The kinetics of the spontaneous, proton- and Al^III-catalysed hydrolysis of 1,5-anhydrocellobiitol — Models for cellulose depolymerization in paper aging and alkaline pulping, and a benchmark for cellulase efficiency

Abstract

The kinetics of the spontaneous, proton- and AlIII-catalysed hydrolyses of the C1—O4′ bond in 1,5-anhydrocellobiitol have been measured at elevated temperatures (125.0–220.0 °C). Data for the first two processes extrapolate to the expression k = (8.6 ± 2.1 × 10–16) + (1.4 ± 0.2 × 10–9-pH) s–1 at 25 °C. These room-temperature figures were used to model cellulose depolymerization by the af Ekenstam equation. The spontaneous process is too slow to contribute to loss of paper strength on aging, and even the acid-catalysed process is significant only below ~pH 4.0. However, the spontaneous hydrolysis readily accounts for the reduction of cellulose degree of polymerization (DP) during alkaline (e.g., kraft) pulping of cellulose fibres. Efficient electrophilic catalysis by AlIII was observed at 150.0 °C in 0.1 mol/L succinate buffers of room temperature pH 3.05 and 3.35 (k2 = 8.1 ± 0.4 × 10–3 and 4.2 ± 0.2 × 10–3 (mol/L) –1 s–1, respectively). The apparent activation energy of the AlIII-catalysed process was 31 ± 4 kJ mol-1, lower than that of the proton-catalysed path, suggesting the electrophilic catalysis increases in importance as the temperature approaches ambient. Consequently, it appears that the culprit in the impermanence of “rosin-alum” -sized paper is AlIII, directly acting as a Lewis acid, not the AlIII hydration sphere as a Brønsted acid. Conservation measures should either address this or be generic (e.g., low-temperature storage). Key words: cellulose, hydrolysis, kraft pulping, paper conservation, rosin-alum sizing.

Deacidification for the conservation and preservation of paper-based works: A review

“…Aluminum sulfate, often called "papermaker's alum," can be considered a major source of both Brønsted and Lewis acidity in many of the books and documents that are of greatest concern. The role of aluminum sulfate in papermaking, as well as its increased use after 1807 in combination with rosin for the hydrophobic sizing of paper has been previously reviewed (Wilson and Parks 1979;Barrett 1989;Gurnagul et al 1993;El-Saied et al 1998;Baty and Sinnott 2005). We elaborate on its peculiar role in paper degradation below.…”

“…uncatalyzed process, and suggested that this degradation may be relevant to paper-based heritage collections in some cases. Baty and Sinnott (2005) greatly expanded that study using an improved model compound that effectively modeled cellulose around the glycosidic linkage for steric and inductive effects and concluded that, while the mechanism should be highly significant to alkaline pulping, the uncatalyzed process is too slow at ambient (library) conditions to do significant damage. Therefore, cellulose hydrolysis must be practically expected to procede by a catalytic mechanism in paperbased heritage collections.…”

“…The goal of the present article is first to highlight a highly significant and vexing mode of paper's degradation, the proton-or Brønsted-acid-catalyzed hydrolysis of cellulose (Baty and Sinnott 2005)-and the effort to stop it-called deacidification (Smith 1970(Smith , 1987(Smith , 1988Williams 1971;Mihram 1986;Sun 1988;Lienardy and van Damme 1990;Sparks 1990;Barbe 1991;Zimmermann 1991;Carter 1996a,b;Daniels 1996;Porck 1996;Zappalà 1997;Bluher and Vogelsanger 2001;Zervos and Moropoulou 2006). Our intent is to be rigorous both in terms of the mechanistic chemistry of paper degradation, which the various deacidification procedures are designed to prevent, and also to be rigorous in placing the deacidification procedures in the teleological and historical context of conservation.…”

Deacidification of Papers with Hexamethylenetetramine (HMT) in Alcohols and Supercritical Carbon Dioxide

“…1.2.2 SCCO 2 treatment The scheme of the experimental device used for SCCO 2 treatment was described in our previous paper (Baty and Sinnott, 2005). Before deacidification, rolled paper samples (about 20 g) were cleaned by SCCO 2 at 35°C under 18-22 MPa for 30 min in order to remove some possible impurities such as dust, microbial metabolites, additives and paper degradation products.…”

Long-Time Data Storage: Relevant Time Scales

“…CDs, even when kept in a safe environment do not last much longer. Special paper may survive 1,000 years, see for example, [3]. Script carved in stone may survive a very long time, maybe one million years if it is protected from erosion.…”