Complexation and Speciation of Metals

FIGURE 3.13 The nitrilotriacetate anion binding in four places to the Zn metal ion sodium nitrilotriac-etate was once strongly advocated as a substitute for phosphates in household detergent builders, but was not used in the United States because of concern over its tendency to bind with and transport toxic heavy metal ions. (From Manahan, S.E., Environmental Chemistry, Taylor Francis/CRC Press, Boca Raton, FL, 2009. With permission.) 

FIGURE 3.14 A hypothetical structural formula of amolecule of fulvic acid fulvic acid forms soluble complex ions and chelates with metals in water. The molecule contains some aromatic rings, that is, carboxylic acid (-COjH) groups and phenolic (-OH) groups. 

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