Conservation of acidic papers using a dispersion of oleic acid-modified MgO nanoparticles in a non-polar solvent

Abstract

Abstract In this study, a new method was developed for the deacidification of acidic papers, by using a deacidifying dispersion of oleic acid-modified magnesium oxide (MgO) nanoparticles in cyclohexane. We reported that oleic acid-modified MgO nanoparticles were prepared by using a surface modification method. The results showed that the carboxylic group of oleic acid could react with the hydroxyl group on the surface of nanoparticles and the reaction was esterification. MgO nanoparticles were transformed from hydrophilic to lipophilic, with well dispersibility in cyclohexane for 6 h. Pure MgO nanoparticles all sank in cyclohexane after 30 s, so the deacidifying agents of pure MgO nanoparticles in cyclohexane could not be prepared for the deacidification of papers. The stable dispersion of oleic acid-modified MgO nanoparticles in cyclohexane then was used for the deacidification of papers. The accelerated aging tests were also used to evaluate the effect of the new method. Results showed that the surface pH of all types of papers were alkaline after the deacidification treatment and tensile strength values of those remained stable after accelerated aging. The deacidification treatment had ignorable influence on the appearance of papers, as well as inks and pigments on the paper surface. As the use of hydrophobic oleic acid-modified MgO nanoparticles, hydrophobicity of papers changed from hydrophilic to hydrophobic.