improve the rigidity of MIRFM and accelerate the polymerization process, so there is no need to add base or acid as a catalyst, which guarantees the success of molecular imprinting. MIRFM shows higher recovery and improved purification effect for SAs, in comparison to silica, HLB, C18, and SCX. Because of its excellent hydrophilicity and specificity, MIRFM is promising to be applied in biological, environmental, and clinical fields.
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MICROCHIMICA ACTA
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2016
·Vol. 183
·期 7
·2289-2296
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IF 4.831
Peng Juan,Feng Yun,Han Xiao-Xia,Gao Zuo-Ning
The authors describe an electrochemical sensor for simultaneous determination of bisphenol A (BPA) and hydroquinone (HQ). It is based on a carbon paste electrode doped with graphene and coated with poly(melamine) (PME/GR-CPE). The modified electrode exhibits excellent conductivity, electrooxidative activity and adsorptive capability. The differential pulse voltammetric peaks for HQ and BPA are separated by around 300 mV. Amperometric responses (at 0.5 V for HQ and 0.8 V for BPA; both vs. SCE) are linear for BPA in the 9.0 μM to 1.0 mM concentration range, and for HQ in the 7.0 μM to 1.0 mM concentration range. The respective detection limits are 10.5 nM and 74.0 nM. The sensor is reproducible, highly stable and sensitive. It was applied to the simultaneous determination of HQ and BPA in spiked tap water and waste water.
A sensor based on poly(melamine) coated on graphene-doped carbon paste electrode for simultaneous determination of bisphenol (BPA) and hydroquinone (HQ) was fabricated. The sensor possessed good reproducibility and high stability. The practical application of the sensor was demonstrated by the detection of HQ and BPA in tap water and wastewater samples.
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FOOD CONTROL
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2016
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IF 3.388
Ruoping Li,Guanghong Yang,Jingliang Yang,Junhe Han,Junhui Liu,Mingju Huang
A simple and rapid method to detect melamine in liquid milk by Surface-enhanced Raman Scattering (SERS) technique was presented. The pretreatment procedure of milk samples only contains hydrochloric acid treatment and twice centrifugation. In order to reduce the distortion about the Raman signals originating from charge transfer and electronic tunnelling effect, SiO 2 shell-isolated gold nanoparticles (Au@SiO 2 NPs) instead of Au NPs were employed to enhance signal intensity. Aggregation occurs when the Au@SiO 2 NPs colloid is mixed with the melamine solution or the treated milk containing melamine. Different from aggregated Au NPs, these aggregated Au@SiO 2 NPs on Cu substrate can undistortedly enhance the Raman signals of melamine using surface plasma effect. Quantitative analysis was tried and the results showed a good linearity (R 2 ≈ 0.99) when the melamine concentration was between 0.5 mgL −1 and 5 mgL −1 . The detection sensitivity satisfies the requirement of the Codex Alimentarius Commission and this method can be practically used for melamine detection in milk.
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Journal of Materials Chemistry C
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2016
·Vol. 4
·期 25
·6104-6109
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IF 5.066
He Ren,Mingzhe Li,Yanyan Fu,Lan Jin
This paper reports the fabrication of ultrathin films (UTFs) of silver nanoclusters functionalized by chromotropic acid (CTA) and layered double hydroxide nanosheets (CTA-AgNCs/LDH) via the layer-by-layer (LBL) assembly technique, and their fluorescence turn on response for the detection of melamine has been demonstrated. UV-vis absorption and fluorescence spectra show the uniform growth of the UTFs and the enhancement of interlayer CTA-AgNCs upon increasing the deposition cycle. The SEM image and XRD results indicate that the (CTA-AgNCs/LDH)n UTFs possess long-range order stacking in the normal direction of the substrate, with CTA-AgNCs accommodated between the LDH nanosheets as a monolayer arrangement. Compared with CTA-AgNCs solution, the fluorescence intensity of UTFs has been improved significantly resulted from the localization and confinement effects of LDH nanosheets. Moreover, the (CTA-AgNCs/LDH)10 displays sensor performance for melamine with a linear response range (0.03–0.1 μM), low detection limit (4 nM) and good stability. A high selectivity of UTFs toward melamine over the other amino acids, metal ions and some saccharides has also been demonstrated. The sensitive assay for melamine could be attributed to the interaction based on the recognition of triple hydrogen bonds between melamine and (CTA-AgNCs/LDH) films. Therefore, this work provides a convenient way to immobilize Ag nanoclusters using the LDH nanosheet as a 2D matrix, which has great potential for the development of melamine detection.
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RSC Advances
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2016
·Vol. 6
·期 16
·13217-13223
·
IF 3.289
Xiaomin Fu,Zhengcong Gu,Qiyi Lu,Jiayao Liao,Shihong Chen
C60/graphite-like carbon nitride nanosheet (C60/g-C3N4 NS) hybrids were prepared by a simple π–π interaction, and used to construct a solid state electrochemiluminescence (ECL) sensor. Based on the fact that melamine could efficiently quench the ECL intensity of g-C3N4 NS, such a sensor achieved detection of melamine. The possible quenching mechanisms were discussed. Due to the combination of the excellent ECL behavior of g-C3N4 NS with the outstanding electronic conductivity of C60, the prepared sensor exhibited a response for melamine with a wide linear range of 5.0 × 10−13 to 2.7 × 10−11 M and 2.7 × 10−11 to 1.9 × 10−8 M. The detection limit was 1.3 × 10−13 M. In this work, the linear range of melamine was improved by six orders of magnitude and the detection limit as low as sub-picomolar. Such a construction strategy provided a simple, sensitive, low-cost and green detection method for melamine.
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Journal of Materials Chemistry C
·
2017
·Vol. 5
·期 31
·7806-7812
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IF 5.256
Lin Chen,Ying Huang,Tian Tian Xing,LingPu Ge,Tong Yang,Bin Chen,Cheng Zhi Huang
Facile detection of melamine in milk was realized through a portable multi-channel sensing device using Au nanoparticles with urchin-like structures as sensing probes. The detection mechanism was based on the aggregation of Au nano-urchins, induced by the formation of Au–N bonding with melamine. The Au nano-urchins were synthesized by a seed-mediated growth method in the presence of hydroquinone, which has the localized surface plasmon absorption at about 680 nm. The results showed that the melamine detection was environment pH dependent. The optimal melamine detection condition occurred when the pH of the BR buffer was 5.72. A better selectivity to melamine was fulfilled when compared with its structurally similar compounds: cytosine, uracil, and thymine. The multi-channel sensing device has a detection limit of 18 nM for melamine in milk, which could meet the requirement for monitoring the melamine amount in milk.
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POLYMER DEGRADATION AND STABILITY
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2014
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IF 2.633
Meng Zhang,Jinwen Zhang,Shuigen Chen,Yonghong Zhou
In this work, a melamine and cardanol-derived Mannich base polyol (MCMP) was synthesized via a two-step process. First, cardanol was allowed to react with paraformaldehyde melamine and diethanolamine to yield mixed Mannich bases which were subsequently propoxylated to give the MCMP. Rigid polyurethane foams (RPUFs) were prepared using MCMP and a polyisocyanate. Effects of expandable graphite (EG), ammonium polyphosphate (APP) and diethyl ethylphosphate (DEEP) on the flame retardancy, mechanical properties , thermal stability and morphology of the resultant RPUFs were studied. It was demonstrated that the melamine incorporated into the MCMP molecular structure increased the thermal stability and the flame retardancy of the RPUF. The fire resistance of the foam could be further enhanced by the addition of flame retardants . EG is more effective than APP and DEEP in enhancing the limiting oxygen index of MCMP-based RPUFs. The flame-retardant-filled RPUFs display a better compressive strength , thermal stability, char residue, heat release and smoke emission than does the non-filled foams.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2015
·
IF 2.858
Zhan-Chao Wu,Zhao-Zhan Wang,Jie Liu,Jin-Hua Yin,Shao-Ping Kuang
A new porous magnetic chitosan modified by melamine (MA-CS/Fe 3 O 4 ) was synthesized. The compositions and surface topographies were characterized by infrared (IR) spectroscopy, X-ray diffraction (XRD) analysis, thermogravimetric (TG) analysis and scanning electron microscope (SEM), respectively. The results of adsorption kinetics showed the adsorption behavior could be better described by the pseudo-second-order equation ( R > 0.999). The adsorption isotherm was well fitted by the Langmuir equation ( R > 0.999), and the values of separation factors were in the range of 0–1.0. The maximum adsorption capacity for Cu(II) was 2.58 mmol g −1 at the optimal experimental conditions, which were pH = 5.5, t = 25 min, C 0 = 5.0 mmol L −1 . The rate-controlling step was supposed to be chemical adsorption rather than mass transport. The adsorbent still exhibited high adsorption capacity after five regeneration cycles. The adsorption mechanism was due to coordination between Cu(II) and N atoms.
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ACS Applied Materials & Interfaces
·
2014
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IF 5.9
Lingling Li,Gehui Wu,Tao Hong,Zhouyang Yin,Dong Sun,E. S. Abdel-Halim,Jun-Jie Zhu
A rapid and sensitive fluorescence sensing system for melamine based on charge transfer quenching of the fluorescence of graphene quantum dots (GQDs) in the presence of Hg2+ is proposed. The synthesized GQDs were strongly luminescent with predominantly aromatic sp2 domains. Melamine could coordinate with mercury through nitrogen atoms in both its amine and triazine groups and bring more Hg2+ to the surface of GQDs through π–π stacking, thus leading to quenching of the GQDs’ fluorescence. The quenching mechanism was investigated in detail and ascribed to charge transfer from the GQDs to Hg2+ with melamine acting as the linkage agent. The melamine demonstrated a linear range 0.15–20 μM and a detection limit of 0.12 μM, which was far below the regulatory level, suggesting the promising practical usage of this sensing system. This sensing system also possessed high selectivity for melamine in the presence of possible interferences. Finally, this novel sensor was successfully applied for melamine detection in raw milk and satisfactory recovery was achieved.
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TALANTA
·
2013
·
IF 3.498
Wenjing Cheng,Zhujuan Liu,Yan Wang
Highly selective molecularly imprinted layer-coated silica gel (MIP@SiO 2 ) for melamine (MEL) was prepared by the surface molecular imprinting technique on the supporter of silica gel. Non-imprinted polymer layer-coated silica gel (NIP@SiO 2 ) and bulk molecularly imprinted polymer (MIP) were also prepared for comparison. Characterization and performance tests of the obtained products revealed that MIP@SiO 2 not only had excellent selectivity to the target molecule MEL compared with NIP@SiO 2 , but also displayed absorption capacity superior to MIP due to the molecular recognition sites on the surface of silica gel. As the MIP@SiO 2 were adopted as the adsorbents of solid-phase extraction for detecting MEL in milk samples, the recoveries of spiked samples ranged from 75.6% to 96.8% with the relative standard deviation of spiked samples less than 10%, which reveals that the MIP@SiO 2 were efficient SPE adsorbents for melamine .
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