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Current Green Chemistry -Element Recovery and Sustainability” deals with an interesting side of green chemistry. Even green chemists rarely consider sustainability in respect of the use of the elements. It is predicted that the global supply of elements regarded as critical could soon be exhausted. The first chapter gives an overview of the issue of elemental sustainability and the recovery of scarce elements. It is a real problem that “low carbon technologies” that are utilized by electric cars, energy saving light bulbs, fuel cells and catalytic converters require the use of rare and precious metals. The reader will encounter the critical elements, the expected trends, and the possible solutions of the problems involved.
Then the possibilities for elemental recovery are shown by integrating traditional methods in a zero-waste recycling flow sheet. This may be exemplified by the combination of metallurgy with special waste treatments. “Ionometallurgy”, meaning the processing of metals with ionic liquids, is a new technology. Ionic liquids may be used effectively for the extraction and digestion of metal-containing wastes as sources. It seems to be probable that hybrid systems of molecular and ionic components may provide the optimum separation capabilities. Biomass resources represent a serious capacity for utilization also as biosorbents. Biomass, with highly complex biological structures, may surely be utilised for water remediation in respect of the clean-up of water and the recovery of metals.This new possibility is to be developed in the forthcoming years. Another new technology, “phytoextraction” is based on the fact that plants can tolerate, or even accumulate quite high concentrations of metals (eg. nickel or gold). For example, heavy metal-contaminated soils may be cleaned up in this way, but waste rock, contaminated land or low-grade ore, may also be the sources. The recovery of the “f-block elements” comprising the 4f series (the lanthanides, cerium to lutetium) and the 5f series (the actinides, thorium to lawrencium) represents a special challenge. The majority of these elements, particularly the lanthanides, are used in up-to-date products/technologies, such as in flat-screen televisions, hybrid cars and nuclear power production. The “f-block elements” may be extracted by special techniques including the use of P=O and/or P=S compounds. Ruthenium, rhodium, palladium, osmium, iridium and platinum are among the rarest elements; still, these elements find a wide range of industrial and consumer applications including their use in catalytic converters and as catalysts, in electronics, and in biomedical devices and anticancer drugs. Reliable analyses show that in the industrial sector not much more development is possible, to minimise further the loss of the platinum group elements. However, improvements are warranted in the end-use applications by increasing the recycling rate. The next chapter is closely connected to the previous one in discussing the importance of waste electronic and electrical equipment recovery. The manufacture of mobile phones and personal computers utilises significant amounts of gold, silver, palladium, cobalt and indium, underlining the importance of recycling these elements from “urban mines”. Substitution of the current materials is also a prospective possibility. The last chapter compares the advantages of the “circular economy” against the “linear economy”. Considering the increasing consumption of materials, the latter “throw away” approach can no longer be tolerated. The population of the world needs a better knowledge and analysis of the flow of resources into products and their flow into waste. Solutions and examples are shown e.g. from the car industry.
This book shows a sustainable approach to the use and recovery of the critical elements that are needed. The multi-disciplinary team of authors, including chemists, engineers and biotechnological specialists presents good means for the solution of problems, illustrated via examples. The book is warmly recommended to researchers in academia and industry who are committed to any kind of chemistry utilising rare and precious metals in any form. The contents of this book may also be useful at any level of university courses for students.
Department of Organic Chemistry and Technology
Budapest University of Technology and Economy