Low-temperature plasma preparation and application of carbon black nanoparticles

• We use a novel plasma method for the preparation of high-quality carbon black (CB).
• The method is environmentally benign and economic.
• CB nanoparticles are successfully modified by polyvinylpyrrolidone.
• The modified CB is used as a pigment for the preparation of water-based ink-jet ink.
• Physical and printing properties of the ink are comparable with the commercial one.

A new route is presented for the production of carbon black (CB) in which the propane is cracked into CB and hydrogen using electric energy from a low-current, high-voltage plasma discharge. The spherical CB produced by this process possessed a narrow size distribution, an average diameter of 50 nm and a high oil absorption number (OAN) of 136 mL/100 g. The prepared CB nanoparticles were first hydroxymethylated with a formaldehyde solution and subsequently oxidized using concentrated nitric acid to introduce hydroxyl and carboxyl acid groups onto the CB surface. These hydrophilic groups were beneficial for breaking up the large CB particles into smaller particles, and they significantly improved the dispersity of the CB nanoparticles in aqueous media. The modified CB was then coated by polyvinylpyrrolidone (PVP), in which the carbonyl oxygens acted as proton acceptors to form hydrogen bonds with the carboxyl acid groups. Finally, the PVP-coated CB was dispersed in an aqueous solution and was formulated into a pigmented ink-jet ink. The physical and printing properties of the prepared ink were demonstrated to be comparable with the commercial ink.