Adsorption of 2,4-D on magnetic graphene and mechanism study

Liu, Wei; Yang, Qi; Yang, Zhilin; Wang, Wenjing

doi:10.1016/j.colsurfa.2016.09.039

Cited by 75 publications

(28 citation statements)

References 58 publications

(92 reference statements)

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“…2b)， which was probably because the dense Au seeds were distributed on the surface of the PEI-coated Fe 3 O 4 very uniformly, and the 3 nm Au seeds were too small to impact the microspheres' structure to induce plasmonic coupling. 18 PVP covered all the facets of Au seeds, which facilitated isotropic growth of Ag NPs and played a key role in forming uniform Ag shells. The MS values tended to decrease slightly after the PEI-coating, Au seed-absorbing and Ag shell-forming process.…”

Section: Characterization Of the Cssmmentioning

confidence: 99%

“…9 Constant efforts have been spent on improving this, while few pay off. [16][17][18][19][20][21] For example, poly-(vinylpyrrolidone) (PVP) has been utilized as a surface passivation agent, preventing nanoparticles from aggregation. 10 By contrast, noble metal colloid substrates are more efficient and have facile control over individual morphology.…”

Section: Introductionmentioning

confidence: 99%

“…Generally accepted sandwich solid substrates are costly and difficult for further chemical modification. 18,22 It has been proved that poly-(N-isopropylacrylamide) (pNIPAM) Nevertheless, there are two common methods to introduce nanogaps on colloid substrates: stability of nanoparticles, but also enhances some of their properties, such as modification and biocompatibility.…”

Section: Introductionmentioning

confidence: 99%

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Polyethylenimine-interlayered core–shell–satellite 3D magnetic microspheres as versatile SERS substrates

Wang

et al. 2015

Nanoscale

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Precise fabrication of subtle nanogaps amid individual nanoparticles or between adjacent ones to obtain the highest SERS enhancement is still a challenge. Here, we reported a novel approach for fabricating core-shell-satellite 3D magnetic microspheres (CSSM), that easily form a porous 1.5 nm PEI interlayer to accommodate molecules and create sufficient hotspots between the inner Fe3O4@Ag core and outer assembled Au@Ag satellites. Experiments and finite-difference time-domain (FDTD) simulation demonstrated that the enhancement factor (EF) was about 2.03 × 10(8) and 6.25 × 10(6), respectively. In addition, the micro-scale magnetic core endowed the CSSM with a superior magnetic nature, which enabled easy separation and further enhanced Raman signals due to enrichment of targeted analytes and abundant interparticle hotspots created by magnetism-induced aggregation. Our results further demonstrated that the CSSM is expected to be a versatile SERS substrate, which has been verified by the detection of the adsorbed pesticide thiram and the non-adsorbed pesticide paraquat with a detection limit as low as 5 × 10(-12) M and 1 × 10(-10) M, respectively. The novel CSSM can overcome the long-standing limitations of SERS for the trace characterization of various analytes in different solutions and promises to transform SERS into a practical analytical technique.

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Section: Characterization Of the Cssmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Polyethylenimine-interlayered core–shell–satellite 3D magnetic microspheres as versatile SERS substrates

Wang

et al. 2015

Nanoscale

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“…HRTEM images of Fig. 27 Few new nuclei form in the growth process due to the low concentration of reactant, which is beneficial for synthesis of particles with narrow size distribution. The PEI-coating progress was also confirmed by Zeta potential measurement, in which the ζ-potential increases obviously from −29.6 mV to +38.5 mV, hinting that positively charged PEI were completely assembled onto the surface of Fe 3 O 4 .…”

Section: Characterization Of Fe 3 O 4 @Pei@ag Microspheresmentioning

confidence: 99%

“…The PEI-coating progress was also confirmed by Zeta potential measurement, in which the ζ-potential increases obviously from −29.6 mV to +38.5 mV, hinting that positively charged PEI were completely assembled onto the surface of Fe 3 O 4 . 27 PVP wholly covered all the facets of Au seeds, which facilitated isotropic growth of Ag particles, which played a key role in forming uniform Ag shells. 1(d) shows that dense small Au nanoparticles spreaded uniformly on the surface of the Fe 3 O 4 @PEI particles.…”

Section: Characterization Of Fe 3 O 4 @Pei@ag Microspheresmentioning

confidence: 99%

Polyethylenimine-interlayered silver-shell magnetic-core microspheres as multifunctional SERS substrates

Wang

et al. 2015

J. Mater. Chem. C

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The fabrication of an ideal noble metal modified magnetic microsphere as high performance SERS substrate that possesses good dispersibility, strong magnetic responsiveness, and high sensitivity is still a challenge. Herein, we reported a novel route to fabricating Ag-coated magnetic core-shell microspheres (Fe 3 O 4 @PEI@Ag) with most of the desired advantages by using polyethyleneimine (PEI) as an interlayer. The size and coverage level of the Ag-NPs shell on Fe 3 O 4 @PEI@Ag microspheres were easily controlled by varying the amount of AgNO 3 .Meanwhile, the magnetic core endowed the Fe 3 O 4 @PEI@Ag microspheres with superior magnetic nature, which enabled convenient separation and further enhanced Raman signals due to enrichment of targeted analytes and abundant interparticle hotspots created by magnetism-induced aggregation. Considering these features, the Fe 3 O 4 @PEI@Ag is expected to be a versatile SERS substrate, which was verified by the detection of adsorbed PATP molecules and human IgG with a detection limit as low as 10 -11 M and 10 -14 g/mL, respectively. Therefore, the novel Fe 3 O 4 @PEI@Ag microsphere has an enormous potential for practical SERS detection applications, especially in the target protein quantitative detection field.Surface-enhanced Raman scattering (SERS) is a powerful fingerprint vibrational spectroscopy with high sensitivity, and it is widely used in biochemical detection, analytical chemistry, environment monitoring and biological sensing. 1-3 All these applications are based on proper utilization of "free-electron-like" metal materials, such as Au, Ag, and Cu, and only these noble metal structures with rough surface can provide obvious SERS effect. 4 Therefore, the key of its prominent application lies in fabricating high performance SERS substrates. So far, researchers have fabricated many SERS substrates, among which metal film over periodic nanostructure and Au/Ag colloids in suspension are extensively utilized. 5 The periodic nanostructure can achieve well sensitivity and high reproducibility, but has disadvantages of high cost and difficult to be further chemically modified. Au/Ag colloidal nanoparticles are more efficient with flexible control over individual geometry, easy to mass fabricate, and have good biocompatibility. 6 However, the drawbacks of Au/Ag colloid substrates are their limited enhancement ability and poor stability. 7 Therefore, a reliable and practical SERS substrate with high sensitivity is still a challenge. It should be noted that, up to now, the main problem of SERS detection is that it is difficult to conduct quantitative analysis and hard to apply in the complex system only depend on the noble metal SERS substrate itself.Magnetic microspheres have been extensively investigated for various applications. 8 Due to their excellent magnetic responsiveness, magnetic microspheres can assist in convenient recycling of novel metals, magnetic enrichment of analytes and rapid separation from reaction system. 9, 10 Recently, noble metal modified magnetic micro...

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Removal of 2,4-D herbicide from aqueous solution by aminosilane-grafted mesoporous carbons

Gościańska

Olejnik

2019

Adsorption

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2,4-Dichlorophenoxyacetic acid (2,4-D) is the most commonly used herbicide in plant protection products. 2,4-D is poorly biodegradable and it is often found in aquatic environment. The development of an effective way to reduce the amount of this toxic contaminant from aqueous solution became an urgent issue. Therefore, in this study series of aminosilane-grafted mesoporous carbons were synthesized, characterized and then applied as adsorbents for 2,4-D. The impact of various factors such as the contact time (0-360 min) of herbicide with adsorbents, pH (2-11), temperature (25, 45, 60 °C) and initial concentration (6.25-150 mg/l) of the 2,4-D on the sorption capacity of materials was analyzed. The results proved that functionalization of mesoporous carbons with aminosilane increased the sorption capacity (q e = 142-191 mg/g) towards herbicide compared to pristine material (q e = 109 mg/g). The functional groups presented on the surface of materials enhanced the interaction between mesoporous carbons and herbicide. The most effective adsorbent for 2,4-D was the material that had the highest amount of basic groups on the surface (2.79 mmol/g) of all samples tested (0.06-0.52 mmol/g). For all studied materials the Langmuir model was the most suitable to describe the isotherms of 2,4-D adsorption (R 2 = 0.999). While the kinetics of herbicide adsorption on the functionalized mesoporous carbons were best fitted to the pseudo-second-order model. The presented study proved that the aminosilane-grafted mesoporous carbons could be promising adsorbents for effective removal of 2,4-D from aqueous environment.

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Adsorption of 2,4-D on magnetic graphene and mechanism study

Cited by 75 publications

References 58 publications

Polyethylenimine-interlayered core–shell–satellite 3D magnetic microspheres as versatile SERS substrates

Polyethylenimine-interlayered core–shell–satellite 3D magnetic microspheres as versatile SERS substrates

Polyethylenimine-interlayered silver-shell magnetic-core microspheres as multifunctional SERS substrates

Removal of 2,4-D herbicide from aqueous solution by aminosilane-grafted mesoporous carbons

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