Extraction of mercury by dithizone and stability of the extracted complex

Abstract

It emerges from previous investigations that chromate forms complexes with both oxalic acid (and other dicarboxylic acids and hydroxycarboxylic acids) and alcohols, an important role in this being played by the presence of the nondissociated OH group. It appears that it is the redox transformation of the complex formed in the course of the condensation that leads to the mutual increase in the rates of the reactions, the oxalic acid too meanwhile being consumed. In contrast, if one of the substrates is not attached in this way (e.g. in the cases of iodide and thiocyanate ions), the oxalic acid consumption is not observed, but the rate of oxidation of the substrate increases considerably. In this case, the induction turns into catalysis ( 14).An explanation is required for the finding that a plot of the reciprocal of the reaction time necessary for attainment of a given conversion vs. the alcohol concentration yields a satisfactory straight line over a relatively wide alcohol concentration interval. The cause of this is probably the fact that the single-step three-electron oxidation (step 2) is the ratedetermining process, and further that identical amounts of "chromate" are consumed in the reaction by measurement of the change in the chromate concentration up to not too high conversions.

Sensitive determination of trace mercury by UV–visible diffuse reflectance spectroscopy after complexation and membrane filtration-enrichment

“…Dithizone is one of the most popular reagent employed in the spectrophotometric determination of mercury(II) in solution [41][42][43], and is selected for mercury(II) sensing because of its higher selectivity and sensitivity. Furthermore, dithizone and its complex Hg-dithizone show low solubility in water.…”

Sensitive determination of mercury by a miniaturized spectrophotometer after in situ single-drop microextraction

“…Dithizone has a low solubility (5-7.2 × 10 −8 g mL −1 of H 2 O) and a high extraction constant (pK ex = 26.85 in CCl 4 at pH 1-1.5). Due to the high extraction capacity, dithizone was successfully applied for the extraction and determination of mercury [34,35]. In order to examine the maximal absorption spectra of Hg-dithizone complex, a commercial vis spectrophotometer was used to scan the absorption spectra of Hg-dithizone complex.…”

Simple and low cost dithizone-functionalized polymer membranes as a tool for mercury preconcentration and monitoring in aqueous bodies. Preliminary results using X-ray absorption near-edge structure (XANES).

“…see (Atwood and Zaman, 2006), dithizone is a well-established and -known ligand (e.g. see (Elly, 1973;Litman et al, 1977). In our previous work (Hatzistavros and Kallithrakas-Kontos, 2014), we created novel Hg-selective PVC-based thin film membranes and identified dithizone as a very promising ligand for mercury preconcentration on environmental water matrices, at trace (ppb) levels.…”