Grantee Research Project Results
2004 Progress Report: Effect of Pitting Corrosion Promoters on the Treatment of Waters Contaminated with a Nitroaromatic Compounds Using Integrated Reductive/Oxidative Processes
EPA Grant Number: R831276C008Subproject: this is subproject number 008 , established and managed by the Center Director under grant CR831276
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Gulf Coast HSRC (Lamar)
Center Director: Ho, Tho C.
Title: Effect of Pitting Corrosion Promoters on the Treatment of Waters Contaminated with a Nitroaromatic Compounds Using Integrated Reductive/Oxidative Processes
Investigators: Hernandez, Rafael , Kuo, Chiang Hai
Institution: Mississippi State University
EPA Project Officer: Aja, Hayley
Project Period: December 1, 2003 through November 30, 2004
Project Period Covered by this Report: December 1, 2003 through November 30, 2004
Project Amount: Refer to main center abstract for funding details.
RFA: Gulf Coast Hazardous Substance Research Center (Lamar University) (1996) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research
Objective:
The main goal of this research project is the development of a reductive/oxidative integrated technology for the treatment of waters contaminated with nitroaromatic compounds (NACs). The idea is to develop a cost-effective technology that can mineralize and/or transform NACs into low-molecular weight nontoxic compounds, which cannot be done using today’s technologies as stand-alone treatment processes. The specific objectives of the research project are to: (1) evaluate the effect of different pitting corrosion promoters on 2,4-dinitrotoluene (DNT) reduction and byproducts oxidation kinetics using iron or manganese and advanced oxidation processes (AOPs), respectively, and determine the optimum operating conditions for both processes and the toxicity of the effluents from the oxidation step operating at optimum conditions using Microtox; (2) synthesize bimetallic iron/manganese species and analyze the reaction byproducts obtained during the application of these bimetallic species for the treatment of water contaminated with DNT (this will be the first time that iron/manganese bi-metallic species are synthesized and evaluated for the treatment of DNT contaminated water); and (3) develop a kinetic rate expression that couples metal corrosion with NACs degradation and a kinetic expression for nitroamines (DNT reduction byproducts) mineralization using AOPs.
Progress Summary:
The effect of corrosion promoters on DNT degradation by iron or manganese was evaluated using the recirculated batch reactor described elsewhere. The experiments were conducted under anaerobic conditions (< 0.5 mg/L O2 dissolved in water) and 4 g/L iron or manganese. The initial DNT concentration in all the experiments was 20 mg/L. Figure 1 shows the effect of adding ferric chloride (FeCl3) or sodium chloride (NaCl) to DNT contaminated water (synthetic) on the DNT reaction with zero valent iron (ZVI). In the absence of corrosion promoters, 30 percent of the initial DNT was removed in 3 hours. A noticeable increase in DNT degradation can be observed at a concentration as low as 5 μM FeCl3. Higher FeCl3 concentrations accelerated further the rate of reaction of DNT with ZVI. The highest FeCl3 concentration examined was 3 mM, which yielded 100 percent DNT disappearance in 3 hours. A comparison of DNT degradation using 3 mM FeCl3 or NaCl indicates faster DNT degradation kinetics are obtained in the presence of FeCl3. This result could be attributed to the fact that FeCl3 is a better corrosion promoter compared to NaCl and thus causes a larger rate of electron generation. It is these electrons that react with DNT adsorbed onto the metal surface forming reduction byproducts.
Results for the DNT degradation using zero-valent manganese in the presence of FeCl3 or NaCl are presented in Figure 2. In this case, only the highest concentrations of FeCl3 or NaCl (3 mM) evaluated had a significant effect on DNT degradation. In this case, addition of FeCl3 also resulted in faster DNT degradation. It appears the manganese oxide layer is more resistant to oxidation than ZVI. A relatively high concentration of a corrosion promoter is necessary to break it, obtain access to the metallic surface, and accelerate the corrosion process and DNT degradation.
Figure 1. Effect of FeCl3 or NaCl on DNT Degradation by ZVI
Figure 2. Effect of FeCl3 or NaCl on DNT Degradation by Zero-Valent Manganese
The calculated surface area normalized first order rate constants for the reaction of DNT with ZVI or manganese in the presence of 3 mM FeCl3 were 0.245 and 0.176 L/m2minute, respectively. These rate constants are orders of magnitude higher than several values reported for reactions of ZVI with NACs. The reaction acceleration obtained by adding corrosion promoters could reduce significantly capital and operating costs of treating NACs-contaminated waters using zero-valent metals.
The initial surface areas of the metals were 0.0537 m2/g iron and 0.0405 m2/g manganese. The surface areas at the end of the reaction period (in the presence of 3 mM FeCl3) were 2.8053 m2/g and 0.3922 m2/g for ZVI and manganese, respectively. The large increase in the surface area of ZVI suggested formation of dislocations, cracks, and pits on its surface. Figure 3 shows scanning electron micrographs of the ZVI surface before and after reaction with DNT. Prior to reaction, the ZVI surface was smooth and nonporous, which explains the relatively small surface area. Figure 3 (right micrograph) indicates that numerous pits were formed during reaction, causing the surface area increase. The appearance of pits on the ZVI surface also indicates the main corrosion mechanism was pitting, a form of localized corrosion that occurs in the presence of aggressive anionic species such as chloride. The salt that forms inside the pits hydrolyzes and generates hydrochloric acid (HCl). The induced pits act as continuous sources of electrons and the microacidic (HCl) environment generated inside the pits minimizes passivation, autocatalyzes metal pitting, and accelerates DNT degradation.
Figure 3. Scanning Electron Micrographs of the ZVI Surface Before and After Reaction With DNT in the Presence of 3 mM FeCl3
The small increase in manganese surface area during reaction with DNT in the presence of FeCl3 indicates manganese has more resistance to corrosion compared to ZVI. It seems manganese will maintain its metallic properties longer (slower rate of deactivation) than ZVI in the presence of corrosion promoters. Other experiments have shown that the yield and selectivity for some reduction byproducts depend on the metal identity. Presently, bimetallic manganese/iron species are being synthesized to optimize for corrosion resistance, yield, and selectivity of the reduction byproducts. These new metallic species will be integrated to advanced oxidation processes to mineralize the DNT reduction byproducts.
Future Activities:
The bimetallic iron/manganese particles are being synthesized and will be evaluated for treating DNT-contaminated water. The bimetallic species will be integrated to an advanced oxidation process to mineralize the DNT byproducts generated during the reduction step. A paper will be submitted to Environmental Science & Technology or the Journal of Environmental Engineering. Additionally, papers will be presented at the 2005 Southern States Environmental Conference and the 2005 Annual Meeting of the American Institute of Chemical Engineers.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other subproject views: | All 2 publications | 1 publications in selected types | All 1 journal articles |
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Other center views: | All 64 publications | 19 publications in selected types | All 18 journal articles |
Type | Citation | ||
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Hernandez R, Zappi M, Kuo C-H. Chloride effect on TNT degradation by zerovalent iron or zinc during water treatment. Environmental Science & Technology 2004;38(19):5157-5163. |
R831276C008 (2004) |
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Supplemental Keywords:
peroxone, pitting corrosion, hybrid treatment processes, amines oxidation, waste, ecological risk assessment, environmental engineering, hazardous waste, advanced treatment technologies, bioremediation, contaminated waste sites, groundwater contamination, petroleum contaminants, hydrocarbon,, RFA, Scientific Discipline, Waste, Water, Contaminated Sediments, Environmental Chemistry, Remediation, Hazardous Waste, Hazardous, Environmental Engineering, corrosion promoters, hazardous waste treatment, advanced treatment technologies, contaminated sediment, hazardous waste storage, contaminated soil, reductive oxidative processes, groundwater remediation, ethanol, contaminated groundwater, hazardous wate, nitroaromatic compounds, oxidizing agentsRelevant Websites:
http://dept.lamar.edu/gchsrc/ Exit
Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
CR831276 Gulf Coast HSRC (Lamar) Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R831276C001 DNAPL Source Control by Reductive Dechlorination with Fe(II)
R831276C002 Arsenic Removal and Stabilization with Synthesized Pyrite
R831276C003 A Large-Scale Experimental Investigation of the Impact of Ethanol on Groundwater Contamination
R831276C004 Visible-Light-Responsive Titania Modified with Aerogel/Ferroelectric Optical Materials for VOC Oxidation
R831276C005 Development of a Microwave-Induced On-Site Regeneration Technology for Advancing the Control of Mercury and VOC Emissions Employing Activated Carbon
R831276C006 Pollution Prevention through Functionality Tracking and Property Integration
R831276C007 Compact Nephelometer System for On-Line Monitoring of Particulate Matter Emissions
R831276C008 Effect of Pitting Corrosion Promoters on the Treatment of Waters Contaminated with a Nitroaromatic Compounds Using Integrated Reductive/Oxidative Processes
R831276C009 Linear Polymer Chain and Bioengineered Chelators for Metals Remediation
R831276C010 Treatment of Perchlorate Contaminated Water Using a Combined Biotic/Abiotic Process
R831276C011 Rapid Determination of Microbial Pathways for Pollutant Degradation
R831276C012 Simulations of the Emission, Transport, Chemistry and Deposition of Atmospheric Mercury in the Upper Gulf Coast Region
R831276C013 Reduction of Environmental Impact and Improvement of Intrinsic Security in Unsteady-state
R831276C014 Integrated Chemical Complex and Cogeneration Analysis System: Greenhouse Gas Management and Pollution Prevention Solutions
R831276C015 Improved Combustion Catalysts for NOx Emission Reduction
R831276C016 A Large-Scale Experimental Investigation of the Impact of Ethanol on Groundwater Contamination
R831276C017 Minimization of Hazardous Ion-Exchange Brine Waste by Biological Treatment of Perchlorate and Nitrate to Allow Brine Recycle
R831276C018 Integrated Chemical Complex and Cogeneration Analysis System: Greenhouse Gas Management and Pollution Prevention Solutions
The 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.
Project Research Results
1 journal articles for this subproject
Main Center: CR831276
64 publications for this center
18 journal articles for this center