Dissertation/Thesis Abstract

Hot-water pre-extraction of hardwoods: Impact of processing on extract and pulp properties
by Duarte, Gustavo, Ph.D., State University of New York College of Environmental Science and Forestry, 2010, 179; 3449178
Abstract (Summary)

The aim of this work is to further evaluate the viability of the integrated biorefinery concept. On one side the properties of hot-water extracts are studied, in order to develop a purification method that allows for further processing of the extracts. It was found that poly-DADMAC is an effective flocculant for the extracts, removing the majority of suspended particles while maintaining the sugar levels high, improving subsequent purification techniques such as filtration. The optimum pH for the effectiveness of the polymer was found to be around 4.5. The use of an inert anchoring agent, Kaolin, drastically improves the efficiency of the flocculant, reducing the treatment time in more than an order of magnitude, while the presence of indifferent electrolytes hinders its efficiency. This pre-treatment allowed for the destabilization of the colloidal suspension, lowering the turbidity from values of the order of 1200 NTU to 4 NTU over a 24-hour period.

On the other side, the effect that extraction has on fiber properties and consequent paper properties is studied and models are developed to predict and better understand them. For that two hardwood species (Acer saccharum and Eucalyptus globulus) were extracted and consequently pulped. Generally the two different species behaved differently, but in both cases it was found that extracted chips are much easier to pulp (smaller H-factors required to reach the same kappa) than non-extracted. The hemicellulose content in the pulps drops drastically from 20–22% to approximately 5%. This difference will affect all other pulp properties. In fact, with the exception of viscosity, the majority of pulp and paper properties are hindered by the hot-water pre-extraction, which also reflects in a lower total yield. The viscosity initially increases significantly, but for longer extraction periods the gain is not very significant. For eucalyptus there is also no significant gain (in hemicellulose removal) in extracting more than 90 min.

The models developed have very high correlation factors and they not only help explaining which parameters affect the different properties the most, but also provide some foresight into the fibers and laboratory handsheets properties.

Indexing (document details)
Advisor: Ramarao, Bandaru V.
Commitee: Amidon, Thomas E., Bujanovic, Biljana, Ferreira, Paulo J., Francis, Raymond, Vonhof, Sarah
School: State University of New York College of Environmental Science and Forestry
Department: Environmental & Resources Engineering
School Location: United States -- New York
Source: DAI-B 72/06, Dissertation Abstracts International
Subjects: Chemical engineering
Keywords: Extracts, Fiber properties, Hardwoods, Hot-water extraction, Kraft pulp properties, Purification
Publication Number: 3449178
ISBN: 9781124556970