Adsorption of deflocculant IVP-332 (modified copper phthalocyanine) on carbon black samples

The adsorption of IVP-332 additive in o-xylene, which is a deflocculating agent designed to produce non-aqueous pigment pastes based on carbon black, was studied on samples of carbon black used in the domestic coatings industry. The IVP-332 additive is a modified copper phthalocyanine.

The electronic spectra of the IVP-332 additive in o-xylene have been determined. The determination of the equilibrium concentration of the additive after adsorption was also carried out by the spectrophotometric method. Various carbon black samples served as adsorbents. Channel carbon black K-354, furnace carbon black P-803 and P-234, as well as carbon black 2429 G with a specific surface area S of 150, 250, 110 and 187 m²/g, respectively. The experimental adsorption isotherms have a concave shape, which indicates that, along with the dissolved substance, there is a strong competing adsorption of the solvent on all the studied soot.

The effect of porosity on the adsorption value is especially clearly seen from the absolute adsorption isotherms (assigned to 1 m 2 of the surface). In this case, the lowest adsorption is observed in the case of soot 2429 G and especially P-803 with the highest value of S. The value of the effective site (A_m) occupied by the adsorbed deflocculant molecule in the adsorbed monolayer and its thickness are determined.

High A_m values and small monolayer thicknesses indicate the unavailability of a large number of pores of the studied carbon black for IVP-332 deflocculant molecules and the close to horizontal arrangement of adsorbed molecules in these pores. The weak adsorption capacity of the deflocculant is explained both by the weak dispersion interaction with the soot surface due to the presence of an expanded π-electron conjugation system in the aromatic copper phthalocyanine molecule and by the competing adsorption of the solvent.

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