Author: Punam PatelPublisher:
ISBN:
Category :
Languages : en
Pages : 232
Book Description
Degradation of Chlorinated Aromatic Compounds Using Zero-valent Metals
Author: Punam PatelReductive Dechlorination of Chlorinated Aliphatic and Aromatic Compounds Using Zero Valent Metals
Author: Young-Hun KimChemical Degradation Methods for Wastes and Pollutants
Author: Matthew A. TarrPublisher: CRC Press
ISBN: 0824756479
Category : Science
Languages : en
Pages : 452
Book Description
Chemical Degradation Methods for Wastes and Pollutants focuses on established and emerging chemical procedures for the management of pollutants in industrial wastewater and the environment. This reference offers an in-depth explanation of the degradation process, mechanisms, and control factors affecting each method, as well as issues crucial to the application of these approaches in real-world treatment sites. It examines ten of the most common and useful chemical technologies for environmental remediation and sanitation of industrial waste streams and offers implementation guidelines and examples of remediation strategies that are crucial to effective wastewater cleansing.
Surface Complexation Modeling
Author: David A. DzombakPublisher: John Wiley & Sons
ISBN: 9780471637318
Category : Science
Languages : en
Pages : 430
Book Description
Provides a description of the thermodynamic model, data treatment procedures and the thermodynamic constants for hydrous ferric oxide. Includes detailed coverage of the model and the parameter extraction procedure.
The Destructive Removal of Chlorinated Organic Compounds from Water Using Zero-valent Metals Or Hydrogen and Supported Palladium
Author: Cindy Gail SchreierAbiotic Degradation of Chlorinated Hydrocarbons (CHCs) with Zero-valent Magnesium (ZVM) and Zero-valent Palladium Bimetallic (Pd/Mg)-reductant
Author: Fang YuPublisher:
ISBN:
Category : Chlorohydrocarbons
Languages : en
Pages : 71
Book Description
Chlorinated hydrocarbons (CHCs) in groundwater can be treated by monometallic and bimetallic metal reductants through abiotic degradation. The breakdown of CHC is achieved by gaining electrons from those reductants and removing chlorines from CHC molecules to transform the CHCs into less chlorinated compounds. As a proven technology in groundwater treatment, permeable reactive barriers (PRBs) have been used to passively treat contaminated groundwater, in which granular metals can be used as reactive materials. This study explored the abiotic degradation of CHCs by zero-valent magnesium (ZVM) and bimetallic palladium/magnesium (Pd/Mg) reductants. Different CHCs (carbon tetrachloride, chloroform, dichloromethane (DCM), 1,2-dichloroethane (1,2-DCA), 1,1,2-trichloroethane (1,1,2-TCA), 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA), 1,2-dichloropropane (1,2-DCP), and 1,2,3-Trichloropropane (1,2,3-TCP) were chosen as target contaminants. Results showed that even with its high reduction potential, ZVM did not treat CHCs effectively due to corrosion of Mg by water, which formed Mg (OH)2(s) precipitate on the metal surface and prevented further reaction. Such inhibition can be reduced by lowering pH conditions. However, in the presence of Pd, CHCs were removed at a much faster rate at neutral pH conditions. Hydrocarbons were produced as sole products, which indicated complete degradation of CHCs by Pd/Mg. Recalcitrant CHCs such as DCM, 1, 1,2-TCA, 1,2-DCP and 1,2,3-TCP were found to be effectively degraded by Pd/Mg. No significant effect of Pd loading on CHC degradation was observed, while the degradation was accelerated by increasing the Mg loading.
Investigations of Reductive Dechlorination Reactions of Chlorinated Ethenes and Ethanes on Zero-valent Metals Using Compound Specific Isotopic Analysis
Author: Nancy Anne VanStonePublisher:
ISBN: 9780494157541
Category :
Languages : en
Pages : 426
Book Description
Reductive dechlorination reactions occurring on zero-valent metal surfaces for chlorinated ethenes and chlorinated ethanes are investigated using compound specific isotopic analysis (CSIA) to measure carbon isotopic fractionation and carbon kinetic isotope effects (KIE). Reductive dechlorination of chlorinated contaminants on zero-valent iron (Fe0) is used for remediation purposes at over 100 sites worldwide employing permeable reactive barrier (PRB) technology. Degradation can occur via 3 main pathways: (1) alpha-elimination, (2) beta-elimination and (3) hydrogenolysis. Experiments documenting carbon isotopic fractionation observed during degradation of a suite of chlorinated ethenes are described, and it is demonstrated that reproducible carbon isotopic fractionation occurs for perchloroethene (PCE), trichloroethene (TCE), cis-dichloroethene (cis-DCE) and vinyl chloride (VC). The results for Fe0 from two different sources show distinct differences in both rates of reaction and isotopic fractionation factors (epsilon), particularly for the cis-DCE and VC. Using ground water samples from pre- and post-treatment of a Fe0 PRB at F.E. Warren Air Force Base, it is established that carbon isotopic fractionation of chlorinated ethenes follows the same principles under field conditions, and it is shown that CSIA, in combination with traditional compositional analysis, can help to resolve complex performance-related problems for PRBs. Finally, it is demonstrated that reaction pathways and mechanisms can be investigated using CSIA and ranges of epsilon and KIE are established for the investigated reactions on different zero-valent metals. In batch experiments monitoring dichloroethane (DCA) degradation on Zn0, CSIA was used to determine that a common rate limiting step occurs for hydrogenolysis and alpha-elimination reactions of 1,1-DCA. As well, overall epsilon and KIE are greater for beta-elimination of 1,2-DCA than for hydrogenolysis and alpha-elimination of 1,1-DCA. The degradation of a chlorinated ethene, cis-DCE, was investigated on Fe0. Direct measurements of epsilon and KIE for hydrogenolysis and beta-elimination were measured using CSIA. It is established that these reactions do not share a rate limiting step, and unique and reproducible carbon isotopic fractionation is associated with each reaction pathway. CSIA has been shown to be a versatile tool, aiding research as both a reliable diagnostic (i.e. identification of degradation) and as a valuable analytical instrument for mechanistic studies.
Nanotoxicology for Agricultural and Environmental Applications
Author: Mahendra RaiPublisher: Elsevier
ISBN: 0443155712
Category : Technology & Engineering
Languages : en
Pages : 325
Book Description
Published as part of Elsevier's series, Nanobiotechnology for Plant Protection, Nanotoxicology for Agricultural and Environmental Applications provides an introduction to nanotechnology and its applications in agriculture and the environment.Divided into five parts, this book addresses nanotechnology and regulations, nanotoxicity, nanotoxicity to agriculture and food, nanotoxicity to the environment, and risk management measures to avoid exposure.Students, practitioners, and researchers working in plant science, agricultural science, nanoscience, and environmental chemistry alike will benefit from this necessary reference. - Highlights the factors contributing to toxic effects of nanoparticles, including shape, size, structure, surface charge, and dosage - Explores the mode of action and entry of nanoparticles, methods of toxicity evaluation, and the associated challenges - Describes recent developments in nanotoxicity to soil ecosystems, crop plants, and food systems - Emphasizes the impact of nanoparticles and their detoxification by plants on the nutritional quality of food and plants - Discusses the impact of toxicity of nanoparticles released in air, soil, and water and methods to reduce their effects
Accelerated Degradation of Chlorinated Solvents by Copper-modified Nanoscale Zero Valent Iron (Cu-nZVI) Stabilized with Carboxymethyl Cellulose
Author: Andrew FranzePublisher:
ISBN:
Category : Bioremediation
Languages : en
Pages : 89
Book Description
Nanoscale zero valent iron (nZVI) is a remediation technology that can be used to treat chlorinated hydrocarbons (CHCs) in contaminated aquifers. Nanoparticles remain mobile in water and can be transported with groundwater flow to contaminated zones. However, due to magnetic and van der Waals forces, unstabilized nZVI agglomerates. Carboxymethylcellulose (CMC) was used as a polyelectrolyte stabilizer in this study. nZVI serves as an electron donor and can dechlorinate CHCs. nZVI reactivity with CHCs can be enhanced by addition of a secondary metal catalyst. This study evaluates the potential of copper amended nZVI (Cu-nZVI) to degrade select CHCs. The objective of this study was to characterize degradation of select CHCs in batch reactors with regard to degradation kinetics and degradation byproduct distributions. The following CHCs were studied: CF, 1,1,2,2-TeCA, 1,1,1-TCA, 1,1,2-TCA, PCE, TCE, cis-DCE, trans-DCE, and 1,2,3-TCP. Degradation kinetics were quantified using a pseudo first-order rate constant (kobs). Initial degradation of CHCs was reported separately from later degradation, which occurred after 0.5 hr. The change in reaction kinetics with time could be caused by particle aging. The effect of Cu loading and nZVI concentration was evaluated with CF degradation. Increasing Cu loading or nZVI concentrations yielded faster degradation rates. Increasing Cu loading systematically increased methane byproduct production. The loss of reactivity with CF after 0.5 hr was greater for nZVI when compared to Cu-nZVI. Degradation kinetics were faster and byproduct distribution was more favorable for Cu-nZVI than nZVI for all CHCs studied. Cu-nZVI outperformed most other bimetallic nZVI reductants reported in the literature for CF and chlorinated ethanes treatment. Cu-nZVI invokes a-elimination of CF and 1,l,1-TCA, which produces reactive carbene intermediates capable of degrading into benign products such as methane, ethane, and ethene. Cu-nZVI also showed potential for 1,2,3-TCP remediation. However, Cu-nZVI was particularly ineffective at degrading chlorinated ethenes. Chlorinated ethene degradation pathways and mechanisms induced by Cu-nZVI were not clearly identified. Particle longevity experiments showed that reactivity with 1,1,1-TCA decreases as particles age. Unstable Cu-nZVI particles showed a slow linear decline in reactivity with time, whereas CMC stabilized Cu-nZVI particles showed a rapid power function decline in reactivity with time. The unstable particles were 12-fold faster compared to stablized particles 24 hr after particle synthesis. Even with declines in reactivity, 1,1,1-TCA was rapidly degraded (over a few hours) by both stable and unstable Cu-nZVI seven days after particle synthesis. Cu-nZVI hydrogen production was minor and was limited to occurring immediately after particle synthesis. Cu-nZVI shows great potential for treating certain CHCs.
Recent Advances in Microbial Degradation
Author: . InamuddinPublisher: Springer Nature
ISBN: 9811605181
Category : Science
Languages : en
Pages : 483
Book Description
Microbes play a major role in the degradation of various pollutants. Therefore, microbes find potential application in the area of energy and environmental technology. The book provides in-depth literature on the topics of environmental and industrial importance. It is compiled to explore the application of microbe used in the degradation of aflatoxin, polymers, biomass into fuel, disinfectants, food products, xenobiotic compounds, lipids, steroids, organic pollutants, proteins, oil waste, and wastewater pollutants. This book will be of interest to teachers, researchers, scientists, and capacity builders. Also, the book serves as additional reading material for undergraduate and graduate students of microbiology and environmental sciences. National and international remediation and restoration scientists, policymakers will also find this to be a useful read.