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. 2017 Nov 25;10(12):1355.
doi: 10.3390/ma10121355.

Novel Magnetic Zinc Oxide Nanotubes for Phenol Adsorption: Mechanism Modeling

Marwa F Elkady  1   2 , Hassan Shokry Hassan  3 , Wael A Amer  4 , Eslam Salama  5 , Hamed Algarni  6   7 , Essam Ramadan Shaaban  8
Affiliations

Novel Magnetic Zinc Oxide Nanotubes for Phenol Adsorption: Mechanism Modeling

Marwa F Elkady et al. Materials (Basel). .

Abstract

Considering the great impact of a material's surface area on adsorption processes, hollow nanotube magnetic zinc oxide with a favorable surface area of 78.39 m²/g was fabricated with the assistance of microwave technology in the presence of poly vinyl alcohol (PVA) as a stabilizing agent followed by sonic precipitation of magnetite nano-particles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs identified the nanotubes' morphology in the synthesized material with an average aspect ratio of 3. X-ray diffraction (XRD) analysis verified the combination of magnetite material with the hexagonal wurtzite structure of ZnO in the prepared material. The immobilization of magnetite nanoparticles on to ZnO was confirmed using vibrating sample magnetometry (VSM). The sorption affinity of the synthesized magnetic ZnO nanotube for phenolic compounds from aqueous solutions was examined as a function of various processing factors. The degree of acidity of the phenolic solution has great influence on the phenol sorption process on to magnetic ZnO. The calculated value of ΔH⁰ designated the endothermic nature of the phenol uptake process on to the magnetic ZnO nanotubes. Mathematical modeling indicated a combination of physical and chemical adsorption mechanisms of phenolic compounds on to the fabricated magnetic ZnO nanotubes. The kinetic process correlated better with the second-order rate model compared to the first-order rate model. This result indicates the predominance of the chemical adsorption process of phenol on to magnetic ZnO nanotubes.

Keywords: magnetic nano-zinc oxide; microwave technology; nanotube structure; phenol uptake process.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
X-ray diffraction (XRD) patterns for pure ZnO nanotubes and magnetic ZnO nanotubes.
Figure 2
Figure 2
Scanning electron microscopy (SEM) images of the magnetic ZnO nanotubes.
Figure 3
Figure 3
Transmission electron microscopy (TEM) images of the magnetic ZnO nanotubes.
Figure 4
Figure 4
Magnetization curves of magnetic ZnO nanotubes.
Figure 5
Figure 5
Influence of contact time on phenol sorption process on to magnetic ZnO nanotubes (pH = 5, initial phenol concentration = 10 ppm, agitation speed = 440 rpm, material dosage = 2 g/L and temperature = 25 °C).
Figure 6
Figure 6
Influence of magnetic ZnO nanotubes dosage on both phenol percentage removal and phenol uptake capacity (pH = 5, initial phenol concentration = 10 ppm, agitation speed = 440 rpm, contact time = 90 min and temperature = 25 °C).
Figure 7
Figure 7
Influence of solution pH on the percentage of phenol removal on to magnetic ZnO nanotubes (initial phenol concentration = 10 ppm, material dosage = 2 g/L, agitation speed = 440 rpm, contact time = 90 min and temperature = 25 °C).
Figure 8
Figure 8
Influence of initial phenol concentration on both the percentage of phenol removal and phenol uptake capacity on to magnetic ZnO nanotubes (pH = 5, material dosage = 2 g/L, agitation speed = 440 rpm, contact time = 90 min and temperature = 25 °C).
Figure 9
Figure 9
Influence of phenol solution temperature on the percentage of phenol removal on to magnetic ZnO nanotubes (initial phenol concentration = 10 ppm, material dosage = 4 g/L, agitation speed = 440 rpm, contact time = 90 min and pH = 5).
See this image and copyright information in PMC

References

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