Resumo

GABRIEL PARRA, Rosalío et al. Ultrasonic treatment for deinking of laser paper using two frequencies, 25 and 45 khz. Rev. mex. de cienc. forestales [online]. 2015, vol.6, n.28, pp.126-141. ISSN 2007-1132.

The aim of this research was to analyze the effects of applying an ultrasonic treatment, combined with flotation and washing stages, to improve the efficiency of deinking process of waste paper printed with laser technology. Waste office paper was hand cut in small sizes of about 3 cm2, and then disintegrated in a specialized device to get a water-based suspension. This process was done using 1.5 % consistency for 5 minutes. After disintegrated, the fiber suspension was treated in an ultrasonic bath using two frequencies, 25 and 45 kHz. Experimental data was collected by means of an experimental design 25-1 using frequency, consistency, temperature, treatment time, and frequency modulation mode (sweep, degass or no modulation), as factors. Ink particle size and number of particles per square meter in each stage of the deinking process, were evaluated as response variables. Results showed that the efficiency in breakdown of the toner particles was dependent of the frequency and the modulation mode used during the ultrasonic stage. The maximum number of ink particles in the range of 50-100 µm (optimal size for particle removal), was obtained by using a frequency of 25 kHz, 0.5 % consistency, 55 °C, modulation of 1 and treated for 20 min.

Palavras-chave : Deinking; flotation; washing; frequency modulation; laser paper; ultrasonic treatment.