Grantee Research Project Results
2002 Progress Report: Membrane-Based Nanostructured Metals for Reductive Degradation of Hazardous Organics at Room Temperature
EPA Grant Number: R829621Title: Membrane-Based Nanostructured Metals for Reductive Degradation of Hazardous Organics at Room Temperature
Investigators: Bhattacharyya, Dibakar , Bachas, Leonidas G. , Ritchie, Stephen M.C.
Current Investigators: Bhattacharyya, Dibakar , Bachas, Leonidas G. , Ritchie, Stephen M.C. , Meyer, David , Lewis, Scott , Tee, Y.
Institution: University of Kentucky , The University of Alabama
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 2002 through December 31, 2004 (Extended to March 31, 2006)
Project Period Covered by this Report: January 1, 2002 through December 31, 2003
Project Amount: $345,000
RFA: Exploratory Research: Nanotechnology (2001) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Nanotechnology , Safer Chemicals
Objective:
The overall objective of this project is to develop a fundamental understanding of the reductive dechlorination of selected classes of hazardous organics by immobilized nanosized metal particles in polymeric membrane systems. This integrated research involves developing techniques for synthesizing nanoparticles (< 50 nm) in various membrane platforms, the role of metal surface area and surface sites, the potential role of ordered nanodomain in membranes for separation and reaction, and membrane partitioning/reaction kinetics are being explored. The additional benefits of this work include the significant reduction of materials usage and the miniaturization of dechlorination reactor systems by a more efficient use of metals and the selectivity process.
Progress Summary:
Our work has provided highly successful results relating to the synthesis of nanosized iron and bimetallic iron/nickel particles using three different membrane-based methods. These include: (1) direct membrane-phase metal particle formation; (2) external particle synthesis in solution followed by membrane incorporation and (3) use of metal chelating polymers (such as poly-acrylic acid) on membrane supports. These fundamentally new techniques for creating environmentally applicable nanoparticles in an ordered fashion by immobilization in a membrane matrix provide a versatile platform to address diverse needs in both industrial manufacturing and remediation. We have successfully demonstrated: (1) formation of nanoscale particles directly in cellulose acetate and polyelectrolyte-based membranes in the 20-50 nm range; (2) significantly higher reaction rates of trichloroethylene (TCE) (as the main model organic) degradation (versus bulk and nanoscale iron results) using only one-tenth of the metal loading; and (3) enhanced reaction rates through the incorporation of nickel, as a second protective metal.
Nanoparticle Synthesis With Applicable Dechlorination Results
Method 1: Direct Membrane-Phase Metal Particle Formation
Material Preparation. Although the number and type of metal ions used in membranes can be tailored for specific applications involving dechlorination reactions, the present discussion will be limited to the case of bimetallic Fe/Ni nanoparticle systems. Membranes were obtained by first preparing a 0.3 M Fe2+/0.075 M Ni2+ solution (4:1, Fe:Ni) using FeCl2/NiCl2 and allowing it to mix for 1 hour. This solution then was added to a casting solution containing cellulose acetate dissolved in acetone until the final composition by weight of the casting solution was 17 percent cellulose acetate, 14 percent water, 0.9 percent hydrated FeCl2, 0.3 percent hydrated NiCl2, and 67.8 percent acetone. This composition was selected based on the classical composition for preparing dense reverse osmosis membranes. Modifications were made to allow for larger metal loading in the membrane. The solution was mixed and allowed to sit at 4°C until the presence of gas bubbles within the solution could not be visibly detected. A film was cast on a glass plate using a Gardner's® knife set at 14 mils. Initial solvent evaporation was allowed to proceed for 30 seconds to allow formation of a skin layer on the surface of the polymer film.
The glass plate then was immediately immersed in a chilled coagulation bath containing 0.02 M NaBH4 in water at a temperature of 1°C. The film was soaked for 15 minutes to allow for the complete de-mixing of the polymer solution with simultaneous particle formation. Excess NaBH4 was used to help prevent oxidation of the metal particles upon formation. Upon removal, the membrane was dried and rinsed twice with 500-mL portions of water. The first wash was at pH 2 to induce rapid reaction of residual NaBH4 with water. The second wash was performed at pH 6.2 to equilibrate the membrane with the optimal pH for dechlorination studies. Samples were taken of the coagulation and reduction baths to determine metal loss during synthesis. A sample of the reduced membrane was saved in ethanol for particle analysis.
Analytical Techniques. Organic analysis was performed using a Hewlett Packard 5890 Series II gas chromatograph (GC) equipped with a Series 6150 mass spectrometer (MS). For the bimetallic experiments, an OI Analytical Model 4560 Purge-and-Trap (PT) was coupled to the GC/MS and used for direct analysis of the aqueous phase. A 12 to 15 percent error in analysis was observed over an extracted organic concentration from 75 to 300 mg/L. For PT-GC/MS, the associated error was determined to be 15 to 20 percent, based on feed analysis. For example, for a theoretical feed of 11.7 mg/L, organic analysis typically yielded a concentration of approximately 9 mg/L. However, theoretical calculations do not consider vapor phase partitioning of the feed in the volumetric flask. In addition to unknown samples, periodic known samples were analyzed following the same procedure to insure proper operation of the equipment. The amount of Cl¯ in each sample was determined using an Orion Model 9617BN combination ion-selective electrode manually calibrated for a working range of 1-10 mg/L, with a standard deviation in mV response from 0.2 to 0.5 mV, where a 10 mV response is equivalent to 1 mg/L Cl¯. The standard addition method also was used to check results. For soluble metal analysis, the amount of iron and nickel was determined using a Varian SpectrAA 220 Fast Sequential atomic adsorption spectrometer equipped with a Fisher Scientific data coded hollow cathode lamp. The sensitivity of the instrument permits linear analysis over a range from 1 to 3 mg/L of metal with a maximum error greater than 4 percent.
Particle size was determined using either: (1) Phillips Tecnai 12 transmission electron microscope (TEM) operating with an 80-kV source (Fe0 systems); (2) JEOL 2010 field emission TEM operating with a 200-kV source (Fe0/Ni0 systems); or (3) Hitachi S-3200 and Hitachi S-900 Scanning Electron Microscope (SEM). All scopes are equipped with an EDX detector and digital camera. For all cases, samples both with and without osmium coating were dried overnight at 50°C and embedded in Spurr's resin for 48 hours at 60°C. A cross section of the membrane was cut and mounted on a copper grid.
Membrane Characterization. The films obtained using phase inversion were approximately 25 cm by 25 cm with a thickness of 120 µm. Prior to examining bimetallic systems, cellulose acetate films containing 25-nm Fe0 particles were synthesized using the techniques outlined above. A representative TEM image of the cross section of these films is shown in Figure 1.
Figure 1. TEM Image of the Cross Section of an Fe0/Cellulose Acetate Mixed-Matrix Membrane. Average particle size was determined to be 25-nm.
Results from TEM analysis of the Fe/Ni/Cellulose Acetate membranes are shown in Figure 2. The membrane-immobilized bimetallic particles were found to have an average diameter of 30 nm, which is very close to the desired 2-20 nm diameter. These particles are much better than clusters obtained in solution phase, which had a bimodal size distribution around 300 and 640 nm. For selected samples, SEM photographs also were obtained of freeze-fractured cross-sections to verify particle size both in the cross-section and at the surface. These photographs (see Figure 2) also showed an average diameter of 30 nm. Because cluster size will be dependent on the ability to isolate freshly formed Fe0/Ni0 atoms, it is evident that the membrane was not dense enough to allow stable nanoparticle formation within the desired range. For cases where metal loss was analyzed, an 11 ± 2-percent loss of Ni0 and 8 ± 1-percent loss of Fe0 were observed.
Figure 2. TEM (left) and SEM (right) Images of Fe/Ni Bimetallic Nanoparticles Synthesized in a Cellulose Acetate Film. The average particle size, both at the surface and in the cross section, is about 30 nm.
Dechlorination Studies. Initial studies using only Fe0 nanoparticles in cellulose acetate showed degradation of 1,1,2,2-tetrachloroethane (TtCA), with up to a 70-percent reduction in parent compound levels in 2 hours using only 8.5 mg of immobilized metal. Therefore, it is possible to use these systems for dechlorination. However, oxidation problems during synthesis tended to create a wide variability in dechlorination results. This variability of results is what ultimately led to the use of a second "protective" metal to help prevent the onset of oxidation. In the literature, it is believed that the use of a hydrogenolysis catalyst, such as Pd or Ni, can greatly enhance dechlorination because of the greater potential conversion of H+ to active H with subsequent sorption to the metal surface. In the case of Ni, a galvanic cell is formed between the Fe (anode) and Ni (cathode). The Fe will undergo corrosion at the water interface, transferring electrons to the Ni. These electrons lead to the formation of active H, and thus higher reaction rates should be expected.
Typical dechlorination studies involved the use of two 120-mL glass bottles capped with Mininert® (Supelco) valves filled with 110 mL of a chlorinated organic solution at pH 4, allowing for a 10-mL headspace. The chlorinated organic solutions were made using deionized ultrafiltered (DIUF) water that had been de-oxygenated by bubbling nitrogen (99.995 percent, research grade) through it for 1 hour. The reduced membrane was cut into strips and placed in one of the glass bottles. The second glass bottle was used as a volatility control. Both bottles were placed on a wrist-action shaker and mixed throughout the duration of the experiment.
A summary of results for the various membrane trials using Fe/Ni bimetallic nanoparticles is given in Figure 3. The data given for parent compound degradation (expressed as C/C0) have been corrected for both adsorption and volatility losses.
Figure 3. The Time-Dependent Concentration Profile for the Destruction of TCE Using 31-mg of Fe0/Ni0 Immobilized in Cellulose Acetate. For these experiments, initial TCE concentration, C0 = 9 mg/L TCE and pH = 4.0.
For the TCE experiments, films contained 31 ± 2 mg of metal (Fe0/Ni0) at a metal ratio of 4:1 (Fe:Ni). The average initial concentration for all runs is 9 ± 2 mg/L TCE. Using this small quantity of metal (0.28 g metal per L of solution treated), it was possible to achieve more than a 75-percent reduction in TCE levels in 4.25 hours. Headspace analysis showed ethane as the only observable product. For shorter reaction times (< 2 hours), traces of (Z) and (E) dichloroethylene (DCE) could be extracted from the baseline of the MS chromatogram. However, quantification of this data was not possible at this time using the current GC/MS configuration. Future work will involve the use of more selective gas separation columns for headspace analysis. For longer reaction times, products of coupling reactions (butane and hexane) could be observed. This is consistent with findings reported in the literature by Arnold and Roberts (2000) and Schrick, et al. (2002), who conducted aqueous phase dechlorination (nonmembrane) studies of TCE using dispersed metallic nanoparticles.
The kinetic data obtained for these seven experiments were fitted to a pseudo first-order kinetic model with respect to the aqueous phase TCE concentration to obtain the governing reaction rate constant for the immobilized system. The resulting slope (observed rate constant) from a straight line fit of ln (CW/CW,O) versus t (hour) is 0.3383 h-1, where R2 = 0.9233 (see Figure 4).
Figure 4. Determination of the Observed Pseudo First Order Rate Constant for the Destruction of TCE Using Fe0/Ni0 Immobilized in Cellulose Acetate. The above data are based on seven experiments.
To compare this with available literature data, it is necessary to first calculate the surface area normalized rate constant (kSA), as originally presented in the work of Johnson, et al. (1996). This value is obtained using the metal surface area loading in solution. Based on a 30-nm diameter, the available particle surface area per unit weight can be taken as 25 m2/g. For treatment of 110 mL of solution with 31 mg of metal, the surface area loading is 7.2 m2/L. It is important to note that this is not necessarily the active surface area, which must be determined using chemisorption. Using this loading, the value of kSA for the immobilized system is 4.7 x 10-2 L m-2 h-1. This value is on the same order of magnitude as the value of 9.8 x 10-2 L m-2 h-1 reported for aqueous phase bimetallic (Fe/Ni) dechlorination by Shrick, et al. (2002). However, this value is for a 3:1 (Fe:Ni) ratio.
Preliminary results for the dechlorination of TtCA using this system also were obtained. For these experiments, the initial aqueous phase TtCA concentration is 12 mg/L. Using 47 mg of immobilized metal, a 50 percent reduction in TtCA can be achieved. A 16-hour experiment also was performed to show that 99 percent of the TtCA could be removed if given long enough to react. After 2.5 hours, the major products formed were (Z) and (E) DCE, TCE, and trace amounts of 1,1,2-trichloroethane (TCA). After 16 hours, only ethane and its coupling products (butane, hexane) were observed in the headspace.
In summary, we have successfully demonstrated: (1) formation of nanoscale particles directly in cellulose acetate membranes in the 20-30 nm range; (2) significantly higher reaction rates of selected organics (versus bulk and nanoscale Fe0 results) using only one-tenth of the metal loading; and (3) the observed effect of enhanced reaction rates through the incorporation of a second protective metal (Ni). Future work in this area will include: variation of polymeric materials to determine partitioning effects, and the use of convective flow to improve particle surface accessibility with shorter residence times.
Method 2: External Particle Synthesis in Solution Followed by Membrane Incorporation
This part of the research was conducted at the University of Alabama, with the main objective to incorporate Fe0 particles in membranes without the oxidation problems mentioned earlier. This work has focused on the following tasks: (1) formation and characterization of zero-valent nanoparticles in solution; (2) diafiltration to transfer particles to a methanol suspension without exposure to oxygen; (3) incorporation of the nanoparticles in a solution of cellulose acetate, membrane formation, and characterization; and (4) generation of preliminary TCE degradation results.
Material Preparation. Original attempts to make nanosized iron particles were based on the reduction of an iron chloride solution with sodium borohydride in water. Nanoparticles formed in this fashion were closer to the micrometer range in size (0.5-1.2). Subsequent efforts were focused on the inclusion of a surfactant during nanoparticle formation. A typical formulation for the surfactant consists of cetyltrimethylammonium bromide, 1-butanol, and cyclohexane. Ferric chloride is dissolved to form an emulsion. This emulsion then was reduced with sodium borohydride in water.
Iron nanoparticles are extremely reactive due to their high surface area. Oxidation of the particles after formation is therefore a serious concern. We overcame this problem by diafiltering the nanoparticle suspension first with water, and then with methanol. Diafiltration permits the removal of soluble components, while the overall suspension volume remains constant. In this way, the nanoparticles are never exposed to air. Rather, oxygen exposure is limited to its very low solubility in liquids. The water diafiltration is followed by a methanol diafiltration. Methanol acts as a reducing agent, and permits longer storage of the nanoparticles without oxidation. We have successfully stored nanoparticles in methanol for 1 week with negligible formation of the orange residue indicative of iron oxide.
For this research project, the polymer selected was the same as indicated in Method 1, outlined above. Cellulose acetate is soluble in acetone, but rapidly falls out of solution when exposed to water. Transfer of the nanoparticles to the cellulose acetate-acetone solution as a suspension is desirable, because it limits exposure of the particles to air. However, a water suspension would result in precipitation of the polymer. In our case, the suspension is in methanol, and thus there is more tolerance for solvent transfer to the acetone solution without polymer precipitation. This is important, because the suspension must not only be transferred, but the nanoparticles must be dispersed throughout the solution before casting and membrane formation. In general, our polymer-nanoparticle suspensions are dark gray to black.
The membranes are formed by casting a 750-µm film of the polymer suspension on a glass plate. A Gardner® blade is used to ensure uniform thickness. Phase inversion of the film is performed in ethanol to prevent hydrolysis of nanoparticles in the film. Methanol (from the nanoparticle suspension obtained from diafiltration) and acetone are completely soluble in ethanol, allowing for successful use of phase inversion without the need for water.
Membrane Characterization. TEM analysis of the Fe0 nanoparticles was performed for both initial (prior to membrane incorporation) and immobilized forms. For surfactant-based formation, the resulting nanoparticles had an average size of 50 nm. A representative TEM micrograph for these particles is given in Figure 5. A representative TEM micrograph of the iron nanoparticle containing membrane is shown in Figure 6. Two observations can be made from these figures. First, nanoparticles are approximately the same size after the casting procedure. This means that there has not been any agglomeration of nanoparticles in the polymer solution. The second observation is in regard to the location of the nanoparticles. In this case, the nanoparticles are located in the pore space of the membrane. It is desirable for the nanoparticles to be imbedded in the polymer to protect the nanoparticles from oxidation and hydrolysis.
Figure 5. Zero-Valent Iron Nanoparticles Formed by Surfactant Technique and Separated by Diafiltration
Figure 6. Iron Nanoparticles in the Pores of a CA Membrane
Dechlorination Studies. These experiments involved the preliminary evaluation of chloride formation, TCE degradation, and iron dissolution tests of the material. Two types of membranes have been examined: surfactant followed by reduction (Type 1), and simple borohydride reduction of ferric chloride (Type 2). Separation and incorporation procedures in the membranes were similar for the two types, except that the ratio of iron to cellulose acetate was 1:50 for Type 1, and 1:20 for Type 2. The metal loading for each film type is: 3.2 mg for Type-1 and 8 mg for Type-2. TCE samples were prepared at 70 mg/L in a degassed, 10 g/L HEPES solution at the desired pH (~ 6.1). A typical TCE degradation run involved contact of 40 mL of the TCE solution with approximately 40 cm2 of membrane (cut into pieces) in a Teflon-faced septum sealed vial. Samples were agitated in a wrist-shaker for a set time, and the membrane was removed before sample division and subsequent chloride ion, TCE, and iron analyses.
Chloride analyses were performed on Type 1 membrane samples. These membranes have a relatively low iron loading. Repeated tests for roughly 3 hours showed 10-11 percent formation of the maximum possible chloride. A secondary test at lower pH gave less formation of chloride. Type 2 membranes then were used to increase the amount of iron available in the system for TCE degradation. The 2.5 times increase in iron resulted with a corresponding increase in TCE disappearance (30-50 percent), as measured by gas chromatography. These results need to be further scrutinized using control experiments for partitioning and adsorption of TCE to the membrane phase before any specific conclusions can be drawn from the dechlorination studies.
Future studies in this area will include: (1) XPS of the iron nanoparticle containing films to characterize presence of residuals (e.g., boron) and oxidation states of iron; (2) better quantification of reaction by-products and intermediates from degradation of TCE; and (3) TEM of denser membranes to characterize imbedding of nanoparticles in the polymer matrix.
Method 3: Use of Metal Chelating Polymers on Membrane Supports
Ion exchange or chelating groups also can be used to trap metal ions, which are subsequently reduced to form stable nanostructured metals. Polymers (ion exchange and chelating polymers) containing multifunctional chelating agents provide a great number of side ligands such as amines, carboxylic acids, amides, alcohols, amino acids, pyridines, thioureas, etc. These side functional groups can have strong interaction with metal ions to establish stable coordination bonds. Therefore, it is quite reasonable to attach these chelating polymers on a membrane surface or internal pore (functionalized membranes) for metal ion sorption (Huh, et al., 1993; Huang, et al., 1998). These functionalized membranes used to entrap metal ions may possibly be the precursors of nanoparticle synthesis.
Material Preparation. Nanoscale metals can be prepared in polyelectrolyte-based materials by various approaches. The three approaches we have used are: (1) the use of polyglutamic acid (PLGA) to prepare nanoscale metal particles based on the solution phase; PLGA, which has a carboxylic group, is used to pick up metal ions; (2) the preparation of nanoscale metal particles based on the PLGA membrane phase; the membrane needs to be crosslinked because PLGA is a water-soluble polymer, otherwise it will dissolve in aqueous solution; the possible crosslinking agent can be ethylene glycol (EG), or polyether diisocyanate (PEGDI); and (3) the synthesis of metal nanoparticles on crosslinked polyacrylic acid (PAA) composite membrane. Polysulfone (PS), polyether sulfone, or cellulose acetate (CA) was used to prepare the porous supporting layer. The PAA coating layer with metal ions was added to the surface of the supporting membrane to generate a composite membrane. Then, nanoparticles could be formed on the PAA layer by the reduction with sodium borohydride.
For this report, discussion will be limited to cross-linked PAA on membrane supports (Method 3). The PAA coating solution (containing known concentrations of PAA, iron or nickel, and ethylene glycol) was added to a microfiltration-type support membrane, either PS or commercial cellulose acetate/nitrate (MCS). The method involved filtration of the coating solution into the support membrane at the pressure of 4-5 bar for 5 minutes. The coating solution consisted of known concentrations of PAA, ferrous chloride, nickelous chloride, and ethylene glycol in water. After the composite membrane was dried at room temperature for 4 hours, it was put into an oven for thermal treatment at 110 to 120°C for 1.5 hours.
The reaction mechanism of PAA with the cross-linking agent involves ether bond formation between carboxylic groups and ethylene glycol to generate the network structure, which is insoluble in water. It is important to only do a partial cross-linking to leave free carboxylic groups for metal entrapment. For particle formation, the PAA composite membrane was immersed into the NaBH4 solution (5 wt percent) for 90 seconds to form nanoparticles. After the reaction, the membrane was rinsed with water and ethanol three times to remove the residual reactant and product on the membrane surface.
Material Characterization. For both membranes, PAA-PS and PAA-MCS, excellent nanoparticle (10-50 nm) formation was observed. Figure 7 shows the SEM picture of commercial MCS support membrane and nanoscale Fe/Ni bimetallic particles on the PAA/MCS composite membrane. From the surface image of Figure 7 (a) and (b), the large pores in the MCS support membrane surface disappeared and were filled with iron and nickel nanoscale particles with a size of about 20 nm. The membrane coating solution composition was 4.6 wt percent PAA, 2.0 wt percent FeCl24H2O, 0.57 wt percent NiCl26H2O, and 1.8 wt percent ethylene glycol in water. The MCS support membrane was obtained from Millipore, the pore size of membrane was 0.22 µm, and the membrane thickness was 150 µm. The iron to nickel wt ratio used for this system was 4.5:1. EDX results indicated Fe to Ni on the surface to be about 4:1.
Dechlorination Studies. Dechlorination reaction of TCE with iron/nickel bimetallic particles immobilized in PAA-MCS composite membrane is presented in Table 1. For the experiment, the initial TCE concentration was 2.3 mg/L. Iron and nickel loading to solution was 150 and 38 mg/L, respectively. This loading corresponds 7.5 mg of total metals in a 44-cm2 membrane. The TCE amount in the table is expressed as total mg TCE, including both the aqueous and membrane phase in the 40 mL vial used for reaction. The TCE amount in blank control samples (without metal particles) and membrane control (MCS membrane without nanoparticles) remained relatively constant for the 60-minute contact period. In the solution containing nanoscale Fe/Ni particles, about 60 percent of TCE was destroyed within 60 minutes.
Figure 7. (a) SEM Surface Image of Cellulose Acetate and MCS Support Membrane, and (b) SEM Surface Image of Nanoscale Fe/Ni Bimetallic Particles on the PAA-MCS Membrane.
Total mg TCE | TCE Reduction (%) | ||
0 Minutes | 60 Minutes | ||
Volatility Control | 0.095 | 0.098 | - |
MCS Membrane Control | 0.095 | 0.088 | - |
Fe/Ni PAA/MCSComposite membrane | 0.095 | 0.034 | 64 |
In summary, we have successfully demonstrated: (1) cross-linking of PAAs on membrane supports to entrap metals and to form (after reduction) 20-50 nm metal particles; (2) more than 60 percent degradation of TCE with a very small quantity of bimetallic (Fe/Ni ratio 4.5:1) systems in 60 minutes; and (3) preparation of unsupported polyaminoacids (polyglutamic acid) membrane for the direct incorporation of metals. The incorporation of charged polyelectrolytes in membrane nanodomain also allows for the potential of simultaneous separation of toxic ionic solutes (such as arsenic, chromate, etc.) from contaminated water (Hollman and Bhattacharyya, 2003). Future studies will include optimization of membrane systems and detailed kinetic studies involving Fe/Ni, Fe/Ag, and Fe/Pd (for toxic aromatic organics) nanoparticles in charged polyelectrolyte containing membranes.
For Year 1 of the project, we clearly have established the methodology for the synthesis and incorporation of nanosized metals (Fe and Fe/Ni) in three types of membrane polymer domain. We have quantified (following U.S. Environmental Protection Agency [EPA] quality assurance guidelines) TCE degradation behavior with these nanocomposite membranes containing milligram levels (rather than grams) of reactive metal systems. Our budget expenditure to date is consistent with what we originally proposed. We also are happy to report that through the National Science Foundation Infrastructure training grant, the College of Engineering at the University of Kentucky now has a state-of-the-art analytical facility (with three full-time staff members) for environmental measurements. The facility includes brand new instruments such as GS-MS headspace analysis, liquid chromatography/mass spectrometry, high-performance liquid chromatography, ion chromatography, inductively coupled plasma mass spectrometry, elemental analyzer, etc. We have complete access to this facility and establishing intermediate reaction product analysis, very low concentration chloride analysis, metal contents of membranes, etc., will significantly enhance our current and future research activities for this EPA Science to Achieve Results (STAR) grant research project on nanotechnology.
References:
Arnold WA, Roberts LA. Pathways and kinetics of chlorinated ethylene and chlorinated acetylene reaction with Fe(0) particles. Environmental Science and Technology 2000;34(9):1794-1805.
Hollman A, Scherrer N, Cammers-Goodwin A, Bhattacharyya D. Journal of Membrane Science (in press, 2003).
Huh Y. Counter-ion specific swelling behavior of crosslinked poly(L-glutamic acid) membranes in aqueous alcohols. Journal of Membrane Science 1993;81(3):253-261.
Huang J, Guo Q, Ohya H, Fang J. The characteristics of crosslinked PAA composite membrane for separation of aqueous organic solutions by reverse osmosis. Journal of Membrane Science 1998;144(1-2):1-11.
Johnson TL, Schere MM, Tratnyek PG. Kinetics of halogenated organic compound by degradation. Environmental Science and Technology 1996;30(8):2634-2640.
Schrick B, Blough J, Jones A, Mallouk T. Chemistry of Materials 2002;14:5140-5147.
Tannenbaum R. Current Trends in Polymer Science 1998;3:81-98.
Future Activities:
We will continue to optimize nanoparticle synthesis technique in membranes that will result in a high rate of toxic organic dechlorination with minimum metal usage. Some of these activities will include: (1) variation of polymeric materials to determine partitioning effects; (2) the use of convective flow to improve particle surface accessibility with shorter residence times; (3) XPS of the iron nanoparticle containing films to characterize the presence of residuals and oxidation states of iron; (4) better quantification of reaction byproducts and intermediates from degradation of TCE; and (5) extension to iron/silver and iron/Pd system for detoxification of aromatic organics.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 34 publications | 8 publications in selected types | All 6 journal articles |
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Type | Citation | ||
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Hollman AM, Scherrer NT, Cammers-Goodwin A, Bhattacharyya D. Separation of dilute electrolytes in poly(amino acid) functionalized microporous membranes: model evaluation and experimental results. Journal of Membrane Science 2004;239(1):65-79 |
R829621 (2002) R829621 (2003) R829621 (Final) |
not available |
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Meyer D, Bachas L, Bhattacharyya D. Membrane-based synthesis of Fe and Fe/Ni nanoparticles for degradation of chlorinated organics from water. Environmental Progress. |
R829621 (2002) |
not available |
Supplemental Keywords:
engineering, polyelectrolytes, volatile organic compound, VOC, cellulose acetate, innovative technology, reuse, environmental chemistry, sustainability, recycle, toxics., RFA, Scientific Discipline, Toxics, Sustainable Industry/Business, Sustainable Environment, Environmental Chemistry, VOCs, Technology for Sustainable Environment, Analytical Chemistry, Civil/Environmental Engineering, Biochemistry, New/Innovative technologies, Chemistry and Materials Science, Environmental Engineering, Engineering, nanotechnology, reductive degradation of hazardous organics, environmentally applicable nanoparticles, hazardous organics, reductive dechlorination, sustainability, innovative technologies, membrane-based nanostructured metalsRelevant Websites:
http://www.engr.uky.edu/cme/db Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.