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Complexation of Metal Ions by Ligands
Published in James F. Pankow, Aquatic Chemistry Concepts, 2019
Multidentate ligands are often called chelates. The word “chelate” originates from the Greek “chele” (χελε) meaning “crab’s claw”: a crab’s claw is bidentate. Two well-known, man-made chelates used for manipulating metal ion chemistry are nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA). The structures of the protonated and fully deprotonated forms of the two compounds are given in Figures 10.5 and 10.6. When fully deprotonated, the amine nitrogen on NTA offers one of the points of attachment to a metal ion. For deprotonated EDTA, two of the ligand points are amine nitrogens.
Influence of alkyl polyglucoside, citric acid, and nitrilotriacetic acid on phytoremediation in pyrene-Pb co-contaminated soils
Published in International Journal of Phytoremediation, 2018
Xiaoyan Liu, Liya Cao, Xinying Zhang, Jing Chen, Zhuhao Huo, Ying Mao
However, poor bioavailability of PAHs and HMs in soil limits the application of phytoremediation (Lestan et al.2008). Surfactants and chelating agents can increase the bioavailability of the pollutants in the soils for their special chemical structure (Romeh 2015). Alkyl polyglucoside (APG) is new-generation green surfactant produced from renewable resources such as fatty alcohols and glucose. Due to the characteristics of nontoxic and biodegradability, APG was used in many studies and showed good solubilization ability for PAHs (Cederlund and Borjesson 2016; Liu et al.2013). Citric acid (CA) is a low molecular weight organic acid that could be released by plant roots. Enhanced phytoremediation of HMs by CA was observed in various studies (Muhammad et al.2009; Zaheer et al.2015). Nitrilotriacetic acid (NTA), as a biodegradable chelating agent, is not harmful to the organism compared with some synthetic chelating agents (such as EDTA) (Evangelou et al.2007). Chen et al. (2016b) found that the addition of NTA to soil could improve the ability of Scirpus triqueter to accumulate Pb, moreover, the growth of plant was also promoted. It was proved that surfactants and chelating agents could enhance phytoremediation to some extent, however, there were only few researches for their combined application.