tailieunhanh - INTERFACIAL APPLICATIONS IN ENVIRONMENTAL ENGINEERING - CHAPTER 8
Hóa chất Phương pháp đóng Heavy Metal Kim loại nặng độc hại trong không khí, đất, nước và những vấn đề liên tục và những mối đe dọa leo thang đến môi trường mà chúng ta đang sống. Có vô số nguồn ô nhiễm kim loại nặng, hầu hết dân số nói chung không thể tránh [1,2]. Trong phản ứng với mối đe dọa này liên tục và ngày càng tăng, chính phủ liên bang và tiểu bang đã lập các quy định về môi trường để bảo vệ chất lượng nước mặt và nước ngầm từ các chất ô nhiễm. | 8 Chemical Methods of Heavy Metal Binding MATTHEW MATLOCK and DAVID ATWOOD University of Kentucky Lexington Kentucky . I. INTRODUCTION Toxic heavy metals in air soil and water are problems that are constant and escalating threats to the environment in which we live. There are a multitude of sources of heavy metal pollution most of which the general population cannot avoid 1 2 . In response to this continuing and growing threat federal and state governments have instituted environmental regulations to protect the quality of surface water and groundwater from heavy metal pollutants 3 . To meet the federal and state guidelines for heavy metal discharge companies commonly use methods to precipitate or chemically bind the metals before during or after discharge. In order to be competitive economically many of the commercially utilized reagents are not designed to target specific metals. They are either simple to synthesize or easily obtained as byproducts of other chemical reactions. These readily available reagents offer minimal binding sites for heavy metals. It has been found in fact that their mode of action is simply to act as sources of sulfide for the formation of metal sulfides. This is not an acceptable process for metal removal and deactivation. Metal sulfides are known to decompose and release heavy metals back into the environment over varying but usually short periods of time 4-6 . Additionally in forming the metal sulfides some of the reagents produce toxic byproducts such as carbon disulfide 4 7 . In an effort to provide an environmentally sound method for chemically removing heavy metals from the environment new specifically designed chelates for soft heavy metals have been reported. These ligands are not only highly effective for soft metal binding but are also economical and soon to be produced on a multiton scale. riTTBR Copyright n 2003 by Marcel Dekker Inc. All Rights Reserved. The present overview will summarize the various chemical methods .
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