Elsevier

Nano Communication Networks

Volume 1, Issue 4, December 2010, Pages 257-263
Nano Communication Networks

Nano-networks have better adsorption capability than nano-rods

https://doi.org/10.1016/j.nancom.2010.12.001Get rights and content

Abstract

Ion beam bombardment, as a unique and facile technique, was found and developed to fabricate nano-networks from rigid nano-rods. To study the differences of their characteristics, attapulgite (ATP) was chosen as a model. The results of methylene blue adsorption performance investigation demonstrated that attapulgite nano-networks (ATP-N) have better adsorption capability than the attapulgite nano-rods (ATP-R). The mechanism proposed that, compared with nano-rods, nano-networks exhibited larger interspace, better separation, higher pore-size and porosity and higher BET specific surface area due to the microstructure of complex three-dimensional networks caused by physical crosslinking, through a series of analysis of the scanning electron microscopy, BET surface area and X-ray powder diffraction.

Introduction

Compared with nano-rods, nanostructures with intricate morphologies possess many excellent mechanical and rheological properties and have applications in barriers, absorbents, catalysts, carriers, nano-sieves, heat insulation, and so on [8], [6]. Therefore, design and fabrication of nano-materials with intricate morphologies have recently received more attention, especially the fabrication of nano-networks [16]. Most of the research activities have heretofore focused on organic nano-networks that are generally produced by molecular self-assembly. In comparison, it is more difficult to fabricate inorganic nano-networks because the starting materials typically possess a rod shape and self-assembly cannot occur easily [18], [3], [19], [15], [14], [10], so that few proofs can be found on the superiority of nano-networks comparing with nano-rods.

To compare the characteristics of the nano-networks with the nano-rods, we take the adsorption capability, one of the important characteristics, as the model characteristic, because it is significant and widely used in scientific research, convenient and fast to conduct, and sensitive to the microstructure of adsorbents. Moreover, we choose attapulgite (a silicate, with the ideal formula of Si8Mg5O20(OH)2(H2O)4⋅4H2O, the 3.7 Å×6.4 Å cross-section of the zeolite channels, and Si–O tetrahedral form long strips on alternate sides of the oxygen sheet in a manner which confers a regular corrugated Si–O structure) as the model material of nano-networks and nano-rods [5], [2], as it is a natural crystalline hydrated magnesium aluminum silicate with unique three-dimensional structure and consists of nano-scaled rods (with the diameter of 20–40 nm and length of approximately 1 μm), showing a fibrous morphology, and it is facile to obtain the uniform ATP nano-rods through a simple purifying procedure. Most important, in our previous work [4], it was found that ATP nano-rods could be transformed to nano-networks by ion beam bombardment conveniently, and the microstructure of the nano-networks could be sensitively determined by the energy and fluence of the ion beam. This finding contributes to develop a unique and facile technology of transforming nano-networks from nano-rods, which makes it convenient to study the changes of characteristics of ATP in the process of transformation.

In this case, the adsorption performances of ATP nano-networks and nano-rods were investigated in model waste water containing methylene blue. Methylene blue (MB), a common cationic dye in the textile industry, was chosen as a model organic pollutant in the adsorption experiments, because it is not only hazardous for ecosystem but also toxic and even carcinogenic for human beings [1], [7], [9], moreover, acute exposure to MB will cause increased heart rate, vomiting, shock, Heinz body formation, cyanosis, jaundice and quadriplegia and tissue necrosis in humans [13], [17]. This dictates the necessity of MB containing water to undergo treatment before disposal to the environment and the great significance of taking it as the adsorbate. The adsorption results indicate that the nano-networks have a better adsorption ability than the nano-rods. In order to elucidate the mechanism, a series of analysis were conducted through the measurement of scanning electron microscopy (SEM), BET specific surface area and X-ray powder diffraction (XRD). This work, on one way, provides an unique and facile approach of fabricating inorganic nano-networks from nano-rods, on the other way, for the first time, exhibits the proof for the superiority of nano-networks in adsorption performance, which may give some inspirations and thinking to the scientists in the fields of nano-materials, environment protection and chemical industry et al.

Section snippets

Materials

Methylene blue (C16H18N3SCl) is a Merck product (95 wt% of purity), which was oven-dried for 2 h at 110 °C. The UV–vis spectra of MB aqueous solutions displayed an intense band at 664 nm and a weak shoulder at around 612 nm. The crude attapulgite (ATP) was 200 mesh and provided by Jiangsu Junda AT Material Co., Ltd., with a purity of greater than 90%.

Preparation of the ATP Nano-rods

The purchased crude ATP was further purified before sample preparation. 50 g ATP powder was mixed with deionized water (500 ml) and then stirred

Transformation of ATP from nano-rods to nano-networks by ion beam bombardment

Due to the high specific surface area and surface activity of a single ATP rod, it is hard to stably exist isolated in nature world, but easily aggregates with other rods to bunches, as shown in Fig. 1(a) and Fig. 2(a). Therefore, few separate ATP rod can form networks or pores via crosslinking to each other, causing small interspace between the ATP fibers, so that ATP generally exhibits a low porosity and a low BET specific surface area, as illustrated in Fig. 4. Because of the rigid inorganic

Conclusion

In summary, it was found that nano-rods could be transformed to nano-networks conveniently by ion beam bombardment, based on this finding, we developed a unique and facile technique of fabricating nano-networks from rigid nano-rods. It was demonstrated that, through methylene blue adsorption performance investigation, attapulgite nano-networks have better adsorption capability than the nano-rods. The possible reason is that, nano-networks display larger interspace, better separation, higher

Acknowledgements

The authors acknowledge financial support from the National Natural Science Foundation of China (No. 10975154). They also thank the Physical and Chemical Center at the University of Science and Technology of China for the scanning electron microscopy experiments.

Dongqing Cai received B.Sc. degree in Department of Physics and Microelectronics from Shandong University in 2004 and Ph.D. from Institute of Plasma Physics, CAS in 2009. He is currently a research assistant in Key Laboratory of Ion Beam Bioengineering, CAS (Hefei, Anhui, China). His current research interest is mainly on the application of nano-materials.

References (19)

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Dongqing Cai received B.Sc. degree in Department of Physics and Microelectronics from Shandong University in 2004 and Ph.D. from Institute of Plasma Physics, CAS in 2009. He is currently a research assistant in Key Laboratory of Ion Beam Bioengineering, CAS (Hefei, Anhui, China). His current research interest is mainly on the application of nano-materials.

Hong Zhang received M.Sc. degree in State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China in 2007. He is currently pursuing his Ph.D. in Institute of Plasma Physics, CAS. His current research interests include the Waste Water Treatment, Relationship between algae and bacteria.

Yi Tang received B.E. in College of Environmental Science and Engineering, Hunan University in 2008. She is currently pursuing her M.S. in Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, China. Her major is the waste water treatment.

Paul K. Chu received his B.S. in mathematics (Cum Laude and Phi Kappa Phi) from Ohio State in 1977 and went to graduate school at Cornell University in Ithaca, New York. Under the supervision of Prof. Morrison and Prof. James W Mayer of the Department of Materials Science & Engineering at Cornell, Paul conducted research on ion beam processing and characterization of semiconductors and received his M.S. and Ph.D. in chemistry in 1979 and 1982, respectively.

Zengliang Yu, born in 1944, Professor. He received the B.S. degree from radio department of Hefei Industrial University, China, in 1968. From 1968 to 1975, he worked on microwave devices for the Institute of Electronics, Chinese Academy of Sciences, Beijing. Since 1976, he has been with the Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, to research on neutral particle beam injection. From 1980 to 1982, he was with the Technology Division for heating plasma with neutral particle beams in the Max Plank Institute of Plasma Physics, Germany. In 1986, he discovered the bioeffect induced in rice by ion implantation, In 1991, he founded the Ion Beam Bioengineering Laboratory at the Institute of Plasma Physics, and has been its Director and Professor in biophysics. Main interest is in multidiscipline of Physics and Biology, especially in the inter-action between low-energy ions and the organs.

Zhengyan Wu, born in 1972, Ph.D., Professor. He obtained his Ph.D. degree from the Changchun Institute of Applied Chemistry in China in December 2000. From April 2001 to May 2002, He worked as a postdoctoral fellow in Université Louis Pasteur in France. From July 2002 to September 2008, he worked as a research associate in the Albert Einstein College of Medicine in USA. Since October 2008, he has been a professor in the Key Lab of Ion Beam Bioengineering, Hefei Institutes of Physical Science, China. His main work focuses on Material Analysis and Bioanalysis.

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