Abstract:

Deinking remains an important step in environmentally conscious manufacturing of paper. A novel method based on acoustic microcavitation is used for deinking xerographic ink from paper. Microcavitation evolves microimplosions, which are effective in causing deinking preferentially at ink sites. Acoustic microcavitation is brought about by low megahertz acoustic fields giving rise to micron-sized bubbles that live a few microseconds. In exposing a surface to continuous waves for a defined duration one could obtain cavitation effects in an average, overall sense; the details of nucleation, evolution of inertial events, and the precise interplay of field parameters in effecting cavitation, however, get glossed over. Studying pulsed cavitation using tone bursts at low duty cycles, instead of CW insonification, reveals interesting details of the initiation and evolution of acoustic microcavitation. Experiments indicate that the 2-D context of how a xerographic print is deinked might be useful in inferring some attributes of 3-D pulp deinking. Assuringly, the results indicate that paper fibers are entirely undamaged, and the ink separation leaves them immaculately white, and that acoustic methods for deinking are a viable, chemical free, environmentally responsible means of recycling paper.