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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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(a) Adsorption kinetics curves and (b) pseudo-second-order kinetic plots for the adsorption of two dyes on C1 (initial concentration: 200 mg L−1 for MB and AF, dosage of C1: 666 mg L−1).
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f10: (a) Adsorption kinetics curves and (b) pseudo-second-order kinetic plots for the adsorption of two dyes on C1 (initial concentration: 200 mg L−1 for MB and AF, dosage of C1: 666 mg L−1).

Mentions: From the viewpoint of adsorption kinetics, the adsorption is a heterogeneous process that involves physical, chemical, and electrostatic interactions. The adsorption rate of dyes depends on the contact time of the solid and liquid as well as on diffusion process. The temporal evolution of UV spectra for two dyes of MB and AF on C1 dyes is presented in Figure 9, and the adsorption kinetic curves are presented in Figure 10. The C1 exhibits an excellent adsorption performance for two dyes. In general, the removal efficiency of 83.5% and 70.1% can be achieved within the first 60 min for MB and AF, respectively, with the initial concentration of 200 mg·L−1. The adsorption removal of two dyes was rapid at the initial period (10 min) and then became slow with the increased contact time until equilibrium. The removal rate of pollutants is initially rapid, however, it gradually decreases with increased time until it reaches equilibrium. This phenomenon is ascribed to the fact that a large number of vacant adsorption sites on C1 are available at the initial adsorption stage, and after a lapse of time, the remaining vacant sites are difficult to occupy because of repulsive forces between the dye solute molecules on the solid and bulk phases52.


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)

(a) Adsorption kinetics curves and (b) pseudo-second-order kinetic plots for the adsorption of two dyes on C1 (initial concentration: 200 mg L−1 for MB and AF, dosage of C1: 666 mg L−1).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f10: (a) Adsorption kinetics curves and (b) pseudo-second-order kinetic plots for the adsorption of two dyes on C1 (initial concentration: 200 mg L−1 for MB and AF, dosage of C1: 666 mg L−1).
Mentions: From the viewpoint of adsorption kinetics, the adsorption is a heterogeneous process that involves physical, chemical, and electrostatic interactions. The adsorption rate of dyes depends on the contact time of the solid and liquid as well as on diffusion process. The temporal evolution of UV spectra for two dyes of MB and AF on C1 dyes is presented in Figure 9, and the adsorption kinetic curves are presented in Figure 10. The C1 exhibits an excellent adsorption performance for two dyes. In general, the removal efficiency of 83.5% and 70.1% can be achieved within the first 60 min for MB and AF, respectively, with the initial concentration of 200 mg·L−1. The adsorption removal of two dyes was rapid at the initial period (10 min) and then became slow with the increased contact time until equilibrium. The removal rate of pollutants is initially rapid, however, it gradually decreases with increased time until it reaches equilibrium. This phenomenon is ascribed to the fact that a large number of vacant adsorption sites on C1 are available at the initial adsorption stage, and after a lapse of time, the remaining vacant sites are difficult to occupy because of repulsive forces between the dye solute molecules on the solid and bulk phases52.

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