Alkyd paint removal: Ionic liquid vs volatile organic compound (VOC)

The drive towards safer technology in removing paint from substrate requires switching from hazardous volatile organic compounds to greener alternative solvents. Ionic liquids (ILs) have been considered as relatively green solvents and employed in many applications. This study focusses on investigation of ILs as alternative green solvents for paint removal. In this regard, five imdazolium based ILs were studied for alkyd paint removal on coated wooden substrate. The effect of various anions such as dicyanamide [DCA], bis (trifluoromethanesulfonyl) imide [NTf2], hydrogen sulphate [HSO4], acetate [OAc] and chloride [Cl] was investigated. For benchmarking and comparison, three volatile organic solvents such as toluene, acetonitrile, and ethanol were used. Microscopic images showed that [DCA] anion gave significant impact on alkyd removal. In addition, [Bmim][DCA] gave highest swelling percentage of 23% whereas the other ILs did not show significant swelling. Viscosity, anion size and alkyd paint-IL interactions played important roles in removal efficacy. The prolonged immersion time in [Bmim][DCA] decreased the pull off adhesion strength up to 83.3% and consecutively promoted paint detachment from substrate. Similar infrared pattern of bare wooden stick and [Bmim][DCA] treated coated wooden stick indicates significant removal of paint by IL. The experimental results demonstrate promising application of IL as a green solvent for paint removal.