Deinking possibilities in the reduction of mineral oil hydrocarbons from recovered paper grades

The aim of the study was to compare the efficiency of two deinking methods in the reduction of mineral oil hydrocarbons from recovered paper grades, which are going to be used in production of food packaging paper. Old newspapers (ONP) printed with coldset inks, supercalendered (SC) papers printed by rotogravure, and lightweight coated (LWC) papers printed with heatset inks were deinked by flotation and adsorption treatments. After each treatment, filter pads obtained from deinked pulps were analysed on the content of saturated and aromatic mineral oil hydrocarbons (MOSH, MOAH) by GC/FID measurements, as well as on the brightness and ash content. The results have shown that adsorption deinking is almost as efficient as flotation in ink removal in the case of ONP deinking, but less effective in the case of heatset and rotogravure inks (SC and LWC printed papers). However, for most tested samples adsorption deinking was found to be more successful in the reduction of mineral oils than the conventional flotation deinking method. Main conclusion was that over 60% up to 80% of mineral oils can be removed from recovered papers by means of adsorption deinking.