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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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Pore-diffusion model plots for the adsorption of MB and AF on C1.
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f11: Pore-diffusion model plots for the adsorption of MB and AF on C1.

Mentions: where Kt is the intraparticle diffusion rate constant (g·mg−1·min0.5) and C is a constant providing the information about the thickness of the boundary layer. In Figure 11, the plots of Qt vs. t1/2 show at least two linear segments in correspondence with different stages in adsorption. For two linear plots, the Qt vs. t1/2 have intercept value far from zero, which indicates that intraparticle diffusion is not the rate-controlling step of the adsorption process and the external mass transfer may be significant in the rate-controlling step. The first segment is attributed to the outer diffusion due to the mass transfer from the dye solution to the outer surface of the adsorbent (film diffusion or boundary layer diffusion). The second portion indicates a steady adsorption step, corresponding to the diffusion of adsorbate from the adsorbent exterior to the pores or capillaries of the adsorbent internal structure (inner diffusion)56. Thus, the presence of multilinearity and the boundary layer thickness indicate that the adsorption of two dyes on C1 is a complex process and both the surface adsorption and intraparticle diffusion occur during the adsorption process57.


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)

Pore-diffusion model plots for the adsorption of MB and AF on C1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f11: Pore-diffusion model plots for the adsorption of MB and AF on C1.
Mentions: where Kt is the intraparticle diffusion rate constant (g·mg−1·min0.5) and C is a constant providing the information about the thickness of the boundary layer. In Figure 11, the plots of Qt vs. t1/2 show at least two linear segments in correspondence with different stages in adsorption. For two linear plots, the Qt vs. t1/2 have intercept value far from zero, which indicates that intraparticle diffusion is not the rate-controlling step of the adsorption process and the external mass transfer may be significant in the rate-controlling step. The first segment is attributed to the outer diffusion due to the mass transfer from the dye solution to the outer surface of the adsorbent (film diffusion or boundary layer diffusion). The second portion indicates a steady adsorption step, corresponding to the diffusion of adsorbate from the adsorbent exterior to the pores or capillaries of the adsorbent internal structure (inner diffusion)56. Thus, the presence of multilinearity and the boundary layer thickness indicate that the adsorption of two dyes on C1 is a complex process and both the surface adsorption and intraparticle diffusion occur during the adsorption process57.

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