LIGNIN AND POLYURETHANE EXTRACTION FROM BLACK LIQUORS
Conversion of black liquors from the kraft process of a Eucalyptus pulp and paper mill factory into pure lignin. Then pure lignin will be used as sustainable raw-material for green processes able to generate promising added-value compounds products such as fibre precursors.
First, the liquid stream generated from the kraft process, known as black liquor, will be thoroughly characterized using specific and tailored analytical methodologies.
Second, the extraction of lignin from the black liquor will be realized by means of acidification. Reducing the pH of the initial black liquor, it is then possible to proceed with the filtration of particles of lignin which will form, by means of membrane filtration or ultrafiltration. Two procedures can be used for reducing the pH around to 9, LignoBoost process (acidification takes place, enhanced by means of CO2 presence); and LignoForce process, where the black liquor is first oxidized (O2), and then acidified (CO2).
Finally, the lignin obtained from black liquor by acidification, filtration and vacuum drying will be trialled to produce polyurethanes (PUs). Later on, PUs can be used for molecular weight upgrade of the lignins, or for forming blends to be trialled in the spinning process.
TAILORING OF LIGNIN AND PRECURSOR BLENDS
The main goal is to up-scale and validate a standardized methodology to produce electrospun fibres from kraft lignin from optimized and tailor-made solution blends of lignin. Blends for low-cost polymeric, ceramic or metal precursors will be prepared for 3 main routes for their processing into fibres:
- E-spinning, using lab-scale equipment and pilot-scale equipment. After suitable thermostabilization and carbonization steps, the technology will be used for producing electrospun hollow Carbon Fibres, as well as non-wovens, films/layers (deposited, coated or coupled), webs, and also continuous fibres. The use of electrospinning can help to develop effective methods for fabricating stretchable conducting films.
- Wet (coagulation) spinning lab-scale equipment, plus dry-jet wet spinning (lab-scale).
- Melt-spinning, using lab-scale equipment, and pilot-scale equipment. Different approaches will be used to transform kraft lignin into thermoplastic form, thus allowing the melt-processing.
CARBONIZATION OF LIGNIN BLENDS
Correlations between fundamental properties of lignin blends with the spinnability of the fibres will be identified and fully understood, as well as correlations between characteristics of lignin blends (derived from the adding of other precursors), and the conversion to carbonized fibres. Two-route carbonization: oven/furnace thermal treatment and plasma and microwave assisted carbonization.
The lab-scale optimization in blending creation, thermal stabilization and carbonization will help the selection of appropriate chemical and thermal conditions for obtaining tailor-made high-quality carbonized lignin fibres for several applications. The fibres will be subsequently fabricated in fibrous mats and non-wovens to be technically validated for final applications.
PRODUCTION OF BIOBASED PRODUCTS
To obtain at lab scale composite parts with better mechanical and electrical properties based on the incorporation of carbon fibre mats into Structural applications, Non-structural applications and Multifunctional applications.
- Production and quality tests of stretchable electronic films
Stretchable electronics concerns electrical and electronic circuits and combinations of these that are elastically or inelastically stretchable by more than a few percent while retaining function. Stretchable electronics prototypes will be fabricated in the form of electrically conductive hybrid polymer films and their quality will be assed.
- Activated carbon production from non-woven lignin felt
The study will focus on the two main stages in the production of activated carbon from fibrous precursors: stabilization of lignin fibres and chemical activation of the precursor in inert atmosphere. Initially, a chamber furnace will be used for performing the thermal treatments in a batch approach.
Different final applications of the electronic devices can be selected. Within the project, real prototypes will be manufactured to demonstrate in real applications the viability of the pilot line proposed.
LIFE CYCLE ANALYSIS (LCA) AND LIFE CYCLE COST (LCC)
The environmental feasibility of the studied biobased products from a life cycle perspective, through a LCA is included within EUCALIVA.
The LCA analysis will be performed by means of the Sima Pro software (or OpenLCA) and the use of the available databases (Ecoinvent, ELCD…).
The impacts assessed will be compared to the impacts associated to the conventional processes of production of the analysed bio-products. When possible, such comparison will be made with the conventional processes already estimated in the databases (polyethylene terephthalate, polyester resin, etc.).
Parallely to LCA, LCC will be used in order to evaluate all costs associated with the life cycle of the biobased products that are directly covered by any or more of the actors in the products life cycle.