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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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The suggested selective adsorption mechanism, (a) the interaction between sp2 carbon domain and triphenyl structure of MB, (b) the interaction between sp2carbon domain and azo-benzene ring structure of MO calculated according to AM1, (c) suggested selective adsorption mechanism of dyes for porous Si–C–N hybrid material.
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f17: The suggested selective adsorption mechanism, (a) the interaction between sp2 carbon domain and triphenyl structure of MB, (b) the interaction between sp2carbon domain and azo-benzene ring structure of MO calculated according to AM1, (c) suggested selective adsorption mechanism of dyes for porous Si–C–N hybrid material.

Mentions: First, we conclude that the porous Si–C–N hybrid material selectively adsorb the dyes with triphenyl structure because of the Van der Waals force between the sp2-hybridized carbon domain in adsorbent (proved by Raman spectrum and FTIR) and the triphenyl structure of dyes. Herein, the semiemperical quantumchemical method AM1 (Austin Model #1) was adopted to determine Van der Waals forces between sp2-hybridized carbon domains in Si–C–N hybrid material and dyes although it seems rough for the quantitative canculation69. According to the results of AM1 modeling in Figure 17 and Figure S7, the atomic distance between sp2 carbon clusters of porous Si–C–N hybrid material and MB is between 3.84 to 4.49Å, which is within the typical range of Van der Waals distance (3–4Å). However for MO, the atomic distance between carbon clusters and AF is between 5.50–5.87Å, which is beyond the typical range of Van der Waals distance. So, it is believed that the adsorption sites on porous Si–C–N hybrid material may be related to the presence of sp2carbons that are proved by Raman spectra in Figure 5b. Thus, the Van der Waals forces between carbon atoms (sp2) in porous hybrid material and the triphenyl structure of dyes may be the main driving force for the adsorption of MB, AF, MG, MV, or BF. On the other hand, the electrostatic interaction between the Si-NH-Si sites in porous Si–C–N hybrid material and amino groups in dyes should also be considered. The presence of -NH, -NH2, N+ in MB, NH and NH2 in AF, MG and MV, is beneficial to the electrostatic interaction to Si–C–N hybrid material. While the presence of electron-donating groups, such as -N = N- in MO, MR, CR, is hindered to the electrostatic interaction to Si–C–N hybrid material as illustrated in Figure 17.


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)

The suggested selective adsorption mechanism, (a) the interaction between sp2 carbon domain and triphenyl structure of MB, (b) the interaction between sp2carbon domain and azo-benzene ring structure of MO calculated according to AM1, (c) suggested selective adsorption mechanism of dyes for porous Si–C–N hybrid material.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f17: The suggested selective adsorption mechanism, (a) the interaction between sp2 carbon domain and triphenyl structure of MB, (b) the interaction between sp2carbon domain and azo-benzene ring structure of MO calculated according to AM1, (c) suggested selective adsorption mechanism of dyes for porous Si–C–N hybrid material.
Mentions: First, we conclude that the porous Si–C–N hybrid material selectively adsorb the dyes with triphenyl structure because of the Van der Waals force between the sp2-hybridized carbon domain in adsorbent (proved by Raman spectrum and FTIR) and the triphenyl structure of dyes. Herein, the semiemperical quantumchemical method AM1 (Austin Model #1) was adopted to determine Van der Waals forces between sp2-hybridized carbon domains in Si–C–N hybrid material and dyes although it seems rough for the quantitative canculation69. According to the results of AM1 modeling in Figure 17 and Figure S7, the atomic distance between sp2 carbon clusters of porous Si–C–N hybrid material and MB is between 3.84 to 4.49Å, which is within the typical range of Van der Waals distance (3–4Å). However for MO, the atomic distance between carbon clusters and AF is between 5.50–5.87Å, which is beyond the typical range of Van der Waals distance. So, it is believed that the adsorption sites on porous Si–C–N hybrid material may be related to the presence of sp2carbons that are proved by Raman spectra in Figure 5b. Thus, the Van der Waals forces between carbon atoms (sp2) in porous hybrid material and the triphenyl structure of dyes may be the main driving force for the adsorption of MB, AF, MG, MV, or BF. On the other hand, the electrostatic interaction between the Si-NH-Si sites in porous Si–C–N hybrid material and amino groups in dyes should also be considered. The presence of -NH, -NH2, N+ in MB, NH and NH2 in AF, MG and MV, is beneficial to the electrostatic interaction to Si–C–N hybrid material. While the presence of electron-donating groups, such as -N = N- in MO, MR, CR, is hindered to the electrostatic interaction to Si–C–N hybrid material as illustrated in Figure 17.

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