|
In situ chemical reduction (ISCR) is a new type of environmental remediation technique used for soil and/or groundwater remediation to reduce the concentrations of targeted environmental contaminants to acceptable levels. It is the mirror process of In Situ Chemical Oxidation (ISCO). ISCR is usually applied in the environment by injecting chemically reductive additives in liquid form into the contaminated area or placing a solid medium of chemical reductants in the path of a contaminant plume.〔http://www.epa.gov/ada/gw/iscr.html〕 It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation. The ''in situ'' in ISCR is just Latin for "in place", signifying that ISCR is a chemical reduction reaction that occurs at the site of the contamination. Like ISCO, it is able to decontaminate many compounds, and, in theory, ISCR could be more effective in ground water remediation than ISCO. Chemical reduction is one half of a redox reaction, which results in the gain of electrons. One of the reactants in the reaction becomes oxidized, or loses electrons, while the other reactant becomes reduced, or gains electrons. In ISCR, reducing compounds, compounds that accept electrons given by other compounds in a reaction, are used to change the contaminants into harmless compounds. ==History== ISCR is a relatively new type of ground water remediation technology. The most work on this method of remediation has been done in the past 10–15 years, so there are still many gaps in the understanding of the chemistry behind this process. The development of ISCR started out when K.H. Sweeney conducted research with zero-valent copper and iron in the late 1970s. He was able to treat a number of different chlorinated substances such as DDT, endrin, chloroform, and hexachlorocyclopentadiene to name a few. His work has been the basis of ISCR today. In the 1990s, Gillham, Tratnyek, Kriegman, Zhang, and Batchelor all made significant contributions in testing different metals and oxides for the use of ISCR.〔 Gillham and Tratnyek in particular applied the reductive chemistry to groundwater treatment with the emplacement of ZVI barriers. Although it has been shown that other metals like aluminum and magnesium can produce the same effect in the laboratory, ground water treatment most generally focuses on the use of iron.〔 Other major contributions in this field includes Zhang, who researched nanoscale iron, and Batchelor, who researched zero-valent iron clay (ZVI Clay). This past decade, more aspects of ISCR have been researched and new methods of implementation, such as ZVI clay and emulsified ZVI (EZVI), have been created. Scientists have also found that certain iron minerals, like green rust, magnetite, and pyrite, also have reductive capabilities although they contain ferrous iron rather than ZVI.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「In situ chemical reduction」の詳細全文を読む スポンサード リンク
|