Remediation Using

Chapter 26

Environmental Applications: Treatment/Remediation Using Nanotechnology: An Overview

Downloaded by NANYANG TECHNOLOGICAL UNIV on August 25, 2015 | http://pubs.acs.org Publication Date: December 14, 2004 | doi: 10.1021/bk-2005-0890.ch026

Daniel Strongin Department of Chemistry, Temple University, Philadelphia, PA 19122

Contributions in this chapter address the hypothesis that nanotechnology can be used for the treatment and remediation of toxins in the environment. Toward this end papers are presented that detail research on a variety of nanostructured materials ranging from natural protein structures to nanostructures produced by lithographic techniques that have already been developed in the electronics industry. The motivation behind this session was to bring to the forefront the diversity of nanostructure design and application, and to expose different approaches to researchers in a variety of scientific fields.

The chemical waste resulting from industrialized nations presents a serious set of environmental problems. The treatment and/or remediation of toxic wastes generated over many years by industry, the military, the civilian sector, and national laboratories is a daunting challenge. It is not surprising that an intense scientific effort has gone into the development of chemical, biochemical, and photochemical remediation schemes to remove or destroy toxins in soils and waters. Common degradation techniques, for example, 202

© 2005 American Chemical Society

In Nanotechnology and the Environment; Karn, B., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2004.

203 implemented to remediate waste waters include zero valent iron chemistry(7^, photodetoxification using UV/Ozone systems (2) biodégradation (3,4), and phytoremediation (5,6). A working hypothesis by researchers in the nano-arena has been that nanomaterials may provide a chemistry conducive to environmental remediation that cannot be obtained at more traditional spatial dimensions (i.e., > μια). The 9


Environmental Applications: Treatment/Remediation using Nanotechnology

symposium was an ambitious attempt to bring many different nanotechnology based remediation and treatment strategies together into one session. The session not only highlighted the activity in this area, but emphasized the unique structural properties of nanoparticles that set them apart from more traditional size particles. The first session was started by Dr. Jose Rodriguez of Brookhaven National Laboratory who gave an overview of the application of nanogold particles supported on TiOs for SO2 destruction. T i 0 is a commonly used catalyst in industry for S 0 removal, but it is shown in the first talk that nanogold particles has the potential to improve the performance of T i 0 alone. The nanogold-Ti0 system shows a very high efficiency toward S-0 bond cleavage, a necessity in S 0 destruction. The reactivity of this system stems from the unique electronic structure of the nanogold supported on Ti02, emphasizing the new realm of chemical reactivity available at the nanoscale. Not all metals, however, are easily deposited on solid supports as well defined nanoparticles so that new synthetic strategies are being pursued by researchers. Professor Somorjai of the University of California followed Dr. Rodriguez's talk by giving an overview of using modern lithography to prepare patterned metal nanostmctured on solid supports. Specifically, Professor Somorjai uses electron beam lithography, to produce platinum nanoparticles between 5 and 50 nm. Professor Somorjai also emphasized that nanotechnology is intimately intertwined with catalysis, since industrial catalysts are often of nanosize and nature's catalysts, enzymes, are composed of inorganic clusters surrounded by high molecular weight protein. Professor Somorjai argued that advances in nanotechnology could help achieve an sought after goal in the area of catalysis; the achievement of close to 100% catalyst selectivity often found in natural enzymatic systems. It would be advantageous apply the high selectivity of enzymes to remediation efforts. Due to the expense and poor stability of enzymes in remediation efforts, their use is problematic. Dr. Jungbae Kim of Pacific Northwest National Laboratory gave a exciting talk that gave an overview of stabilizing enzymatic activity by using enzyme-polymer composites in nano-meter scale or single-enzyme scale. These researchers crosslinked a composite silicate shell around the individual enzyme molecules yielding a highly stabilized system. Professor Martin Schoonen followed this talk with a study that characterized the charge development of the biologically relevant 2

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protein ferritin in environmentally relevant solutions. Ferritin, which has a roughly spherical shape, has an inorganic core composed of nanosized iron oxyhydroxide. In a followup talk, Hazel-Ann Hosein of Temple University concluded the first session by showing that ferritin could be used as a precursor for the formation of nano iron metal and oxyhydroxide. In essence, ferritin could be used to template the growth of potentially useful nanoparticles.

References 1. Xu, Y.; Zhang, W.-X. Hazardous and Industrial Wastes 1999, 31st, 231239. 2. Hoffmann, M . R.; Martin, S. T.; Choi, W.; Bahneman, D. W. Chemical Reviews 1995, 95, 69-96. 3. Karamanev, D. G. J. Sci. Ind. Res. 1999, 58, 764-772. 4. Starrett, S.; Bhandari, Α.; Xia, K. Water Environ. Res. 1999, 71, 853-860. 5. Teaca, C.-A. Cellul. Chem. Technol. 1999, 33, 351-352. 6. Gadd, G. M . J. Chem. Technol. Biotechnol. 2001, 76, 325.


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