UV-visible responses of mineral suspensions

A recent study has shown the relation between UV-visible response and size of some mineral suspensions in water [9], After filtration of commercial suspensions of talc, kaolin and carbonate (Table 6), the UV-visible spectra of the different granulometric fractions are normalised (see Chapter 2) and compared (Table 7). 

19 - a-800 nm 5) Absorbance depends slightly on the wavelength except for kaolin (slurry) 

Moreover, a linear relation between normalised absorbance values and the reciprocal wavelength (Fig. 5) can be proposed to model the UV response of colloids 

The difference observed between UV spectra of particles in slurry form and in powder form can mainly be explained by the presence of organic compound(s) used in the formulation that may absorb in the UV region (particularly for kaolin). For the range of 200-300 nm (1/X from 0.003 to 0.005), carbonate powder spectrum deviates negatively and kaolin deviates positively from linearity. Further validation should be made to check the observed linearity. 

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