Bioremoval of marker pen inks by exploiting lipase hydrolysis

New and eco-sustainable methods based on the catalytic activity of lipases for the removal of acrylicmarker pen inks were investigated. Different biocleaning methodologies were tested using lipases fromdifferent sources (viz. bacteria and fungi) dispersed in aqueous systems and microemulsions. Blue, green,red and black marker pens were selected for their chemical composition. Unglazed ceramic substrateswere painted using marker pens, and some of these samples were subjected to natural and artificialageing in order to compare the effectiveness of cleaning methods on fresh and aged ink layers. It wasevidenced that acrylic polymer-based inks may be removed with an oil in water microemulsion, butcleaning effectiveness was generally enhanced when a lipase was added. Moreover, it was found thatall the tests were more effective on the unaged samples, therefore, the cleaning intervention should beperformed as soon as possible. Cleaning effectiveness was evaluated by measuring colour differences,acquiring visible reflectance spectra and determining the percentage of white in images of the treatedsamples by Image J open source software, for the first time used to this purpose.The results illustrate that only a multi-technique approach can correctly evaluate the effectiveness ofdifferent cleaning methods.