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Poster Session Abstracts (N-Z)
Nanomaterials Obtaining Technology
G. Ospanova, M. Tlebayev, E. Koltsova, T.
Bayzhumanov. Kazakh National Technical University (KazNTU), Almaty, Kazakhstan
Carbon nanotubes are one of the most advanced materials. Carbon nanotubes are widely used in analytical technics (sensors for analysis), in microelectronics (microelements, high density resonators, diodes and transistors, super condensers, etc.), and in molecular biotechnology.
We developed technology to obtain carbon nanotubes and nanofibres. Catalytical methane pyrolysis was used to obtain carbon nanotubes and hydrogen. The formula for such interaction is as follows: CH4 + catalyst = C + 2H2. Special equipment was used for methane catalytical pyrolysis. It was calculated that carbon nanotubes cost is $11-18/kg; whereas hydrogen cost depends on its purity and ranges from $22 to $82. Then, we propose a kinetic scheme of carbon nanotubes and nanofibres formation from methane and mathematical model of methane catalytic pyrolysis.
So, we developed cost effective and practical technology for carbon nanotubes and clean hydrogen production.
Natural Organic Matter Mitigates the Toxicity of a
Fullerene Water Suspension
Dong Li, Delina Lyon, Qilin Li, Pedro Alvarez.
Department of Civil and Environmental Engineering, Rice University, Houston, Texas, USA
This study investigated the association of a C60 water suspension (nC60) with natural organic matter, present as a soil constituent or dissolved in the water column, and its effect on the antibacterial activity of nC60. Sorption of nC60 to soil reduced its bioavailability and antibacterial activity, and the sorption capacity strongly depended on the organic content of the soil. Adsorption of aquatic dissolved humic substances onto nC60 and possible subsequent reactions were also found to eliminate nC60 toxicity at humic acid concentrations as low as 0.05 mg/L. These findings indicate that the potential impacts of nC60 on microbial activities that are important to ecosystem health can be significantly mitigated by natural organic matter in the environment.
Pesticide Remediation with Alginate Entrapped Iron
Nanoparticles: A Bench Scale Investigation
Jay Thompson, Achintya Bezbaruah, Bret Chisholm. North Dakota State University, Fargo, ND, USA
Nanoscale zero-valent iron entrapped in a calcium-alginate matrix was examined as a possible pesticide remediation technology. Iron nanoparticles were prepared by borohydride reduction of ferrous iron in solution. Particles were subsequently entrapped in calcium-alginate, resulting in iron-impregnated alginate beads with diameters on the order of 5mm. Bare iron nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy and BET surface area analysis. Batch and column studies were conducted on a pesticide mixture (alachlor, dicamba and picloram). The reaction kinetics of the entrapped iron was found to be similar to free iron nanoparticles. Slightly reduced pesticide removal with entrapped iron (compared to free iron) was because of limited availability of reactive nanoparticle surface area and higher mass transfer resistance due to the alginate coating. Nanoscale zero-valent iron entrapped in a calcium-alginate matrix can potentially be used in permeable reactive barriers for groundwater remediation as well as in point-of-use treatment systems.
Photocatalytic Degradation of 4-Chlorophenol Using New
Visible Light Responsive BiTiZrOx Nano-Size Photocatalysts
B. Neppolian, Evrim Celik, H. Choi. Department of
Environmental Science and Engineering, Gwangju Institute of Science and
Technology, Gwangju, South Korea
Chlorophenols are highly toxic, and hazardous compounds, normally present in soil, water and wastewater as persistent pollutants because of its non-biodegradable nature. Chlorophenols are widely used as herbicides, pesticides, and wood preservatives which are the main sources of chlorophenols. Among the different chlorophenols, 4-chlorophenol (4-CP) is commonly found in the wastewater of pulp and paper, pharmaceutical and dyestuff industries (1).
Many physicochemical methods have been employed for the safe removal or degradation of chlorophenols. However, each method has its own limitations. Heterogeneous photocatalysis has been considered to be one of best methods under the Advanced Oxidation Technologies (AOTs) for the efficient treatment of water, wastewater as well as air pollution. The main advantage of the heterogeneous AOTs is the complete degradation (oxidation) of organics into CO2 and water along with mineral acids within a short period of time without leaving any other solid wastes.
Utilizing naturally available solar energy is a main focus in the near future, not only for facing the future energy demand but also for the complete degradation of pollutants using visible light responsive photocatalysts. In this regard, we have synthesized new BiTiZrOx nano-size photocatalysts which could be able to work under the visible light irradiation more effectively than the commercial catalysts. BiTiZrOx nano-size photocatalysts were synthesized by ultrasonic assisted hydrothermal method. The characterization studies were carried out with different sophisticated instruments in order to understand the nature of the catalysts for the photocatalytic degradation of organic pollutants. The catalysts were calcined at various temperatures from 400 to 550 °C. Among the different calcined catalysts, 450 °C catalysts showed profound effect on the degradation of 4-chlorophenol in comparison to the other catalysts. This is due to the nano-particle size (~ 10 nm), high crystallinity, high surface area of the catalysts and strong absorption towards visible region of light as well. All these factors are responsible for the higher degradation of 450 °C calcined catalysts. Around 72 % degradation of 4-chlorophenol was achieved within 3 hrs irradiation, whereas, other calcined catalysts including commercially available photocatalysts such as, P-25 showed less degradation. This new nanosize catalyst is proved to an alternate and efficient catalyst for the degradation of organic compounds by utilizing visible light irradiation.
Reference
(1). B. Neppolian, H. Jung and H. Choi, J. Adv. Oxidn. Techs. 2007, 10, 369–374.
Potential Toxicity of
Nanomaterials and their Removal
Wen Zhang, Xiaoshan
Zhu, Xuezhi Zhang, Yung Chang, Hu Qiang, Bruce Rittman, John Crittenden,
Yongsheng Chen. Department of Civil and Environmental Engineering, Arizona State University, Tempe, AZ, USA
The rapid growth of nanotechnology is stimulating research on the potential environmental impacts of manufactured nanomaterials (MNMs). Our project is to focus on methodology development for measuring the interactions between MNMs and bio-systems, evaluation of the potential toxicity of MNMs, and investigation of potential treatment technologies that could remove them from treatment processes.
Unlike larger particles, MNMs can probably accumulate or even penetrate across the cell membrane which is the last protection barrier of living cells from the exotic intrusion. The ZnO MNMs with average of 100nm diameter were coated onto the surface of cantilever probe that was confirmed by Scanning Electronic Microscope techniques. The Zebra fish embryos at different stages were prepared and spiked on the plastic plate by mechanical trapping method. It was observed that, after a short-term exposure, the aggregates of ZnO MNMs accumulated on the surface of the embryo but the embryo survival was not affected significantly. However, hatching delay was found although the mechanisms are still unclear. Adhesion force results indicated that the chorion of the embryo at an early stage had a large portion of adhesion forces distributed from 2000 to 2800 pN which means the chorion tended to be stickier. There was also a lower level of adhesion force domain from 800 to 1600 pN. After 8 hours the force distribution moved slightly to the range of low force domain which indicated the average adhesion force decreased slightly and the chorion became less sticky and more hardened.
The potential effects of chronic exposure (32 d) of the aquatic organism—juvenile carp (Carassius auratus) to the MNM, fullerene aggregates (nC60/aq, C60 suspended in water after long-term stirring), was also investigated at the sub-lethal concentrations (0.04 to 1.0 mg/L). The preliminary results suggested that certain oxidative stress response enzymes and the glutathione (GSH) content, could be used as useful biomarkers or bioindicators to assess the effects of exposure of the fish to nC60/aq. Furthermore, the lipid peroxidation experiment suggested that the liver was the primary target organ of the fish and thus was more susceptible to nC60/aq exposure than several other tested organs/tissues (e.g., muscles, gills). As a result, the body weight and the total length of juvenile carp exposed to 1.0 mg/L nC60/aq for 32 d decreased significantly (p<0.05)..
In addition, removal of MNMs from water was investigated by coagulation, flocculation, sedimentation, and membrane ultrafiltration of hematite MNMs ranging in size from 53 nm to 240 nm. The coagulation, flocculation, or sedimentation process alone or in combination, could not remove all the hematite MNMs even at a very high alum dose (60 mg/L). A lower alum concentration of 20 mg/L resulted in removal of ca. 90% of the MNMs after 24 hours treatment. However, the ultrafiltation process completely removed the tested MNMs and the resulting permeate was essentially free of hematite, suggesting that ultrafiltration can be used as an effective way to remove MNMs.
The environmental behaviors and the toxicity of MNMs learned from this study provided the insight information that may help scientists and manufacturers to design and manufacture more environmentally benign MNMs while at the same time avoiding environmental disasters such as DDT and PCB occurred in the past.
The Response of Soil Microbial Activity and Diversity to
Nano-silver Application
Marianne Bischoff, Mary-Jane Orr, Larry Nies, Ronald
F. Turco. Purdue University, West Lafayette, IN, USA
The impact of manufactured nano-scale metals on the environment is an area of great interest due to increasing manufacture and use of these materials as antimicrobial agents. Data on the effect of these materials in soils is scarce. In this study, manufactured nano-silver and nano-zinc oxide were applied to three soils with different physical characteristics. Soil respiration was determined after 3, 10 and 30 days exposure to the nano-metals by treating the soils with 14C-glucose and measuring 14CO2 after 1, 4 and 24 hours. All three soils showed reduction in respiration at 1 hour 14CO2 respiration measurements after treatment with nano-silver. In Drummer (silty clay loam) soil with an organic matter (OM) content of 3.6% and cation exchange capacity (CEC, meq 100 g-1) of 23.2, a 36% decrease in microbial activity was noted after 3 days exposure to a nano-Ag concentration of 1000 µg g-1. In contrast, Clermont soil (silty loam; OM 1.96%; CEC 8.6) showed a 29% decrease in respiration at 10 µg g-1 and a 49% decrease at 25 µg g-1 after 3 days exposure. Tracy soil (sandy loam, OM 1.5%; CEC 8.0) showed an intermediate response with a 46% reduction in soil respiration at 500 µg g-1 after 3 days. In contrast, the response of these soils to nano-zinc oxide was negligible. Differences in respiration could result from differences in soil physical properties influencing the availability of the nano-Ag to soil populations or microbial population composition resulting in different cumulative responses to nano-Ag application. The impact of nanosilver on the biological diversity in the systems was also assessed at the community level using DGGE after PCR amplification of genomic DNA using universal bacterial 16S rDNA primers or eukaryote 18S rDNA. This work shows that in light textured soil, the application of nano-Ag has altered DGGE banding patterns suggesting a community level response to the presence of nano material.
Screening of Available ZVI Products for Mending an
Existing Permeable Reactive Barrier in the 100-D Area at the Hanford Site
Nick Jaynes1, Adam Logar1,
Martin Foote1, Gary F. Wyss1, Marek H. Zaluski1,
Michael Hogan1, Scott Petersen2. (1) MSE Technology
Applications, Butte, Montana, USA; (2) Fluor Hanford, Washington, USA
MSE Technology Applications, Inc, (MSE) has conducted investigations associated with injection of nano size zero-valent iron (nZVI) into the subsurface at the 100-D Area at the U.S. Department of Energy (DOE) Hanford Site, Washington State. The purpose of this work was to demonstrate the feasibility of using nZVI to repair portions of the In situ Redox Manipulation (ISRM) barrier located in the 100-D Area of the Hanford Site and installed to intercept a hexavalent chromium plume moving towards the Columbia River. The investigation included a comprehensive screening of commercially available zero valent iron (ZVI) products.
As a result of conducting extensive literature research and consulting internal and external resources, MSE developed a database in September of 2007 that contained 30 ZVI candidate materials for potential use at the Hanford 100-D Area. Simple batch experiments were performed to evaluate the materials on their ability to create a reducing environment and reduce hexavalent chromium.
MSE chose to further test the top six ranked materials in the database (EZVI, Polyflon Particles, NanoFe I, NanoFe II, Zloy, and RNIP-M2) under a set of 3 screening tests to further evaluate the injectability and reactivity of these materials. Micropowder S-3700 (MZVI) was also tested for comparison purposes due to its previous history with the MZVI injection project. The screening tests consisted of another series of batch tests, a horizontal flow cell injection and a geochemical test.
Batch test were conducted with each ZVI material. These 4-hour tests were performed on the mixture of ZVI material, clean silica sand and surrogate groundwater. Measurements of specific conductivity, pH, ORP, temperature and dissolved chromium were taken upon completion of the test.
Following the batch tests, injectability tests were performed on all ZVI materials. Each material was injected through a horizontal flow cell packed with a surrogate blend of silica sand. Samples of the flow cell effluent, solid core samples, and visual observation were used to evaluate the mobility of each ZVI material.
Finally, three materials were further evaluated on their ability to create a reducing environment and reduce hexavalent chromium over a moderate time period. The materials were tested in vertical columns containing Ringold E soils and two concentrations of ZVI, 1.5% and 0.075%. The columns were flushed with surrogate groundwater for 20 pore volumes.
This work was conducted through the support of Fluor Hanford under Contract Number 30994.
Surfactive Stabilization of Multi-Walled Carbon Nanotube
Dispersions with Dissolved Humic Substances
Mark. A. Chappell1, Aaron J. George2,
Beth E. Porter2, Cynthia L. Price1, Katerina M. Dontsova2,
Alan J. Kennedy1, Jeffery A. Steevens1. (1) Environmental
Laboratory, Engineering Research & Development Center, U.S. Army Corps of
Engineers, Vicksburg, MS, USA; (2) SpecPro, Inc., Vicksburg, MS, USA
Soil humic substances (HS) have been shown to stabilize carbon nanotube (CNT) dispersions in solution yet the mechanisms by which this occurs are widely misunderstood. For this paper, we hypothesize that this behavior is a property of the surfactive nature of HS. Experiments were conducted by dispersing multi-walled CNT in solutions containing a range of dissolved HS concentrations obtained from the commercial Aldrich humic acid or water-extractable HS from Catlin silt loam soil (fine-silty, mixed, mesic, superactive Oxyaquic Argiudolls). CNT dispersions demonstrated enhanced stability at 50 and 300 mg L-1 added HS from Aldrich HA and Catlin HS, respectively. Dynamic light-scattering data showed that increasing the concentration of HS decreased CNT mean particle diameter (MPD) to approx. 250 nm for Aldrich HA and to approx. 450 nm for the Catlin HS. CNT particle size polydispersivity (PD) also reached a minimum at approx. 0.3 and 0.35 with increasing Aldrich HA and Catlin HS, respectively, indicating enhanced homogeneity of particle sizes but with significant differences between the two humic materials. HS adsorption isotherms revealed that maximum dispersion stability and minimization of MPD and PD corresponded with saturation of CNT particles with HS – a behavior indicative of surfactants. To verify this conclusion, CNT dispersion potential was studied in the presence of two nonionic (Brij 35 and Triton X) and one anionic (SDS) surfactants. Trends in CNT MPD and PD minimas, and surfactant adsorption were observed with increasing dispersion stability. Results showed that the highly surfactive nature of dissolved HS readily stabilized CNT dispersions. It is our opinion that natural levels of HS present in most waters is sufficient to readily disperse CNT in the environment.
Toxicity of CdSe/ZnS Nanocrystals to D. Magna
H.P. Pace1, J.F. Ranville2. (1)
Colorado School of Mines, Department of Environmental Science and Engineering,
Golden, CO, USA; (2) Colorado School of Mines, Department of Chemistry and
Geochemistry, Golden, CO, USA
With the rapid expansion of the nanotechnology industry, quantum dots (QDs) are situated to become a prominent new source of metal contamination. We are currently researching the acute toxicity of CdSe/ZnS QDs on Daphnia magna using 48hr exposure studies. Toxicity of QDs was hypothesized to be directly related to either one of two scenarios: 1) the solubilization of the QD and subsequent release of toxic metals (Zn, Cd) or 2) the physical or chemical impairment of key physiological functions by the nanoparticle itself. To test this hypothesis we investigated QDs with two different CdSe core diameters, 2nm green emitting QDs and 5nm red emitting QDs. To investigate potential particle effects we also examined two separate surface coatings, polyethylene oxide (PEO) and 11-mercaptoundecanoic acid (MUA), which are polar and anionic respectively (Evident Technologies, Troy NY and NN-Labs, Fayetteville AR). These coatings, which serve to render the QDs water stable, increase the hydrodynamic diameter of all QDs to approximately 25nm. Thus, while the metal content of the red and green emitting QDs (2nm vs. 5nm) was substantially different, the total particle size was the same. Using a fluorescence scan of the QDs (400-800nm) we monitored the QD concentrations during exposures. We found that PEO coated QDs remained well-dispersed throughout the 48hr exposures with no significant change in QD concentration whereas MUA coated QDs had a higher tendency to aggregate. In addition, we characterized the QDs before and after exposure via filtrations and ICP-OES metal analysis (unfiltered, 0.02µm and 3kDa filtrations). Finally, fluorescence microscopy and synchrotron micro-XRF showed accumulation of nanoparticles within exposed daphnids.
Toxicity of Multi-Walled Carbon Nanotubes in Water to
Sediment-Dwelling Invertebrates
Joseph N. Mwangi1, Ning Wang2,
Christopher G. Ingersoll2, Doug K. Hardesty2, Eric L.
Brunson2, Li Hao3, Baolin Deng1. (1)
Department of Civil and Environmental Engineering, University of Missouri,
Columbia, MO, USA; (2) USGS, Columbia Environmental Research Center, Columbia,
MO, USA; (3) Department of Mechanical and Aerospace Engineering, University of
Missouri, Columbia, MO, USA
Carbon nanotubes (CNTs) could be widely used in electronics, optics, material science, and medical fields due to their unique properties such as high electrical and thermal conductivity and also mechanical strength. Potential environmental effects of the CNTs however, are largely unknown. Given that these materials are relatively insoluble in water, sediment may be the final repository of these materials when released in an aquatic environment. The objective of this study is to evaluate the potential toxicity of multi-walled carbon nanotubes (MWCNTs) associated with water or sediment to sediment-dwelling invertebrates. Two samples of MWCNTs were obtained from different producers and used for preliminary 14-d water-only toxicity tests with amphipods (Hyalella azteca), midge (Chironomus dilutus), oligochaetes (Lumbriculus variegatus), and juvenile mussels (Villosa iris). The exposures were conducted in water adjusted to 100 mg/L hardness with 4 replicates/treatment. The treatments included 200 mg of sonicated or 200 mg of non-sonicated MWCNTs added to each 300-ml glass exposure beaker containing 200 ml of water. The control treatment received 200 ml of water. The tests were conducted in static conditions with aeration of water and 50% water replacement every Monday, Wednesday and Friday. At the end of tests, the survival of amphipod ranged from: (1) 88 to 100 in the controls, (2) 5 to 8% in the non-sonicated MWCNTs treatments, and (3) 3 to 5% in the MWCNTs sonicated treatments. Survival of midge ranged from: (1) 63 to 80% in the controls, (2) 55 to 60% in the MWCNTs non-sonicated treatments, (3) 8 to 43% in the MWCNTs sonicated treatments. Survival of mussels ranged from: (1) 80 to 98% in the controls, (2) 23 to 35% MWCNTs in the non-sonicated treatments and (3) 3 to 43% in the MWCNTs sonicated treatments. The ash-free biomass of oligochaete ranged from: (1) 5 to 12 mg/treatment in the controls, (2) 0.8 to 2 mg/treatment in non-sonicated MWCNTs treatments and 2 to 3 mg/treatment in MWCNTs sonicated treatments. These results indicated that the MWCNTs were toxic to the four tested species. Light microscopy and environmental scanning electron microscopy indicated that the MWCNTs were consumed by the test organisms; moreover, it appears that the MWCNTs may smother test organisms or may interfere with the ability of test organisms to consume food added during the exposures. Further tests are planned to evaluate the toxicity of these MWCNT added to sediment to these sediment-dwelling invertebrates.
Ultracentrifugation onto Supporting Grids as a Tem
Specimen Preparation Method for Carbonaceous Nanoparticles
Emilia Cieslak, Jamie R. Lead. School of Geography, Earth and Environmental Sciences, University of Birmingham, United Kingdom
Ultracentrifugation, along with stabilization using polymer gels, has been successfully used as a way of preparing native colloidal material from natural waters for examination using transmission electron microscopy. This, and other techniques (resin embedding, ultramicrotomy), allowed images of minimally perturbed natural aquatic colloids to be obtained. Here we apply a similar approach to study carbonaceous nanoparticles in water samples. Single-walled and multi-walled carbon nanotubes as well as water stirred fullerenes (nC60 clusters) were used in the experiments. Additionally, these nanoparticles were examined in the presence of natural aquatic colloids (like Suwannee River humic acid) under well controlled conditions, to better understand their interactions. The presented preparatory methodology has proven to be superior to traditional preparation methods.
Use of Biopolymer to Encapsulate Iron Nanoparticles:
Diffusion and Treatability Studies
Rabiya Shabnam, Achintya Bezbaruah, Senay Simsek,
Eakalak Khan, John McEvoy, Yildirim Bora Suzen. North Dakota State University, Fargo, ND, USA
Zero-valent iron nanoparticle (nZVI) is the most popular among the metal nanoparticles used in environmental remediation. Though nZVI have been extensively used for remediation, their efficacy has been evaluated excluding their possible interactions with environmental microorganisms. It is hypothesized in this study that a symbiotic relationship does exist or can be established between nZVI and microorganisms by controlling their immediate environment. Nanoparticles can reduce a contaminant as the first step in the degradation process and microorganism can preferentially take over the process and reduce/oxidize the degradation byproduct(s) to benign end products or vice-versa. The experiments discussed in this paper are conducted in ‘micro-reactors’ made of biopolymers (e.g., alginate). The calcium alginate capsules/microreactors are made and optimized for diameter, membrane thickness, and bursting force. Diffusion studies done using monosaccharide (Xylose) and pesticide (Alachlor) show good contaminant diffusion into the microreactors (~3.4 mm dia). nZVI and microorganisms are being separately encapsulated in the microreactors and treatability batch studies with specific contaminants are conducted. Separate batch studies are to be conducted with nZVI and microorganisms encapsulated together. The results from these batch studies will be compared and conclusions drawn. The batch experiments to find out shelf life of the microreactors will also be conducted. The study on microorganism-nanoparticle interactions is expected to yield vital clues on the possible symbiotic relationship that may exist (or can be established) between iron nanoparticles and microorganisms.
The Use of Nanoparticles Based on
Encapsulated Oligonucleotides as an Environmental Tracer System
Tracking the movement of waters with or
without associated pollutants, including nanopollutants, through the
environment is presently limited not only by the number of unique tracers that
are available but also by the environmental persistence of some of the tracer
formulations. These two issues severely limit the ability to undertake
simultaneous multiple tracer studies.
In order to address the above limitations of existing tracer technologies we have developed a system based on encapsulating oligonucleotide tracers in a biocompatible polymer. The oligonucleotide provides a unique identifier for each tracer batch. A large number of unique identifiers are possible and these can be determined using quantitative molecular approaches.
The biocompatible polymer is based on polyamidoamine homopolymer and polyamidoamine-polyethylene glycol (PAA-PEG) copolymers, which were originally developed for oligonucleotide anti-sense therapy applications. The homopolymer and PAA-PEG copolymer react autocatalytically to encapsulate the oligonucleotide and produce stable nanoparticles of about 40nm radius. The particles are quantitatively retained on a 300,000Da ultrafiltration membrane as determined by quantitative polymerase chain reaction (qPCR). Recoveries of the oligonucleotide in particles by ultrafiltration and qPCR correlate well with particle number and copy number per particle calculated according to particle volumes and reported DNA condensation densities.
The particles generated to date have been shown to slowly degrade in river water samples over a period of three months. The rate of degradation is not sufficient to preclude the use of the particles as an environmental tracer but indicates that they are not persistent. Preliminary field trials have been undertaken on two freshwater rivers in the UK. The first of these took place in a small, poorly channelled brook. The particles were easily detected in the brook samples taken 1.7 km downstream of the addition point 1.5-2 hours after addition with a peak concentration detected after 2-2.5 hours. The second trial took place over a 7 km stretch of a well channelled river in Scotland and the particle tracer performed in a similar manner to Rhodamine WT dye with both reaching maximum concentration 620 minutes after addition. Excellent recoveries were also achieved.
The particles can be generated on a large scale and we have already produced particle batches from 70 mg of oligonucleotide. These batches contained 3e15 particles with each particle containing about 450 oligonucleotides. We are currently scaling up production of the tracer batches to include one gram of oligonucleotide, which should in theory generate approximately 5e16 particles.