The effect of pulping reagents on the deinking flotation of laser-printed w
astepaper was investigated with regard to the removal efficiency of toner a
nd mineral filler particles at different pH values. These results show that
caustic pulping causes the toner to be released from the fibres as larger
particles and a poor floatation response is obtained On the other hand, neu
tral pulping not only causes the toner to be released as smaller particles
but also increases the simultaneous floatation removal oftener and mineral
filler particles. On the basis of these flotation results and atomic force
microscopy force experiments, it is known that the remarkable removal of mi
neral fillers and toner particles under acidic conditions is related to the
heterocoagulation oftener and filler particles.