Bioremoval of marker pen inks by exploiting lipase hydrolysis

Abstract

[EN] New and eco-sustainable methods based on the catalytic activity of lipases for the removal of acrylic marker pen inks were investigated. Different biocleaning methodologies were tested using lipases from different 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 substrates were painted using marker pens, and some of these samples were subjected to natural and artificial ageing in order to compare the effectiveness of cleaning methods on fresh and aged ink layers. It was evidenced that acrylic polymer-based inks may be removed with an oil in water microemulsion, but cleaning effectiveness was generally enhanced when a lipase was added. Moreover, it was found that all the tests were more effective on the unaged samples, therefore, the cleaning intervention should be performed 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 treated samples 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 of different cleaning methods. (C) 2017 Elsevier B.V. All rights reserved.