In the LigniOx project, industrially applicable oxidation and post-treatment concepts were developed for lignin by-products originating from variable industrial processes (kraft, organosolv, 2G bioethanol production) and feedstock (softwood, hardwood, wheat straw). In all cases, the oxidation conditions, post-treatment protocol and process concepts were optimized in order to obtain high-performing lignin derived concrete plasticizer, as well as techno-economically feasible and safe oxidation process. Based on the oxidation protocols developed, a pilot scale oxidation reactor was constructed, and the LigniOx oxidation and post-treatment were successfully scaled-up for all the lignins. The viability of the process concept was demonstrated in industrially relevant conditions with kraft lignin and industrial product prototypes were produced.
Performance of the produced LigniOx lignins was tested in mortar and concrete in comparison to commercial reference admixtures. LigniOx lignins show potential to compete with commercial fossil-based concrete admixtures, especially naphta or melamine condensates. Somewhat higher dosage was needed compared to the polycarboxylate ether (PCE) based reference tested in concrete. A blend of kraft or organosolv lignins with a commercial product met the requirements of a superplasticizer. Several other end-use possibilities for LigniOx lignins as versatile dispersants were investigated. All the LigniOx lignins showed good dispersion performance for special carbon black, and at significantly lower dispersant dosage provided an equal performance as the commercial polyacrylic acid and lignosulphonate-based reference products. LigniOx lignin was tested as a surfactant to enhance the enzymatic hydrolysability in bioethanol production, and also here, comparable yield improvement was shown as with a commercial reference surfactant. Furthermore, LigniOx lignins were tested for applications as gypsum plasticizer, anti-scaling agent, and flotation aid (depressant) with promising results.
Conceptual design was performed to aid the integration of industrial LigniOx processes at the biorefineries after the LigniOx IA. Techno-economic evaluation as well as environmental life cycle assessment (LCA) and socio-economic impacts were assessed for the studied value chains in comparison with a benchmark superplasticizer product. The LCA study clearly demonstrated that integrating the LigniOx production to an existing pulp mill or a biorefinery gives significant environmental benefits compared to a fossil-based reference product or a stand-alone production facility, but even the stand-alone cases exhibited good overall performance. For kraft lignin, a techno-economically feasible process concept that can be integrated into the kraft pulp mill could even provide benefits compared to the current lignin isolation processes and was patented. Regulatory issues were considered to ensure that the safety, quality, and purity of the new products are in line with EU legislation. LigniOx products do not need REACH registration in EU nor are they considered as microplastics due to their high solubility. Biodegrability of the studied LigniOx products was better than that for the starting materials. For application testing, safety data sheets (SDS) and CAS numbers were applied and approved for LigniOx materials.
