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Hierarchically porous silicon-carbon-nitrogen hybrid materials towards highly efficient and selective adsorption of organic dyes.

Meng L, Zhang X, Tang Y, Su K, Kong J - Sci Rep (2015)

Bottom Line: The hybrid material was conveniently generated by the pyrolysis of commercial polysilazane precursors using polydivinylbenzene microspheres as sacrificial templates.On the contrary, the hybrid materials do not adsorb the dyes with azo benzene structures, such as methyl orange, methyl red and congro red.Thus, the hierarchically porous Si-C-N hybrid material from a facile and low cost polymer-derived strategy provides a new perspective and possesses a significant potential in the treatment of wastewater with complex organic pollutants.

View Article: PubMed Central - PubMed

Affiliation: MOE Key Laboratory of Space Applied Physics and Chemistry, Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi'an, 710072, P. R. China.

ABSTRACT
The hierarchically macro/micro-porous silicon-carbon-nitrogen (Si-C-N) hybrid material was presented with novel functionalities of totally selective and highly efficient adsorption for organic dyes. The hybrid material was conveniently generated by the pyrolysis of commercial polysilazane precursors using polydivinylbenzene microspheres as sacrificial templates. Owing to the Van der Waals force between sp-hybridized carbon domains and triphenyl structure of dyes, and electrostatic interaction between dyes and Si-C-N matrix, it exhibites high adsorption capacity and good regeneration and recycling ability for the dyes with triphenyl structure, such as methyl blue (MB), acid fuchsin (AF), basic fuchsin and malachite green. The adsorption process is determined by both surface adsorption and intraparticle diffusion. According to the Langmuir model, the adsorption capacity is 1327.7 mg·g(-1) and 1084.5 mg·g(-1) for MB and AF, respectively, which is much higher than that of many other adsorbents. On the contrary, the hybrid materials do not adsorb the dyes with azo benzene structures, such as methyl orange, methyl red and congro red. Thus, the hierarchically porous Si-C-N hybrid material from a facile and low cost polymer-derived strategy provides a new perspective and possesses a significant potential in the treatment of wastewater with complex organic pollutants.

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Nitrogen adsorption–desorption isotherms of (a) C1-MB and (b) C1-AF.
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f18: Nitrogen adsorption–desorption isotherms of (a) C1-MB and (b) C1-AF.

Mentions: The FTIR spectroscopy and XPS analyses were performed to gain insights into the adsorption mechanism. The analyses of FTIR spectra of C1, MB/AF, and MB/AF adsorbed C1 (MB-C1/AF-C1) are presented in Figure S8. For C1, the symmetric deformation vibration corresponding to Si–CH3 at 1268 cm−1 is still present. Similarly, the peak at 2924 cm−1 related to the C–H asymmetric stretching vibrations (C (sp3) –H band) is faintly visible, indicating the presence of saturated groups. An intense and broad peak at 3440 cm−1 indicates the retention of N–H bond which is consistent with the mass spectrometry analysis. Importantly, the broad peaks at 1624 and 1404 cm−1 are ascribed to the conjugated bands of free carbons (C = C, sp2), which is indicative of a polyaromatic-like conjugation structure. Besides, the intense peak at 1032 cm−1 is attributed to amorphous Si–NH–Si phase, which is also important for the adsorption of dyes. After absorption of MB on C1 (C1-MB), the characteristic peaks of MB, such as the ring stretch at 1577 cm−1 and three peaks at 1122, 1037, and 616 cm−1 corresponding to sulfonate groups, are recorded in the spectrum of the adsorptive adduct, indicating that MB has been anchored to the surface of C1. In the case of AF adsorbed C1 (C1-AF), the characteristic peaks of AF, such as the peaks at 1625 and 1584 cm−1, respectively, related to NH2 and aromatic rings of AF and the two peaks at 1037 and 629 cm−1 derived from sulfonate groups of AF, are recorded in the spectrum of the adsorptive adduct, which indicates that AF has been attached to the surface of C1. There are no other new peaks observed for C1-MB and C1-AF, thus, indicating that it is a physical adsorption. Figure 18 shows the nitrogen adsorption isotherms, demonstrating that the specific surface area of the porous material dramatically reduces to 3.88 m2·g−1 and 2.19 m2·g−1 for C1-MB and C1-AF, respectively, which indicates that most micropores have been filled with MB and AF molecules after the adsorption. Figure S9 exhibits that the carbon content of C1-MB and C1-AF increase significantly compared to C1 after adsorption, indicating the adsorption of a large number of dye molecules (MB and AF) on C1.


Hierarchically porous silicon-carbon-nitrogen hybrid materials towards highly efficient and selective adsorption of organic dyes.

Meng L, Zhang X, Tang Y, Su K, Kong J - Sci Rep (2015)

Nitrogen adsorption–desorption isotherms of (a) C1-MB and (b) C1-AF.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4300473&req=5

f18: Nitrogen adsorption–desorption isotherms of (a) C1-MB and (b) C1-AF.
Mentions: The FTIR spectroscopy and XPS analyses were performed to gain insights into the adsorption mechanism. The analyses of FTIR spectra of C1, MB/AF, and MB/AF adsorbed C1 (MB-C1/AF-C1) are presented in Figure S8. For C1, the symmetric deformation vibration corresponding to Si–CH3 at 1268 cm−1 is still present. Similarly, the peak at 2924 cm−1 related to the C–H asymmetric stretching vibrations (C (sp3) –H band) is faintly visible, indicating the presence of saturated groups. An intense and broad peak at 3440 cm−1 indicates the retention of N–H bond which is consistent with the mass spectrometry analysis. Importantly, the broad peaks at 1624 and 1404 cm−1 are ascribed to the conjugated bands of free carbons (C = C, sp2), which is indicative of a polyaromatic-like conjugation structure. Besides, the intense peak at 1032 cm−1 is attributed to amorphous Si–NH–Si phase, which is also important for the adsorption of dyes. After absorption of MB on C1 (C1-MB), the characteristic peaks of MB, such as the ring stretch at 1577 cm−1 and three peaks at 1122, 1037, and 616 cm−1 corresponding to sulfonate groups, are recorded in the spectrum of the adsorptive adduct, indicating that MB has been anchored to the surface of C1. In the case of AF adsorbed C1 (C1-AF), the characteristic peaks of AF, such as the peaks at 1625 and 1584 cm−1, respectively, related to NH2 and aromatic rings of AF and the two peaks at 1037 and 629 cm−1 derived from sulfonate groups of AF, are recorded in the spectrum of the adsorptive adduct, which indicates that AF has been attached to the surface of C1. There are no other new peaks observed for C1-MB and C1-AF, thus, indicating that it is a physical adsorption. Figure 18 shows the nitrogen adsorption isotherms, demonstrating that the specific surface area of the porous material dramatically reduces to 3.88 m2·g−1 and 2.19 m2·g−1 for C1-MB and C1-AF, respectively, which indicates that most micropores have been filled with MB and AF molecules after the adsorption. Figure S9 exhibits that the carbon content of C1-MB and C1-AF increase significantly compared to C1 after adsorption, indicating the adsorption of a large number of dye molecules (MB and AF) on C1.

Bottom Line: The hybrid material was conveniently generated by the pyrolysis of commercial polysilazane precursors using polydivinylbenzene microspheres as sacrificial templates.On the contrary, the hybrid materials do not adsorb the dyes with azo benzene structures, such as methyl orange, methyl red and congro red.Thus, the hierarchically porous Si-C-N hybrid material from a facile and low cost polymer-derived strategy provides a new perspective and possesses a significant potential in the treatment of wastewater with complex organic pollutants.

View Article: PubMed Central - PubMed

Affiliation: MOE Key Laboratory of Space Applied Physics and Chemistry, Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi'an, 710072, P. R. China.

ABSTRACT
The hierarchically macro/micro-porous silicon-carbon-nitrogen (Si-C-N) hybrid material was presented with novel functionalities of totally selective and highly efficient adsorption for organic dyes. The hybrid material was conveniently generated by the pyrolysis of commercial polysilazane precursors using polydivinylbenzene microspheres as sacrificial templates. Owing to the Van der Waals force between sp-hybridized carbon domains and triphenyl structure of dyes, and electrostatic interaction between dyes and Si-C-N matrix, it exhibites high adsorption capacity and good regeneration and recycling ability for the dyes with triphenyl structure, such as methyl blue (MB), acid fuchsin (AF), basic fuchsin and malachite green. The adsorption process is determined by both surface adsorption and intraparticle diffusion. According to the Langmuir model, the adsorption capacity is 1327.7 mg·g(-1) and 1084.5 mg·g(-1) for MB and AF, respectively, which is much higher than that of many other adsorbents. On the contrary, the hybrid materials do not adsorb the dyes with azo benzene structures, such as methyl orange, methyl red and congro red. Thus, the hierarchically porous Si-C-N hybrid material from a facile and low cost polymer-derived strategy provides a new perspective and possesses a significant potential in the treatment of wastewater with complex organic pollutants.

Show MeSH