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The results presented are from a study on the production of highly dispersed silicas by their precipitation from solutions of sodium metasilicate and ammonium salts. The applied ammonium salts were NH 4 HCO 3 and .NH 4 / 2 CO 3 . The precipitation process was conducted in the absence or presence of 1 wt.% non-ionic surfactant (Rokanol K-7, Rokafenol N-6 or Rokafenol N-9).The highly dispersed silicas obtained were subjected to a physicochemical analysis typical for fillers. The analysis included estimation of the bulk density and the capacities to absorb water, dibutyl phthalate and paraffin oil. Particle size and morphology were evaluated using scanning electron microscopy. In addition, particle size distribution for the precipitated silicas was examined by dynamic light scattering.Silicas with the best physicochemical properties were obtained by precipitation using ammonium hydrogen carbonate. In particular, the silica precipitated in the presence of 1 wt.% Rokafenol N-9 demonstrated a magnificent capacity to absorb paraffin oil.

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