Physicochemical properties of organic pigments on a silica core

The surface of pyrogenic silica was modified with silane coupling agent, such as N‐2‐(aminoethyl)‐3‐aminopropyltrimethoxysilane. Pigments were obtained by attaching different organic dyes, to a modified silica surface. The adsorption process was conducted in an aqueous suspension of the modified silica in the presence of the dye. In order to determine effect of silane on the dye adsorption process various amounts of the modifying compound was used. The microscopic properties, colour and particle size distribution were examined for the modified silicas and the obtained pigments.