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Search: authors:"Antje Potthast"

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

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 ...

A cautionary note on thermal runaway reactions in mixtures of 1-alkyl-3-methylimidazolium ionic liquids and N-methylmorpholine-N-oxide

N-Methylmorpholine-N-oxide (NMMO) cannot be completely separated by extraction from mixtures with common 1,3-dialkylimidazolium ionic liquids (ILs) due to strong ionic interactions between the two components. At elevated temperatures, above approx. 90 °C, especially under dry conditions and in the presence of acid, alkylating or acylating agents, remaining NMMO in ILs tends to ...

Chromophores from hexeneuronic acids: identification of HexA-derived chromophores

Hexeneuronic acids (HexA) have long been known as triggers for discoloration processes in glucuronoxylan-containing cellulosic pulps. They are formed under the conditions of pulping from 4-O-methylglucuronic acid residues, and are removed in an “A stage” along the bleaching sequences, which mainly comprises acidic washing treatments. The chemical structures of HexA-derived ...

Drying of a cellulose II gel: effect of physical modification and redispersibility in water

The agglomeration of cellulosic materials upon drying, often called hornification, causes a reduction of water retention, among other undesired effects. It is one of the main issues in industrial cellulose processing, especially with regard to nanocelluloses. As a consequence, high transportation and storage costs arise since nanocelluloses need to remain in aqueous suspensions ...

Surface properties and porosity of highly porous, nanostructured cellulose II particles

Recently, a new member of the nanocellulose family was introduced, a cellulose II gel consisting of nanostructured and spherical particles. In this study, we compared two different drying techniques to obtain highly porous powders from this gel with preserved meso- and macroporous nanostructure: first, freeze-drying after solvent exchange to tBuOH and second, supercritical drying ...