Realizing Nanolime Aqueous Dispersion via Ionic Liquid Surface Modification to Consolidate Stone Relics

Afterdecades of research in the conservation of cultural heritage,nanolime (NL) has emerged as a potential alternative inorganic materialto the frequently used organic materials. However, its poor kineticstability in water has been a major challenge that restricted itspenetration depth through cultural relics and resulted in unsatisfactoryconservation outcomes. Here, for the first time, we realize NL waterdispersion by modification of ionic liquid (1-butyl-3-methylimidazoliumtetrafluoroborate) via a sample aqueous solution deposit method. Ourfindings indicate that the cation of the ionic liquid (IL) binds stronglyto the surface of NL particles (IL-NL) by forming hydrogen bonds withCa(OH)(2) facets. The absorption of IL causes an unexpectedsignificant alteration in the morphology of NL particles and resultsin a drastic reduction in NL's size. More importantly, thisabsorption endows NL excellent kinetic stability dispersed into waterand implements NL water dispersion, which makes a breakthrough interms of extreme poor kinetic stability of as-synthesized NL and commercialNL in water. The mechanism driving IL-NL water dispersion is explainedby Stern theory. In the context of consolidating weathered stone,the presence of IL may delay carbonation of NL but the penetrationdepth of IL-NL through stone samples is three times deeper than thatof as-synthesized and commercial NLs. Additionally, the consolidationstrength of IL-NL is similar to that of as-synthesized NL and commercialNL. Moreover, IL-NL has no significant impact on the permeability,pore size, and microstructure of consolidated stone relics. Our researchcontributes to the field of NL-related materials and will enhancethe dissemination and utilization of NL-based materials in the preservationof water-insensitive cultural heritage.

Automated summary

After years of research, nanolime (NL) has emerged as a potential alternative for the conservation of cultural heritage. However, its poor kinetic stability in water has been a major challenge. This study successfully achieved water dispersion of NL by modifying an ionic liquid (IL). The IL binds to NL particles and significantly alters their morphology and size, resulting in excellent kinetic stability and improved penetration depth. This research contributes to the field of NL-related materials and enhances their utilization in preserving water-insensitive cultural heritage.