Results of fibre and toner flotation depending on oleic acid dosage

Abstract

The literature was reviewed with respect to deinking flotation methods with toner samples, specifically emphasizing the speciation of copy machine and laser printing, which produce an increasing quantity of paper that is difficult to recycle. Speciation here refers to the physical-chemical characteristics of the toner, which change because of the polymerization (fusion) and oxidation process, due to exposure to heat, light and oxygen (air) during the printing process. To simulate the deinking flotation, after the ideal disintegration process, samples of toner were prepared in order to provide free toner particles. Synthetic toner has iron content and the same physical-chemical features as free disintegrated printed toner particles. We report the toner ( I) and fibre ( Y) recovery and the brightness ( B) of laboratory filter pads formed of deinked product as deinking efficiencies. The application of oleic acid as the collector in the flotation stage gives a better flotation recovery in alkaline than in acidic conditions. The highest brightness ( BF = 93.66%) and flotation recoveries ( I = 90, Y = 92.82%) were achieved during testing at an oleic acid concentration of 3.38·10−6 mol l−1, which is the lowest dose used. This makes the use of oleic acid economical and environmentally friendly.