New protic ionic liquids for fungi and bacteria removal from paper heritage artefacts

Abstract

In this work, new protic ionic liquids (PILs) with 1-ammonium-2-propanol cation and nine different anions: formate (For), acetate (Ac), lactate (Lac), trifluoroacetate (TFA), chloroacetate (ClA), trichloroacetate (TClA), 3-chloropropionate (3-ClP), 4-chlorobutyrate (4-ClB) and mandelate (Man) were prepared in order to study their antimicrobial activity and possible application for fungi and bacteria removal from deteriorated paper heritage. Ten filamentous fungal strains isolated from specific pigmented area of the damaged books: Trichoderma sp., Cladosporium sp., Penicillium sp.⁽¹⁻³⁾, Penicillium citrinum, Aspergillus sp.^(1,2), Aspergillus flavus, Fusarium graminearum, eight Gram positive and Gram negative ATCC bacterial strains: B. subtilis⁽⁶⁶³³⁾, S. aureus⁽⁶⁵³⁸⁾, E. faecalis^(19433), K. rhizophila⁽⁹³⁴¹⁾, E. coli^(11229), S. enteritidis^(13076), P. mirabilis^(12453), P. aeruginosa^(15692) and two yeast Candida strains: Candida albicans^{(ATCC 10231)} and Candida albicans^(L) were used in this study. The results indicated that antimicrobial activity of selected ionic liquids is significantly affected by the size and specific functional groups in the anion structure. These facts opened the possibility for molecular design of new ionic liquids with strong inhibition properties against the specific bacterial, mould and yeast strains. The significant antimicrobial properties observed in this research suggest that studied PILs may have potential applications in the paper art and artefact cleaning and conservation replacing thus, conventional solvents and organic substances that are toxic for humans and environment.