Study On Deinking Process Of Water-based Ink Printed Papers And Its Mechanism

Water-based ink has becomes more and more popular as it is environment friendly.However, the waste paper printed with water-based ink remains one of the troublesomecontaminants in newsprint deinking operations. The conventional deinking chemicals, whichare excellent flotation collectors for oil-based inks, are rather ineffective for removingwater-based inks. In flotation deinking plants, the presence of a relatively small proportion ofwaste water-based ink printed papers leads to a drastic loss of brightness of deinked pulps.For this reason, the extensive application of water-based ink has been limited. Further more;the presence of water-based ink printed papers in blends of secondary fibers has significantlyaffected the normal operation of paper mill and lowered the quality of paper products. Toovercome the deinking difficulties, the study of this dissertation has mainly focused on theeffect of pulping, flotation and surfactants on water-based ink printed papers deinking, as wellas its mechanism explored.Pulping process of waste water-based ink printed papers deinking was studied in the firstpart of this study. In the neutral condition, the effect of pulping temperature, pulping time andpulping consistency on waste water-based ink printed papers deinking was studied. Theresults showed that when the pulping time of10mins, pulping temperature of50℃, pulpingconsistency of10%, and the effect of deinking is optimal, the brightness of deinked pulp is61.3%ISO.Flotation process of waste water-based ink printed papers deinking was studied in thesecond part of this study. To CTAB and Al₂（SO₄）₃as a deinking agent, the effect of flotationtemperature, flotation time and flotation consistency on waste water-based ink printed papersdeinking was studied. The results showed that when the flotation time of5mins, flotationtemperature of50℃, flotation consistency of1%, the effect of deinking is optimal, thebrightness of deinked pulp is61.3%ISO.The effect of different surfactants on waste water-based ink printed papers deinking wasstudied in the third part of this study. The results showed that deinking effect of cationicsurfactants is better than deinking effect of nonionic surfactants, and deinking effect ofanionic surfactants is the worst of all. The optimum dosage of surfactants is related to its owncharacteristics, and surfactants are different, so the optimum dosage is not the same. Theoptimum dosage of DTCA, Tween-20, and CTAB is0.8%, however the optimum dosage ofDBS and Tween-80is0.6%. With the non-ionic surfactants and anionic surfactants used in conjunction, original brightness of deinked pulp can be increased7⁹%ISO. With thenon-ionic surfactants and cationic surfactants used in conjunction, original brightness ofdeinked pulp can be increased3⁵%ISO.