Download or read book Aggregation and Transport of Nanoscale Zerovalent Iron Particles in Model Groundwater Systems written by Mohan Basnet and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Nanoscale zerovalent iron (NZVI) particles are promising engineered nanomaterials for the in situ remediation of various environmental contaminants into innocuous products. In field applications, direct injection of NZVI into the subsurface has been suggested as a promising technique for achieving rapid remediation. However, challenges have been encountered in field application that includes passivation, aggregation and limited transport. Therefore, the success of site remediation using NZVI depends on the progress made to increase nanoparticle reactivity, reduce aggregation and improve mobility. The overall objective of this research was to evaluate the aggregation and transport behavior of NZVI particles in environmentally relevant model groundwater environments. Palladium-doped NZVI (Pd-NZVI) was chosen to ensure heightened reactivity towards the contaminants to address the passivation problem whereas particle surface-modification with stabilizing polymers was investigated to reduce particle aggregation and concurrently improve transport. In this study, rhamnolipid biosurfactant was proposed for the first time as a novel stabilizing surface-modifier and its efficacy was compared with previously proposed surface-modifiers (carboxymethylcellulose and soy protein). By monitoring changes in particle hydrodynamic diameter as a function of time using dynamic light scattering followed by a systematic assessment of transport behavior in sand packed columns, it is shown that while bare Pd-NZVI is prone to rapid aggregation surface-modified Pd-NZVI exhibited good colloidal stability and improved transport at low ionic strengths (10 mM). In particular, rhamnolipid significantly enhanced transport even at much lower concentrations than the other surface modifiers (10 mg/L compared to 100 mg/L). However, an increase in solution ionic strength influenced both aggregation and transport behavior. Nonetheless, at the highest ionic strength tested, the transport of rhamnolipid-coated Pd-NZVI was significantly higher than that of Pd-NZVI coated with other surface modifiers suggesting that rhamnolipid is most suitable in field application.The transport potential of surface-modified Pd-NZVI was further examined in granular matrices of varied complexities: in quartz sand, in loamy sand and clay-amended quartz sand over a wide range of environmentally relevant ionic strengths. Data suggests that collector geochemical composition and heterogeneity can dramatically alter Pd-NZVI transport potential; markedly reduced transport potential was observed in loamy sand than in quartz sand.Given that microbes and biofilms are ubiquitous in the subsurface environment, the role of biofilm on Pd-NZVI transport was investigated by using biofilm-coated quartz sand to pack transport columns. Transport results showed heightened Pd-NZVI retention in the presence of biofilms suggesting that biofilms may act as a collector surface for nanoparticle retention in the groundwater environment. A viability assay suggests that the retained Pd-NZVI is non-toxic to the Pseudomonas aeruginosa cells in biofilms. However, some inhibitory effect was observed to planktonic bacterial cells. Finally, considering the cost associated with the use of Pd, an alternative reactive nanoparticle, sulfidated NZVI (S-NZVI), was also studied whereby the aggregation and transport behavior of S-NZVI was systematically investigated in a wide range of environmentally relevant water chemistries. Data suggests that sulfidation can influence NZVI surface electrokinetic properties, and thus its stability and transport in granular matrices.Overall, this study makes a major impact in the field of environmental remediation as it addresses key aspects of nanotechnology-enabled site remediation, particularly aspects pertaining to nanoparticle surface coating, collector grain physical, geochemical and biological heterogeneity, and groundwater chemistry." --

Download or read book Nanoscale Zerovalent Iron Particles for Environmental Restoration written by Tanapon Phenrat and published by Springer. This book was released on 2019-01-31 with total page 597 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first complete edited volume devoted to providing comprehensive and state-of-the art descriptions of science principles and pilot- and field-scaled engineering applications of nanoscale zerovalent iron particles (NZVI) for soil and groundwater remediation. Although several books on environmental nanotechnology contain chapters of NZVI for environmental remediation (Wiesner and Bottero (2007); Geiger and Carvalho-Knighton (2009); Diallo et al. (2009); Ram et al. (2011)), none of them include a comprehensive treatment of the fundamental and applied aspects of NZVI applications. Most devote a chapter or two discussing a contemporary aspect of NZVI. In addition, environmental nanotechnology has a broad audience including environmental engineers and scientists, geochemists, material scientists, physicists, chemists, biologists, ecologists and toxicologists. None of the current books contain enough background material for such multidisciplinary readers, making it difficult for a graduate student or even an experienced researcher or environmental remediation practitioner new to nanotechnology to catch up with the massive, undigested literature. This prohibits the reader from gaining a complete understanding of NZVI science and technology. In this volume, the sixteen chapters are based on more than two decades of laboratory research and development and field-scaled demonstrations of NZVI implementation. The authors of each chapter are leading researchers and/or practitioners in NZVI technology. This book aims to be an important resource for all levels of audiences, i.e. graduate students, experienced environmental and nanotechnology researchers, and practitioners evaluating environmental remediation, as it is designed to involve everything from basic to advanced concepts.

Download or read book Iron Nanomaterials for Water and Soil Treatment written by Marta I. Litter and published by CRC Press. This book was released on 2018-09-03 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanotechnology has a great potential for providing efficient, cost-effective, and environmentally acceptable solutions to face the increasing requirements on quality and quantity of fresh water for industrial, agricultural, or human use. Iron nanomaterials, either zerovalent iron (nZVI) or iron oxides (nFeOx), present key physicochemical properties that make them particularly attractive as contaminant removal agents for water and soil cleaning. The large surface area of these nanoparticles imparts high sorption capacity to them, along with the ability to be functionalized for the enhancement of their affinity and selectivity. However, one of the most important properties is the outstanding capacity to act as redox-active materials, transforming the pollutants to less noxious chemical species by either oxidation or reduction, such as reduction of Cr(VI) to Cr(III) and dehalogenation of hydrocarbons. This book focuses on the methods of preparation of iron nanomaterials that can carry out contaminant removal processes and the use of these nanoparticles for cleaning waters and soils. It carefully explains the different aspects of the synthesis and characterization of iron nanoparticles and methods to evaluate their ability to remove contaminants, along with practical deployment. It overviews the advantages and disadvantages of using iron-based nanomaterials and presents a vision for the future of this nanotechnology. While this is an easy-to-understand book for beginners, it provides the latest updates to experts of this field. It also opens a multidisciplinary scope for engineers, scientists, and undergraduate and postgraduate students. Although there are a number of books published on the subject of nanomaterials, not too many of them are especially devoted to iron materials, which are rather of low cost, are nontoxic, and can be prepared easily and envisaged to be used in a large variety of applications. The literature has scarce reviews on preparation of iron nanoparticles from natural sources and lacks emphasis on the different processes, such as adsorption, redox pathways, and ionic exchange, taking place in the removal of different pollutants. Reports and mechanisms on soil treatment are not commonly found in the literature. This book opens a multidisciplinary scope for engineers and scientists and also for undergraduate or postgraduate students.

Download or read book Surface Functionalization of Nanoscale Zerovalent Iron Particles for Trichloroethene Degradation written by Sourjya Bhattacharjee and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis investigates the applicability of surface functionalization techniques for nanoscale zerovalent iron (NZVI) particles for improving the degradation of a toxic, common groundwater contaminant, trichloroethene (TCE). Although NZVI has emerged as a promising environmental remediation agent in the past decade and has the potential to transform a number of chlorinated organic pollutants to non-toxic end products, factors such as loss of electrons to reactions with water, formation of passivating oxide layers on NZVI surface and aggregation of NZVI to micron-sized particles pose significant challenges in the application of NZVI for TCE remediation. This research investigated techniques for the modification of NZVI surface with secondary metals (e.g. palladium), inorganic ions (e.g. sulfide), polyelectrolytes and surfactants (e.g. carboxymethylcellulose and rhamnolipid), and solid supports (e.g. activated carbon) to enhance reactivity through mitigation of the challenges mentioned above. The research was aimed at assessing the increases in reactivity, and also characterizing the fundamental physico-chemical processes that were responsible for the changes in reactivity. It was observed that organic macromolecules such as rhamnolipid (M.W. 600 g mol-1) sorbed on NZVI and prevented the deposition of rate enhancing surface dopants namely, palladium and sulfide, and inhibited TCE degradation. Conversely larger molecules such as carboxymethylcellulose (M.W. 700000 g mol-1) and humic acids bound to NZVI hindered deposition of the surface dopants to a lesser extent. Powdered activated carbon when used as a support for embedding NZVI was observed to significantly enhance the TCE degradation rate, however the method adopted for deposition of NZVI critically affected the rate enhancements because of changes in structural properties of activated carbon. Lastly, a phase transfer approach was developed to degrade the solvent (oil) phase of TCE using a rhamnolipid coated Pd-NZVI. This approach enabled 50% higher degradation of TCE solvent compared to a system where phase transfer was not employed." --

Download or read book Transport of Nanoscale Zero Valent Iron in Heterogeneous Soils written by Md. Abdullah Asad and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subsurface remediation using nanoscale zero valent iron (nZVI) is a promising in-situ technology that can convert groundwater contaminants into non-toxic compounds. Despite its promising characteristics, field scale implementation of nZVI technology has faced major challenges due to poor subsurface mobility and limited longevity, all leading to smaller nZVI travel distance. How far nZVI travels in the subsurface is an important parameter as it influences the amount of contaminants that could be reached and thereby remediated. This thesis examined various factors (viscosity, groundwater velocity, injection flux, soil heterogeneity, lag period) on nZVI travel distance through a numerical model and by performing a statistical analysis which revealed that viscosity has a statistically significant impact on nZVI travel distance while the impact of groundwater velocity and injection flux are statistically insignificant. The model also revealed that soil heterogeneity plays an important factor and that longer nZVI injection periods are better for nZVI deployment in the field.

Download or read book Environmental Application and Implication of Nanoscale Zerovalent Iron written by Qiliang 'Luke' Wang and published by LAP Lambert Academic Publishing. This book was released on 2015-01-06 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, the environmental application and implication of nanoscale zerovlanet iron (NZVI) are studied. Reduction and removal of Bromate and TCE DNAPL using NZVI were evaluated for drinking water treatment and groundwater remediation. A visualization technique for TCE DNAPL removal using reactive NZVI and bimetallic nanoparticles was conducted using a glass micromodel with a view toward improved contaminant displacement. Inert/pseudo-inert gases, including argon, nitrogen, and carbon dioxide, were utilized to stabilize synthesized NZVI after lyophilization to prevent self-ignition. In addition, the aging effect was investigated for these stabilized NZVI both in humid and dry conditions. A new and simple method was proposed for encapsulating NZVI using poly (vinyl pyrrolidone) (PVP) nanofibrous membranes by an electrospinning technology to maintain catalytic activity. At last, mobilization and deposition of NZVI in a porous medium were observed using a water-saturated glass micromodel; a high-resolution microscope was utilized to visualize the transport phenomena of microscopic aggregations of NZVI inside the micromodel.

Download or read book Nanoparticles and the Environment written by Jillian Fiona Banfield and published by ISSN. This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews in Mineralogy & Geochemistry (RiMG) volumes contain concise advances in theoretical and/or applied mineralogy, crystallography, petrology, and geochemistry.

Download or read book Multilevel Modeling of Secure Systems in QoP ML written by Bogdan Księżopolski and published by CRC Press. This book was released on 2015-07-02 with total page 734 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introducing the Quality of Protection Modeling Language (QoP-ML), this book provides for the abstraction of security systems while maintaining emphasis on the details of quality protection . It delineates the steps used in cryptographic protocol and introduces a multilevel protocol analysis that expands current understanding. Every operation defined by QoP-ML is described within parameters of security metrics, therefore evaluating the impact of the operation on the entire system's security.

Download or read book New Trends in Emerging Environmental Contaminants written by Swatantra P. Singh and published by Springer Nature. This book was released on 2021-12-12 with total page 623 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is based on recent trends for the research in emerging environmental contaminants in different compartment of the environment. It provides a recent understanding for the fate, transport, and degradation of emerging contaminants in different environmental sectors, including water, air, and soil. The contents discuss the fate and transport of microplastics, PPCPs, along with the method of detection and degradation. It includes removal of variety of pollutants including microplastics, pharmaceuticals, and personal care products from the water using adsorption technique, electrooxidation, membrane technology and other advance oxidation methods. This volume will be of great value to those in academia and industry involved in environmental science and engineering research.

Download or read book Soil and Groundwater Remediation Technologies written by Yong Sik Ok and published by CRC Press. This book was released on 2020-03-23 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers various soil and water treatment technologies due to increasing global soil and water pollution. In many countries, the management of contaminated land has matured, and it is developing in many others. Topics covered include chemical and ecological risk assessment of contaminated sites; phytomanagement of contaminants; arsenic removal; selection and technology diffusion; technologies and socio-environmental management; post-remediation long-term management; soil and groundwater laws and regulations; and trace element regulation limits in soil. Future prospects of soil and groundwater remediation are critically discussed in this book. Hence, readers will learn to understand the future prospects of soil and groundwater contaminants and remediation measures. Key Features: Discusses conventional and novel aspects of soil and groundwater remediation technologies Includes new monitoring/sensing technologies for soil and groundwater pollution Features a case study of remediation of contaminated sites in the old, industrial, Ruhr area in Germany Highlights soil washing, soil flushing, and stabilization/solidification Presents information on emerging contaminants that exhibit new challenges This book is designed for undergraduate and graduate courses and can be used as a handbook for researchers, policy makers, and local governmental institutes. Soil and Groundwater Remediation Technologies: A Practical Guide is written by a team of leading global experts in the field.

Download or read book Investigations on Mobility of Carbon Colloid Supported Nanoscale Zero valent Iron nZVI for Groundwater Remediation written by and published by . This book was released on 2015 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Injection of nanoscale zero-valent iron (nZVI) is an innovative technology for in situ installation of a permeable reactive barrier in the subsurface. Zerovalent iron (ZVI) is highly reactive with chlorinated hydrocarbons (CHCs) and renders them into less harmful substances. Application of nZVI instead of granular ZVI can increase rates of dechlorination of CHCs by orders of magnitude, due to its higher surface area. This approach is still difficult to apply due to fast agglomeration and sedimentation of colloidal suspensions of nZVI, which leads to very short transport distances. To overcome this issue of limited mobility, polyanionic stabilisers are added to increase surface charge and stability of suspensions. In field experiments maximum transport distances of a few metres were achieved. A new approach, which is investigated in this thesis, is enhanced mobility of nZVI by a more mobile carrier colloid. The investigated composite material consists of activated carbon, which is loaded with nZVI. In this cumulative thesis, transport characteristics of carbon-colloid supported nZVI (c-nZVI) are investigated. Investigations started with column experiments in 40 cm columns filled with various porous media to investigate on physicochemical influences on transport characteristics. The experimental setup was enlarged to a transport experiment in a 1.2-m-sized two-dimensional aquifer tank experiment, which was filled with granular porous media. Further, a field experiment was performed in a natural aquifer system with a targeted transport distance of 5.3 m. Parallel to these investigations, alternative methods for transport observations were investigated by using noninvasive tomographic methods. Experiments using synchrotron radiation and magnetic resonance (MRI) were performed to investigate in situ transport characteristics in a non-destructive way. Results from column experiments show potentially high mobility under environmental relevant conditions. Addition of mono-and bivalent salts, e.g. more than 0.5 mM/L CaCl2, might decrease mobility. Changes in pH to values below 6 can inhibit mobility at all. Measurements of colloid size show changes in the mean particle size by a factor of ten. Measurements of zeta potential revealed an increase of -62 mV to -82 mV. Results from the 2D-aquifer test system suggest strong particle deposition in the first centimetres and only weak straining in the further travel path and no gravitational influence on particle transport. Straining at the beginning of the travel path in the porous medium was observed with tomographic investigations of transport. MRI experiments revealed similar results to the previous experiments, and observations using synchrotron radiation suggest straining of colloids at pore throats. The potential for high transport distances, which was suggested from laboratory experiments, was confirmed in the field experiment, where the transport distance of 5.3 m was reached by at least 10% of injected nZVI. Altogether, transport distances of the investigated carbon-colloid supported nZVI are higher than published results of traditional nZVI

Download or read book Groundwater Engineering written by Rajandrea Sethi and published by Springer. This book was released on 2019-07-03 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook employs a technical and quantitative approach to explain subsurface hydrology and hydrogeology, and to offer a comprehensive overview of groundwater-related topics such as flow in porous media, aquifer characterization, contaminant description and transport, risk assessment, and groundwater remediation. It describes the characterization of subsurface flow of pristine and polluted water and provides readers with easily applicable tools for the design of water supply systems, drinking-water source protection, and remediation interventions. Specific applications range from groundwater exploitation as a drinking water supply to the remediation of contaminated aquifers, from the definition and safeguarding of drinking-water sources to the assessment of human health risks in connection with groundwater contamination events. The book represents an ideal learning resource for upper-undergraduate and graduate students of civil engineering, environmental engineering, and geology, as well as practitioners in the fields of water resource management and environmental protection who are interested in groundwater engineering and technical hydrogeology.

Download or read book Electrokinetics Across Disciplines and Continents written by Alexandra B. Ribeiro and published by Springer. This book was released on 2015-08-25 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: The socio-economic activities due to world development are promoting increasing pressures on land, creating competition and conflicts, resulting in suboptimal use of resources. Integrated planning and management of land resources is a top subject of Agenda 21 (managed by FAO), which deals with the cross-sectoral aspects of decision-making for the sustainable use and development of natural resources. This is essential for life-support systems and its productive capacity. In this context, there is a need to find new strategies for sustainable development that links social and economic progress with environmental protection and enhancement. Electrokinetic transport processes (EK) uses a low-level direct current as the “cleaning agent”. EK has been applied to the remediation of polluted soils and other contaminated matrices. It also shows a great potential to be used in different fields, as in saline soil restoration, nutrients recovery from wastes or repair and maintenance of building structures. EK may be an integrated approach for new strategies aiming at sustainable development and to support waste strategies, with worldwide interest. EK can also be coupled with phytoremediation and integrated with nanotechnology, enlarging the scope of its application. The conciliation of the EK in the recovery of secondary resources, remediation and conservation is a multidisciplinary novel approach that opens new technical possibilities for waste minimization, through upgrading of particulate waste products and the recovery of secondary resources for industrial, agricultural or social use.

Download or read book The Formation and Aggregation of Iron Oxyhydroxide Nanoparticles in the Aqueous Environment written by Benjamin Adam Legg and published by . This book was released on 2013 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nucleation, growth, and aggregation are interconnected processes which control the formation nanoparticles within aqueous environments and the development of nanoparticle structures. These processes are of fundamental engineering importance for the development of new nanoparticle synthesis methodologies and the creation of hierarchical self-assembled structures. They are also fundamentally important concepts for describing how nanoparticles and minerals are formed and distributed throughout the natural environment. The development of more sophisticated models for nucleation, growth, and aggregation within the aqueous environment has become a pressing scientific need, because nanoparticle size, shape, and aggregate structure are known to impact particle reactivity, bioavailability, transport and fate within the environment. In recent years, it has become apparent that complex interactions may exist between the processes of nucleation, growth, and aggregation, and these interactions are especially important during the formation of nanometer scale particles. For example, aggregation has been shown to serve as a mechanism for the growth of nanocrystals, and as a potential driver for phase transformations. However, the details of these interactions are not fully understood. In this work, a combination of advanced in situ characterization techniques, including cryogenic transmission electron microscopy (cryo-TEM) and small angle x-ray scattering (SAXS), have been combined to better understand the development of nanoscale structures in aqueous systems. These techniques are complementary. Cryo-TEM provides new capabilities for nanoscale imaging of particles in aqua. It is especially useful for imaging fragile aggregate structures, which cannot be dried without damage, and for obtaining snapshots of reactive solutions that are evolving over time. Furthermore, cryo-TEM can be used to produce three-dimensional tomographic reconstructions (cryo-ET), providing structural models for particles and nanoparticles. However, TEM methodologies are limited by sampling statistics and are not ideal for determining the kinetics of structural change. SAXS is a complementary method that allows suspension properties such as particle size and aggregate structure to be characterized in a time-resolved fashion. SAXS has the potential to provide more statistically robust measurements, and to provide detailed reaction kinetics. However, SAXS data interpretation requires some level of a priori knowledge of the structure being characterized. Thus, by combining SAXS with cryo-TEM, a structurally accurate and statistically robust description of nanoparticle aggregate structure can be obtained. This dissertation consists of four studies, which seek explain how iron oxyhydroxide nanoparticles nucleate and develop new structures via aggregation, within the aqueous environment. The aim of the first study is to determine the structure of ferrihydrite nanoparticle aggregates in aqua. This is achieved using complimentary cryo-TEM and SAXS methodologies. Ferrihydrite nanoparticles are known to form complex aggregate structures. Interpretation of SAXS data is difficult due to suspension polydispersity. Cryo-ET is used to obtain three-dimensional images of the nanoparticle suspensions. A variety of aggregate structures are observed, with branched networks of linear chains of particles being prevalent in most suspensions. The tomographic structural models are processed to determine aggregate fractal dimensions, using an autocorrelation function based approach. These results are combined with SAXS data to obtain a more comprehensive understanding of the suspension complexity. The networks of linear chains are shown to possess low fractal dimensions, between 1.0 and 1.4; significantly lower than would be expected from traditional models for aggregation. This has important consequences for the aggregate's physical behavior, and allows very large aggregates to exist in stable colloidal suspension without flocculation. The second study addresses how the ferrihydrite aggregate structure responds to changes in the ionic strength of the suspension, and how low-dimensional aggregate structures may influence nanoparticle transport through subsurface environments. Introducing ferrihydrite particle aggregates into solutions of 2 mM to 50 mM NaNO3 is shown to induce aggregate collapse, with more salt leading to the formation of denser aggregate structures and eventual flocculation. Complementary experiments show that millimolar quantities of NaNO3 induce a fundamental change in nanoparticle transport through a saturated quartz sand column. In deionized water, where low fractal dimension aggregates are stable, nanoparticles deposit evenly throughout the column, which soon saturates with particles so that subsequent injections are transported freely. When conditions favor aggregate collapse, dense localized accumulations occur and more nanoparticles can be deposited within the column. These deposits may be mechanically unstable, leading to irregular transport behavior. In the third study, the relationship between aggregation and iron oxyhydroxide phase transformations is explored. Previous researchers have found that akaganeite ([beta]-FeOOH) nanoparticles transform to create hematite ([alpha]-Fe2O3) nano-spindles in response to hydrothermal aging, but the mechanism of transformation is unknown. Some researchers have proposed a process based on the aggregation of hematite precursors, while others advocated for dissolution and re-precipitation mechanisms. In this study, the kinetics of the phase transformation from akaganeite to hematite is studied, and cryo-TEM is used to characterize the aggregate structures in the transforming suspension. The hematite spindles are shown to be nanoporous, while akaganeite nanoparticles display a tendency for oriented aggregation. Hematite spindles are frequently found in intimate contact with akaganeite nanoparticle aggregates during the process of phase transformation, suggesting a model for phase transformation in which the dehydration of akaganeite to form hematite is enhanced by aggregation. In the final study, the nucleation and growth of akaganeite nanoparticles from acidic (pH 1.5-3) FeCl3 solutions is tracked with in situ small angle x-ray scattering (SAXS). The hydrothermal precipitation process studied can generate highly monodisperse particles, whose size, shape, and nucleation rate can be tuned by varying solution saturation and temperature. Classical nucleation modeling is applied to determine new values for the interfacial energy of ferric oxyhydroxide clusters. The interfacial energy (interfacial tension) of the nucleus is shown to be pH dependent and ranges from 0.06 to 0.12 J/m2 within the range of experimental conditions. The interfacial tension decreases with decreasing pH. At the onset of nucleation, this corresponds to very small critical nuclei, containing just 4 to 30 iron atoms. The free energy of the early critical nuclei (40-70 kJ/mol) is found to be small relative to the effective activation energy for particle growth (140-200 kJ/mol). This suggests a situation where differences in growth kinetics may be as important for determining the first formed phase as differences in precipitate solubility or interfacial energy. A thermodynamic construction for the free energy of an embryonic cluster is presented that can be extended to clusters of arbitrarily small size, including iron monomers. This construction can be used to define the interfacial tension of dissolved species, and determine this interfacial tension from readily available solubility data. The interfacial tension of the monomer is shown to closely track the experimentally determined interfacial tension of the critical nucleation clusters, suggesting a new method for estimating oxyhydroxide interfacial tensions when direct experimental measurements are unavailable. In combination, these studies reveal the wide array of structures and behaviors that can occur in aqueous suspensions of ferric oxyhydroxide nanoparticles. In aqua methodologies with nanoscale resolution have allowed novel nanoparticle structures to be observed (e.g. linear particle chains and nanoporous hematite), and have been used to show the impact of nanoparticle aggregation on a variety of important physical processes (e.g. nanoparticle transport and phase transformation). These in aqua methods are also powerful tools for quantitative characterization of fundamental processes such as nanoparticle nucleation and growth; allowing important material properties (i.e. interfacial energy) that were previously unknown to be obtained. This type of information will allow for the refinement of existing iron oxyhydroxide synthesis approaches, to provide better control over particle size, shape, and phase, and will allow scientists to predict where nanoparticles may form within the environment.

Download or read book Effect of Groundwater Biogeochemistry on Zero Valent Iron Nanoparticles written by Sai Rajasekar Chandrasekar Rajajayavel and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Accidental spills and past improper disposal practices of chlorinated solvents have led to widespread soil and groundwater contamination. Drinking water standards for trichloroethylene (TCE) and many other chlorinated organic contaminants are in the range of 5 μg/L and these compounds have received extensive regulatory attention because these compounds are often carcinogenic and neurotoxic. Direct injection of reactive nanoscale zerovalent iron particles (NZVI) is considered to be a promising approach for remediation of chlorinated compounds. NZVI is a strong reducing agent that can effectively transform TCE and other chlorinated organic compounds to non-toxic end products. The objective of the research was to assess various biogeochemical conditions on the reactivity of iron nanoparticles in particular sulfidation of NZVI for remediation of TCE. In addition, the feasibility of coupled NZVI-based remediation and bioremediation using polymer-coated bimetallic NZVI and a dechlorinating mixed culture consortia (KB-1) was investigated. We demonstrated that the extent of sulfidation of NZVI enhances the rate of dechlorination of TCE compared to non-sulfidated NZVI, and this enhancement depends on the Fe/S molar ratio of the sulfidated NZVI particles. Batch experiments where TCE was reacted with NZVI sulfidated to different extents (Fe/S molar ratios 0.62 to 66) showed that the surface-area normalized first-order TCE degradation rate constant increased 40 fold compared to non-sulfidated NZVI. FX-ray photoelectron spectroscopy analyses showed formation of a surface layer of FeS and FeS2. This indicates sulfide ions reacted with NZVI iron sulfide on surface of S-NZVI. We propose that more electrons are preferentially conducted from sulfidated NZVI than from unamended NZVI to TCE, likely because of greater binding affinity of TCE on the reactive sites of the iron sulfide outer layer. Aging of sulfidated iron nanoparticles (S-NZVI) and their influence on rate of TCE dechlorination was compared to the aged non-sulfidated NZVI. Long-term experiments indicate that pseudo-first order H2 evolution rate constant for non-sulfidated NZVI was 0.092 ± 0.005 d-1 and was significantly higher than the S-NZVI (Fe/S=25) at 0.051 ± 0.005 h-1. This difference in hydrogen evolved corresponds to the amount of reactive Fe(0) consumed in the absence of TCE. To further support, the efficacy of long-term reactivity S-NZVI batch TCE degradation experiment with anaerobically aged S-NZVI (40 days) degraded significantly more TCE than the non-sulfidated NZVI. Bimetallic, palladium-doped iron nanoparticles (Pd-NZVI) are capable of rapid transformation of higher initial TCE concentration, and the ability to form rapid H2 (electron donor for bacteria) may facilitate TCE biodegradation. Dehalococcoides are the only species of bacteria that are capable of degrading TCE completely to ethene under anaerobic conditions. Therefore, we investigated the interaction of carboxymethyl cellulose (CMC) stabilized palladium (Pd-NZVI) on the dechlorinating mixed culture KB-1 for reductive dechlorination of 1, 2 dichloroethane (DCA). Results suggest that systems with CMC alone as a sole carbon source and electron donor were capable of degrading 1, 2-DCA, and methane formation. The microcosms with KB-1 and polymer coated Pd-NZVI degraded 1, 2-DCA at a significantly higher rate constant compared to KB-1 and CMC systems. In addition, methanogenesis by KB-1 showed no statistically significant difference in the methane formation rate constants between Pd-CMC-NZVI and CMC only systems.Overall, this research demonstrates NZVI reactivity towards TCE and its longevity (efficacy) under anaerobic conditions can be enhanced with sulfidation. In addition, this research also shows that CMC stabilized bimetallic NZVI, is not inhibitory to Dehalococcoides spp. and could promote complete bioremediation." --

Download or read book 21st Century Nanoscience written by Klaus D. Sattler and published by CRC Press. This book was released on 2022-01-18 with total page 4153 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 21st Century Nanoscience Handbook will be the most comprehensive, up-to-date large reference work for the field of nanoscience. Handbook of Nanophysics, by the same editor, published in the fall of 2010, was embraced as the first comprehensive reference to consider both fundamental and applied aspects of nanophysics. This follow-up project has been conceived as a necessary expansion and full update that considers the significant advances made in the field since 2010. It goes well beyond the physics as warranted by recent developments in the field. Key Features: Provides the most comprehensive, up-to-date large reference work for the field. Chapters written by international experts in the field. Emphasises presentation and real results and applications. This handbook distinguishes itself from other works by its breadth of coverage, readability and timely topics. The intended readership is very broad, from students and instructors to engineers, physicists, chemists, biologists, biomedical researchers, industry professionals, governmental scientists, and others whose work is impacted by nanotechnology. It will be an indispensable resource in academic, government, and industry libraries worldwide. The fields impacted by nanoscience extend from materials science and engineering to biotechnology, biomedical engineering, medicine, electrical engineering, pharmaceutical science, computer technology, aerospace engineering, mechanical engineering, food science, and beyond.

Download or read book Advanced Nano Bio Technologies for Water and Soil Treatment written by Jan Filip and published by Springer Nature. This book was released on 2020-01-17 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are proposing this comprehensive volume aimed at bridging and bonding of the theory and practical experiences for the elimination of a broad range of pollutants from various types of water and soil utilizing innovative nanotechnologies, biotechnologies and their possible combinations. Nowadays, a broad range of contaminants are emerging from the industry (and also representing old ecological burdens). Accidents and improper wastewater treatment requires a fast, efficient and cost-effective approach. Therefore, several innovative technologies of water and soil treatments have been invented and suggested in a number of published papers. Out of these, some nanotechnologies and biotechnologies (and possibly also their mutual combinations) turned out to be promising for practical utilization – i.e., based on both extensive laboratory testing and pilot-scale verification. With respect to the diverse character of targeted pollutants, the key technologies covered in this book will include oxidation, reduction, sorption and/or biological degradation. In relation to innovative technologies and new emerging pollutants mentioned in this proposed book, an important part will also cover the ecotoxicity of selected pollutants and novel nanomaterials used for remediation. Thus, this work will consist of 8 sections/chapters with a technical appendix as an important part of the book, where some technical details and standardized protocols will be clearly presented for their possible implementation at different contaminated sites. Although many previously published papers and books (or book chapters) are devoted to some aspects of nano-/biotechnologies, here we will bring a first complete and comprehensive treatise on the latest progress in innovative technologies with a clear demonstration of the applicability of particular methods based on results of the authors from pilot tests (i.e., based on the data collected within several applied projects, mainly national project “Environmentally friendly nanotechnologies and biotechnologies in water and soil treatment” of the Technology Agency of the Czech Republic, and 7FP project NANOREM: “Taking Nanotechnological Remediation Processes from Lab Scale to End User Applications for the Restoration of a Clean Environment”). This multidisciplinary book will be suitable for a broad audience including environmental scientists, practitioners, policymakers and toxicologists (and of course graduate students of diverse fields – material science, chemistry, biology, geology, hydrogeology, engineering etc.).