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Abstract

There is much current interest in development of processes which lead to .
greater utilisation of secondary fibres in papermalcing operations, both in Australia and
overseas. The removal of ink from paper (deinking) is a major step in these
processes. After repulping, ink can be removed from aqueous suspension by a
number of techniques, one of which is flotation. Most commercial deinking facilities
use flotation as the principle method of ink removal.
Studies have been made on the effects of flotation conditions, feedstock
composition, and surfactant during flotation deinking of newspaper (ONP) and
magazines (OMG). Type of surfactant and amount of surfactant appear to affect
deinking performance. Temperature, pH, and furnish also appear to affect deinking
efficiency of the various surfactants investigated. There is an optimum pH of 8.5 for
flotation deinking of a 70/30 mixture of ONP/OMG using a fatty acid type deinking
surfactant.
Increasing proportions of magazines (ash content of 26%) in the feedstock
results in a deinked pulp with higher brightness. However, it was found that the
higher brightness attained is largely due to the addition of higher brightness materials
from the magazines, rather than a more efficient mechanism of ink removal from the
ONP. Addition of Ca2+ in the pulping stage at low level of addition seem to
improve the brightness response for deinking of newspaper with fatty acids. High
level of addition of Ca2+ seems to have detrimental effect.
An attempt is made to explain the results in terms of a model describing the
flotation deinking process and the interactions occurring between surfactant molecules,
ink particles, fibres, and air bubbles.

Item Type:	Thesis - Research Master
Authors/Creators:	Ariadi, Bimo
Keywords:	Newsprint, Printing ink
Copyright Holders:	The Author
Copyright Information:	Copyright 1995 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (M.Sc.)--University of Tasmania, 1996. Includes bibliographical references
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