51. Organic ligands unexpectedly increase the toxicity of chromium(III) for luminescent bacteria
- Author
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Teng Xu, Wenhua Zhang, Wenjun Long, Liangqiong Peng, and Weijie Zhou
- Subjects
biology ,Chemistry ,Scanning electron microscope ,Metal ions in aqueous solution ,Photobacterium phosphoreum ,Luminescent bacteria ,chemistry.chemical_element ,02 engineering and technology ,010501 environmental sciences ,021001 nanoscience & nanotechnology ,biology.organism_classification ,01 natural sciences ,Oxalate ,chemistry.chemical_compound ,Chromium ,Toxicity ,Environmental Chemistry ,Ecotoxicology ,0210 nano-technology ,0105 earth and related environmental sciences ,Nuclear chemistry - Abstract
Organic ligands are commonly believed to decrease the toxicity of metal ions, but there is few experimental evidence, especially for chromium (Cr(III)), which often coexists with organic compounds in industrial effluents. Here, the complexation of Cr(III) with acetate, lactate, l-tartrate, biphthalate and oxalate was tested under the conditions of a toxicity test, with high ion strength, by spectroscopic techniques. The stability constants of the complexes were found to follow the order Cr(III) oxalate > Cr(III) lactate > Cr(III) biphthalate > Cr(III) L-tartrate > Cr(III) acetate. Then, aquatic toxicity of Cr(III) to Photobacterium phosphoreum for a 15-min exposure period was tested in the absence and presence of organic ligands. Results unexpectedly show that the complexation of Cr(III) with acetic, lactate, l-tartrate and biphthalate resulted in enhanced toxicity to luminescent bacteria, whereas the coordination of Cr(III) with oxalate sharply alleviated the toxicity of individual oxalate and inorganic Cr(III), which was further confirmed by the scanning electron microscopy (SEM). Our findings show thus that organics do not always mitigate the toxicity of Cr(III) in acidic water.
- Published
- 2019
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