Adsorption of basic dyes from model aqueous solutions onto novel spherical silica support

Removal of CI Basic Blue 9 or CI Basic Red 5 from model aqueous solutions has been studied with spherical silica precipitated in an emulsion system used as an adsorbent. The process of removal of the dye impurities has been studied for the dyes in a wide range of concentrations (50-2000 mg dm(-3)) in model systems. The degree of dye adsorption, chemical stability of the pigments obtained and their detailed physicochemical and morphological characterisation have been ascertained. In particular, the dye removal method proposed has been found to be highly effective in removing CI Basic Blue 9 (99.9%). The degree of dye extraction from the silica (SiO2) surface at the dye concentration in the model solutions in the range 1000-2000 mg dm(-3) did not exceed 1.0%. The pigment composites produced are characterised by high uniformity of the particles (polydispersity index = 0.005) with the diameters ranging from 360 to 510 nm. The pigment particles are spherical in shape and of intense blue or red colour.