USING ULTRASOUND TO DEINK XEROGRAPHIC WASTE

Mixed office waste containing xerographic ink is becoming an important source of recycled fiber. This research examined the use of ultrasoun d to break down xerographic ink particles prior to removal by conventi onal flotation. The raw material was standard xerographic sheets print ed with common toners (styrene-butadiene and styrene-acrylate). Prelim inary tests were carried out with a 500-W piezoelectric transducer cap able of batch processing. Results from these tests provided a base for subsequent tests with an ultrasonic whistle suitable for continuous, flow-through operation. Both systems reduced xerographic particles to sizes suitable for removal by flotation. Performance of the continuous system was strongly affected by treatment pH, the number of treatment cycles, and pulp consistency. Response-surface methodology was employ ed to determine the best operating conditions for the ultrasonic whist le. Results for the continuous, flow-through ultrasound system suggest that scale-up experiments should be pursued.