This groundbreaking book uniquely focuses on the exploration of the green synthesis of metal nanoparticles and their characterization and applications. Metal nanoparticles are the basic elements of nanotechnology as they are the primary source used in the design of nanostructured devices and materials. Nanomaterials can be manufactured either incidentally, with physical or chemical methods, or naturally; and the high demand for them has led to their large-scale production by various toxic solvents or high energy techniques. However, due to the growing awareness of environmental and safety issues, the use of clean, nontoxic and environment-friendly ways to synthesize metal nanoparticles has emerged out of necessity. The use of biological resources, such as microbes, plant parts, vegetable wastes, agricultural wastes, gums, etc., has grown to become an alternative way of synthesizing metal nanoparticles. This biogenic synthesis is green, environmentally friendly, cost-effective, and nontoxic. The current multi-authored book includes recent information and builds a database of bioreducing agents for various metal nanoparticles using different precursor systems. Green Metal Nanoparticles also highlights different simple, cost-effective, environment-friendly and easily scalable strategies, and includes parameters for controlling the size and shape of the materials developed from the various greener methods.

The design and development of nanoparticles is of great interest in the current energy and electronic industry. However, based on the current materials available the production cost can be high with insignificant magnetic and mechanical properties. Specifically, rare-earth magnetic materials composed of neodymium and samarium are known for their high magnetic performance, however, due to the cost of development there is a need to develop a versatile and cost effective material. Alternatively, cobalt carbide nanomaterials have shown to be a promising alternative for rare-earth free magnets as they exhibit comparable properties as hexaferrite magnetic materials. The primary goal of this dissertation focuses on the development of nanoparticles for permeant magnetic, and magnetic refrigeration applications. The first part of this work focuses on the synthesis of cobalt carbide (CoxC, x=2,3) nanoparticles using a novel polyol synthesis method by introducing a small amount of Ru, Cu, or Au as nucleating agent. It was found that the morphology and magnetic properties of the as-synthesized CoxC nanoparticles change as a result of directional growth of nanoparticles using nucleating agents. Needle-like particle morphology ranges from 20-50 nm in width and as long as 1 [micro]m in length were synthesized using Ru as nucleating agent. These particles exhibit magnetization saturation of 33.5 emu/g with a coercivity of 2870 Oe and a maximum energy product 1.92 MGOe (BHmax) observed. Particle morphology is a critical aspect in the development of magnetic nanoparticles as anisotropic particles have shown increased coercivity and magnetic properties. These CoxC nanomaterials have a higher maximum energy product compared to previous work providing further insight into the development of non-rare earth magnetic material. The second part of this dissertation work focuses on the sol-gel synthesis of perovskite LaCaMnO3(LCMO) nanomaterials. In this process, various chain lengths of polyethylene glycol (PEG) was added into a solution consisting of La, Ca, and Mn salts. The solution was left for the gelation process, and high temperature sintering to obtain the final product. By varying the polymer chain of the PEG, the size of the as synthesized LaCaMnO3 nanomaterials were altered. The as-synthesized LCMO nanomaterials have shown a maximum change in magnetic entropy ( -[delta]Sm) was found to be 19.3 Jkg−1K−1 at 278 K for a field change of 0-3 T and 8.7 Jkg−1K−1 for a field change of 0-1 T. This is a significant improvement in comparison to current literature of the material suggesting that this is a promising alternative to Gd materials that is prone to oxidation. With additional development, LCMO or related maganites could lead to application in commercial technologies.

This Proceedings of APCRE'05 contains the articles that were presented at the 4th Asia-Pacific Chemical Reaction Engineering Symposium (APCRE'05), held at Gyeongju, Korea between June 12 and June 15, 2005, with a theme of "New Opportunities of Chemical Reaction Engineering in Asia-Pacific Region". Following the tradition of APCRE Symposia and ISCRE, the scientific program encompassed a wide spectrum of topics, including not only the traditional areas but also the emerging fields of chemical reaction engineering into which the chemical reaction engineers have successfully spearheaded and made significant contributions in recent years. In addition to the 190 papers being accepted, six plenary lectures and 11 invited lectures are placed in two separate chapters in the front.* Provides an overview of new developments and application in chemical reaction engineering* Topics include traditional and emerging fields * Papers reviewed by experts in the field

Inhaltsangabe:Introduction: The development of small and smallest particle is one of today s key features in modern science. The goal is to form materials with improved properties than their classical ancestors with just a fractional amount of raw material. Another key feature of nanoparticles is their different, and sometimes unexpected, behavior concerning reactivity, compared with their bulk materials. Because of this, nanoparticles have a wide range of applications, especially in the field of catalysis. Here, characteristics of nanoparticles - more edges, corners, defects or oxygen vacancies are used to obtain a high performance of the catalysts. Nanoscaled particles also exhibit larger surface area and higher metal dispersion, which further contributes to the catalytic possibilities. To gain such particles, two different pathways are given: first, there is the so-called top down pathway, considered as further developments of micro technology, where physical preparation methods like lithography are used. The second way is the bottom up method where self-assembling systems, formed by surfactants, are used. Concerning gold nanoparticles, it is reported that the use of C16TAB at specified conditions, gives gold nanorods with a sharp size-distribution because the direction of growth is predetermined. Being a cationic surfactant, C16TAB affects the electrochemical potentials and introduces bromide-ions as an additional species to the reaction. To achieve gold nanoparticles from aqueous HAuCl4-solutions, the above-mentioned method needs a separate reducing agent such as ascorbic acid (Asc0), NaBH4 or N2H4. A way of synthesizing spherical gold nanoparticles is the use of Nd:YAG laser with a salt induced agglomeration. By modifying the formulation of the salt solution, different sizes are obtained. This way of synthesis, a combination of physical top-down and self-assembling bottom-up processes, can be modified by adding surfactants, like PEG, to optimize size distribution and physical characteristics, like UV-Vis absorption. This method is an elegant way of synthesis; however, problems may occur by functionalizing the particles, because of a high salt content. Here, a high influence of purity, concentration and composition to the size and shape of gold nanoparticles might be given. Therefore, a route of synthesis is needed, which shows high efficiency in producing gold nanoparticles and in stabilizing them with a manageable amount of [...]