The goal is description of mechanisms for extraction/separation of welldefined higher value material components by the use of chemical, enzymatic and thermomechanical methods. Activities include qualified structural characterization and development of a platform of advanced experimental and modeling methods.
In order to develop novel processes for fractionation of wood polymers, focus is on knowledge that will enable us to substantially increase the yield and the precision in the wood fractionation process. Areas of particular interest are: morphology and chemical composition changes in wood during different treatments, the search for new specific enzymatic systems for breaking LCC-structures (lignin-carbohydrate complexes) and, finally, utilization of the unique properties of the dissolved polymers and nano-/microparticles in new methods for efficient downstream fractionation.
The long-term viability of the forest industry relies on increased process material efficiency by the development of new process technologies. In the long-term perspective, there may be a shift from the present paradigm with cellulose fibres as the main product (material efficiency 35-55%). New material biorefinery processes may instead have material efficiency of at least 75%. The challenge will be to develop processing schemes that allow separation and fractionation of wood components in the form of well-defined wood polymers. The processing steps need to be mild enough to largely preserve the native wood polymer structure. In addition, the LCC complexes, which link lignin and hemicelluloses need to be disintegrated.
Due to the complexity of the wood cell wall, it is a great challenge to design an economical viable process, which provides high material efficiency for all major biopolymers. A detailed understanding of structure and chemistry of the wood material is required, including the changes taking place during processing.
In the first phase of the WWSC program we explored different chemical, enzymatic and thermomechanical processing steps, and also placed individual process steps into different process configurations. A technical achievement is the development of a novel energy-efficient nanopulping method (patent pending) to produce nanocellulose from chemical pulp. Furthermore, a novel cross-flow ultra-filtration method has been developed to separate nanofibril fractions of different sizes. Furthermore, we have developed a mild steam explosion operation, which allows an energy efficient pretreatment/first separation of biopolymers. Finally, we have shown that specific enzymes can be an integrated part of a processing scheme so that a more material efficient extraction of the wood polymers is achieved.
At the end of the first part of WWSC we designed a demonstrator process, which was tested in laboratory scale. The results were encouraging and showed that it is possible to separate the different biopolymers with increased efficiency and with only limited degradation of the wood polymers. We have identified the need for deeper understanding of the chemical, physical and structural changes during processing in order to design a process with high material efficiency.
The possible LCC structures in the wood cell wall have been addressed, and the possibility to enzymatically degrade such structures. This increased our understanding of LCC structures and enzymes that can act on different parts of LCC structures were identified. We have also found an explanation to why MFC (and similar materials) is difficult to dewater and also demonstrated some ways to avoid this problem. Moreover, there are also a number of promising on-going scientific studies related to
7 enzyme discovery, structural changes of wood tissue (chemical composition and physical structure) and protection of the hemicelluloses. These changes occur when the wood material is treated during different chemical, enzymatic and thermomechanical processing steps.
The proposed Project 1 has been designed to address more fundamental questions related to the mechanisms behind the different processing steps. The two major process parts are i) Up-stream processing aimed at decomposing the wood into wood polymers using chemical, enzymatic and thermomechanical processing steps and ii) Down-stream processing aimed at separating wood polymers and dewater “hard-tofilter “ materials, e.g MFC.
In addition to activities already mentioned, the solubility and mobility of large molecules in wood tissue will be addressed. In the second part (downstream separation) we will also focus on how different properties of molecules and particles can be utilized to achieve efficient separation, fractionation and dewatering