Critical evaluation of approaches toward mass deacidification of paper by dispersed particles

Abstract

Mass deacidification has been an important topic in cellulose science and will continue to be a critical issue as long as acidic books and paper-based materials are-a often major-part of library and archive stocks. Different means are available to judge the result of a deacidification treatment and to address its sustainability and efficacy. The present study compares deacidification by dispersed particles with procedures that apply homogeneously dissolved alkaline compounds, both under humid and dry accelerated aging conditions. Analysis by size-exclusion chromatography coupled to light scattering detection is used in combination with accelerated aging. The number of chain scissions, i.e. cellulose degradation, is the parameter used for evaluation, expressed as stabilization factors relative to the non-treated specimen. Upon deacidification with homogeneous solutions stability factors of about four were reached, while deacidification with dispersed particles gave only two times longer life times (stability factor of two). Mechanistic aspects are discussed in terms of alkaline reserve, cellulose degradation and mobilities of deacidification agents.

Deacidification of Acidic Books and Paper by Means of Non-aqueous Dispersions of Alkaline Particles: A Review Focusing on Completeness of the Reaction

“…The two general classes of such treatments are summarized in Table 1. Leiner & Kifer 1995;Leiner & Burd 1998;Polovka et al 2006;Potthast & Ahn 2017 Notes: An example of a highly fluorinated liquid is 3M Performance Fluid PF-5060; the product literature says it has zero adverse effect on the ozone layer; hexa-methyldisiloxane (HMDS) is used in organic synthesis, analytical chemistry, and in paper deacidification. For non-aqueous dispersion systems, a highly fluorinated liquid is used in the Bookkeeper® process, and heptane is used in the ZfB:2 process.…”

“…Efficacy factors have been used to compare deacidified paper specimens with untreated specimens exposed to the same conditions of accelerated aging (Buchanan et al 1994;Liénardy 1994;Banik 2004Banik , 2005Banik et al 2006;Hanus et al 2008;Ramin et al 2009;Katuscak 2006Katuscak , 2012Ahn et al 2013;Potthast and Ahn 2017). As will be detailed later in this article, relative to the other tested methods of wholebook deacidification, the non-aqueous dispersion treatment often have been found to be among the least effective.…”

“…By contrast, other available treatments achieved factors of 4. Potthast et al 2017 * Efficacy factors included in the table generally compare the time of accelerated aging needed to reduce paper strength or DP of deacidified paper to a critical level; the base case consists of specimens from the same source but without the deacidification. Strength criteria (or DP), as well as other details, differ from study to study.…”

“…In addition, one of the key elements of the new standard is its reliance on evaluation of changes in the degree of polymerization of paper specimens exposed to accelerated aging. Potthast and Ahn (2017) used such an approach when conducting parallel evaluations of two kinds of deacidification treatments -non-aqueous dispersion and solution-based treatments. The tests were carried out with typical acidic paper from selected books.…”

“…If one refers back to Table 2, although the non-aqueous dispersion system was successful in some of the evaluations in extending the projected useful life of treated acidic paper (Buchanan et al 1994;Hanus et al 2008;Ramin et al 2009;Banik 2005;Banik et al 2006;Katuscak et al 2010Katuscak et al , 2012Ahn 2013), not all such tests met the Library of Congress requirement of achieving an efficacy factor of at least 3 (Buchanan et al 1994;Vrska et al 2004;Ramin et al 2009;Potthast and Ahn 2017). Based on some recent tests, the non-aqueous dispersion systems were judged to be less effective than several different deacidification programs that were considered (Katuscak et al 2010(Katuscak et al , 2012.…”