Using solvents to remove a toner-print so that office paper might be reused

J. M. Allwood

The environmental impact of office paper recycling might be avoided if toner print could be removed from paper in a way that left the paper immediately reusable. This article reports on experiments that investigate the use of solvents to allow black toner print to be removed from white cut-size office paper. Hansen solubility parameters are estimated for detaching the pigment in toner print from paper and compared to the parameters for paper. These imply that solvents can be found that would allow toner print to be removed without harming the underlying paper. However, immersion in solvents alone detaches just 10 per cent of the toner pigment. Rubbing combined with solvents increases removal to 50 per cent. Adding ultrasonic agitation increases removal to 80 per cent. Mixing different solvents and increasing the volume of solvent can further improve removal to the point where the cleaned paper is useful, although still distinguishable from new. For instance, soaking the printed paper in a mixture of 60 per cent dimethylsulphoxide and 40 per cent chloroform for 4 min, while applying ultrasonic agitation, results in paper that can be readily reprinted. The results need to be validated on other toner and paper types. Further work is needed to investigate the influence of temperature, of adding surfactants and to consider the economic, safety and environmental implications.