Effectiveness of sulfonation to produce lignin-containing cellulose micro/nanofibrils (LCM/NF) by grinding

Currently, less energetic and more ecological methods as well as new raw materials are studied to produce cellulose micro/nanofibrils which are very attractive bio-based and renewable nanomaterials. In this context, the valorisation of Posidonia oceanica, a dominant sea grass on the Mediterranean Sea, is carried out by preparing cellulose micro/nanofibrils with high lignin content (LCM/NF). To evaluate the role of lignin sulfonation in facilitating the mechanical microfibrillation, an alkaline pretreatement using sodium sulfite (Na2SO3) was suggested. Thereafter, lignocellulosic micro/nanofibrils (LCM/NF) were produced (with and without lignin sulfonation) by combining steam explosion process or twin-screw extrusion as energy efficient pretreatments with a conventional grinding step. The chemical composition of the fibres, before and after pulping, was analysed. To select the most efficient combination of treatments, after the microfibrillation step, the obtained LCM/NF suspensions were characterized by several techniques such as morphological analysis. Tensile test was also performed on LCM/NF nanopapers. It has been shown that sulfonation, pulps with sulfonic group contents between 50 and 70 mu mol/g, coupled with steam explosion or twin-screw extrusion, allowed producing LCM/NF gels with relative low viscosity and nanopapers with Young's modulus around 5 GPa. Finally, it is worth noting that sulfonation is an efficient pretreatment for decreasing the consumed energy during grinding and the ensuing quality can be investigated in many applications such as packaging etc. [GRAPHICS] .

Automated summary

Currently, researchers are studying less energy-consuming and more environmentally friendly methods to produce cellulose micro/nanofibrils, which are highly attractive as bio-based and renewable nanomaterials. They have investigated the use of Posidonia oceanica, a dominant sea grass in the Mediterranean Sea, to produce cellulose micro/nanofibrils with high lignin content. The study found that sulfonation pretreatment, combined with steam explosion or twin-screw extrusion, can facilitate the mechanical microfibrillation and result in cellulose micro/nanofibril gels with low viscosity and nanopapers with high Young's modulus.