Oxidative Aftertreatment of Carbon Black

Due to production conditions, only gas blacks (and channel blacks) are covered to a certain extent with acidic surface oxides. Furnace blacks contain only small amounts of oxygen in the form of basic surface oxides. 

Some color blacks receive oxidative aftertreatment on a commercial scale to amend their color properties. Depending on the oxidizing agent and the reaction conditions selected, different types of surface oxides are formed in varying quantities. 

Oxidized carbon blacks may contain up to 15 wt% oxygen. They are strongly hydrophilic. Some of them form colloidal solutions spontaneously in water. In polar printing ink systems, lacquers, and coatings, a better wettability and dispersibility is achieved through surface oxidation [4.26], thus reducing binder consumption. 

Oxidation of powdery black with ozone is also carried out on a commercial scale. Another common method of surface oxidation is carried out during pelletization. Nitric acid, instead of water, is used as a pelletizing agent. The surface is oxidized while the wet pellets are dried at elevated temperature [4.27], 

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Figure 59. Equipment for the oxidative aftertreatment of carbon black in a fluidized bed...

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