Cadmium oxine complex

The extent to which the free cadmium ion complexes with the oxinate ion to form the 1 1 cation is governed by... 

Figure 3.33 shows how the fraction of free cadmium ion, 3o. the fraction of 1 1 cadmium oxinate, Sj, and the fraction of 1 2 cadmium oxinate, 82, vary with a change in aqueous phase pH for a Chox of 0-5 ppm. As the pH of the aqueous phase is increased, most of the cadmium starts out as Cd + but gradually is complexed as the 1 1 and 1 2 complex. The fraction of total cadmium existing as the 1 1 complex reaches a maximum at around 8.8, then decreases, whereas the fraction as the 1 2 complex continuously increases until all of the metal is complexed as the 1 2 complex at around... 

The distribution ratio for the partitioning of cadmium oxinate 1 2 complex from an aqueous phase to a Cig bonded surface can be defined in terms of a ratio of the concentration of CdOx2 that would be present on the surface to the sum of all of the forms of the metal in the aqueous phase. This is defined as... 

Equation (3.75) is an important outcome of our derivation efforts. Let us proceed to interpret this equation as it relates to the cadmium-oxine system. Equation (3.75) states that the distribution ratio for the 1 2 complex between an aqueous phase and a chemically bonded silica such as a Cig sorbent depends on the magnitude of the molecular partition coefficient and the degree to which cadmium is found as the 1 2 complex. Given that Eqs. (3.70)-(3.72) enable one to calculate Sq, Si, and Sj, respectively, and that we... 

Table 3.16 Measured Absorbance for Recovered Cadmium as the Oxine Complex at an Acidic and an Alkaline pH...

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