Higher carboxylic acids citric acid

Depressants can impede adsorption of collectors on the mineral surfaces in the following order citric acid > Alizarin Red S > EDTA-Na. But adsorption of these depressants themselves on the minerals is in the order of (VIII) > (I) > (VII) > (HI) > (VI). These order show that adsorbability of effective depressants is higher than that of carboxylate collectors which chemisorb on mineral surfaces. 

The three p/C.,s for citric acid are 3.1,4.7, and 5.4. Explain why the first pK is lower than for normal carboxylic acids, and why the third pK, is higher than normal. 

Simultaneous presence ofbarium and titanium in the solution of citric acid causes the effect that can not be described as the superposition of the solutions of barium citrate and titanium citrate. In addition to the familiar Ti-0 bonds and shift of carboxylic groups NMR peaks, the central carbon peak in the C-NMR spectra is displaced to higher frequency (Fang, 2001 Kakihana, 1999b), which means a deprotonation of-OH group and most likely formation of metal-oxygen bonds. This observation is particularly interesting if one takes into account p/Q = 10.96 and low pH of citric acid solution. Barium and titanium participate in the formation of the metal complex with Ba Ti CA ratio of... 

Based on earlier research on the separation of the lanthanides, ion exchange separations were also done using citric add as a complexant. Because the citrate eluent is plagued by relatively slow kinetics, other hydroxy-carboxylic adds were tested as elutriants for the higher actinide elements. Lactic add was among the first spedes tried, but better interactinide separations were observed using a-hydroxyisobutyric acid... 

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